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Oxygen redox in layered oxide cathodes for Na‐ion batteries is considered a promising approach for improving the energy density. However, oxygen‐redox‐based cathodes suffer from sluggish kinetics and undesirable structural change during charge/discharge, leading to poor electrochemical performances. Herein, introducing vacancies (□) in the transition metal layers enables the enhanced oxygen redox‐based electrochemical performances in the P3‐type Mn‐based layered oxide cathode is demonstrated. The vacancies can play a role of the local distortion buffers, resulting in the enhanced oxygen redox kinetics and the suppressed structural deformation such as P3‐O3(II) phase transition. The oxygen‐redox‐based P3‐type Na0.56[Ni0.1Mn0.81□0.09]O2 exhibits the large discharge capacity of ≈140.95 mAh g−1 at 26 mA g−1 with a high average discharge voltage of ≈3.54 V (vs Na+/Na). Even at 650 mA g−1, its discharge capacity and average operation voltages delivered ≈122.06 mAh g−1 and ≈3.22 V, respectively. Especially, the small gap of average discharge voltage indicates both improves power‐capability and enhanced kinetics of oxygen redox in P3‐type Na0.56[Ni0.1Mn0.81□0.09]O2. Moreover, the vacancy buffer in the transition metal layers results in the stable cycle‐performance of P3‐type Na0.56[Ni0.1Mn0.81□0.09]O2 with the capacity retention of ≈80.80% for 100 cycles, due to the suppressed P3‐O3(II) phase transition. [ABSTRACT FROM AUTHOR]

Although the high‐energy Ni‐rich layered cathodes suffer from undesirable surface reactions with the electrolyte, the polyvinylidene fluoride (PVDF) binder has a limitation on surface stabilization because of its weak affinity and low adhesion/cohesion. Here, it is demonstrated that the novel fluorine‐free and hydroxyl‐rich siloxane nanohybrid (SNH) binder can enhance the electrochemical performances of LiNi0.8Mn0.1Co0.1O2 cathode (NCM811) via successful surface stabilization. The high silanol content in the SNH binder enhances the affinity to both NCM811 and conductive agent, facilitating uniform electron/ion pathways with high mass loading, improved shear thinning, and superior mechanical properties. Moreover, the fluorine‐free organic‐inorganic hybrid structure prevents the dissolution of transition metals, active material structural changes, and electrolyte interaction, leading to greatly enhanced cyclability of the SNH‐based NCM811 electrode (≈81.9% in half‐cell; ≈87.82% in full‐cell after 200 cycles) compared to PVDF‐based NCM811 electrode (≈58.8% in half‐cell; ≈61.24% in full‐cell after 200 cycles). Various analyses also indicate that the application of the fluorine‐free SNH binder successfully stabilizes both the surface and bulk structure of the NCM811 cathode during charge/discharge. The binder design represents a straightforward yet highly effective approach to achieving remarkably prolonged cyclability in lithium‐ion batteries, surpassing the performance of other fluorine‐based or polymer‐based binders. [ABSTRACT FROM AUTHOR]

Batteries that utilize low‐cost elemental sulfur and light metallic lithium as electrodes have great potential in achieving high energy density. However, building a lithium–sulfur (Li–S) full battery by controlling the electrolyte volume generally produces low practical energy because of the limited electrochemical Li–S redox. Herein, the high energy/high performance of a Li–S full battery with practical sulfur loading and minimum electrolyte volume is reported. A unique hybrid architecture configured with Ni–Co metal alloy (NiCo) and metal oxide (NiCoO2) nanoparticles heterogeneously anchored in carbon nanotube‐embedded self‐standing carbon matrix is fabricated as a host for sulfur. This work demonstrates the considerable improvement that the hybrid structure's high conductivity and satisfactory porosity promote the transport of electrons and lithium ions in Li–S batteries. Through experimental and theoretical validations, the function of NiCo and NiCoO2 nanoparticles as an efficient polysulfide mediator is established. These particles afford polysulfide anchoring and catalytic sites for Li–S redox reaction, thus improving the redox conversion reversibility. Even at high sulfur loading, the nanostructured Ni–Co metal alloy and metal oxide enable to have stable cycling performance under lean electrolyte conditions both in half‐cell and full‐cell batteries using a graphite anode. [ABSTRACT FROM AUTHOR]

Developing sustainable Li‐ion batteries requires high‐energy cathodes based on low‐cost, earth‐abundant elements, moving away from low‐reserve nickel and cobalt. Fe‐based oxide cathodes with Fe3+/4+ and O2−/n− redox couples offer potential but face low initial Coulombic efficiency and significant voltage hysteresis. This study investigates Li‐excess Fe‐based disordered rock‐salt (DRX) oxyfluorides (Li2Fe0.5M0.5O2F; M = Fe, Ti, Mn) using combined electrochemical/spectroscopic characterization and first‐principles calculation. Oxygen‐dependent Fe3+/4+ redox, related to Fe 3d–O 2p hybrid state, can be stabilized when combined with Mn3+/4+ redox in DRX structure owing to the unusual decrease in its redox potential. The moderately high charge transfer gap stabilizes Fe4+ against ligand‐to‐metal charge transfer (LMCT) on charge, reduces the amount of oxygen oxidation, thereby increasing Coulombic efficiency. On discharge, it allows metal‐to‐ligand charge transfer (MLCT) without substantial overpotential, reducing hysteresis in oxygen redox. The resulting composition exhibits high capacity (309 mAh g−1) and energy density (998 Wh kg−1), providing insights for next‐generation Ni‐ and Co‐free cathode materials. [ABSTRACT FROM AUTHOR]

The need for safe secondary power sources has generated significant interest in the development of all-solid-state batteries. Despite the development of solid electrolytes with excellent Li-ion conductivity, the challenges inherent to forming an intimate and stable interface between the cathode active material and the solid electrolyte limit the potential performance of all-solid-state batteries. Herein, we propose an efficient process by which a thin and uniform coating of layered oxide cathodes with sulfide solid electrolytes (argyrodite Li6PS5Cl) may be obtained. The morphology of the coating agent with a thickness of approximately 30 nm and high uniformity is controlled by preparing Li6PS5Cl by one-pot synthesis. As a result, the material exhibits an excellent Li-ion conductivity of 4.6 mS cm−1 at a particle size of less than 1 μm. The controlled argyrodite Li6PS5Cl was directly coated onto the LiNi0.5Co0.2Mn0.3O2 cathode in an aprotic solvent environment. The coin-type all-solid-state cell developed using these argyrodite-coated cathode materials delivered a high discharge capacity of 149.6 mA h g−1 at 0.1C without additional external operating pressure during the charge–discharge process and retained 93.7% of its initial capacity after 100 cycles at 0.1C. It is revealed that the concrete contact between the LiNi0.5Co0.2Mn0.3O2 cathode and Li6PS5Cl suppresses the cathode degradation reactions. The proposed method for coated cathode materials, which features the synthesis of controlled sulfide solid electrolyte materials and their simple coating process in the liquid-phase, can accelerate the development of all-solid-state batteries. [ABSTRACT FROM AUTHOR]