Regulating Interfacial Nucleophilic Chemistry via Hybrid Electrolyte Enables Stable 4.8 V-Class Li-Rich||Li-Metal Batteries
Chenyang Jiao, Qizheng Zheng, Kang Zhang, Jiyuan Xue, Na Liu, Baodan Zhang, Yueli Lin, Xuequan Zhu, Changhao Wang, Hong‐Gang Liao, Chong‐Heng Shen, Yeguo Zou, Yu Qiao, Shi‐Gang Sun
Abstract
High-energy-density Li-rich layered oxide-based Li-metal batteries depend critically on the unique anionic redox. However, severe electrolyte decomposition and interfacial structural degradation hinder the longevity and stability of Li-rich||Li-metal batteries. Here, we show that a rational hybrid electrolyte design strategy can regulate interfacial chemistry through precise manipulation of cathode surface-exposed nucleophilic species. As a proof of concept, ethyl methyl sulfone is employed as the primary solvent due to its oxidative stability and resistance to nucleophilic attack, simultaneously strategically fabricating a fluorinated ether as a cosolvent that directs nucleophilic reaction toward its targeted functionality. Furthermore, this hybrid electrolyte design simultaneously facilitates the formation of a LiF-rich cathode electrolyte interphase (CEI) and reorganizes the solid electrolyte interphase on the Li metal from the preferential decomposition of cosolvents and anions. As a result, ultrahigh Coulombic efficiency (CE) (>99.4%) for Li-rich cathodes and enhanced Li-metal plating/stripping reversibility are achieved. Consequently, the optimized electrolyte demonstrates exceptional cycling stability, retaining 92% capacity over 100 cycles with ultrahigh average CE (>99.3%) under demanding conditions (limited Li supply, N/P = 2). Remarkably, this hybrid electrolyte enabled superior operation with anode-free cell architectures and enabled extreme temperatures (-30 to 55 °C) cycling. By effectively transforming detrimental nucleophilic attack into interfacial enhancement, this work establishes a new paradigm for electrolyte design in utilizing anionic redox chemistry.