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Sodium‐ion batteries (NIBs) have emerged as a promising alternative to commercial lithium‐ion batteries (LIBs) due to the similar properties of the Li and Na elements as well as the abundance and accessibility of Na resources. Most of the current research has been focused on the half‐cell system (using Na metal as the counter electrode) to evaluate the performance of the cathode/anode/electrolyte. The relationship between the performance achieved in half cells and that obtained in full cells, however, has been neglected in much of this research. Additionally, the trade‐off in the relationship between electrochemical performance and cost needs to be given more consideration. Therefore, systematic and comprehensive insights into the research status and key issues for the full‐cell system need to be gained to advance its commercialization. Consequently, this review evaluates the recent progress based on various cathodes and highlights the most significant challenges for full cells. Several strategies have also been proposed to enhance the electrochemical performance of NIBs, including designing electrode materials, optimizing electrolytes, sodium compensation, and so forth. Finally, perspectives and outlooks are provided to guide future research on sodium‐ion full cells. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) present great appeal in various energy storage systems, especifically for stationary grid storage, on account of the abundance of sources and low cost. Unfortunately, the commercialization of SIBs is mainly limited by available electrode materials, especially for the cathodes. Prussian blue analogs (PBAs), emerge as a promising alternative for their structural feasibility in the application of SIBs. Decreasing the defects (vacancies and coordinated water) is an effective strategy to achieve superior electrochemical performance during the synthetic processes. Herein, we summarize crystal structures, synthetic methods, electrochemical mechanisms, and the influences of synthesis conditions of PBAs in detail. This comprehensive overview on the current research progresses of PBAs will give guides and directions to solve the existing problems for their application in SIBs. [ABSTRACT FROM AUTHOR]

As a class of promising cathodes in the field of large-scale power storage systems especially for alkali-metal-ion batteries (MIBs), Prussian blue (PB) and its analogues (PBAs) have received wide research attention due to their open framework, high theoretical specific capacity, and simple synthesis method. For large-scale applications, cathode materials with low-cost and long cycle life are preferred. However, only a few of the review papers have concentrated on the detailed analysis of low-cost PBAs, including Fe-based and Mn-based PBAs, which also show excellent electrochemical performance. This review aims to first provide an all-sided understanding of low-cost PBAs in terms of their application and recent progress in MIBs. Then, the major challenges such as inferior electrochemical properties of low-cost PBAs are discussed. Meanwhile, we provide feasible strategies to prepare PBA electrodes with advanced electrochemical performance. Finally, we present some personal perspectives and guidance for future research, aiming to narrow the gap between laboratory investigation and practical application. [ABSTRACT FROM AUTHOR]

The development of large‐scale energy storage systems (ESSs) aimed at application in renewable electricity sources and in smart grids is expected to address energy shortage and environmental issues. Sodium‐ion batteries (SIBs) exhibit remarkable potential for large‐scale ESSs because of the high richness and accessibility of sodium reserves. Using low‐cost and abundant elements in cathodes with long cycling stability is preferable for lowering expenses on cathodes. Many investigated cathodes for SIBs are dogged by structural and morphology changes, unstable interphases between the cathode and the electrolyte, and air sensitivity, causing unsatisfactory cycling performance. Therefore, understanding the mechanism of capacity degeneration in depth and developing precise solutions are critical for designing low‐cost cathodes that are highly stable under cycling. Herein, recent progress in long‐cycle‐life and low‐cost cathodes for SIBs is focused on, and a comprehensive discussion of the key points in SIBs toward large‐scale applications is provided. The roots of the unstable cycling performance of low‐cost cathodes are discussed. Also, effective strategies are summarized from the recent progress on long‐cycle‐life and low‐cost cathodes. This review is expected to encourage deeper investigation of long‐lifespan cathodes for SIBs, particularly for potential large‐scale industrialization. [ABSTRACT FROM AUTHOR]

Layered transition metal oxide (NaxTMO2), being one of the most promising cathode candidates for sodium‐ion batteries (SIBs), have attracted intensive interest because of their nontoxicity, high theoretical capacities, and easy manufacturability. However, their physical and electrochemical properties of water sensitivity, sluggish Na+ transport kinetics, and irreversible multiple‐phase translations hinder the practical application. Here, a concept of surface lattice‐matched engineering is proposed based on in situ spinel interfacial reconstruction to design a spinel coating P2/P3 heterostructure cathode material with enhanced air stability, rate, and cycle performance. The novel structure and its formation process are verified by transmission electron microscopy and in situ high‐temperature X‐ray diffraction. The electrode exhibits an excellent rate performance with the highly reversible phase transformation demonstrated by in situ charging/discharging X‐ray diffraction. Additionally, even after a rigorous water sensitivity test, the electrode materials still retain almost the same superior electrochemical performance as the fresh sample. The results show that the surface spinel phase can play a vital role in preventing the ingress of water molecules, improving transport kinetics, and enhancing structural integrity for NaxTMO2 cathodes. The concept of surface lattice‐matched engineering based on in situ spinel interfacial reconstruction will be helpful for designing new ultra‐stable cathode materials for high‐performance SIBs. [ABSTRACT FROM AUTHOR]

Sodium‐ion oxide cathodes with triphase heterostructures have attracted intensive attention, since the sodium‐storage performance can be enhanced by utilizing the synergistic effect of different phases. However, the composite structures generally suffer from multiple irreversible phase transitions and high lattice strain because of interlayer‐gliding during the charge/discharge process. Here, the concept of strain engineering via manipulating the local chemistry of heterostructured oxide cathode is proposed to regulate the relevant physical and chemical properties, resulting in highly reversible structural evolution (P2/P3/spinel → P2/P3″/spinel) and low intrinsic stress in the potential window of 1.5–4.0 V. Also, the simple structural evolution at a relatively high cut‐off potential of 4.3 V can be detected by in situ X‐ray diffraction and other electrochemical characterization techniques during Na+ extraction/insertion. Meanwhile, the electrode exhibits a high reversible capacity (169.4 mAh g−1 at 0.2 C) and excellent rate performance from 1.5 to 4.3 V. Overall, this study reveals the mechanisms of regulating local chemistry to realize strain engineering of the cathode materials and paves the way for the further improvement of high‐performance sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Organic materials have attracted much attention in sodium ion batteries (SIBs) because of their advantages such as being environmentally benign and having high designability. Capacities and cycle life of organic materials are the most important parameters in most research which has been paid much effort to obtain an impressive electrochemical performance on the material level, and the sodium‐detachable ability of these materials to directly match with the sodium‐free anode is neglected. In this work, one organic sodium salt (C6H2Na2O6) exhibits the unique ability (charging first in half cell) unlike other reported organic cathode materials (normally discharging first) for SIBs. The redox mechanism and structure change are investigated by in situ and ex situ tests to give a better understanding for C6H2Na2O6. Satisfying electrochemical performance (74% capacity retention after 600 cycles at 0.05 A g−1 and 63% capacity retention at 5 A g−1 when compared with capacity at 0.05 A g−1) is achieved by the C6H2Na2O6 electrode. In addition, matched with hard carbon, full cells are assembled successfully like other transition metal containing cathode materials because C6H2Na2O6 electrode can deliver its sodium ions to a sodium‐free anode directly without any presodiation. [ABSTRACT FROM AUTHOR]

Prussian blue analogs (PBAs), as promising cathode materials for sodium‐ion batteries (SIBs), have received extensive research interest due to their appealing characteristics, e.g., the low cost of their raw materials, easy manufacturing, open frameworks, and high theoretical specific capacity. There are some challenges for PBAs cathodes, however, hindering their performance output, making them currently unacceptable for practical applications. To improve the performance and cycling stability of PBAs, a clear in‐depth understanding of the relationship of their electrochemical reaction process to their ion insertion/extraction mechanisms and structural evolution is extremely important. Nowadays, advanced characterization techniques have become an important tool to guide the construction of high‐performance PBAs cathodes. In this review, the various advances by using advanced characterization techniques to reveal the reaction mechanisms for PBAs cathodes are summarized and discussed. By appreciating how the advanced characterization techniques to guide fabrication of high‐performance PBAs or reveal their detailed reaction mechanisms, it is hoped that this review can assist readers to find more valuable and advanced technologies to help to resolve some key problems and enhance their performance so as to accelerate the practical application of PBAs cathode for SIBs. [ABSTRACT FROM AUTHOR]

Recently, environmental degradation along with the energy crisis has led to an urgent necessity to develop renewable and clean energy storage devices. The sodium ion batteries (SIBs) have become promising candidates in the whole energy storage system, due to its rich and low‐cost sodium resources. To accelerate the commercialization of SIBs, the energy density of SIBs needs to be further improved. Increasing the operating voltage of SIBs is considered to be an effective method, which requires stable and high‐voltage cathode materials. Comparatively, polyanionic sulfate materials (PSMs) with stable skeletons, adjustable structures, operational safety, and the high electronegativity of SO42− are believed to be the most promising high‐energy‐cathodes. In this review, recent progresses on several typical sulfates for SIBs are summarized. What's more, based on their intrinsic characteristics, the structures and kinetic behaviors of PSMs are also discussed. Reported measures to optimize their electrochemical performances and structural stability are summarized and reviewed. The key challenges and corresponding opportunities for PSMs are also discussed. The insights presented in this review may be a guide for designing and developing stable and practical PSMs for room‐temperature SIBs, which is conducive to promoting their industrialization. [ABSTRACT FROM AUTHOR]

Manganese‐based Prussian Blue, Na2−δMn[Fe(CN)6] (MnPB), is a good candidate for sodium‐ion battery cathode materials due to its high capacity. However, it suffers from severe capacity decay during battery cycling due to the destabilizing Jahn–Teller distortions it undergoes as Mn2+ is oxidized to Mn3+. Herein, the structure is stabilized by a thin epitaxial surface layer of nickel‐based Prussian Blue (Na2−δNi[Fe(CN)6]). The one‐pot synthesis relies on a chelating agent with an unequal affinity for Mn2+ and Ni2+ ions, which prevents Ni2+ from reacting until the Mn2+ is consumed. This is a new and simpler synthesis of core–shell materials, which usually needs several steps. The material has an electrochemical capacity of 93 mA h g−1, of which it retains 96 % after 500 charge–discharge cycles (vs. 37 % for MnPB). Its rate capability is also remarkable: at 4 A g−1 (ca. 55 C) it can reversibly store 70 mA h g−1, which is also reflected in its diffusion coefficient of ca. 10−8 cm2 s−1. The epitaxial outer layer appears to exert an anisotropic strain on the inner layer, preventing the Jahn–Teller distortions it normally undergoes during de‐sodiation. [ABSTRACT FROM AUTHOR]

Room‐temperature sodium–sulfur (RT Na–S) batteries have attracted extensive attention because of their low cost and high specific energy. RT Na–S batteries, however, usually suffer from sluggish reaction kinetics, low reversible capacity, and short lifespans. Herein, it is shown that chain‐mail catalysts, consisting of porous nitrogen doped carbon nanofibers (PCNFs) encapsulating Co nanoparticles (Co@PCNFs), can activate sulfur via electron engineering. The chain‐mail catalysts Co@PCNFs with a micrograde hierarchical structure as a freestanding sulfur cathode (Co@PCNFs/S) can provide space for high mass loading of sulfur and polysulfides. The electrons can rapidly transfer from chain‐mail catalysts to sulfur and polysulfides during discharge–charge processes, therefore boosting its conversion kinetics. As a result, this freestanding Co@PCNFs/S cathode achieves a high sulfur loading of 2.1 ± 0.2 mg cm−2, delivering a high reversible capacity of 398 mA h g−1 at 0.5 C (1 C = 1675 mA g−1) over 600 cycles and superior rate capability of an average capacity of 240 mA h g−1 at 5 C. Experimental results, combined with density functional theory calculations, demonstrate that the Co@PCNFs/S can efficiently improve the conversion kinetics between the polysulfides and Na2S via transferring electrons from Co to them, thereby realizing efficient sulfur redox reactions. [ABSTRACT FROM AUTHOR]

Most of the cathode materials for potassium ion batteries (PIBs) suffer from poor structural stability due to the large ionic radius of K+, resulting in poor cycling stability. Here we report a low‐strain potassium‐rich K1.84Ni[Fe(CN)6]0.88⋅0.49 H2O (KNiHCF) as a cathode material for PIBs. The as‐prepared KNiHCF cathode can deliver reversible discharge capacity of 62.8 mAh g−1 at 100 mA g−1, with a high discharge voltage of 3.82 V. It can also achieve a superior rate performance of 45.8 mAh g−1 at 5000 mA g−1, with a capacity retention of 88.6 % after 100 cycles. The superior performance of KNiHCF cathode results from low‐strain de‐/intercalation mechanism, intrinsic semiconductor property and low potassium diffusion energy barrier. The high power density and long‐term stability of KNiHCF//graphite full cell confirmed the feasibility of K‐rich KNiHCF cathode in PIBs. This work provides guidance to develop Prussian blue analogues as cathode materials for PIBs. [ABSTRACT FROM AUTHOR]

With the unprecedentedly increasing demand for renewable and clean energy sources, the sodium‐ion battery (SIB) is emerging as an alternative or complementary energy storage candidate to the present commercial lithium‐ion battery due to the abundance and low cost of sodium resources. Layered transition metal oxides and Prussian blue analogs are reviewed in terms of their commercial potential as cathode materials for SIBs. The recent progress in research on their half cells and full cells for the ultimate application in SIBs are summarized. In addition, their electrochemical performance, suitability for scaling up, cost, and environmental concerns are compared in detail with a brief outlook on future prospects. It is anticipated that this review will inspire further development of layered transition metal oxides and Prussian blue analogs for SIBs, especially for their emerging commercialization. [ABSTRACT FROM AUTHOR]

In the article (DOI: 10.1002/inf2.12475), Yao Xiao and co‐workers report an oxide cathode material of Na0.6Mn0.95Mg0.05O2 with layered/tunnel intergrowth structure, which exhibits superior Na+ storage performance, offering new opportunities for realizing high‐energy‐density and long‐cycle‐life sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Low‐cost layered oxides free of Ni and Co are considered to be the most promising cathode materials for future sodium‐ion batteries. Biphasic Na0.78Cu0.27Zn0.06Mn0.67O2 obtained via superficial atomic‐scale P3 intergrowth with P2 phase induced by Zn doping, consisting of inexpensive transition metals, is a promising cathode for sodium‐ion batteries. The P3 phase as a covering layer in this composite shows not only in excellent electrochemical performance but also its tolerance to moisture. The results indicate that partial Zn substitutes can effectively control biphase formation for improving the structural/electrochemical stability as well as the ionic diffusion coefficient. Based on in situ synchrotron X‐ray diffraction coupled with electron‐energy‐loss spectroscopy, a possible Cu2+/3+ redox reaction mechanism has now been revealed. The P2@P3 Na0.78Cu0.33−xZnxMn0.67O2 composite induced by Zn doping with revealed redox behavior of Cu2+/3+ is a promising cathode for Na ion batteries. Zn doping not only induces the formation of a P3 phase, which shows a distinct crystal and atomic arrangement with nanoscale thickness, but also offered a high and flat voltage profile, leading to improvement in both structural/electrochemical stability and humidity resistance. [ABSTRACT FROM AUTHOR]

Abstract: The cathode materials in the Na‐ion battery system are always the key issue obstructing wider application because of their relatively low specific capacity and low energy density. A graphene oxide (GO) wrapped composite, Na2Fe2(SO4)3@C@GO, is fabricated via a simple freeze‐drying method. The as‐prepared material can deliver a 3.8 V platform with discharge capacity of 107.9 mAh g−1 at 0.1 C (1 C = 120 mA g−1) as well as offering capacity retention above 90% at a discharge rate of 0.2 C after 300 cycles. The well‐constructed carbon network provides fast electron transfer rates, and thus, higher power density also can be achieved (75.1 mAh g−1 at 10 C). The interface contribution of GO and Na2Fe2(SO4)3 is recognized and studied via density function theory calculation. The Na storage mechanism is also investigated through in situ synchrotron X‐ray diffraction, and pseudocapacitance contributions are also demonstrated. The diffusion coefficient of Na+ ions is around 10−12–10−10.8 cm2 s−1 during cycling. The higher working voltage of this composite is mainly ascribed to the larger electronegativity of the element S. The research indicates that this well‐constructed composite would be a competitive candidate as a cathode material for Na‐ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Sodium‐ion batteries (SIBs) have been considered as the most promising candidate for large‐scale energy storage system owing to the economic efficiency resulting from abundant sodium resources, superior safety, and similar chemical properties to the commercial lithium‐ion battery. Despite the long period of academic research, how to realize sodium‐ion battery commercialization for market applications is still a great challenge. Thus, from the perspective of future practical application, this review will identify the factors that are restricting commercialization, and evaluate the existing active materials and sodium‐ion‐based full‐cell system. The design and development trends that are needed for SIBs to meet the requirements of practical applications in large‐scale energy storage will also be discussed in detail. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) have recently attracted considerable attention and are considered as an alternative to lithium ion batteries (LIBs), owing to the cheap price and abundance of sodium resources. However, the commercialization of SIBs has so far been impeded by the low energy density and unstable cycle life of electrodes, especially as cathodes. Although some cathode candidates with a stable cycle life and high energy density have been developed using nanotechnologies, the commercial feasibility is seldom taken into account. This research news article provides an insight into the commercial prospects of existing cathode materials for SIBs in terms of environmental friendliness, manufacturing cost, synthesis methods and electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract: A high performance Li3V2(PO4)3 cathode material for lithium ion batteries was synthesized by the microwave-assisted hydrothermal method followed by a post annealing process. The synchrotron X-ray diffraction analysis results confirmed that single-phase Li3V2(PO4)3 with monoclinic structure was obtained. Scanning electron microscope and transmission electron microscope images revealed that the as-prepared Li3V2(PO4)3 was composed of nanowires and microsized particles. Electrochemical results demonstrated that the Li3V2(PO4)3 electrode measured at 10 C after 500 cycles can deliver discharge capacities of 85.4 mAh g−1 and 103.4 mAh g−1, with a capacity retention of 99.3% and 95.9%, in the voltage ranges of 3.0–4.3 V and 3.0–4.8 V, respectively, indicating good cycling stability. Furthermore, the electrochemical performance of Li3V2(PO4)3 in ionic liquid electrolytes between 3.0 V and 4.8 V was also measured. [Copyright &y& Elsevier]

Abstract: LiNi1/3Mn1/3Co1/3O2 (NMC) as a cathode material for lithium ion batteries has been synthesized by the sol–gel method. The X-ray diffraction Rietveld refinement results indicated that single-phase NMC with hexagonal layered structure was obtained. Scanning electron microscope images revealed well crystallized NMC with uniform particle size in the range of 100–200 nm. The performance of the NMC electrodes with sodium carboxylmethyl cellulose (CMC), poly(vinylidene fluoride) (PVDF), and alginate from brown algae as binders was compared. Constant current charge–discharge test results demonstrated that the NMC electrode using CMC as binder had the highest rate capability, followed by those using alginate and PVDF binders, respectively. Electrochemical impedance spectroscopy test results showed that the electrode using CMC as the binder had lower charge transfer resistance and lower apparent activation energy than the electrodes using alginate and PVDF as the binders. The apparent activation energies of NMC electrodes using CMC, alginate, and PVDF as binders were calculated to be 27.4 kJ mol−1, 33.7 kJ mol−1, and 36 kJ mol−1, respectively. [Copyright &y& Elsevier]

Abstract: A series of Li x CoPO4 (x =0.90, 0.95, 1, 1.05) compounds with different lithium content in the starting compositions were prepared by the sol–gel method. The phase identification was carried out by X-ray diffraction and neutron diffraction. The structure, atom positions, and occupancies were characterized by neutron diffraction. The morphology of Li x CoPO4 (x =0.90, 0.95, 1, 1.05) was examined by field emission scanning electron microscopy. Electrochemical analysis indicated that Li0.95CoPO4 presented the highest discharge capacity at various current densities among all the different x value compounds. The Li0.95CoPO4 showed better cycling stability and coulombic efficiency in the room temperature ionic liquid electrolyte ([C3mpyr][NTf2] containing 1M LiNTf2) at various current densities in the voltage range of 3.5–5.0V than in the conventional electrolyte (1M LiPF6 in ethylene carbonate:diethyl carbonate). [Copyright &y& Elsevier]

Nanocrystalline MnO2 was synthesized by the hydrothermal method with or without pulsed magnetic fields. It was found that the morphology of the MnO2 prepared without magnetic field has an urchin-like structure, while the MnO2 prepared with magnetic fields has a rambutan-like structure. A pronounced increase in the Brunauer–Emmett–Teller specific surface area was obtained when the intensities of the pulsed magnetic fields increased. The battery performances were improved for the samples prepared with magnetic fields. The MnO2 prepared under a magnetic field of 4 T shows a capacity of 121.8 mAh g−1, while the MnO2 prepared without magnetic field only shows 103.0 mAh g−1 after 30 cycles. [ABSTRACT FROM AUTHOR]

Abstract: Nickel sulfides, pure Ni3S2 and a mixture of Ni7S6–NiS, were synthesized through a solvothermal process. The nickel sulfide powders were characterized by X-ray diffraction, scanning electron microscopy, and electrochemical testing. The results showed that the capacity of NiS–Ni7S6 is much higher than that of Ni3S2, when used as the cathode in a lithium cell with an organic solvent-based electrolyte, l M lithium bis(trifluoromethanesulfonyl)amide (LiNTf2) in poly(ethylene glycol) dimethyl ether 500. The NiS–Ni7S6 electrodes were also tested with an ionic liquid electrolyte consisting of 1 M LiNTf2 in N-methyl-N-propyl pyrrolidinium bis(trifluoromethanesulfonyl)amide ([C3mpyr][NTf2]) to compare with organic-solvent based electrolytes. The results revealed that the ionic liquid is a useful solvent for use with this cathode material. [Copyright &y& Elsevier]

Abstract: Highly flexible and bendable free-standing polypyrrole (PPy) films were prepared using the electrochemical polymerization method. The paper-like films are soft, lightweight, mechanically robust, and highly electrically conductive. The morphologies and electrochemical behaviour of the free-standing pure PPy films were affected by the electrochemical polymerization conditions. The free-standing films show promise as cathodes for flexible and bendable batteries. [Copyright &y& Elsevier]

Recently, room‐temperature stationary sodium‐ion batteries (SIBs) have received extensive investigations for large‐scale energy storage systems (EESs) and smart grids due to the huge natural abundance and low cost of sodium. The SIBs share a similar "rocking‐chair" sodium storage mechanism with lithium‐ion batteries; thus, selecting appropriate electrodes with a low cost, satisfactory electrochemical performance, and high reliability is the key point for the development for SIBs. On the other hand, the carefully chosen elements in the electrodes also largely determine the cost of SIBs. Therefore, earth‐abundant‐metal‐based compounds are ideal candidates for reducing the cost of electrodes. Among all the high‐abundance and low‐cost metal elements, cathodes containing iron and/or manganese are the most representative ones that have attracted numerous studies up till now. Herein, recent advances on both iron‐ and manganese‐based cathodes of various types, such as polyanionic, layered oxide, MXene, and spinel, are highlighted. The structure–function property for the iron‐ and manganese‐based compounds is summarized and analyzed in detail. With the participation of iron and manganese in sodium‐based cathode materials, real applications of room‐temperature SIBs in large‐scale EESs will be greatly promoted and accelerated in the near future. State‐of‐the‐art high‐abundance and low‐cost metal‐based cathode materials for sodium‐ion batteries are comprehensively summarized and analyzed, providing a step toward the real‐life, commercial application of sodium‐ion batteries. Constructive suggestions and guidance are provided and future prospects regarding this promising field are discussed. [ABSTRACT FROM AUTHOR]

A composite of manganese monoxide loaded onto carbon nanotubes (CNTs@MnO) has been synthesized by a facile approach, in which the CNTs form a continuous conductive network connecting the electrocatalyst MnO nanoparticles together to facilitate good electrochemical performance. The electrocatalyst MnO shows favourable rechargeability, and good phase and morphology stability in lithium oxygen batteries. Excellent cycling performance is also demonstrated, in which the terminal voltage is higher than 2.4 V after 100 cycles at 0.4 mA cm−2, with 1000 mAh g−1(composite) capacity. Therefore, this hybrid material is promising for use as a cathode material for lithium oxygen batteries. [ABSTRACT FROM AUTHOR]

In this study, LiNi0.5Mn1.5O4 (LNMO) nanoparticles were prepared as a 5V cathode material via a rheological phase method and annealed at different temperatures: 680°C, 750°C, and 820°C. The sample annealed at 750°C shows the best performance. A room temperature ionic liquid (RTIL) containing 1M lithium bis(trifluoromethanesulfonyl) imide (LiNTf2) in N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl) imide (C4mpyrNTf2) was used as novel electrolyte in conjunction with the LNMO cathodes and their electrochemical properties have been investigated. The results show that the LNMO using RTIL as electrolyte has better coulombic efficiency and comparable discharge capacities to those of the cells assembled with standard liquid electrolyte (1M LiPF6 in ethylene carbonate/diethyl carbonate). Electrochemical impedance spectroscopy shows that the RTIL is much more stable as the electrolyte for LiNi0.5Mn1.5O4 than the conventional electrolyte. [ABSTRACT FROM AUTHOR]

Abstract: LiV3O8–polyaniline nanocomposites have been synthesized via chemical oxidative polymerization directed by the anionic surfactant sodium dodecyl benzene sulfate. The polyaniline particles are uniformly coated on the LiV3O8 nanorods. The composite with 12 wt.% polyaniline retains a discharge capacity of 204 mAh g−1 after 100 cycles and had better rate capability (175 mAh g−1 at 2 C and 145 mAh g−1 at 4 C) than the bare LiV3O8 electrode in the potential range of 1.5–4.0 V. The polyaniline coating can buffer the dissolution into the LiPF6 electrode that occurs in LiV3O8 during cycling. The charge transfer resistance of the composite electrode was much lower than that of the bare LiV3O8 electrode, indicating that polyaniline coating significantly increases the electrical conductivity between the LiV3O8 nanorods. Polyaniline is a conductive binder which buffers the dissolution of LiV3O8 into the electrolyte and reduces the contact resistance among nanorods, so performance of the composite is significantly improved. [Copyright &y& Elsevier]

Lithium-rich layered cathodes are known famously for its superior capacity over traditional layered oxides but trapped for lower initial coulombic efficiency, poorer rate capability and worse cyclic stability in spite of diverse attempts. Herein, a new K-stabilized Li-rich layered cathode synthesized through a simple oxalate co-precipitation is reported for its super electrochemical performances. Compared with pristine Li-rich layered cathode, K-stabilized one reaches a higher initial coulombic efficiency of 87% from 76% and outruns for 94% of capacity retention and 244 mAh g −1 of discharge capacity at 0.5C after 100 cycles. Moreover, 133 mAh g −1 of discharge capacity can be delivered even charged at 10C showing a highly-improved rate capability. X-ray diffraction and electrochemical impedance spectroscopy tests show that enlarged Li slab layer caused by K + accommodation can provide facile Li + diffusion paths and facilitate Li + migration from the crystal lattice. As a consequence, the introduction of K + in the host layered structure can inhibit the detrimental spinel structure growth during cycling. Therefore, the K-stabilized Li-rich layered materials can be considered to be an attractive alternative to meet with the higher power and energy density demands of advanced lithium-ion battery. [ABSTRACT FROM AUTHOR]

Porous hierarchical LiMn 0.5 Fe 0.5 PO 4 spheres were synthesized via a novel template-engaged method using pre-synthesized hollow spherical Li 3 PO 4 as template and FeCl 2 ·4H 2 O/MnCl 2 ·4H 2 O as Fe 2+ /Mn 2+ source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the porous hierarchical spheres exhibit hollow structure and have a size distribution of 0.4–1 um consisting of aggregated ∼50 nm nanoparticles. A mechanism of the reaction from Li 3 PO 4 to LiMn 0.5 Fe 0.5 PO 4 was proposed on the basis of the phase and morphology transformation of the intermediates. With the short Li + diffusion path and porous structure, the carbon coated LiMn 0.5 Fe 0.5 PO 4 spheres show high specific capacity and superior rate capability with the discharge capacities of 159.3 mA h g −1 at 0.1C and 80.6 mA h g −1 at 20C. The porous hierarchical spheres also exhibit an excellent cycling stability with about 90.7% of the initial value at 1C after 100 cycles. [ABSTRACT FROM AUTHOR]