Electron-Deficient Species-Driven Interphase Transformation for Practical Lithium Batteries

Abstract

Lithium metal batteries with Ni-rich layered cathodes are promising candidates due to their high energy density; however, the unstable interphase formed in traditional carbonates accelerates premature irreversible capacity loss. In this study, we exploit the electron-deficient nature of boron (B)-containing species, which can initiate the chain polymerization of unstable alkyl lithium. This process facilitates the continuous conversion of these components into stable B-containing polymers, enhancing mechanical strength and ionic conductivity and ultimately achieving dynamic interphase transformation. Simultaneously, the unexpected generation of smaller solvation structures rich in multiple salt anions promotes Li+ transportation and the formation of LiF-rich interphases. Such an interphase bestows Li||LiNi0.8Co0.1Mn0.1O2 cells with a stable operation of up to 450 cycles under 4.6 V. Even practical 1.5 Ah graphite pouch cells can maintain 84% capacity after 1600 cycles. Thanks to the broad applicability of this unique in situ mechanism, it can be generalized to various LiPF6-based carbonate electrolytes. Our work provides a low-cost and highly accessible strategy for modifying the interphase, paving the way for high energy-density batteries that can meet diverse and demanding operating conditions.