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Lithium‐ion batteries (LIBs) with ternary oxide cathode materials are the prevalent energy storage devices for electric vehicles, and the huge amounts of spent LIBs pose severe challenges in terms of environmental impact and resource management. Particularly, the proper handling of degraded cathode materials is of central importance for the sustainable and closed‐loop development of LIBs industry. In this context, direct regeneration of degraded ternary oxides toward reusable high‐performance cathode materials is environmentally and economically favorable in contrast to present metallurgical recycling methods. In this work, a simple and effective two‐step method is demonstrated to regenerate the degraded NCM 622 (LiNi0.6Co0.2Mn0.2O2) materials by elemental compensation and structural restoration. Moreover, a multi‐functional LTO (Li4Ti5O12) surface coating is simultaneously designed to guarantee rapid Li+ diffusion and stable surface of the regenerated product. Therefore, the regenerated LTO‐coated NCM materials show excellent electrochemical performance; specifically, the initial discharge capacity (183.0 mAh g−1 at 0.1 C), rate capability (90.0 mAh g−1 at 10 C), and cycling stability (79.3% capacity retention after 200 cycles) are even comparable with those of fresh materials. The as‐established upcycling strategy may shed light on the value‐added recycling of degraded cathode materials and thereby a virtuous cycle of LIBs. [ABSTRACT FROM AUTHOR]

The photo‐assisted strategy is regarded as a crucial approach to enhance the conversion kinetics of polysulfides in lithium–sulfur (Li–S) batteries. However, the development of photo‐assisted Li–S batteries still faces important challenges, such as the rapid recombination of photogenerated electron−holes on cathode and more severe shuttle effect. Herein, a breakthrough in overcoming the challenges has been made by constructing a promising photo‐assisted Li−S battery based on semiconducted metal−organic frameworks. During the discharging progress, the photoexcited electrons generated by H2BPDC ligand based on ligand‐to‐metal charge transfer (LMCT) effect, are injected into the Ti‐oxo clusters in Ti‐MOF, thereby facilitating the sulfur reduction to Li2S. And photoexcited holes are capable of promoting the decomposition kinetics of Li2S during charging. More importantly, the stronger chemical interaction between Ti‐BPDC‐d and polysulfides under light inhibits the polysulfides dissolution and shuttling, which fundamentally addresses the issue of light‐accelerated shuttling. As a result, the photo‐assisted Li–S batteries deliver a reversible capability of 1090.21 mAh g−1 at 0.2 C with a capacity retention of 82.91% over 150 cycles, and a superior rate capability of 673.58 mAh g−1 at 5 C. The findings are promising in advancing the design principles for photo‐rechargeable Li−S batteries. [ABSTRACT FROM AUTHOR]

Highlights: Optimization strategies for high-performance Na3V2(PO4)3 (NVP) cathode material are well summarized and discussed, including carbon coating or modification, foreign-ion doping or substitution and nanostructure and morphology design. The foreign-ion doping or substitution is highlighted, involving the Na, V, and PO43− sites, which include single-site doping, multiple-site doping, single-ion doping and multiple-ion doping. Challenges and future perspectives for high-performance NVP cathode material are presented. Na3V2(PO4)3 (NVP) has garnered great attentions as a prospective cathode material for sodium-ion batteries (SIBs) by virtue of its decent theoretical capacity, superior ion conductivity and high structural stability. However, the inherently poor electronic conductivity and sluggish sodium-ion diffusion kinetics of NVP material give rise to inferior rate performance and unsatisfactory energy density, which strictly confine its further application in SIBs. Thus, it is of significance to boost the sodium storage performance of NVP cathode material. Up to now, many methods have been developed to optimize the electrochemical performance of NVP cathode material. In this review, the latest advances in optimization strategies for improving the electrochemical performance of NVP cathode material are well summarized and discussed, including carbon coating or modification, foreign-ion doping or substitution and nanostructure and morphology design. The foreign-ion doping or substitution is highlighted, involving Na, V, and PO43− sites, which include single-site doping, multiple-site doping, single-ion doping, multiple-ion doping and so on. Furthermore, the challenges and prospects of high-performance NVP cathode material are also put forward. It is believed that this review can provide a useful reference for designing and developing high-performance NVP cathode material toward the large-scale application in SIBs. [ABSTRACT FROM AUTHOR]

Rechargeable aluminum ion batteries (AIBs) have recently gained widespread research concern as energy storage technologies because of their advantages of being safe, economical, environmentally friendly, sustainable, and displaying high performance. Nevertheless, the intense Coulombic interactions between the Al3+ ions with high charge density and the lattice of the electrode body lead to poor cathode kinetics and limited cycle life in AIBs. This paper reviews the recent advances in the cathode design of AIBs to gain a comprehensive understanding of the opportunities and challenges presented by current AIBs. In addition, the advantages, limitations, and possible solutions of each cathode material are discussed. Finally, the future development prospect of the cathode materials is presented. [ABSTRACT FROM AUTHOR]

Iron oxychloride (FeOCl) with a layered structure may be a potential cathode material for rechargeable sodium ion batteries, due to its large interlayer spacing and high theoretical capacity. Here, the FeOCl material is employed as the cathode material for sodium ion batteries for the first time. Its morphology, electrochemical sodium storage performance, and reaction mechanisms are systematically investigated. The as-prepared FeOCl cathode exhibits a high discharge capacity of 321 mAh g−1 in the voltage range of 1.4–4.0 V (vs. Na/Na+) at 10 mA g−1 during the first cycle; however, the discharge capacity fades to 69 mAh g−1 after 30 cycles due to the large volume change of FeOCl and phase separation during cycling. The intercalation and conversion reaction mechanism of FeOCl during reversible sodium ion storage is demonstrated by the results of energy-dispersive spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. [ABSTRACT FROM AUTHOR]

The residual impurities (including conductive carbon and PVDF) in S-LFP play a positive role in promoting the regeneration of S-LFP, which results in much improved lithium storage performance for the regenerated LFP. [Display omitted] • The failure of S-LFP comes from great loss of Li+ and conversion of LiFePO 4 to FePO 4. • A novel regeneration strategy was proposed to repair S-LFP by the aid of inherent impurities. • Residual conductive carbon and PVDF promote the regeneration of S-LFP by different mechanisms. • The structure and composition of DR-LFP achieve great recovery when compared to S-LFP. • Addition of extra glucose during regeneration boosts further performance improvement. The direct regeneration method, recognized for its cost-effectiveness, has garnered considerable attentions in the field of battery recycling. In this study, a novel direct regeneration strategy is proposed to repair spent LiFePO 4 (S-LFP) cathodes without the need for impurity removal. Instead, the residual conductive carbon and polyvinylidene fluoride (PVDF) in S-LFP are employed as inherent reductive agents. Systematic characterization and analysis reveal that the failure of S-LFP primarily originates from a substantial loss of Li+ and the conversion of LiFePO 4 to FePO 4. Meanwhile, it is demonstrated that both residual conductive carbon and PVDF play positive roles in promoting the regeneration of S-LFP through distinct mechanisms. As a result, the regenerated LFP exhibits significant recovery in crystal structure and chemical composition as compared to S-LFP, which leads to notably improved lithium storage performance. Furthermore, to further enhance the lithium storage property, a specific amount of glucose (10 %) is introduced during the regeneration of S-LFP, yielding a regenerated product that performs comparably to commercial LFP. Clearly, our approach, in contrast to traditional regeneration methods, maximizes the utilization of residual impurities within S-LFP, resulting in effective regeneration of S-LFP, thereby proving both informative and cost-effective. [ABSTRACT FROM AUTHOR]

The Na 3 V 2 (PO 4) 3 surface was innovatively modified with negative temperature coefficient (NTC) thermosensitive Pr 6 O 11 material, to enhance interface compatibility with electrolytes and improve conductivity, and finally significantly improve the sodium battery performance. [Display omitted] • Through the optimization of Pr 6 O 11 surface modification and electrode fabrication, the electrochemical performance of NVP was significantly improved, the side reactions were reduced, and the interface compatibility and high temperature stability were enhanced. • The effective strategy clearly reveals the mechanism by which the addition of Pr 6 O 11 improves the interface compatibility and sodium storage performance. • Cycle test at 8C current density, the capacity retention rates of NVP-2 %Pr 6 O 11 electrode after 1000 cycles at 27 °C and 45 °C were 81.18 % and 78.97 %, respectively, which were significantly higher than 20.59 % and 14.99 % of pure NVP. Na 3 V 2 (PO 4) 3 (NVP) is one of the most promising cathode materials for sodium-ion batteries (SIBs) due to its robust three-dimensional framework, high tunability, and relatively high Na+ intercalation potentials. However, its utility is generally constrained by low conductivity, inefficient charge transfer, and subpar interface kinetics. This work presents an efficient and simple method to address these issues. We innovatively modified the NVP surface with Pr 6 O 11 nanoparticles, a negative temperature coefficient (NTC) thermosensitive material, to enhance interface compatibility with electrolytes and improve conductivity. This modification significantly enhances the overall sodium-ion storage performance. Specifically, the optimized NVP-2 %Pr 6 O 11 electrode exhibits excellent electrochemical properties with the aid of an optimized conductivity network compared to the unmodified NVP. Cycled at an 8C current density, the NVP-2 %Pr 6 O 11 electrode achieves high specific capacities of 102.6 mAh·g−1 at 27 °C and 95.6 mAh·g−1 at 45 °C. After 1000 cycles, the capacity retention rates are 81.18 % and 78.97 %, respectively, significantly higher than the 20.59 % and 14.99 % of pure NVP. In coin full-battery testing, the NVP-2 %Pr 6 O 11 electrode retains 89.76 % capacity after 500 cycles at 8C. In addition, the assembled The NVP-2 %Pr 6 O 11 //HC pouch full battery exhibits better sodium-ion storage and thermal safety performance compared to the NVP-SP//HC battery. This simple modification strategy provides an effective insight into the application of NVP electrodes in energy storage. [ABSTRACT FROM AUTHOR]

Transition metal oxides (TMOs) are important anode materials in sodium-ion batteries (SIBs) due to their high theoretical capacities, abundant resources, and cost-effectiveness. However, issues such as the low conductivity and large volume variation of TMO bulk materials during the cycling process result in poor electrochemical performance. Nanosizing and compositing with carbon materials are two effective strategies to overcome these issues. In this study, spherical MnFe2O4@xC nanocomposites composed of MnFe2O4 inner cores and tunable carbon shell thicknesses were successfully prepared and utilized as anode materials for SIBs. It was found that the property of the carbon shell plays a crucial role in tuning the electrochemical performance of MnFe2O4@xC nanocomposites and an appropriate carbon shell thickness (content) leads to the optimal battery performance. Thus, compared to MnFe2O4@1C and MnFe2O4@8C, MnFe2O4@4C nanocomposite exhibits optimal electrochemical performance by releasing a reversible specific capacity of around 308 mAh·g−1 at 0.1 A·g−1 with 93% capacity retention after 100 cycles, 250 mAh·g−1 at 1.0 A g−1 with 73% capacity retention after 300 cycles in a half cell, and around 111 mAh·g−1 at 1.0 C when coupled with a Na3V2(PO4)3 (NVP) cathode in a full SIB cell. [ABSTRACT FROM AUTHOR]

To mitigate the greenhouse effect and environmental pollution caused by the consumption of fossil fuels, recent research has focused on developing renewable energy sources and new high-efficiency, environmentally friendly energy storage technologies. Among these, Li–CO2 batteries have shown great potential due to their high energy density, long discharge plateau, and environmental friendliness, offering a promising solution for achieving carbon neutrality while advancing energy storage devices. However, the slow kinetics of the CO2 reduction reaction and the accumulation of Li2CO3 discharge on the cathode surface lead to a significant reduction in space and active sites. This in turn results in high discharge overpotential, low energy efficiency, and low power density. This study elucidates the charge–discharge reaction mechanisms of lithium–carbon dioxide batteries and systematically analyzes their reaction products. It also summarizes the latest research advancements in cathode materials for these batteries. Furthermore, it proposes future directions and efforts for the development of Li–CO2 batteries. [ABSTRACT FROM AUTHOR]

Novel MnCo 2 O 4 -discs and MnCo 2 O 4 -rings were respectively prepared through a facile hydrothermal approach with a post annealing treatment. These MnCo 2 O 4 -discs exhibited battery-type electrochemical response with a high capacity of 296.1C/g at 1 A/g in 2 M of KOH electrolyte. The assembled MnCo 2 O 4 -discs//AC asymmetric supercapacitor delivered a high energy density of 35.8 W h kg−1 at the power density of 927.5 W kg−1. [Display omitted] • Novel MnCo 2 O 4 -discs were hydrothermally prepared with a post annealing treatment. • A high specific capacity of 296.1C/g at 1 A/g was delivered. • Just a little capacity decay over 5000 cycles at a high current density of 6 A/g. • The ASC device delivered an energy density of 35.8 W h kg−1 at 927.5 W kg−1. Herein, porous MnCo 2 O 4 with disc-like (MnCo 2 O 4 -discs) and ring-like (MnCo 2 O 4 -rings) microstructures were respectively synthesized using an initial hydrothermal method at different temperatures and a calcination treatment in air. The electrochemical properties of these MnCo 2 O 4 materials were investigated in three-electrode and two-electrode systems, and as such, MnCo 2 O 4 presented a battery-like electrochemical response. The specific capacity of MnCo 2 O 4 -discs was determined to be 296.1C/g at 1 A/g, superior to 246.3C/g for MnCo 2 O 4 -rings. An asymmetric supercapacitor (ASC) was assembled with MnCo 2 O 4 as the cathode and activated carbon (AC) as the anode to evaluate the potential for practical application. The MnCo 2 O 4 -discs//AC ASC exhibited an energy density (E d) of 35.8 W h kg−1 at a power density (P d) of 927.5 W kg−1. For the MnCo 2 O 4 -rings//AC ASC, an inferior E d of 31.4 W h kg−1 under 890.9 W kg−1 was achieved. Furthermore, the two ASCs presented outstanding cyclic performance after 5000 cycles at 6 A/g. The exceptional properties of MnCo 2 O 4 microstructures can be applied to the assembly of ASC devices, which can have promising potential for application in electrochemical energy storage. This synthetic method is straightforward, cost-effective, and can be extended to fabricate similar electrode materials with superior electrochemical performance. [ABSTRACT FROM AUTHOR]

Among the challenges related to rechargeable magnesium batteries (RMBs) still not resolved are positive electrode materials with sufficient charge storage and rate capability as well as stability and raw material resources. Out of the materials proposed and studied so far, vanadium oxides stand out for these requirements, but significant further improvements are expected and required. They will be based on new materials and an improved understanding of their mode of operation. This report provides a critical review focused on this material, which is embedded in a brief overview on the general subject. It starts with the main strategic ways to design layered vanadium oxides cathodes for RMBs. Taking these examples in more detail, the typical issues and challenges often missed in broader overviews and reviews are discussed. In particular, issues related to the electrochemistry of intercalation processes in layered vanadium oxides; advantageous strategies for the development of vanadium oxide composite cathodes; their mechanism in aqueous, "wet", and dry non-aqueous aprotic systems; and the possibility of co-intercalation processes involving protons and magnesium ions are considered. The perspectives for future development of vanadium oxide-based cathode materials are finally discussed and summarized. [ABSTRACT FROM AUTHOR]

Layered perovskite related oxides, LnBaCo2O5+δ (Ln = rare‐earth element) are potential ceramic cathodes for intermediate temperature solid oxide fuel cells. Herein, a simple way to tune the performance of NdBaCo2O5+δ (NBC) perovskite as a cathode by doping the Co‐site with bismuth cation is reported. Compared with the parent oxide, the obtained stabilized double perovskites NdBaCo2−xBixO5+δ (x = 0.1 and 0.2) show a much improved electrocatalytic activity, achieving area‐specific resistance of 0.268, 0.107 and 0.152 Ω cm2 at 700 °C in air for NBC, x = 0.1, and 0.2, respectively. Density functional theory results demonstrate that bismuth doping effectively reduces the formation energy of oxygen vacancies. Moreover, the bismuth doping of NdBaCo2−xBixO5+δ cathode is much more robust against CO2 than that of NBC cathode. This work indicates that bismuth doping in the B‐site of LnBaCo2O5+δ may be a highly attractive strategy for the future development of cathode materials. [ABSTRACT FROM AUTHOR]

Li-excess cathode materials with a disordered rock-salt structure (DRX) Li1.2Ti0.4Mn0.4O2 and Li1.3Nb0.3Mn0.4O2 were prepared by mechanochemically assisted solid-state synthesis at various synthesis conditions using different lithium sources (Li2O and LiOH). As-prepared samples were characterized by X-ray powder diffraction (XRD), thermal analysis in combination with mass spectrometry (DSC/TG/MS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), electron paramagnetic resonance spectroscopy (EPR), in situ time-resolved synchrotron powder X-ray diffraction (SPXRD) and galvanostatic cycling. The effects of different lithium sources and synthesis temperature on the crystal and local structure and the impact of additional thermal treatment (re-heating) on electrochemical performance of the DRX oxides were investigated. The results obtained show that the optimal synthesis temperature is 950 °C and the use of LiOH as a lithium source leads to the synthesis of the DRX oxides with a fully disordered structure, which is stable when re-heated at a temperature of 600 °C. In addition, re-heating leads to further optimization of the properties of the DRX oxides; this results in a significant improvement of their electrochemical properties. [ABSTRACT FROM AUTHOR]

Zinc-ion capacitors (ZICs), combining the merits of both high-energy zinc-ion batteries and high-power supercapacitors, are known as high-potential electrochemical energy storage (EES) devices. However, the research on ZICs still faces many challenges because of the lack of appropriate cathode materials with robust crystal structures and rich channels for stable and fast Zn2+ ion transport. In this study, we synthesized a robust, conductive, two-dimensional metal–organic framework (MOF) material, zinc-benzenehexathiolate (Zn-BHT), and investigated its electrochemical performance for zinc storage. Zn2+ ions could insert into/extricate from the host structure with a high diffusion rate, enabling the Zn-BHT cathode to exhibit a surface-controlled charge storage mechanism. Due to its unique structure, Zn-BHT exhibited a good reversible discharge capacity approaching 90.4 mAh g−1 at 0.1 A g−1, as well as a desirable rate capability and good cycling performance. In addition, a ZIC device was fabricated using the Zn-BHT cathode and a polyaniline-derived porous carbon (PC) anode, which depicted a high working voltage of up to 1.8 V and a high energy density of ~37.2 Wh kg−1. This work shows that conductive MOFs are high-potential electrode materials for ZICs and provide new enlightenment for the development of electrode materials for EES devices. [ABSTRACT FROM AUTHOR]

Layered transition metal oxides are highly promising host materials for K ions, owing to their high theoretical capacities and appropriate operational potentials. To address the intrinsic issues of KxMnO2 cathodes and optimize their electrochemical properties, a novel P3‐type oxide doped with carefully chosen cost‐effective, electrochemically active and multi‐functional elements is proposed, namely K0.57Cu0.1Fe0.1Mn0.8O2. Compared to the pristine K0.56MnO2, its reversible specific is increased from 104 to 135 mAh g−1. In addition, the Cu and Fe co‐doping triples the capacity under high current densities, and contributes to long‐term stability over 500 cycles with a capacity retention of 68 %. Such endeavor holds the potential to make potassium‐ion batteries particularly competitive for application in sustainable, low‐cost, and large‐scale energy storage devices. In addition, the cathode is also extended for sodium storage. Facilitated by the interlayer K ions that protect the layered structure from collapsing and expand the diffusion pathway for sodium ions, the cathode shows a high reversible capacity of 144 mAh g−1, fast kinetics and a long lifespan over 1000 cycles. The findings offer a novel pathway for the development of high‐performance and cost‐effective sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

The extensively studied Prussian blue analogs (PBAs) in various batteries are limited by their low discharge capacity, or subpar rate etc. which are solely reliant on the cation (de)intercalation mechanism. In contrast to the currently predominant focus on cations, we report the overlooked anion‐cation competition chemistry (Cl−, K+, Zn2+) stimulated by high‐voltage scanning. With our designed anion‐cation combinations, the KFeMnHCF cathode battery delivers comprehensively superior discharge performance, including voltage plateau >2.0 V (vs. Zn/Zn2+), capacity >150 mAh g−1, rate capability with capacity maintenance above 96 % from 0.6 to 5 A g−1, and cyclic stability exceeding 3000 cycles. We further verify that such comprehensive improvement of electrochemical performance utilizing anion‐cation competition chemistry is universal for different types of PBAs. Our work would pave a new and efficient road towards the next‐generation high‐performance PBAs cathode batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Na superionic conductor (NASICON)-structured Na 4 MnCr(PO 4) 3 (NMCP) possessing unique three-electron transfer process renders admirable energy density for sodium ion batteries (SIBs). However, the current issues like its sluggish Na+ diffusion kinetics, deficient intrinsic conductivity, and unsatisfactory structural stability, hinder its practical application. Herein, a selective replacement of O elements in PO 4 group by Cl anions in the NMCP system was developed to significantly enhance its electrochemical performance. The results affirm that the enhanced performance of Cl doped samples can be attributed to the enlargement of cell size, the creation of Na vacancies and the weakness of Na2 O bond after Cl doping. The as-prepared Na 3.85 □ 0.15 MnCr(PO 3.95 Cl 0.05) 3 /C (NMCPC − 15/C) cathode delivers a high capacity (128.0 mAh/g at 50 mA g−1) and excellent rate performance (73.0 mAh/g at 1000 mA g−1) in contrast to NMCP/C that merely provides 105.2 mAh/g at 50 mA g−1 and reduces to 47.4 mAh/g at 1000 mA g−1. Meanwhile, NMCPC − 15/C shows a capacity retention of 60.7 % at 1000 mA g−1 after 500 cycles, while only 37.1 % for NMCP/C in the same test conditions. Moreover, the satisfactory performance and energy density of NMCPC − 15/C||hard carbon (HC) full cell confirm the potential practicality of NMCPC − 15. Therefore, chloride ions doping into NMCP has practical application prospects in the preparation of high-performance cathode materials and our work also offers new inspiration to apply anion doping strategies in promoting the performance of the other NASICON-structured cathodes for SIBs. [ABSTRACT FROM AUTHOR]

Addressing challenges in oxygen reduction efficiency and CO 2 endurance is essential for advancing the electrochemical energy conversion performance of solid oxide fuel cells (SOFCs). This investigation introduces an innovative strategy by employing Ce doping to enhance the oxygen reduction kinetics and CO 2 resistance of NdBaCoFeO 5+ δ (NBCF) cathodes. Ce doping effectively regulates the oxygen vacancy content, the ratio of Co3+/Co4+ and Fe3+/Fe4+ in NBCF, leading to substantial improvements in oxygen exchange, lattice diffusion, and charge transfer processes. Consequently, a significant enhancement in the oxygen reduction reaction catalytic activity and CO 2 endurance is achieved. At 800 °C, the introduction of 10 mol% Ce doping results in a 65.3% reduction in Rp, reaching 0.024 Ω cm2. Simultaneously, the power density experiences a 50.8% enhancement, reaching 1.0 W cm−2. The current investigation presents a novel avenue towards the advancement of next-generation high-efficiency and stable cathode materials for SOFCs. [ABSTRACT FROM AUTHOR]

Nowadays, Al (dual) batteries are mainly based on graphite cathode materials. Besides this material, the limited life cycle and the rate performance of other possible cathode materials have hampered the development of practical and sustainable rechargeable aluminium batteries (RABs). Herein, we report an organic A4‐metal‐free porphyrin system bearing diphenylamimo‐phenyl functional units as an Al‐storage cathode material, which is capable of delivering a reversible capacity of 83 mAh g−1 at 1 A g−1 after 200 cycles and displays a good cycling stability. Achieving such high rate performance opens a pathway to developing practical sustainable cathodes for aluminium batteries. [ABSTRACT FROM AUTHOR]

Lithium iron phosphate (LiFePO4, LFP), an olivine–type cathode material, represents a highly suitable cathode option for lithium–ion batteries that is widely applied in electric vehicles and renewable energy storage systems. This work employed the ball milling technique to synthesize LiFePO4/carbon (LFP/C) composites and investigated the effects of various doping elements, including F, Mn, Nb, and Mg, on the electrochemical behavior of LFP/C composite cathodes. Our comprehensive work indicates that optimized F doping could improve the discharge capacity of the LFP/C composites at high rates, achieving 113.7 mAh g−1 at 10 C. Rational Nb doping boosted the cycling stability and improved the capacity retention rate (above 96.1% after 100 cycles at 0.2 C). The designed Mn doping escalated the discharge capacity of the LFP/C composite under a low temperature of −15 °C (101.2 mAh g−1 at 0.2 C). By optimizing the doping elements and levels, the role of doping as a modification method on the diverse properties of LFP/C cathode materials was effectively explored. [ABSTRACT FROM AUTHOR]

Fuel cells have substantial development potential for commercial energy generation applications. Adding an ionic conducting electrolyte to a cathode to make a composite cathode lowers the Thermal Expansion Coefficient (TEC), raises the Triple Phase Boundary (TPB) area, and enhances the electrochemical performance of Solid Oxide Fuel Cells (SOFCs). In this review, the article presents the basic principles, criteria, and composite cathode development of SOFCs that operate SOFCs in the intermediate temperature ranges (600–800 °C). These composite cathodes improve the inter-component compatibility, Oxygen Reduction Reaction (ORR), and characteristics of mixed electronic-ionic conductors. In comparison with a single-phase cathode, composite material can reduce Polarization Resistance (R p) by about 30–40% and improve maximum power density (MPD) by about 30–50%. PBCO-40SDC and SBCN-20SDC composites exhibit enhanced stability and maintain their electrochemical performance with polarization resistances of 0.008 Ω cm2 and 0.079 Ω cm2 when operating at temperature of 700 °C. • Recent methods in IT-SOFC composite cathode development were explored. • Properties of nine materials studied, including conductivity and stability. • PBCO-40SDC outperforms with low polarization resistance at 700 °C. • Noteworthy development: exsolution of catalytically active nanoparticles. • Comprehensive study on thermal, electrical, and catalytic properties. [ABSTRACT FROM AUTHOR]

The high overpotential caused by the slow kinetics of oxygen reduction (ORR) and oxygen evolution (OER) has greatly limited the practical application of lithium‐oxygen (Li−O2) batteries. The adoption of force‐field‐assisted system based on a newly developed piezocatalysis is promising in reducing the overpotential. Herein, a force‐assisted Li−O2 battery is first established by employing MoS2/Pd nanocomposite cathode, in which the piezoelectric polarization as well as built‐in electric field are formed in MoS2 piezoelectric catalyst under ultrasound activation, leading to the continuously separated electrons and holes to enhance the ORR and OER kinetics. Moreover, the introduction of Pd can promote the electrons transfer and further inhibit the complexation of electron–hole pairs, contributing to enhanced catalytic activity in the decomposition/generation of discharge products, resulting in reduced discharge/charge overpotentials. Thus, the force‐assisted MoS2/Pd‐based Li−O2 battery is capable of adjusting the output and input energies by the assisted ultrasonic wave. An ultra‐low charging platform of 2.86 V and a high discharging platform of 2.77 V are achieved. The proposed unique force‐assisted strategy can also be applied to lithium carbon dioxide battery system through the effective reduction and separation of CO2 and CO32−, providing significant insights in achieving efficient energy conversion for metal−air batteries. [ABSTRACT FROM AUTHOR]

Fig. 1 The framework of this review work. [Display omitted] • This review summarises the evolution and degradation mechanisms of LiFePO 4 cathode materials. • The main recycling techniques of LiFePO 4 cathode materials from laboratory scale to industrial production were discussed. • The challenges and opportunities of different recycling techniques were highlighted and perspectives of LiFePO 4 cathode recycling were proposed. Lithium iron phosphate (LiFePO 4) has emerged as one of the most popular cathodes due to its excellent properties of low cost, high safety and stability. However, owing to the limited lifespan caused by degradation, the widespread use of LiFePO 4 batteries would generate a large number of spent batteries, the improper disposal of which causes environmental pollution and waste of resources. Therefore, the recycling of these batteries is important for environmental protection, resource conservation and economic efficiency. This review summarises LiFePO 4 cathode materials from their development and degradation mechanisms, illustrating the reasons and necessity of their recycling. In addition, battery recycling technologies are systematically discussed from laboratory scale to industrial production in terms of efficiency, economic benefits and environmental impact. Finally, we identify the challenges of LiFePO 4 cathode recycling and offer some perspectives on these challenges. These endeavors demonstrate that the degradation of large-scale batteries drives the formation of recycling demand. Therefore, it is necessary to accurately assess the degradation mechanism which is a precondition of cathode recycling. Besides, the cathode recycling mechanism should be paid much attention, simplifying the recycling process. Moreover, it is essential to illustrate the impact of impurities and defects generated during the cycling. As such, this review provides valuable insights in innovating and boosting LiFePO 4 cathode recycling technologies on an industrial scale. [ABSTRACT FROM AUTHOR]

Developing triple-conducting cathode is an available way to enhancing the electrochemical performance of protonic ceramic fuel cells (PCFCs). Here we report a systematical investigation on the performance of cobalt-free perovskites Ba 0.5 Sr 0.5 Fe 1- x Zn x O 3-δ (x = 0, 0.1, and 0.2; BSF, BSFZ 0.1 , and BSFZ 0.2) as triple-conducting cathodes for PCFCs. Zn doping improves the hydration capacity, oxygen vacancy concentration, surface exchange coefficient, and bulk diffusion coefficient of BSFZ x (x = 0.1 and 0.2) as compared to the bare BSF. Theory calculations show that Zn doping benefits the oxygen vacancy formation, which is conducive to the promotion of cathodic oxygen reduction reaction (ORR). Among materials investigated, the BSFZ 0.2 perovskite possesses an abundance of oxygen vacancies, strong hydration capacity and exceptional triple conductivity (H+/O2−/e−), and thus showing the lowest polarization resistance (R p) of 0.328 Ω cm2 at 700 °C under wet air. At 700 °C, the cell reaches a maximum power density of 497 mW cm−2 in H 2 using BSFZ 0.2 -30 wt% BaZr 0.4 Ce 0.4 Y 0.15 Zn 0.05 O 3-δ (BZCYZ) composite cathode based on 25-μm-thick BZCYZ electrolyte, and there is no obvious deterioration in performance after operation for 100 h. The rate-limiting steps of ORR on BSFZ 0.2 -BZCYZ composite cathode are determined to be the surface oxygen incorporated into lattice reaction processes. These findings demonstrate that the proposed BSFZ 0.2 holds great potential as a cobalt-free triple-conducting cathode for PCFCs. [Display omitted] • Cobalt-free BSFZ x perovskites are developed as highly active triple-conducting cathodes for PCFCs. • Zn doping enhances hydration capacity, surface and bulk oxygen kinetics and ORR activity. • DFT + U calculation results show Zn doping enhances oxygen vacancy concentration. • Surface oxygen incorporated into lattice process on BSFZ 0.2 composite cathode is the rate-limiting step. [ABSTRACT FROM AUTHOR]

Regarding high-nickel cathode materials, a higher sintering temperature can indeed improve the initial capacity. However, it also results in larger primary particle sizes, which can negatively impact cycling performance. The critical factor in producing high-performance high-nickel cathode materials is ensuring that nano-sized primary particles are maintained at elevated sintering temperatures throughout the manufacturing process. [Display omitted] The burgeoning demand for electric vehicles with extended driving ranges has propelled ongoing development efforts for ultra-high nickel (Ni > 0.9) cathode materials. Despite significant ongoing research focused on Ni-rich cathode materials, a more comprehensive foundational understanding of ultra-high nickel cathode materials is essential. In our research, we employed LiNi 0.94 Co 0.06 O 2 as a model ultra-high nickel cathode material to systematically delve into the interplay between sintering temperature, structural features, and electrochemical behavior. Within a sintering temperature spectrum of 660–720 °C, we discerned that specimens produced at diminished temperatures manifest a reduced initial discharge capacity yet excel in cycling endurance. In stark contrast, their counterparts produced at augmented temperatures behave inversely. Identifying a singular sintering temperature that achieves equilibrium between initial discharge capacity and cycling performance proves elusive. Through X-ray diffraction and high-resolution transmission electron microscopy, it became evident that samples synthesized at lower temperatures exhibit pronounced lithium-nickel mixing and develop a thicker NiO layer on the surface, leading to compromised initial discharge performance and capacity. Utilizing focused ion beam scanning electron microscopy, differential capacity analysis, and in-situ X-ray diffraction, we confirm that samples synthesized at lower temperatures possess smaller particle sizes, enabling them to withstand volumetric expansion stress during cycling, resulting in enhanced cycling performance. In the realm of ultra-high nickel cathode materials, elevating the sintering temperature is a conduit to superior initial discharge efficiency and capacity. Yet, the imperative of preserving diminutive particle dimensions, as a stratagem to bolster cycling performance, stands out as a pivotal research frontier. [ABSTRACT FROM AUTHOR]

Great attention has been given to high‐performance and inexpensive lithium‐ion batteries (LIBs) in response to the ever‐increasing demand for the explosive growth of electric vehicles (EVs). High‐performance and low‐cost Co‐free Ni‐rich layered cathodes are considered one of the most favorable candidates for next‐generation LIBs because the current supply chain of EVs relies heavily on scarce and expensive Co. Herein, we review the recent research progress on Co‐free Ni‐rich layered cathodes, emphasizing on analyzing the necessity of replacing Co and the popular improvment methods. The current advancements in the design strategies of Co‐free Ni‐rich layered cathodes are summarized in detail. Despite considerable improvements achieved so far, the main technical challenges contributing to the deterioration of Co‐free Ni‐rich cathodes such as detrimental phase transitions, crack formation, and severe interfacial side reactions, are difficult to resolve by a single technique. The cooperation of multiple modification strategies is expected to accelerate the industrialization of Co‐free Ni‐rich layered cathodes, and the corresponding synergistic mechanisms urgently need to be studied. More effects will be aroused to explore high‐performance Co‐free Ni‐rich layered cathodes to promote the sustainable development of LIBs. [ABSTRACT FROM AUTHOR]

The sluggish kinetics of oxygen reduction reaction (ORR) at low temperatures and the fast degradation of the cathode are the main obstacles to the commercialization of solid oxide fuel cells (SOFCs). However, it is still very challenging to achieve both high catalytic activity and favorable stability for single‐phase materials. Herein, a highly active and durable nanocomposite cathode (Ba0.5Sr0.5)0.75Pr0.25Co0.575Fe0.3W0.125O3‐δ (BSPCFW) for low‐temperature SOFC (≤650 °C) is presented, which self‐assembles into two cubic perovskites: the simple perovskite Pr0.38Ba0.25Sr0.37Co0.62Fe0.38O3‐δ (PBSCF‐c) and the B‐site cations ordered double perovskite Ba1.30Sr0.70Co1.0Fe0.25W0.75O6‐δ (BSCFW‐c). The former PBSCF‐c serves as the highly conductive and active catalyst for ORR, while the latter BSCFW‐c with a large lattice parameter introduces a key beneficial lattice tensile strain into the PBSCF‐c phase through a coherent interface, which significantly promotes the ORR activity at low temperatures with the area specific resistance of 0.034 Ω cm2 at 650 °C, and the long‐term stability of 2 years storage and 1280 h operation in symmetrical cell. The introduction of the beneficial lattice tensile strain in self‐assembled composite catalysts is an effective way to synergistically enhance the electrochemical activity and durability of the electrode materials for electrochemical devices. [ABSTRACT FROM AUTHOR]

Energy density, power density, as well as the cost of aqueous zinc‐ion batteries (AZIBs), are largely determined by the cathode material. Among the various cathodic candidates, vanadium‐based materials with various oxidation states of vanadium cations and open frameworks have emerged as highly promising options. In this work, a heterogeneous with hydrangea‐like (NH4)2V4O9/V5O12·6H2O as cathode materials for AZIBs. The hydrogen bonds formed by NH4+ of (NH4)2V4O9, in conjunction with the lattice water in V5O12·6H2O, sufficiently strengthen the cohesion of the layered structure and expand the interlayer space. As a result, accelerating the diffusion of Zn2+ ultimately leads to an enhanced overall discharge capacity. Remarkably, the hydrangea‐like (NH4)2V4O9/V5O12·6H2O electrode at a current density of 100 mA g−1 shows a high reversible capacity of 209 mAh g−1 after 150 cycles and higher rate capability (172 mAh g−1 at 500 mA g−1). The outstanding electrochemical performance can be attributed to the unique structure of the cathode material and accelerated diffusion coefficient of Zn2+. [ABSTRACT FROM AUTHOR]

With the synergistic effect of Li doping and interlayer water insertion, the novel K 0.4 Mn 0.9 Li 0.1 O 2 ·0.33H 2 O achieved a high capacity retention and structural stability during the charging/discharging process. [Display omitted] Layered Mn-based cathode (K x MnO 2) has attracted wide attention for potassium ion batteries (PIBs) because of its high specific capacity and energy density. However, the structure and capacity of K x MnO 2 cathode are constantly degraded during the cycling due to the strong Jahn-Teller effect of Mn3+ and huge ionic radius of K+. In this work, lithium ion and interlayer water were introduced into Mn layer and K layer in order to suppress the Jahn-Teller effect and expand interlayer spacing, respectively, thus obtaining new types of K 0.4 Mn 1-x Li x O 2 ·0.33H 2 O cathode materials. The interlayer spacing of the K 0.4 MnO 2 increased from 6.34 to 6.93 Å after the interlayer water insertion. X-ray photoelectron spectroscopy studies demonstrated that proper lithium doping can effectively control the ratio of Mn3+/Mn4+ and inhibit the Jahn-Teller effect. In-situ X-ray diffraction exhibited that lithium doping can inhibit the irreversible phase transition and improve the structural stability of materials during cycling. As a result, the optimal K 0.4 Mn 0.9 Li 0.1 O 2 ·0.33H 2 O not only delivered a higher capacity retention of 84.04 % compared to the value of 28.09 % for K 0.4 MnO 2 ·0.33H 2 O, but also maintained a greatly enhanced rate capability. This study provides a new opportunity for designing layered manganese-based cathode materials with high performance for PIBs. [ABSTRACT FROM AUTHOR]

High performance and durability of electrode materials are key requirements for intermediate-temperature solid oxide fuel cells (IT-SOFCs). Herein, a novel doubles perovskite oxides Sm 0.8 Ca 0.2 Ba 1-x Ca x Co 2 O 5+δ (x= 0.1 and 0.2; SCBCC) were prepared by A site calcium co-doping strategy. x= 0.1 sample shows stabilized an orthorhombic structure with the space group Pmmm. Compared with parent SmBaCo 2 O 5+δ , substitution of Ca for Sm and Ba effectively reduces the thermal expansion coefficient (TEC) (20.2 × 10−6 K−1 to 13.2 × 10−6 K−1). x= 0.1 sample exhibits excellent chemical compatibility with CeO 2 -based electrolytes up to 1000 °C, the conductivity values reach 340–400 S cm−1 at 600–800 °C. The sample with x = 0.1 showed the best catalytic activity and carbon dioxide resistance. The area specific resistance and maximum power density of the x= 0.1 cathode are 0.022 Ω cm2 and 885 mW cm−2 at 800 °C. x = 0.1 double perovskite has good chemical compatibility and electrochemical properties while greatly reducing TEC, making this double perovskite a promising material for IT-SOFCs. • The structure and properties of SCBCC are studied as a cathode for IT-SOFC. • The introduction of calcium into SBC significantly improves TEC and conductivity. • SCBCC1 exhibits good chemical compatibility and electrochemical properties. • The SCBCC1 exhibits a good anti-carbon dioxide poisoning capability. [ABSTRACT FROM AUTHOR]

The dependence of physico-chemical, structural, and electrochemical properties of cathode materials for aqueous zinc-ion batteries based on the manganese dioxide with birnessite-type structure on the conditions of the MnO2 hydrothermal synthesis are analyzed. The manganese oxides obtained are capable of the reversible zinc ion intercalation into their crystal lattice because of large interlayer distances. Two approaches to the synthesis are considered: a reaction between manganese sulfate and potassium permanganate at 160°С (MnO2-I) and hydrothermal treatment of potassium permanganate solution at 220°С (MnO2-II). From the structural analysis, both methods are shown to allow obtaining the birnessite-type manganese dioxide. At the same time, the electrochemical properties of the cathodes obtained differ in the prototypes of aqueous zinc-ion batteries. The MnO2-II-based material demonstrated higher initial specific capacity (180 mA h g–1 at the current density of 0.3 A g–1), while its cyclic stability is by 40% lower than that for the MnO2-I-based material. This can be explained by higher surface area and lower crystallinity of the active material. [ABSTRACT FROM AUTHOR]

Lithium-rich material (SOP) with special nano-micron composite structure is synthesized by simple one-step oxalic acid method. The SOP sample is made of micron particles (1–3 μm) and nano-particles (~ 100 nm). Compared with the co-precipitation prepared lithium-rich materials (COP), SOP has good rate performance and cycle stability. The specific discharge capacity of SOP sample reaches 104.2 mAh/g at 10 C, while that of COP sample is only 68.5 mAh/g. After 300 cycles, SOP still has a specific discharge capacity of 201 mAh/g and the capacity retention rate is 89.6%, while COP only has a specific discharge capacity of 135.8 mAh/g and the capacity retention rate is 58%. Structure allocation with nano-micron particles is conducive to electrochemical performance improvement. This study provides a new idea for the synthesis of lithium-rich material with better performance. [ABSTRACT FROM AUTHOR]

Solution combustion synthesis (SCS) is considered as an efficient and energy-saving method for preparing LiFePO4/C composite material with the nanostructure (Nano-LiFePO4/C). In this study, Nano-LiFePO4/C cathode material was prepared using SCS using a cost-effective combination of urea and sorbitol as mixed fuels. The effect of mixed fuels on combustion behavior and microstructure as well as on electrochemical performance was studied using XRD, BET, SEM, TEM, and electrochemical characterization methods. Multiple characterization results indicated that the maximum temperature (Tm) and particle size were influenced by the usage of urea and sorbitol. The sample derived under optimum conditions exhibits a mesoporous nanostructure with a large surface specific area and attractive electrochemical performance with a discharge capacity of 153.5 mAh/g at 0.1 C, which shows strong potential for commercial applications in the future. [ABSTRACT FROM AUTHOR]

Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi0.5Mn1.5O4 (LNMO) cathode. In particular, the oxygen stoichiometry on the crystal surface differs from that on the crystal interior in LNMO. The detection of local oxygen loss in LNMO and its correlation with the crystal structure and the cycling stability of LNMO remain challenging. In this study, the effect of oxygen deficiency in LNMO controlled by sintering temperature on the surface crystal structure and electrochemical performance of LNMO is comprehensively investigated. The high concentration of oxygen vacancies segregates at the surface regions of LNMO forming a thin rock‐salt and/or deficient spinel surface layer. The atomic‐level surface structure reconstruction was demonstrated by annular dark‐field and annular bright‐field techniques. For the synthesis of LNMO, the higher sintering temperature results in higher crystallinity but the higher oxygen deficiency in LNMO. The high crystallinity of LNMO would increase the thermal stability of LNMO cathodes while the high content of oxygen deficiency would decrease the surface structural stability of LNMO. Therefore, the LNMO sintered at a medium temperature of 850°C achieved the best capacity retention. The results suggest a competitive function mechanism between oxygen stoichiometry and the crystallinity of LNMO on the cycling performance of LNMO. [ABSTRACT FROM AUTHOR]

The development of high‐performance cathode materials for next‐generation lithium‐ion batteries (LIBs) is urgently needed. Among the potential cathode candidates, ternary layer oxide LiNi1/3Co1/3Mn1/3O2 (LNCM) has attracted considerable attention due to its high voltage discharge, large theoretical specific capacity, stable chemical structure and low cost. However, Li+/Ni2+ cation mixing and low conductivity have resulted in poor long‐term cyclability, voltage drop and capacity degradation during high‐rate charging. To address these issues, a sol‐gel technique together with an annealing treatment was used to prepare LNCM with well‐defined structure and good morphology. The material obtained by heating the LNCM precursor at 850 °C for 12 h (LNCM‐850/12) exhibited an initial discharge specific capacity of 217.9 mAh g−1 at 0.2 C and maintained a high reversible capacity of 116.1 mAh g−1 after 200 cycles. The LNCM‐850/12 electrode also demonstrated superior rate capacity and exceptional cycling stability due to its well‐defined structure, low Li+/Ni2+ cation mixing and good morphology. These characteristics improve the electrical/ionic conductivity, reduce the charge transfer resistance and shorten the Li+ diffusion distance, ultimately accelerating the Li+ insertion and extraction. Overall, the careful control of calcination time in LNCM synthesis provides valuable insights for the development of advanced cathodes for LIBs. [ABSTRACT FROM AUTHOR]

Due to the low cost and better security, aqueous zinc-ion batteries (AZIBs) are receiving a great deal of attention for large-scale energy storage. Vanadium-based materials have immense potential as AZIB cathode materials. Herein, the KxVO2 (KVO) cathode materials synthesized by the hydrothermal method. The morphology and structure of KVO were characterized by X-ray diffraction (XRD), Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). FESEM demonstrated that sample displayed sheet morphology. The electrochemical performance of KVO electrode in aqueous zinc ion battery was determined by cyclic voltammetry and galvanostatic charge–discharge test after assembly of Zn-KVO button cell using 3 M ZnSO4 aqueous electrolyte. The Zn-KVO battery has a capacity of 435.8 mAh⋅g−1 at 0.2 A g−1. After 1000 cycles at 4 A g−1, the cycle reversible capacitance retention rate was 78% of the original capacity. Compared with V2O5 electrode, the capacity and cycle stability of KVO electrode have been significantly improved. [ABSTRACT FROM AUTHOR]

In this study, we report a novel medium-entropy perovskite oxide of La 0.7 Sr 0.3 Co 0.25 Fe 0.25 Ni 0.25 Mn 0.25 O 3-δ (LSCFNM73) with high constitutive entropy (S config) as the cathode material of intermediate temperature solid oxide fuel cells (IT-SOFCs). The intrinsic properties of phase structure, electrical conductivity, thermal expansion and oxygen adsorption capacity of La 1-x Sr x Co 0.25 Fe 0.25 Ni 0.25 Mn 0.25 O 3-δ (LSCFNM, x = 0, 0.1, 0.2, 0.3) oxides are evaluated in detail. The LSCFNM73 oxide exhibits the maximum electrical conductivity of 464 S cm−1 at 800 °C and a relatively lower thermal expansion coefficient (TEC) of 15.34 × 10−6 K−1, which is selected as the propriate cathode composition. The B-site of LSCFNM73 contains four elements which can increase the configuration entropy. Additionally, NiO-Yttria stabilized zirconia (YSZ) supported fuel cell is fabricated by tape casting, hot pressing-lamination, co-sintering and screen printing technologies. The fuel cell demonstrates a maximum power density of 1088 mW cm2 at 800 °C, and excellent stability at 750 °C under 0.75V in 120 h and 10 times thermal cycling between 750 °C and 400 °C. Therefore, the medium-entropy LSCFNM73 oxide can be applied in IT-SOFCs as a competitive cathode material. • Medium-entropy oxides of La 1-x Sr x Co 0.25 Fe 0.25 Ni 0.25 Mn 0.25 O 3-δ (LSCFNM, x = 0, 0.1, 0.2, 0.3) are synthesized and evaluated. • B-site of ABO 3 contains four elements can increase the configuration entropy. • The maximum power density of fuel cell at 800 °C is 1088 mW cm−2. • The single fuel cell shows good stability in 120 h at 750 °C and well thermal cycling stability after 10 cycles. [ABSTRACT FROM AUTHOR]

The rapid decrease of the electrocatalytic activity at low temperature (<700 ℃) limits the popularization and application of the classical cathode material LSM (Sr doped LaMnO 3) in SOFC. Herein, we report that the introduction of CBO (CuBi 2 O 4) oxide could not only reduce the sintering temperature of LSM-based cathode, but also significantly improves its electrochemical performance at intermediate temperature range of 500–700 ℃. The polarization resistance (R p) of LSM-CBO20 (including 20 wt. % CBO) composite cathode on GDC electrolyte is only 0.13 Ω cm2 at 700 ℃, which is significantly lower than the LSM cathode. The study found that the quite promoted oxygen surface exchange kinetics and catalytic activity of CBO, and the much reduced sintering temperature of the composite cathode contribute to the dramatic decrease of R p. In addition, when Gd 0.1 Ce 0.9 O 1.95 (GDC) is introduced, the polarization resistance is further reduced to 0.11 Ω cm2 at 700 ℃. The maximum power density of the single cell with LSMGDC-CBO20 triadic phase cathode reaches to 1460 mW cm-2 at 700 ℃. The present study demonstrates that introducing CBO is an effective and promising approach to improve the electrochemical performance of conventional LSM-based cathode at reduced temperatures. [ABSTRACT FROM AUTHOR]

LiNi0.8Co0.1Mn0.1O2 (NCM811) has been regarded as a potential cathode material for next‐generation lithium‐ion batteries. However, the electrochemical performance of this material is severely affected by structural deterioration and capacity degradation, and the residual lithium is one of the main culprits. Herein, we propose an effective strategy to design ultrathin coatings on the surface of NCM811 by using LiBF4 as the precursor. The homogeneous hybrid LiF‐Li2B4O7 coating layers can be obtained due to the reaction between LiBF4 and the residual lithium, which can not only effectively reduce the residual lithium, but also improve interfacial lithium‐ion diffusion kinetics and suppress side reactions. Accordingly, the LiBF4‐modified samples exhibited significantly improved electrochemical performance. The coated sample of NCM811@LBF‐0.7 delivers the 127.1 mAh g−1 discharge capacity with 69.8 % capacity retention even after 300 cycles at 1 C. While the pristine sample only shows 97.1 mAh g−1 and the capacity retention decreases to 31.0 %. This method provides a simple and effective strategy to extend the service life and safety characteristics of high‐energy‐density lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Single‐crystal nickel‐rich materials are promising alternatives to polycrystalline cathodes owing to their excellent structure stability and cycle performance while the cathode material usually appears high cation mixing, which may have a negative effect on its electrochemical performance. The study presents the structural evolution of single‐crystal LiNi0.83Co0.12Mn0.05O2 in the temperature–composition space using temperature‐resolved in situ XRD and the cation mixing is tuned to improve electrochemical performances. The as‐synthesized single‐crystal sample shows high initial discharge specific capacity (195.5 mAh g−1 at 1 C), and excellent capacity retention (80.1 % after 400 cycles at 1 C), taking account of lower structure disorder (Ni2+ occupying Li sites is 1.56 %) and integrated grains with an average of 2–3 μm. In addition, the single‐crystal material also displays a superior rate capability of 159.1 mAh g−1 at the rate of 5 C. This excellent performance is attributed to the rapid Li+ transportation within the crystal structure with fewer Ni2+ cations in Li layer as well as intactly single grains. In sum, the regulation of Li+/Ni2+ mixing provides a feasible strategy for boosting single‐crystal nickel‐rich cathode material. [ABSTRACT FROM AUTHOR]

Li-rich manganese-based cathode materials (LRMs) are considered one of the most promising cathode materials for the next generation of lithium-ion batteries (LIBs) because of their high energy density. However, there are problems such as a capacity decay, poor rate performance, and continuous voltage drop, which seriously limit their large-scale commercial applications. In this work, Li1.2Mn0.54Co0.13Ni0.13O2 coated with Li2MoO4 with a unique spinel structure was prepared with the wet chemistry method and the subsequent calcination process. The Li2MoO4 coating layer with a spinel structure could provide a 3D Li+ transport channel, which is beneficial for improving rate performance, while protecting LRMs from electrolyte corrosion, suppressing interface side reactions, and improving cycling stability. The capacity retention rate of LRMs coated with 3 wt% Li2MoO4 increased from 69.25% to 81.85% after 100 cycles at 1 C, and the voltage attenuation decreased from 7.06 to 4.98 mV per cycle. The lower Rct also exhibited an improved rate performance. The results indicate that the Li2MoO4 coating effectively improves the cyclic stability and electrochemical performance of LRMs. [ABSTRACT FROM AUTHOR]

The influence of rare earth ions on layered perovskite (AA'B 2 O 5+δ) is the key to the development of highly active layered perovskite cathode. Herein, we make a systematic explanation through experiment and first-principles calculation. The lattice constant decreases with the decrease of Ln3+ ionic radius, resulting in a smaller space of interstitial oxygen position and increasing oxygen Frenkel energy. The electrochemical activity of LnBaCo 2 O 5+δ (Ln = Pr, Nd and Sm) electrodes decreases with the decrease of Ln3+ ionic radius, which is mainly attributed to a lower oxygen Frenkel energy. Electrochemical impedance spectra tests show that there are significant differences in the surface exchange process of oxygen because of different surface oxygen vacancy concentration for LnBaCo 2 O 5+δ. For Ln = Pr, Nd, and Sm cathodes, the maximum power densities of the anode-supported Ni-YSZ/YSZ/GDC/LnBaCo 2 O 5+δ single cells reach 1.48, 1.36 and 1.06 W/cm2 at 800 °C, respectively, indicating that PrBaCo 2 O 5+δ with the maximum rare earth ion radius exhibits better oxygen reduction reaction. These findings provide guidance for the design and fabrication of highly active layered perovskite electrode materials. [ABSTRACT FROM AUTHOR]

Alkaline Earth free spinel oxides provide a potential benefit over Sr-doped perovskite-based materials commonly used as electrodes in high-temperature electrochemical energy conversion devices, e.g., solid oxide fuel cells (SOFCs). Sr-segregation is a known issue leading to performance degradation. In this study, Cu x Mn 3-x O 4 (x = 1, 1.2, and 1.5) porous electrodes were examined as SOFC cathodes using electrochemical impedance spectroscopy to investigate the oxygen reduction reaction (ORR) kinetics in relation to the material's intrinsic conductivity, the extrinsic electrode structure, and the cell test design. Similar to the electronic conducting (La,Sr)MnO 3 SOFC cathodes, the ORR kinetics of Cu x Mn 3-x O 4 spinel electrodes was governed by the oxygen adsorption and diffusion at the particle surface as well as the charge transfer at the triple phase boundaries. The overall electrode polarization resistance was highly dependent on contact density with the metallic current collector, active material particle connectivity, electrode thickness, and the intrinsic electronic materials conductivity. We describe the importance of effective electronic charge transport parallel to the electrode surface in maximizing the electrochemically active electrode volume and enhancing electrode performance. We discuss an approach to optimize cell and electrode design with respect to active materials properties. This aspect is critical to ensure reliable evaluation of new materials, since laboratory-scale button-cells typically exhibit a high degree of electrode microstructure (e.g. porosity, thickness) and electrical contact density variation from sample to sample. • Understanding of oxygen reduction reaction kinetics in porous spinel electrode. • Influence of electronic transport on oxygen reduction reaction kinetics. • More electrical contact points for enhanced oxygen reduction activity. • Higher particle electronic conductivity for enhanced oxygen reduction activity. • Better particle connectivity for enhanced oxygen reduction activity. [ABSTRACT FROM AUTHOR]

Solid oxide fuel cells (SOFCs) operating at high temperatures are highly efficient electrochemical devices since they convert the chemical energy of a fuel directly into heat and electrical energy. The electrochemical performance of an SOFC is significantly influenced by the materials and microstructure of the electrodes since the electrochemical reactions in SOFCs take place at three/triple phase boundaries (TPBs) within the electrodes. In this study, graphene in the form of reduced graphene oxide (rGO) is added to cathode functional layer (CFL) to improve the cell performance by utilizing the high electrical properties of graphene. Various cells are prepared by varying the rGO content in CFL slurry (1–5 wt %), the number of screen printing (1–3) and the cathode sintering temperature (900–1100 °C). The electrochemical behavior of the cells is evaluated by electrochemical performance and impedance tests. It is observed that there is a ∼26% increase in the peak performance of the cell coated with single layer CFL having 1 wt % graphene and 1050 °C sintering temperature, compared to that of the reference cell. • Graphene in reduced graphene oxide form is added to cathode functional layer. • Graphene content and cathode functional layer thickness are studied. • Effect of cathode sintering temperature is also considered. • Single functional layer sintered at 1050 °C with 1 wt % graphene performs the best. • ∼26% increase in the peak performance is achieved after the optimizations. [ABSTRACT FROM AUTHOR]

Lithium-rich manganese-based cathodes (LR) are valuable cathode materials for the next generation of lithium-ion batteries (LIBs) with high-energy density. However, the fast voltage/capacity decay on cycling is the major obstacle for the practical application induced by the less-than-ideal anionic redox reactions and structure distortion. Herein, in order to tackle these challenges, a perovskite-like La2Li0.5Co0.5O4 (LLCO) material is selected as protective surface to stabilize the Li1.2Mn0.54Ni0.13Co0.13O2 (LR) substrate through wet chemical coating method. Versatile structure/phase characterizations and electrochemical tests exhibit that the LLCO can not only minish the oxygen evolution and enhance the structure stability, but also restrain the electrolyte corrosion and increase the mechanical strength of cathode materials. Moreover, the coated LLCO with high electronic/ionic conductivity dramatically accelerates the energy storage kinetic, thereby displaying the improved rate performance. Specifically, the optimized LR@LLCO sample (1LLCO) exhibits a high capacity of 250.6 mAh·g−1 after 100 cycles at 0.1 C and excellent capacity retention of 82.6% after 200 cycles at 2 C. This work provides a new idea for the modification of LR cathodes toward commercial high-performance LIBs. [ABSTRACT FROM AUTHOR]

A new strategy to reduce the operating temperature of the solid oxide fuel cell (SOFC) is needed to foster the progress of developing high-performance and stable SOFC as a solution to the thermal stress and degradation of the cell components induced by high-temperature SOFC. The use of lithium (Li) as a cathode can increase the cell's efficiency, as it allows for faster ion transport and a higher reaction rate. This study presents an attractive approach to using a Li-based cathode by combining Li with cobalt (Co) to form LiCo0.6Sr0.4O2 (LCSO). In this work, a precursor consisting of Li, Co, and strontium (Sr) was prepared via the glycine-nitrate combustion method. The precursor was calcined at two different calcination temperatures (800 and 900 °C) prior to ink formulation and symmetrical cell fabrication in order to study the effect of calcination temperature on the structural and electrochemical behaviour of a Li-based cathode. The precursor LCSO powder was characterised using X-ray crystallography (XRD) to determine the crystal structure and composition of the developed LCSO. The electrochemical performance of the fabricated symmetrical cell was tested using electrochemical impedance spectroscopy (EIS) to obtain the cell's resistance information, which is related to the cell's ionic and electronic conductivity. SDC electrolyte with LCSO calcined at 800 °C has a higher crystallinity percentage and a more porous structure compared to LCSO calcined at 900 °C. The porous structure enhanced the electrochemical performance of the cell, where the symmetrical cell has the highest conductivity (0.038 Scm−1) with the lowest activation energy (0.43 eV). The symmetrical cell was also able to achieve 2.89 Ω cm2 of area-specific resistance (ASR) at 800 °C of operating temperature. In conclusion, the SDC electrolyte with LCSO calcined at 800 °C is the promising cathode material for SOFC applications. The result of this study can benefit the SOFC field of research, especially in the development of intermediate temperature-SOFC. [ABSTRACT FROM AUTHOR]

The microstructure stability and rate capability of LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode material was reinforced via coating one negative thermal expansion compound LiAlSiO 4 with high ionic conductivity, leading to significantly enhanced long-term performances of Ni-rich cathode for the advanced lithium-ion batteries. [Display omitted] • Thermal expansion compound LiAlSiO 4 (LASO) is engineered onto Ni-rich material. • LASO-modified Ni-rich cathode exhibits long-term cycling stability. • The microcracks of bulk Ni-rich cathode can be effectively depressed. • LASO-modified Ni-rich cathode displays excellent rate capability. With high specific energy density, Ni-rich layered LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM) material has become one promising cathode candidate for advanced lithium-ion batteries (LIBs). However, severe capacity fading induced by microstructure degradation and deteriorated interfacial Li+ transportation upon repeated cycling makes the commercial application of NCM cathode in dilemma. To address these issues, LiAlSiO 4 (LASO), one unique negative thermal expansion (NTE) composite with high ionic conductivity, is utilized as a coating layer to improve the electrochemical performances of NCM material. Various characterizations demonstrate that LASO modification can endow NCM cathode with significantly enhanced long-term cyclability, through reinforcing the reversibility of phase transition and restraining lattice expansion, as well as depressing microcrack generation during repeated delithiation-lithiation processes. The electrochemical results indicate that LASO-modified NCM cathode can deliver an excellent rate capability of 136 mAh g−1 at a high current rate of 10 C (1800 mA g−1), larger than that of the pristine cathode (118 mAh g−1), especially higher capacity retention of 85.4% concerning the pristine NCM cathode (65.7%) over 500 cycles under 0.2 C. This work provides a feasible strategy to ameliorate the interfacial Li+ diffusion and suppress the microstructure degradation of NCM material during long-term cycling, which can effectively promote the practical application of Ni-rich cathode in high-performance LIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] Advances in cathode material design and understanding of intercalation mechanisms are necessary to improve the overall performance of aluminum ion batteries. Therefore, we designed ZnSe/SnSe 2 hollow microcubes with heterojunction structure as a cathode material for aluminum ion batteries. ZnSe/SnSe 2 hollow microcubes with an average size of about 1.4 µm were prepared by selenization of ZnSn(OH) 6 microcubes successfully. The shell thickness of ZnSe/SnSe 2 hollow microcubes is about 250 nm. On one hand, the hollow cubic structure can effectively alleviate the volume effect, provide shorter ion diffusion paths, and increase the contact area with the electrolyte. On the other hand, ZnSe/SnSe 2 heterojunction structure can establish a built-in electric field to facilitate ion transport. The synergistic effect of the two leads to the improved electrochemical performance of ZnSe/SnSe 2 as the cathode of aluminum ion batteries. The material delivered a reversible capacity of 124 mAh/g after 150 cycles at a current density of 100 mA/g. Meanwhile, coulombic efficiency remained above 98% in almost all cycles. In addition, the electrochemical reaction mechanism and kinetic process of Al3+ and ZnSe/SnSe 2 were studied. [ABSTRACT FROM AUTHOR]

The phase structure of the precursor is crucial for the microstructure evolution and stability of Ni-rich cathode materials. Using sodium lactate as a green complexing agent, cathode electrode materials with different phase structures and unique core–shell structures were prepared by the co-precipitation method in this study. The influence of the phase structure of the nickel-rich precursor on the cathode electrode materials was studied in depth. It was found that α-NCM811 had large interlayer spacing, which was beneficial for the diffusion of lithium ions. In contrast, β-NCM811 had smaller interlayer spacing, a good layered structure, and lower ion mixing, resulting in better cycling performance. The core–shell-αβ-NCM811 with α-NCM811 as the core and β-NCM811 as the shell was prepared by combining the advantages of the two different phases. The core–shell-αβ-NCM811 showed the highest discharge capacity of 158.7 mAh/g at 5 C and delivered excellent rate performance. In addition, the β-NCM811 shell structure with smaller layer spacing could prevent corrosion of the α-NCM811 core by the electrolyte. Thus, the capacity retention rate of the core–shell-αβ-NCM811 was still as high as 86.16% after 100 cycles. [ABSTRACT FROM AUTHOR]