In battery electrolyte design principles, tuning Li+ solvation structure is an effective way to connect electrolyte chemistry with interfacial chemistry. Although recent proposed solvation tuning strategies are able to improve battery cyclability, a comprehensive strategy for electrolyte design remains imperative. Here, we report a solvation tuning strategy by utilizing molecular steric effect to create a “bulky coordinating” structure. Based on this strategy, the designed electrolyte generates an inorganic-rich solid electrolyte interphase (SEI) and cathode–electrolyte interphase (CEI), leading to excellent compatibility with both Li metal anodes and high-voltage cathodes. Under an ultrahigh voltage of 4.6 V, Li/NMC811 full-cells (N/P = 2.0) hold an 84.1% capacity retention over 150 cycles and industrial Li/NMC811 pouch cells realize an energy density of 495 Wh kg–1. This study provides innovative insights into Li+ solvation tuning for electrolyte engineering and offers a promising path toward developing high-energy Li metal batteries.

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Improved durability, enhanced interfacial stability, and room temperature applicability are desirable properties for all‐solid‐state lithium metal batteries (ASSLMBs), yet these desired properties are rarely achieved simultaneously. Here, in this work, it is noticed that the huge resistance at Li metal/electrolyte interface dominantly impeded the normal cycling of ASSLMBs especially at around room temperature (<30 °C). Accordingly, a supramolecular polymer ion conductor (SPC) with “weak solvation” of Li+ was prepared. Benefiting from the halogen‐bonding interaction between the electron‐deficient iodine atom (on 1,4‐diiodotetrafluorobenzene) and electron‐rich oxygen atoms (on ethylene oxide), the O‐Li+ coordination was significantly weakened. Therefore, the SPC achieves rapid Li+ transport with high Li+ transference number, and importantly, derives a unique Li2O‐rich SEI with low interfacial resistance on lithium metal surface, therefore enabling stable cycling of ASSLMBs even down to 10 °C. This work is a new exploration of halogen‐bonding chemistry in solid polymer electrolyte and highlights the importance of “weak solvation” of Li+ in the solid‐state electrolyte for room temperature ASSLMBs.

Li metal is regarded as the most promising battery anode to boost energy density. However, being faced with the hostile compatibility between the Li anode and traditional carbonate electrolyte, its large-scale industrialization has been in a distressing circumstance due to severe dendrite growth caused by unsatisfying solid electrolyte interphase (SEI). With this regard, accurate control over the composition of the SEI is urgently desired to tackle the electrochemical and mechanical instability at the electrolyte/anode interface. Herein, we report a rationally designed fluorinated carbamate-based electrolyte employing LiNO 3 as one of the main salts to induce the preferable anion decomposition to achieve a homogeneous and inorganic (LiF, Li 3 N, Li 2 O)-rich SEI. Thus, this electrolyte achieves a high Coulombic efficiency of 99% of the Li metal anode, a stable cycling over 1000 h for Li|Li symmetric cells, more than 100 cycles in 40-μm-thin Li|high-loading-NCM811 full batteries, and >50 cycles in Cu|LiFePO 4 pouch cells, which is a promising electrolyte for highly reversible Li metal batteries.

Improved durability, enhanced interfacial stability, and room temperature applicability are desirable properties for all‐solid‐state lithium metal batteries (ASSLMBs), yet these desired properties are rarely achieved simultaneously. Here, in this work, it is noticed that the huge resistance at Li metal/electrolyte interface dominantly impeded the normal cycling of ASSLMBs especially at around room temperature (<30 °C). Accordingly, a supramolecular polymer ion conductor (SPC) with “weak solvation” of Li+ was prepared. Benefiting from the halogen‐bonding interaction between the electron‐deficient iodine atom (on 1,4‐diiodotetrafluorobenzene) and electron‐rich oxygen atoms (on ethylene oxide), the O‐Li+ coordination was significantly weakened. Therefore, the SPC achieves rapid Li+ transport with high Li+ transference number, and importantly, derives a unique Li2O‐rich SEI with low interfacial resistance on lithium metal surface, therefore enabling stable cycling of ASSLMBs even down to 10 °C. This work is a new exploration of halogen‐bonding chemistry in solid polymer electrolyte and highlights the importance of “weak solvation” of Li+ in the solid‐state electrolyte for room temperature ASSLMBs.

With the increasing scale of energy storage, it is urgently demanding for further advancements on battery technologies in terms of energy density, cost, cycle life and safety. The development of lithium-ion batteries (LIBs) not only relies on electrodes, but also the functional electrolyte systems to achieve controllable formation of solid electrolyte interphase and high ionic conductivity. In order to satisfy the needs of higher energy density, high-voltage (> 4.3 V) cathodes such as Li-rich layered compounds, olivine LiNiPO4, spinel LiNi0.5Mn1.5O4 have been extensively studied. However, high-voltage cathode-based LIBs fade rapidly mainly owing to the anodic decomposition of electrolytes, gradually thickening of interfacial passivation layer and vast irreversible capacity loss, hence encountering huge obstacle toward practical applications. To tackle this roadblock, substantial progress has been made toward oxidation-resistant electrolytes to block its side reaction with high-voltage cathodes. In this review, we discuss degradation mechanisms of electrolytes at electrolyte/cathode interface and ideal requirements of electrolytes for high-voltage cathode, as well as summarize recent advances of oxidation-resistant electrolyte optimization mainly from solvents and additives. With these insights, it is anticipated that development of liquid electrolyte tolerable to high-voltage cathode will boost the large-scale practical applications of high-voltage cathode-based LIBs.

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