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Sodium‐ion batteries (SIBs) have been recognized as one of the most promising new energy storage devices for their rich sodium resources, low cost and high safety. The electrolyte, as a bridge connecting the cathode and anode electrodes, plays a vital role in determining the performance of SIBs, such as coulombic efficiency, energy density and cycle life. Therefore, the overall performance of SIBs could be significantly improved by adjusting the electrolyte composition or adding a small number of functional additives. In this review, the fundamentals of SIB electrolytes including electrode‐electrolyte interface and solvation structure are introduced. Then, the mechanisms of electrolyte additive action on SIBs are discussed, with a focus on film‐forming additives, flame‐retardant additives and overcharge protection additives. Finally, the future research of electrolytes is prospected from the perspective of scientific concepts and practical applications. [ABSTRACT FROM AUTHOR]

Sodium super ionic conductor (NASICON)‐type Li1.3Al0.3Ti1.7(PO4)3 (LATP) is one of the most promising solid‐state electrolytes (SSEs) owing to its high Li‐ion conductivity, high stability with air, and low cost. However, LATP is less widely deployed due to its high incompatibility with lithium metal. Herein, a facile and inexpensive spray‐coating approach is proposed to construct a thin 3D organic/inorganic composite layer of a commercial boron nitride‐based release agent (BNRA) onto LATP. Apart from protecting LATP, this interfacial BNRA layer enables Li‐ion migration through BN defects and affords low resistance at BNRA/Li interface due to in situ formation of Li–N. Compared to bare LATP, which fails to support Li stripping–plating process in a lean‐lithium Li/Li symmetric cell (2 µm), BNRA‐LATP runs for ≈1800 h. The assembled lean‐lithium LiFePO4 (LFP)/BNRA‐LATP/Li solid state batteries (SSBs) deliver a specific capacity of 150.9 mA h g–1 at 0.5 C with minor capacity decay after 500 cycles. Besides, the BNRA layer eliminates thermal runaway risks of LATP‐based SSBs by fast in‐plane thermal dispersion. This work demonstrates a facile LATP‐protection strategy regarding Li incompatibility and thermal runway issues, and pinpoints the interfacial formation mechanism, fulfilling the pursuit of high‐performance low‐cost SSEs. [ABSTRACT FROM AUTHOR]

O3-type layered oxides are highly promising cathodes for sodium-ion batteries (SIBs), however they undergo complex phase transitions and exhibit high sensibility to air, leading to subpar cycling performance and commercial viability. In this work, we report a layered cathode material (NaNi0.29Cu0.1Mg0.05Li0.05Mn0.2Ti0.2Sn0.11O2) with a sate-of-the-art high-entropy compositional design. We unveil that such a configuration featuring inhomogeneous coordination environment of transition metal (TM) elements, can enable enhanced gliding energy (-0.38 vs -0.58 eV) of TMO2 slabs upon desodiation both theoretically and experimentally, which underlies the fundamental origin of the outstanding structural stability of HEO materials. As a consequence, the complex phase transitions (O3-O'3-P3-P'3-P3'-O3') of conventional O3-type cathode have been eliminated, and the as-obtained material demonstrates exceptional structural robustness and integrity with an ultra-long cycle life in a quasi-solid-state cell (maintaining 73.2% capacity after 1000 cycles at 2 C). Moreover, the material presents satisfactory air stability, with minimal structural and electrochemical degradation when directly exposed to the air. An Ah-scale pouch cell based on the cathode material is constructed, demonstrating a capacity retention of 83.6% after 500 cycles, signaling substantial promise for commercial applications., (© 2024 Wiley‐VCH GmbH.)

High voltage spinel LiMn 1.5 Ni 0.5 O 4 (LMNO) is a promising energy storage material for the next generation lithium batteries with high energy densities. However, due to the major controversies in synthesis, structure, and interfacial properties of LMNO, its unsatisfactory performance is still a challenge hindering the technology's practical applications. Herein, this paper provides general characteristics of LiMn 1.5 Ni 0.5 O 4 such as spinel structure, electrochemical properties, and phase transition. In addition, factors such as electrolyte decomposition and morphology of LMNO that influence the electrochemical performances of LMNO are introduced. The strategies that enhance the electrochemical performances including coating, doping, electrolytes, and oxygen deficiency are comprehensively discussed. Through the discussion of the present research status and presentation of our perspectives on future development, we provide the rational design of LMNO in realizing lithium-ion batteries with improved electrochemical performances., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Sodium-ion batteries (SIBs) have been recognized as one of the most promising new energy storage devices for their rich sodium resources, low cost and high safety. The electrolyte, as a bridge connecting the cathode and anode electrodes, plays a vital role in determining the performance of SIBs, such as coulombic efficiency, energy density and cycle life. Therefore, the overall performance of SIBs could be significantly improved by adjusting the electrolyte composition or adding a small number of functional additives. In this review, the fundamentals of SIB electrolytes including electrode-electrolyte interface and solvation structure are introduced. Then, the mechanisms of electrolyte additive action on SIBs are discussed, with a focus on film-forming additives, flame-retardant additives and overcharge protection additives. Finally, the future research of electrolytes is prospected from the perspective of scientific concepts and practical applications., (© 2023 Wiley-VCH GmbH.)