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Manganese‐based layered oxides are currently of significant interest as cathode materials for sodium‐ion batteries due to their low toxicity and high specific capacity. However, the practical applications are impeded by sluggish intrinsic Na+ migration and poor structure stability as a result of Jahn–Teller distortion and complicated phase transition. In this study, a high‐entropy strategy is proposed to enhance the high‐voltage capacity and cycling stability. The designed P2‐Na0.67Mn0.6Cu0.08Ni0.09Fe0.18Ti0.05O2 achieves a deeply desodiation and delivers charging capacity of 158.1 mAh g−1 corresponding to 0.61 Na with a high initial Coulombic efficiency of 98.2 %. The charge compensation is attributed to the cationic and anionic redox reactions conjunctively. Moreover, the crystal structure is effectively stabilized, leading to a slight variation of lattice parameters. This research carries implications for the expedited development of low‐cost, high‐energy‐density cathode materials for sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Over recent decades, rapid advancements in energy technology have transformed human life. Lithium‐ion batteries (LIBs) have played a pivotal role nevertheless concerns about limited lithium resources and price fluctuations underscore the need for sustainability. Sodium‐ion batteries (SIBs), operating on principles akin to LIBs, have emerged as promising candidates for rechargeable batteries in the next generation of energy storage systems, primarily due to their cost‐effectiveness and sustainable attributes. Analogous to LIBs, the cathode in SIBs assumes a critical role in dictating the electrochemical performance of the battery. Therefore, the research and development of cathode materials for SIBs take on paramount significance. O3‐type SIB cathodes, inspired by the successful O3‐type LIB cathodes (e. g., LiCoO2 and NMC variants), hold promise for commercial applications. This comprehensive overview offers an in‐depth exploration of various unary‐metal oxide cathode materials characterized by an O3‐layered structure. Subsequently, nickel (Ni), manganese (Mn), and Ni/Mn‐based O3 cathode materials are conducted a comprehensive study, assessing the effects of element substitution and doping on capacity, phase transitions, and cycle life. In light of the current challenges, advancing SIB cathode materials of future directions will propose, addressing key considerations in the pursuit of enhanced performance and sustainable energy storage solutions. [ABSTRACT FROM AUTHOR]

Lattice‐oxygen redox in layered metal oxide cathodes offers a promising way to exploit high‐energy density sodium‐ion batteries. However, oxidation and reduction of lattice‐oxygen are always asymmetric, showing poor reversibility upon charging and discharging due to the activated oxygen loss and subsequent structural rearrangement. Here, a layered Na0.7[Li0.2Mn0.7Co0.1]O2 (NLMCO) is developed by balancing lattice‐oxygen activity and reversibility, which can deliver a record energy density of 729.7 Wh kg−1, further exceeding the state‐of‐the‐art Na0.75[Li0.25Mn0.75]O2 (NLMO, 638.4 Wh kg−1). In light of electron paramagnetic resonance spectroscopy, in situ differential electrochemical mass spectroscopy, and electrochemical testing results, the highly activated lattice‐oxygen is effectively stabilized in NLMCO without oxygen molecule release while obvious oxygen release is detected in the highly activated NLMO. Benefiting from the enhanced transition metal‐oxygen covalency and reduced band energy gap, the NLMCO electrode demonstrates simultaneously high lattice‐oxygen activity and reversibility, thus resulting in excellent rate and cycling performance, as well as ultra‐high energy density. The findings highlight the critical association of energy density and lattice‐oxygen redox reversibility, which will inspire more interest in anionic redox‐based high‐energy batteries. [ABSTRACT FROM AUTHOR]

Cation migration often occurs in layered oxide cathodes of lithium‐ion batteries due to the similar ion radius of Li and transition metals (TMs). Although Na and TM show a big difference of ion radius, TMs in layered cathodes of sodium‐ion batteries (SIBs) can still migrate to Na layer, leading to serious electrochemical degeneration. To elucidate the origin of TM migration in layered SIB cathodes, we choose NaCrO2, a typical layered cathode suffering from serious TM migration, as a model material and find that the TM migration is derived from the random desodiation and subsequent formation of Na‐free layer at high charge potential. A Ru/Ti co‐doping strategy is developed to address the issue, where the doped active Ru is first oxidized to create a selective desodiation and the doped inactive Ti can function as a pillar to avoid complete desodiation in Ru‐contained TM layers, leading to the suppression of the Na‐free layer formation and subsequent enhanced electrochemical performance. [ABSTRACT FROM AUTHOR]

Surface Lattice-Matched Engineering Based on In Situ Spinel Interfacial Reconstruction for Stable Heterostructured Sodium Layered Oxide Cathodes (Adv. Funct. Keywords: air stability; heterostructures; layered oxide cathodes; sodium-ion batteries; spinel engineering EN air stability heterostructures layered oxide cathodes sodium-ion batteries spinel engineering 1 1 1 04/06/23 20230404 NES 230404 B Layered Oxide Cathodes b In article number 2213215, Yao Xiao, Shu-Lei Chou, Jia-Zhao Wang, Yan-Fang Zhu, and co-workers propose a concept of surface lattice-matched engineering 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. Air stability, heterostructures, layered oxide cathodes, sodium-ion batteries, spinel engineering. [Extracted from the article]

The development of new insertion electrodes in sodium-ion batteries requires an in-depth understanding of the relationship between electrochemical performance and the structural evolution during cycling. To date in situ synchrotron X-ray and neutron diffraction methods appear to be the only probes of in situ electrode evolution at high rates, a critical condition for battery development. Here, the structural evolution of the recently synthesized O3-phase of Na2/3Fe2/3Mn1/3O2 is reported under relatively high current rates. The evolution of the phases, their lattice parameters, and phase fractions, and the sodium content in the crystal structure as a function of the charge/discharge process are shown. It is found that the O3-phase persists throughout the charge/discharge cycle but undergoes a series of two-phase and solid-solution transitions subtly modifying the sodium content and atomic positions but keeping the overall space-group symmetry (structural motif). In addition, for the first time, evidence of a structurally characterized region is shown that undergoes two-phase and solid-solution phase transitions simultaneously. The Mn/Fe-O bond lengths, c lattice parameter evolution, and the distance between the Mn/FeO6 layers are shown to concertedly change in a favorable manner for Na+ insertion/extraction. The exceptional electrochemical performance of this electrode can be related in part to the electrode maintaining the O3-phase throughout the charge/discharge process. [ABSTRACT FROM AUTHOR]

Owing to the nonleakage and incombustibility, solid electrolytes are crucial for solving the safety issues of rechargeable lithium batteries. In this work, a new class of solid electrolyte, acceptor‐doped LiTaSiO5, is designed and synthesized based on the concerted migration mechanism. When Zr4+ is doped to the Ta5+ sites in LiTaSiO5, the high‐energy lattice sites are partly occupied by the introduced lithium ions, and the lithium ions at those sites interact with the lithium ions placed in the low‐energy sites, thereby favoring the concerted motion of lithium ions and lowering the energy barrier for ion transport. Therefore, the concerted migration of lithium ions occurs in Zr‐doped LiTaSiO5, and a 3D lithium‐ion diffusion network is established with quasi‐1D chains connected through interchain channels. The lithium‐ion occupation, as revealed by ab initio calculations, is validated by neutron powder diffraction. Zr‐doped LiTaSiO5 electrolytes are successfully synthesized; Li1.1Ta0.9Zr0.1SiO5 shows a conductivity of 2.97 × 10−5 S cm−1 at 25 °C, about two orders of magnitude higher than that of LiTaSiO5, and it increases to 3.11 × 10−4 S cm−1 at 100 °C. This work demonstrates the power of theory in designing new materials. [ABSTRACT FROM AUTHOR]

Alloy-based materials (i.e. Sn, Sb, P) are promising candidates for sodium-ion battery (SIB) anodes, but they suffer from capacity decay during charge/discharge cycling due to the pulverization caused by their huge volume change. Nanostructures can slow down the capacity fade, but most of the synthesis methods of such nanostructured anodes are difficult to scale-up. Herein, a ternary Sn 5 SbP 3 /C composite was fabricated by a green, low cost, one-step and easily scalable ball-milling of elementary Sn, Sb, P, and C. The microstructure of the ball-milled powders consists of micrometric agglomerates of active nano Sn 4 P 3 and SnSb and Sn particles. Carbon in the composite acts as a conducting matrix, and it does not only benefit to the ball milling efficiency, but also benefit to the cycle life of the electrode. Each of the active Sn 4 P 3 and SnSb and Sn phases in the composite functions mutually as a buffer for the others. As a result, this ternary composite anode delivers a good capacity of 352 mA h g −1 at the current density of 2 A g −1 , which is notably higher than that of the binary Sn 4 P 3 /C and SnSb/C composites produced under the same conditions. [ABSTRACT FROM AUTHOR]