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Sodium-oxygen batteries have been regarded as promising energy storage devices due to their low overpotential and high energy density. Its applications, however, still face formidable challenges due to the lack of understanding about the influence of electrocatalysts on the discharge products. Here, a phosphorous and nitrogen dual-doped carbon (PNDC) based cathode is synthesized to increase the electrocatalytic activity and to stabilize the NaO2 superoxide nanoparticle discharge products, leading to enhanced cycling stability when compared to the nitrogen-doped carbon (NDC). The PNDC air cathode exhibits a low overpotential (0.36 V) and long cycling stability (120 cycles). The reversible formation/decomposition and stabilization of the NaO2 discharge products are clearly proven by in-situ synchrotron X-ray diffraction and ex-situ X-ray diffraction. Based on the density functional theory calculation, the PNDC has much stronger adsorption energy (-2.85 eV) for NaO2 than that of NDC (-1.80 eV), which could efficiently stabilize the NaO2 discharge products., (© 2024 Wiley‐VCH GmbH.)

Intrinsically safe sodium-ion batteries are considered as a promising candidate for large-scale energy storage systems. However, the high flammability of conventional electrolytes may pose serious safety threats and even explosions. Herein, a strategy of constructing a deep eutectic electrolyte is proposed to boost the safety and electrochemical performance of succinonitrile (SN)-based electrolyte. The strong hydrogen bond between S═O of 1,3,2-dioxathiolane-2,2-dioxide (DTD) and the α-H of SN endows the enhanced safety and compatibility of SN with Lewis bases. Meanwhile, the DTD participates in the inner Na + sheath and weakens the coordination number of SN. The unique solvation configuration promotes the formation of robust gradient inorganic-rich electrode-electrolyte interphase, and merits stable cycling of half-cells in a wide temperature range, with a capacity retention of 82.8% after 800 cycles (25 °C) and 86.3% after 100 cycles (60 °C). Correspondingly, the full cells deliver tremendous improvement in cycling stability and rate performance., (© 2024 Wiley‐VCH GmbH.)

Zn deposition with a surface-preferred (002) crystal plane has attracted extensive attention due to its inhibited dendrite growth and side reactions. However, the nucleation and growth of the Zn(002) crystal plane are closely related to the interfacial properties. Herein, oriented growth of Zn(002) crystal plane is realized on Ag-modified surface that is directly visualized by in situ atomic force microscopy. A solid solution HCP-Zn (~1.10 at. % solubility of Ag, 30 °C) is formed on the Ag coated Zn foil (Zn@Ag) and possesses the same crystal structure as Zn to reduce its nucleation barrier caused by their lattice mismatch. It merits oriented Zn deposition and corrosion-resistant surface, and presents long cycling stability in symmetric cells and full cells coupled with V 2 O 5 cathode. This work provides insights into interfacial regulation of Zn anodes for high-performance aqueous zinc metal batteries., (© 2024 Wiley-VCH GmbH.)

Layered oxides have become the research focus of cathode materials for sodium-ion batteries (SIBs) due to the low cost, simple synthesis process, and high specific capacity. However, the poor air stability, unstable phase structure under high voltage, and slow anionic redox kinetics hinder their commercial application. In recent years, the concept of manipulating orbital hybridization has been proposed to simultaneously regulate the microelectronic structure and modify the surface chemistry environment intrinsically. In this review, the hybridization modes between atoms in 3d/4d transition metal (TM) orbitals and O 2p orbitals near the region of the Fermi energy level (E F ) are summarized based on orbital hybridization theory and first-principles calculations as well as various sophisticated characterizations. Furthermore, the underlying mechanisms are explored from macro-scale to micro-scale, including enhancing air stability, modulating high working voltage, and stabilizing anionic redox chemistry. Meanwhile, the origin, formation conditions, and different types of orbital hybridization, as well as its application in layered oxide cathodes are presented, which provide insights into the design and preparation of cathode materials. Ultimately, the main challenges in the development of orbital hybridization and its potential for the production application are also discussed, pointing out the route for high-performance practical sodium layered oxide cathodes., (© 2024 Wiley‐VCH GmbH.)

Alloying-type antimony (Sb) with high theoretical capacity is a promising anode candidate for both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Given the larger radius of Na + (1.02 Å) than Li + (0.76 Å), it was generally believed that the Sb anode would experience even worse capacity degradation in SIBs due to more substantial volumetric variations during cycling when compared to LIBs. However, the Sb anode in SIBs unexpectedly exhibited both better electrochemical and structural stability than in LIBs, and the mechanistic reasons that underlie this performance discrepancy remain undiscovered. Here, using substantial in situ transmission electron microscopy, X-ray diffraction, and Raman techniques complemented by theoretical simulations, we explicitly reveal that compared to the lithiation/delithiation process, sodiation/desodiation process of Sb anode displays a previously unexplored two-stage alloying/dealloying mechanism with polycrystalline and amorphous phases as the intermediates featuring improved resilience to mechanical damage, contributing to superior cycling stability in SIBs. Additionally, the better mechanical properties and weaker atomic interaction of Na-Sb alloys than Li-Sb alloys favor enabling mitigated mechanical stress, accounting for enhanced structural stability as unveiled by theoretical simulations. Our finding delineates the mechanistic origins of enhanced cycling stability of Sb anode in SIBs with potential implications for other large-volume-change electrode materials., (© 2024 Wiley-VCH GmbH.)

Non-aqueous solvents, in particular N,N-dimethylaniline (NMP), are widely applied for electrode fabrication since most sodium layered oxide cathode materials are readily damaged by water molecules. However, the expensive price and poisonousness of NMP unquestionably increase the cost of preparation and post-processing. Therefore, developing an intrinsically stable cathode material that can implement the water-soluble binder to fabricate an electrode is urgent. Herein, a stable nanosheet-like Mn-based cathode material is synthesized as a prototype to verify its practical applicability in sodium-ion batteries (SIBs). The as-prepared material displays excellent electrochemical performance and remarkable water stability, and it still maintains a satisfactory performance of 79.6% capacity retention after 500 cycles even after water treatment. The in situ X-ray diffraction (XRD) demonstrates that the synthesized material shows an absolute solid-solution reaction mechanism and near-zero-strain. Moreover, the electrochemical performance of the electrode fabricated with a water-soluble binder shows excellent long-cycling stability (67.9% capacity retention after 500 cycles). This work may offer new insights into the rational design of marvelous water stability cathode materials for practical SIBs., (© 2023 Wiley-VCH GmbH.)

Large reserves, high capacity, and low cost are the core competitiveness of disordered carbon materials as excellent anode materials for sodium-ion batteries (SIBs). And the existence and improper treatment of a large number of organic solid wastes will aggravate the burden on the environment, therefore, it is significant to transform wastes into carbon-based materials for sustainable energy utilization. Herein, a kind of hard carbon materials are reported with waste biomass-foam as the precursor, which can improve the sodium storage performance through pre-oxidation strategy. The introduction of oxygen-containing groups can promote structural cross-linking, and inhibit the melting and rearrangement of carbon structure during high-temperature carbonization that produces a disordered structure with a suitable degree of graphitization. Moreover, the micropore structure are also regulated during the high-temperature carbonization process, which is conducive to the storage of sodium ions in the low-voltage plateau region. The optimized sample as an electrode material exhibits excellent reversible specific capacity (308.0 mAh g -1 ) and initial Coulombic efficiency (ICE, 90.1%). In addition, a full cell with the waste foam-derived hard carbon anode and a Na 3 V 2 (PO 4 ) 3 cathode is constructed with high ICE and energy density. This work provides an effective strategy to conversion the waste to high-value hard carbon anode for sodium-ion batteries., (© 2023 Wiley‐VCH GmbH.)

Sodium dual-ion batteries (Na-DIBs) have attracted increasing attention due to their high operative voltages and low-cost raw materials. However, the practical applications of Na-DIBs are still hindered by the issues, such as low capacity and poor Coulombic efficiency, which is highly correlated with the compatibility between electrode and electrolyte but rarely investigated. Herein, fluoroethylene carbonate (FEC) is introduced into the electrolyte to regulate cation/anion solvation structure and the stability of cathode/anode-electrolyte interphase of Na-DIBs. The FEC modulates the environment of PF 6 - solvation sheath and facilitates the interaction of PF 6 - on graphite. In addition, the NaF-rich interphase caused by the preferential decomposition of FEC effectively inhibits side reactions and pulverization of anodes with the electrolyte. Consequently, Sb||graphite full cells in FEC-containing electrolyte achieve an improved capacity, cycling stability and Coulombic efficiency. This work elucidates the underlying mechanism of bifunctional FEC and provides an alternative strategy of building high-performance dual ion batteries., (© 2023 Wiley-VCH GmbH.)

In alkaline seawater electrolysis, the oxygen evolution reaction (OER) is greatly suppressed by the occurrence of electrode corrosion due to the formation of hypochlorite. Herein, a catalyst consisting of MoC nanowires modified with NiFe alloy nanoparticles (NiFe/MoC) on nickel foam (NF) is prepared. The optimized catalyst can deliver a large current density of 500 mA cm -2 at a very low overpotential of 366 mV in alkaline seawater, respectively, outperforming commercial IrO 2 . Remarkably, an electrolyzer assembled with NiFe/MoC/NF as the anode and NiMoN/NF as the cathode only requires 1.77 V to drive a current density of 500 mA cm -2 for alkaline seawater electrolysis, as well as excellent stability. Theory calculation indicates that the initial activity of NiFe/MoC is attributed to increased electrical conductivity and decreased energy barrier for OER due to the introduction of Fe. We find that the change of the catalyst in the composition occurred after the stability test; however, the reconstructed catalyst has an energy barrier close to that of the pristine one, which is responsible for its excellent long-term stability. Our findings provide an efficient way to construct high-performance OER catalysts for alkaline seawater splitting., (© 2023 Wiley-VCH GmbH.)

Hard carbon anodes with all-plateau capacities below 0.1 V are prerequisites to achieve high-energy-density sodium-ion storage, which holds promise for future sustainable energy technologies. However, challenges in removing defects and improving the insertion of sodium ions head off the development of hard carbon to achieve this goal. Herein, a highly cross-linked topological graphitized carbon using biomass corn cobs through a two-step rapid thermal-annealing strategy is reported. The topological graphitized carbon constructed with long-range graphene nanoribbons and cavities/tunnels provides a multidirectional insertion of sodium ions whilst eliminating defects to absorb sodium ions at the high voltage region. Evidence from advanced techniques including in situ XRD, in situ Raman, and in situ/ex situ transmission electron microscopy (TEM) indicates that the sodium ions' insertion and Na cluster formation occurred between curved topological graphite layers and in the topological cavity of adjacent graphite band entanglements. The reported topological insertion mechanism enables outstanding battery performance with a single full low-voltage plateau capacity of 290 mAh g -1 , which is almost 97% of the total capacity., (© 2023 Wiley-VCH GmbH.)

High-voltage lithium-ion batteries (LIBs) have attracted great attention due to their promising high energy density. However, severe capacity degradation is witnessed, which originated from the incompatible and unstable electrolyte-electrode interphase at high voltage. Herein, a robust additive-induced sulfur-rich interphase is constructed by introducing an additive with ultrahigh S-content (34.04 %, methylene methyl disulfonate, MMDS) in 4.6 V LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523)||graphite pouch cell. The MMDS does not directly participate the inner Li + sheath, but the strong interactions between MMDS and PF 6 - anions promote the preferential decomposition of MMDS and broaden the oxidation stability, facilitating the formation of an ultrathin but robust sulfur-rich interfacial layer. The electrolyte consumption, gas production, phase transformation and dissolution of transition metal ions were effectively inhibited. As expected, the 4.6 V NCM523||graphite pouch cell delivers a high capacity retention of 87.99 % even after 800 cycles. This work shares new insight into the sulfur-rich additive-induced electrolyte-electrode interphase for stable high-voltage LIBs., (© 2023 Wiley-VCH GmbH.)

Prussian blue analogues (PBAs) have been regarded as promising cathode materials for alkali-ion batteries owing to their high theoretical energy density and low cost. However, the high water and vacancy content of PBAs lower their energy density and bring safety issues, impeding their large-scale application. Herein, a facile "potassium-ions assisted" strategy is proposed to synthesize highly crystallized PBAs. By manipulating the dominant crystal plane and suppressing vacancies, the as-prepared PBAs exhibit increased redox potential resulting in high energy density up to ≈450 Wh kg -1 , which is at the same level of the well-known LiFePO 4 cathodes for lithium-ion batteries. Remarkably, unconventional highly-reversible phase evolution and redox-active pairs were identified by multiple in situ techniques for the first time. The preferred guest-ion storage sites and migration mechanism were systematically analysed through theoretical calculations. We believe these results could inspire the design of safe with high energy density., (© 2023 Wiley-VCH GmbH.)

It is still very urgent and challenging to simultaneously develop high-rate and long-cycle oxide cathodes for sodium-ion batteries (SIBs) because of the sluggish kinetics and complex multiphase evolution during cycling. Here, the concept of accurately manipulating structural evolution and formulating high-performance heterostructured biphasic layered oxide cathodes by local chemistry and orbital hybridization modulation is reported. The P2-structure stoichiometric composition of the cathode material shows a layered P2- and O3-type heterostructure that is explicitly evidenced by various macroscale and atomic-scale techniques. Surprisingly, the heterostructured cathode displays excellent rate performance, remarkable cycling stability (capacity retention of 82.16% after 600 cycles at 2 C), and outstanding compatibility with hard carbon anode because of the integrated advantages of intergrowth structure and local environment regulation. Meanwhile, the formation process from precursors during calcination and the highly reversible dynamic structural evolution during the Na + intercalation/deintercalation process are clearly articulated by a series of in situ characterization techniques. Also, the intrinsic structural properties and corresponding electrochemical behavior are further elucidated by the density of states and electron localization function of density functional theory calculations. Overall, this strategy, which finely tunes the local chemistry and orbitals hybridization for high-performance SIBs, will open up a new field for other materials., (© 2022 Wiley-VCH GmbH.)

Carbonaceous materials are considered strong candidates as anode materials for sodium-ion batteries (SIBs), which are expected to play an indispensable role in the carbon-neutral era. Herein, novel braided porous carbon fibres (BPCFs) are prepared using the chemical vapour deposition (CVD) method. The BPCFs possess interwoven porous structures and abundant vacancies. The growth mechanism of the BPCFs can be attributed to the polycrystalline transformation of the nanoporous copper catalyst in the early stage of CVD process. Density functional theory calculations suggest that the Na + adsorption energies of the mono-vacancy edges of the BPCFs (-1.22 and -1.09 eV) are lower than that of an ideal graphene layer (-0.68 eV), clarifying in detail the adsorption-dominated sodium storage mechanism. Hence, the BPCFs as an anode material present an outstanding discharge capacity of 401 mAh g -1 at 0.1 A g-1 after 500 cycles. Remarkably, this BPCFs anode, under high-mass-loading of 5 mg cm-2, shows excellent long-term cycling ability with a reversible capacity of 201 mAh g -1 at 10 A g -1 over 1000 cycles. This study provided a novel strategy for the development of high-performance carbonaceous materials for SIBs., (© 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.)

It is vital to dynamically regulate S activity to achieve efficient and stable room-temperature sodium-sulfur (RT/Na-S) batteries. Herein, we report using cobalt sulfide as an electron reservoir to enhance the activity of sulfur cathodes, and simultaneously combining with cobalt single atoms as double-end binding sites for a stable S conversion process. The rationally constructed CoS 2 electron reservoir enables the straight reduction of S to short-chain sodium polysulfides (Na 2 S 4 ) via a streamlined redox path through electron transfer. Meanwhile, cobalt single atoms synergistically work with the electron reservoir to reinforce the streamlined redox path, which immobilize in situ formed long-chain products and catalyze their conversion, thus realizing high S utilization and sustainable cycling stability. The as-developed sulfur cathodes exhibit a superior rate performance of 443 mAh g -1 at 5 A g -1 with a high cycling capacity retention of 80 % after 5000 cycles at 5 A g -1 ., (© 2022 Wiley-VCH GmbH.)

The shuttling behavior and sluggish conversion kinetics of the intermediate lithium polysulfides (LiPS) represent the main obstructions to the practical application of lithium-sulfur batteries (LSBs). Herein, a 1D π-d conjugated metal-organic framework (MOF), Ni-MOF-1D, is presented as an efficient sulfur host to overcome these limitations. Experimental results and density functional theory calculations demonstrate that Ni-MOF-1D is characterized by a remarkable binding strength for trapping soluble LiPS species. Ni-MOF-1D also acts as an effective catalyst for S reduction during the discharge process and Li 2 S oxidation during the charging process. In addition, the delocalization of electrons in the π-d system of Ni-MOF-1D provides a superior electrical conductivity to improve electron transfer. Thus, cathodes based on Ni-MOF-1D enable LSBs with excellent performance, for example, impressive cycling stability with over 82% capacity retention over 1000 cycles at 3 C, superior rate performance of 575 mAh g -1 at 8 C, and a high areal capacity of 6.63 mAh cm -2 under raised sulfur loading of 6.7 mg cm -2 . The strategies and advantages here demonstrated can be extended to a broader range of π-d conjugated MOFs materials, which the authors believe have a high potential as sulfur hosts in LSBs., (© 2022 Wiley-VCH GmbH.)

Porous carbon has been widely used as an efficient host to encapsulate highly active molecular sulfur (S) in Li-S and Na-S batteries. However, for these sub-nanosized pores, it is a challenge to provide fully accessible sodium ions with unobstructed channels during cycling, particularly for high sulfur content. It is well recognized that solid interphase with full coverage over the designed architectures plays critical roles in promoting rapid charge transfer and stable conversion reactions in batteries, whereas constructing a high-ionic-conductivity solid interphase in the pores is very difficult. Herein, unique continuous carbonaceous pores are tailored, which can serve as multifunctional channels to encapsulate highly active S and provide fully accessible pathways for sodium ions. Solid sodium sulfide interphase layers are also realized in the channels, showing high Na-ion conductivity toward stabilizing the redox kinetics of the S cathode during charge/discharge processes. This systematically designed carbon-hosted sulfur cathode delivers superior cycling performance (420 mAh g -1 at 2 A g -1 after 2000 cycles), high capacity retention of ≈90% over 500 cycles at current density of 0.5 A g -1 , and outstanding rate capability (470 mAh g -1 at 5 A g -1 ) for room-temperature sodium-sulfur batteries., (© 2022 Wiley-VCH GmbH.)

Silicon is considered the most promising candidate for anode material in lithium-ion batteries due to the high theoretical capacity. Unfortunately, the vast volume change and low electric conductivity have limited the application of silicon anodes. In the silicon anode system, the binders are essential for mechanical and conductive integrity. However, there are few reviews to comprehensively introduce binders from the perspective of factors affecting performance and modification methods, which are crucial to the development of binders. In this review, several key factors that have great impact on binders' performance are summarized, including molecular weight, interfacial bonding, and molecular structure. Moreover, some commonly used modification methods for binders are also provided to control these influencing factors and obtain the binders with better performance. Finally, to overcome the existing problems and challenges about binders, several possible development directions of binders are suggested., (© 2021 Wiley-VCH GmbH.)

The safety of energy storage equipment has always been a stumbling block to the development of battery, and sodium ion battery is no exception. However, as an ultimate solution, the use of non-flammable electrolyte is susceptible to the side effects, and its poor compatibility with electrode, causing failure of batteries. Here, we report a non-flammable electrolyte design to achieve high-performance sodium ion battery, which resolves the dilemma via regulating the solvation structure of electrolyte by hydrogen bonds and optimizing the electrode-electrolyte interphase. The reported non-flammable electrolyte allows stable charge-discharge cycling of both sodium vanadium phosphate@hard carbon and Prussian blue@hard carbon full pouch cell for more than 120 cycles with a capacity retention of >85 % and high cycling Coulombic efficiency (99.7 %)., (© 2021 Wiley-VCH GmbH.)

Metal-organic frameworks (MOFs) with intrinsically porous structures and well-dispersed metal sites are promising candidates for electrocatalysis; however, the catalytic efficiencies of most MOFs are significantly limited by their impertinent adsorption/desorption energy of intermediates formed during electrocatalysis and very low electrical conductivity. Herein, Co is introduced into conductive Cu-catecholate (Cu-CAT) nanorod arrays directly grown on a flexible carbon cloth for hydrogen evolution reaction (HER). Electrochemical results show that the Co-incorporated Cu-CAT nanorod arrays only need 52 and 143 mV overpotentials to drive a current density of 10 mA cm -2 in alkaline and neutral media for HER, respectively, much lower than most of the reported non-noble metal-based electrocatalysts and comparable to the benchmark Pt/C electrocatalyst. Density functional theory calculations show that the introduction of Co can optimize the adsorption energy of hydrogen (ΔG H* ) of Cu sites, almost close to that of Pt (111). Furthermore, the adsorption energy of water ( Δ E H 2 O ) of Co sites in the CuCo-CAT is significantly lower than that of Cu sites upon coupling Cu with Co, effectively accelerating the Volmer step in the HER process. The findings, synergistic effect of bimetals, open a new avenue for the rational design of highly efficient MOF-based electrocatalysts., (© 2021 Wiley-VCH GmbH.)

Alkali-metal/sulfur batteries hold great promise for offering relatively high energy density compared to conventional lithium-ion batteries. By providing viable sulfur composites that can be effectively used, carbonaceous hosts as a key component play critical roles in overcoming the preliminary challenges associated with the insulating sulfur and its relatively soluble polysulfides. Herein, a comprehensive overview and recent progress on carbonaceous hosts for advanced next-generation alkali-metal/sulfur batteries are presented. In order to encapsulate the highly active sulfur mass and fully limit polysulfide dissolution, strategies for tailoring the design and synthesis of carbonaceous hosts are summarized in this work. The sticking points that remain for sulfur cathodes in current alkali-metal/sulfur systems and the future remedies that can be provided by carbonaceous hosts are also indicated, which can lead to long cycling lifetimes and highly reversible capacities under repeated sulfur reduction reactions in alkali-metal/sulfur during cycling., (© 2021 Wiley-VCH GmbH.)

Intercalation-based anode materials can be considered as the most promising anode candidates for large-scale sodium-ion batteries (SIBs), owing to their long-term cycling stability and environmental friendliness, as well as their natural abundance. Nevertheless, their low energy density, low initial coulombic efficiency, and poor cycling lifespan, as well as sluggish sodium diffusion dynamics are still the main issues for the application of intercalation-based anode materials in SIBs in terms of meeting the benchmark requirements for commercialization. Over the past few years, tremendous efforts have been devoted to improving the performance of SIBs. In this Review, recent progress in the development of intercalation-based anode materials, including TiO 2 , Li 4 Ti 5 O 12 , Na 2 Ti 3 O 7 , and NaTi 2 (PO 4 ) 3 , is summarized in terms of their sodium storage performance, critical issues, sodiation/desodiation behavior, and effective strategies to enhance their electrochemical performance. Additionally, challenges and perspectives are provided to further understand these intercalation-based anode materials., (© 2021 Wiley-VCH GmbH.)

Manganese-based Prussian Blue, Na 2-δ Mn[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 Mn 2+ is oxidized to Mn 3+ . Herein, the structure is stabilized by a thin epitaxial surface layer of nickel-based Prussian Blue (Na 2-δ Ni[Fe(CN) 6 ]). The one-pot synthesis relies on a chelating agent with an unequal affinity for Mn 2+ and Ni 2+ ions, which prevents Ni 2+ from reacting until the Mn 2+ 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  cm 2  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., (© 2021 Wiley-VCH GmbH.)

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 K 1.84 Ni[Fe(CN) 6 ] 0.88 ⋅0.49 H 2 O (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., (© 2021 Wiley-VCH GmbH.)

High initial coulombic efficiency is highly desired because it implies effective interface construction and few electrolyte consumption, indicating enhanced batteries' life and power output. In this work, a high-capacity sodium storage material with FeS 2 nanoclusters (≈1-2 nm) embedded in N, S-doped carbon matrix (FeS 2 /N,S-C) was synthesized, the surface of which displays defects-repaired characteristic and detectable dot-matrix distributed Fe-N-C/Fe-S-C bonds. After the initial discharging process, the uniform ultra-thin NaF-rich (≈6.0 nm) solid electrolyte interphase was obtained, thereby achieving verifiable ultra-high initial coulombic efficiency (≈92 %). The defects-repaired surface provides perfect platform, and the catalysis of dot-matrix distributed Fe-N-C/Fe-S-C bonds to the rapid decomposing of NaSO 3 CF 3 and diethylene glycol dimethyl ether successfully accelerate the building of two-dimensional ultra-thin solid electrolyte interphase. DFT calculations further confirmed the catalysis mechanism. As a result, the constructed FeS 2 /N,S-C provides high reversible capacity (749.6 mAh g -1 at 0.1 A g -1 ) and outstanding cycle stability (92.7 %, 10 000 cycles, 10.0 A g -1 ). Especially, at -15 °C, it also obtains a reversible capacity of 211.7 mAh g -1 at 10.0 A g -1 . Assembled pouch-type cell performs potential application. The insight in this work provides a bright way to interface design for performance improvement in batteries., (© 2021 Wiley-VCH GmbH.)

Room-temperature (RT) sodium-sulfur (Na-S) batteries hold great promise for large-scale energy storage due to the advantages of high energy density, low cost, and resource abundance. The research progress on RT Na-S batteries, however, has been greatly hindered by the sluggish kinetics of the sulfur redox reactions. Herein, an elaborate multifunctional architecture, consisting of N-doped carbon skeletons and tunable MoS 2 sulfiphilic sites, is fabricated via a simple one-pot reaction followed by in situ sulfurization. Beyond the physical confinement and chemical binding of polarized N-doped carbonaceous microflowers, the MoS 2 active sites play a key role in catalyzing polysulfide redox reactions, especially the conversion from long-chain Na 2 S n (4 ≤ n ≤ 8) to short-chain Na 2 S 2 and Na 2 S. Significantly, the electrocatalytic activity of MoS 2 can be tunable via adjusting the discharge depth. It is remarkable that the sodiated MoS 2 exhibits much stronger binding energy and electrocatalytic behavior compared to MoS 2 sites, effectively enhancing the formation of the final Na 2 S product. Consequently, the S cathode achieves superior electrochemical performance in RT Na-S batteries, delivering a high capacity of 774.2 mAh g -1 after 800 cycles at 0.2 A g -1 , and an ultrahigh capacity retention with a capacity decay rate of only 0.0055% per cycle over 2800 cycles., (© 2021 Wiley-VCH GmbH.)

Rechargeable magnesium batteries (RMBs) are promising candidates for next-generation energy storage systems owing to their high safety and the low cost of magnesium resources. One of the main challenges for RMBs is to develop suitable high-performance cathode materials. Layered materials are one of the most promising cathode materials for RMBs due to their relatively high specific capacity and facile synthesis process. This review focuses on recent progress on layered cathode materials for RMBs, including layered oxides, sulfides, selenides, and other layered materials. In addition, effective strategies to improve the electrochemical performance of layered cathode materials are summarized. Moreover, future perspectives about the application of layered materials in RMBs are also discussed. This review provides some significant guidance for the further development of layered materials for RMBs., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein, we report a comprehensive strategy to synthesize a full range of single-atom metals on carbon matrix, including V, Mn, Fe, Co, Ni, Cu, Ge, Mo, Ru, Rh, Pd, Ag, In, Sn, W, Ir, Pt, Pb, and Bi. The extensive applications of various SACs are manifested via their ability to electro-catalyze typical hydrogen evolution reactions (HER) and conversion reactions in novel room-temperature sodium sulfur batteries (RT-Na-S). The enhanced performances for these electrochemical reactions arisen from the ability of different single active atoms on local structures to tune their electronic configuration. Significantly, the electrocatalytic behaviors of diverse SACs, assisted by density functional theory calculations, are systematically revealed by in situ synchrotron X-ray diffraction and in situ transmission electronic microscopy, providing a strategic library for the general synthesis and extensive applications of SACs in energy conversion and storage., (© 2020 Wiley-VCH GmbH.)

Graphite shows great potential as an anode material for rechargeable metal-ion batteries because of its high abundance and low cost. However, the electrochemical performance of graphite anode materials for rechargeable potassium-ion batteries needs to be further improved. Reported herein is a natural graphite with superior rate performance and cycling stability obtained through a unique K + -solvent co-intercalation mechanism in a 1 m KCF 3 SO 3 diethylene glycol dimethyl ether electrolyte. The co-intercalation mechanism was demonstrated by ex situ Fourier transform infrared spectroscopy and in situ X-ray diffraction. Moreover, the structure of the [K-solvent] + complexes intercalated with the graphite and the conditions for reversible K + -solvent co-intercalation into graphite are proposed based on the experimental results and first-principles calculations. This work provides important insights into the design of natural graphite for high-performance rechargeable potassium-ion batteries., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Titanium-based polyanions have been intensively investigated for sodium-ion batteries owing to their superior structural stability and thermal safety. However, their low working potential hindered further applications. Now, a cation and anion dual doping strategy is used to boost the redox potential of Ti-based cathodes of Na 3 Ti 0.5 V 0.5 (PO 3 ) 3 N as a new cathode material for sodium ion batteries. Both the Ti 3+ /Ti 4+ and V 3+ /V 4+ redox couples are reversibly accessed, leading to two distinctive voltage platforms at ca. 3.3 V and ca. 3.8 V, respectively. The remarkably improved cycling stability (86.3 %, 3000 cycles) can be ascribed to the near-zero volume strain in this unusual cubic symmetry, which has been demonstrated by in situ synchrotron-based X-ray diffraction. First-principles calculations reveal its well-interconnected 3D Na diffusion pathways with low energy barriers, and the two-sodium-extracted intermediate NaTi 0.5 V 0.5 (PO 3 ) 3 N is also a stable phase according to formation energy calculations., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lithium-ion batteries (LIBs) have been widely applied and studied as an effective energy supplement for a variety of electronic devices. Titanium dioxide (TiO 2 ), with a high theoretical capacity (335 mAh g -1 ) and low volume expansion ratio upon lithiation, has been considered as one of the most promising anode materials for LIBs. However, the application of TiO 2 is hindered by its low electrical conductivity and slow ionic diffusion rate. Herein, a 2D ultrathin mesoporous TiO 2 /reduced graphene (rGO) heterostructure is fabricated via a layer-by-layer assembly process. The synergistic effect of ultrathin mesoporous TiO 2 and the rGO nanosheets significantly enhances the ionic diffusion and electron conductivity of the composite. The introduced 2D mesoporous heterostructure delivers a significantly improved capacity of 350 mAh g -1 at a current density of 200 mA g -1 and excellent cycling stability, with a capacity of 245 mAh g -1 maintained over 1000 cycles at a high current density of 1 A g -1 . The in situ transmission electron microscopy analysis indicates that the volume of the as-prepared 2D heterostructures changes slightly upon the insertion and extraction of Li + , thus contributing to the enhanced long-cycle performance., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Structural evolution of the cathode during cycling plays a vital role in the electrochemical performance of sodium-ion batteries. A strategy based on engineering the crystal structure coupled with chemical substitution led to the design of the layered P2@P3 integrated spinel oxide cathode Na 0.5 Ni 0.1 Co 0.15 Mn 0.65 Mg 0.1 O 2 , which shows excellent sodium-ion half/full battery performance. Combined analyses involving scanning transmission electron microscopy with atomic resolution as well as in situ synchrotron-based X-ray absorption spectra and in situ synchrotron-based X-ray diffraction patterns led to visualization of the inherent layered P2@P3 integrated spinel structure, charge compensation mechanism, structural evolution, and phase transition. This study provides an in-depth understanding of the structure-performance relationship in this structure and opens up a novel field based on manipulating structural evolution for the design of high-performance battery cathodes., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Developing high-voltage cathode materials is critical for sodium-ion batteries to boost energy density. NASICON (Na super-ionic conductor)-structured Na x MnM(PO 4 ) 3 materials (M represents transition metal) have drawn increasing attention due to their features of robust crystal framework, low cost, as well as high voltage based on Mn 4+ /Mn 3+ and Mn 3+ /Mn 2+ redox couples. However, full activation of Mn 4+ /Mn 3+ redox couple within NASICON framework is still a great challenge. Herein, a novel NASICON-type Na 4 MnCr(PO 4 ) 3 material with highly reversible Mn 4+ /Mn 3+ redox reaction is discovered. It proceeds a two-step reaction with voltage platforms centered at 4.15 and 3.52 V versus Na + /Na, delivering a capacity of 108.4 mA h g -1 . The Na 4 MnCr(PO 4 ) 3 cathode also exhibits long durability over 500 cycles and impressive rate capability up to 10 C. The galvanostatic intermittent titration technique (GITT) test shows fast Na diffusivity which is further verified by density functional theory calculations. The high electrochemical activity derives from the 3D robust framework structure, fast kinetics, and pseudocapacitive contribution. The sodium storage mechanism of the Na 4 MnCr(PO 4 ) 3 cathode is deeply studied by ex situ X-ray diffraction (XRD) and ex situ X-ray photoelectron spectroscopy (XPS), revealing that both solid-solution and two-phase reactions are involved in the Na + ions extraction/insertion process., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Rechargeable room-temperature sodium-sulfur (RT-NaS) batteries represent one of the most attractive technologies for future stationary energy storage due to their high energy density and low cost. The S cathodes can react with Na ions via two-electron conversion reactions, thus achieving ultrahigh theoretical capacity (1672 mAh g -1 ) and specific energy (1273 Wh kg -1 ). Unfortunately, the sluggish reaction kinetics of the nonconductive S, severe polysulfide dissolution, and the use of metallic Na are causing enormous challenges for the development of RT-NaS batteries. Fatal polysulfide dissolution is highlighted, important studies toward polysulfide immobilization and conversion are presented, and the reported remedies in terms of intact physical confinement, strong chemical interaction, blocking layers, and optimization of electrolytes are summarized. Future research directions toward practical RT-NaS batteries are summarized., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Hierarchical hollow CoP and carbon composites were obtained through a facile synthetic method, where carbonization and phosphorization of the precursor were completed within one single step. The composites are composed of hollow CoP@C spheres, which are further made up of CoP nanoparticles with a thin outer carbon layer. Electrochemical performances of the prepared CoP@C composites as anodes for sodium and potassium storage were evaluated and compared. In situ TEM, in situ synchrotron XRD, and DFT calculations were conducted to study the structural evolution and the interaction between Na/K and CoP during cycling processes. Benefiting from the synergistic effect of conductive carbon layer and hierarchical hollow structure, the as-prepared CoP@C composites demonstrate superior sodium and potassium storage capability as anode materials for rechargeable batteries., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Herein, we introduce a 4.0 V class high-voltage cathode material with a newly recognized sodium superionic conductor (NASICON)-type structure with cubic symmetry (space group P2 1 3), Na 3 V(PO 3 ) 3 N. We synthesize an N-doped graphene oxide-wrapped Na 3 V(PO 3 ) 3 N composite with a uniform carbon coating layer, which shows excellent rate performance and outstanding cycling stability. Its air/water stability and all-climate performance were carefully investigated. A near-zero volume change (ca. 0.40 %) was observed for the first time based on in situ synchrotron X-ray diffraction, and the in situ X-ray absorption spectra revealed the V 3.2+ /V 4.2+ redox reaction with high reversibility. Its 3D sodium diffusion pathways were demonstrated with distinctive low energy barriers. Our results indicate that this high-voltage NASICON-type Na 3 V(PO 3 ) 3 N composite is a competitive cathode material for sodium-ion batteries and will receive more attention and studies in the future., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Applications of room-temperature-sodium sulfur (RT-Na/S) batteries are currently impeded by the insulating nature of sulfur, the slow redox kinetics of sulfur with sodium, and the dissolution and migration of sodium polysulfides. Herein, a novel micrometer-sized hierarchical S cathode supported by FeS 2 electrocatalyst, which is grown in situ in well-confined carbon nanocage assemblies, is presented. The hierarchical carbon matrix can provide multiple physical entrapment to polysulfides, and the FeS 2 nanograins exhibit a low Na-ion diffusion barrier, strong binding energy, and high affinity for sodium polysulfides. Their combination makes it an ideal sulfur host to immobilize the polysulfides and achieve reversible conversion of polysulfides toward Na 2 S. Importantly, the hierarchical S cathode is suitable for large-scale production via the inexpensive and green spray-drying method. The porous hierarchical S cathode offers a high sulfur content of 65.5 wt%, and can deliver high reversible capacity (524 mAh g -1 over 300 cycles at 0.1 A g -1 ) and outstanding rate capability (395 mAh g -1 at 1 A g -1 for 850 cycles), holding great promise for both scientific research and real application., (© 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Emerging rechargeable sodium-ion storage systems-sodium-ion and room-temperature sodium-sulfur (RT-NaS) batteries-are gaining extensive research interest as low-cost options for large-scale energy-storage applications. Owing to their abundance, easy accessibility, and unique physical and chemical properties, sulfur-based materials, in particular metal sulfides (MS x ) and elemental sulfur (S), are currently regarded as promising electrode candidates for Na-storage technologies with high capacity and excellent redox reversibility based on multielectron conversion reactions. Here, we present current understanding of Na-storage mechanisms of the S-based electrode materials. Recent progress and strategies for improving electronic conductivity and tolerating volume variations of the MS x anodes in Na-ion batteries are reviewed. In addition, current advances on S cathodes in RT-NaS batteries are presented. We outline a novel emerging concept of integrating MS x electrocatalysts into conventional carbonaceous matrices as effective polarized S hosts in RT-NaS batteries as well. This comprehensive progress report could provide guidance for research toward the development of S-based materials for the future Na-storage techniques., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two-dimensional (2D) superlattices offer promising technological opportunities in tuning the intercalation chemistry of metal ions. Now, well-ordered 2D superlattices of monolayer titania and carbon with tunable interlayer-spacing are synthesized by a molecularly mediated thermally induced approach. The 2D superlattices are vertically encapsulated in hollow carbon nanospheres, which are embedded with TiO 2 quantum dots, forming a 0D-2D-3D multi-dimensional architecture. The multi-dimensional architecture with the 2D superlattices encapsulated inside exhibits a near zero-strain characteristic and enriched electrochemical reactivity, achieving a highly efficient Na + storage performance with exceptional rate capability and superior long-term cyclability., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general π-electron-assisted strategy to anchor single-atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The M atoms can simultaneously anchor on two distinct domains of the hybrid support, four-fold N/C atoms (M@NC), and centers of Co octahedra (M@Co), which are expected to serve as bifunctional electrocatalysts towards the HER and the OER. The Ir catalyst exhibits the best water-splitting performance, showing a low applied potential of 1.603 V to achieve 10 mA cm -2 in 1.0 m KOH solution with cycling over 5 h. DFT calculations indicate that the Ir@Co (Ir) sites can accelerate the OER, while the Ir@NC 3 sites are responsible for the enhanced HER, clarifying the unprecedented performance of this bifunctional catalyst towards full water splitting., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Sodium-ion batteries (SIBs) are attracting increasing attention and considered to be a low-cost complement or an alternative to lithium-ion batteries (LIBs), especially for large-scale energy storage. Their application, however, is limited because of the lack of suitable host materials to reversibly intercalate Na + ions. Layered transition metal oxides (Na x MO 2 , M = Fe, Mn, Ni, Co, Cr, Ti, V, and their combinations) appear to be promising cathode candidates for SIBs due to their simple structure, ease of synthesis, high operating potential, and feasibility for commercial production. In the present work, the structural evolution, electrochemical performance, and recent progress of Na x MO 2 as cathode materials for SIBs are reviewed and summarized. Moreover, the existing drawbacks are discussed and several strategies are proposed to help alleviate these issues. In addition, the exploration of full cells based on Na x MO 2 cathodes and future perspectives are discussed to provide guidance for the future commercialization of such systems., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Prussian blue analogues (PBAs, A 2 T[M(CN) 6 ], A = Li, K, Na; T = Fe, Co, Ni, Mn, Cu, etc.; M = Fe, Mn, Co, etc.) are a large family of materials with an open framework structure. In recent years, they have been intensively investigated as active materials in the field of energy conversion and storage, such as for alkaline-ion batteries (lithium-ion, LIBs; sodium-ion, NIB; and potassium-ion, KIBs), and as electrochemical catalysts. Nevertheless, few review papers have focused on the intrinsic chemical and structural properties of Prussian blue (PB) and its analogues. In this Review, a comprehensive insight into the PBAs in terms of their structural and chemical properties, and the effects of these properties on their materials synthesis and corresponding performance is provided., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Structural modulation and surface engineering have remarkable advantages for fast and efficient charge storage. Herein, we present a phosphorus modulation strategy which simultaneously realizes surface structural disorder with interior atomic-level P-doping to boost the Na + storage kinetics of TiO 2 . It is found that the P-modulated TiO 2 nanocrystals exhibit a favourable electronic structure, and enhanced structural stability, Na + transfer kinetics, as well as surface electrochemical reactivity, resulting in a genuine zero-strain characteristic with only approximately 0.1 % volume variation during Na + insertion/extraction, and exceptional Na + storage performance including an ultrahigh rate capability of 210 mAh g -1 at 50 C and a strong long-term cycling stability without significant capacity decay up to 5000 cycles at 30 C., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Low-cost layered oxides free of Ni and Co are considered to be the most promising cathode materials for future sodium-ion batteries. Biphasic Na 0.78 Cu 0.27 Zn 0.06 Mn 0.67 O 2 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 Cu 2+/3+ redox reaction mechanism has now been revealed., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Highly reversible, stable, and non-dendritic metal anode (Li, Na etc.) is a crucial requirement for next-generation high-energy batteries. Herein, we have built a Li-Na hybrid battery (LNHB) based on Na plating/stripping, which features a high and stable coulombic efficiency of 99.2 % after 100 cycles, low voltage hysteresis (42 mV at 2 mA cm -2 ), and fast charge transfer. As a result of the Li + electrostatic shield layer, the Na deposition showed cubic morphology rather than dendritic, even at high current density of 5 mA cm -2 . The solvation/desolvation of Li + and Na + were modelled by density functional theory calculations, demonstrating the fast desolvation kinetics of Na + . Owing to the superior performance of the Na metal anode, the LNHB coupled with LiFePO 4 cathode exhibited low voltage hysteresis and stable cycling performance that demonstrates its feasibility in practical applications., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Lithium-sulfur (Li-S) batteries are considered as promising candidates for energy storage systems owing to their high theoretical capacity and high energy density. The application of Li-S batteries is hindered by several obstacles, however, including the shuttle effect, poor electrical conductivity, and the severe volume expansion of sulfur. The traditional method is to integrate sulfur with carbon materials. But the interaction between polysulfide intermediates and carbon is only weak physical adsorption, which easily leads to the escape of species from the framework (shuttle effect) of the material causing capacity loss. Recently, however, there has been a trend for the introduction of novel non-carbon materials as sulfur hosts based on the strong chemisorption. This review highlights recent research progress on novel non-carbon sulfur hosts based on strong chemisorption, in Li-S batteries. In comparison with carbon-based sulfur hosts, most non-carbon sulfur hosts have been demonstrated to be polar host materials that could efficiently adsorb polysulfide via strong chemisorption, mitigating their dissolution. The intrinsic mechanism associated with the role of non-carbon-based host materials in improving the performance of Li-S batteries is discussed., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

With the serious impact of fossil fuels on the environment and the rapid development of the global economy, the development of clean and usable energy storage devices has become one of the most important themes of sustainable development in the world today. Supercapacitors are a new type of green energy storage device, with high power density, long cycle life, wide temperature range, and both economic and environmental advantages. In many industries, they have enormous application prospects. Electrode materials are an important factor affecting the performance of supercapacitors. MnO 2 -based materials are widely investigated for supercapacitors because of their high theoretical capacitance, good chemical stability, low cost, and environmental friendliness. To achieve high specific capacitance and high rate capability, the current best solution is to use MnO 2 and carbon composite materials. Herein, MnO 2 -carbon composite as supercapacitor electrode materials is reviewed including the synthesis method and research status in recent years. Finally, the challenges and future development directions of an MnO 2 -carbon based supercapacitor are summarized., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Clean energy has become an important topic in recent decades because of the serious global issues related to the development of energy, such as environmental contamination, and the intermittence of the traditional energy sources. Creating new battery-related energy storage facilities is an urgent subject for human beings to address and for solutions for the future. Compared with lithium-based batteries, sodium-ion batteries have become the new focal point in the competition for clean energy solutions and have more potential for commercialization due to the huge natural abundance of sodium. Nevertheless, sodium-ion batteries still exhibit some challenges, like inferior electrochemical performance caused by the bigger ionic size of Na + ions, the detrimental volume expansion, and the low conductivity of the active materials. To solve these issues, nanocomposites have recently been applied as a new class of electrodes to enhance the electrochemical performance in sodium batteries based on advantages that include the size effect, high stability, and excellent conductivity. In this Review, the recent development of nanocomposite materials applied in sodium-ion batteries is summarized, and the existing challenges and the potential solutions are presented., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)