Fast Charging Lithium Metal Battery Based on Lewis Acid/Base Dual-Site Solid Electrolyte Interphase

Abstract

The unexpected depletion of anions and the restricted diffusion of Li⁺ on the Li anode lead to uncontrolled dendrite growth in Li metal batteries. Solid electrolyte interphase (SEI) engineering has been proven to be an effective method for solving these issues. Herein, a novel SEI layer with Lewis acid/base dual-site is constructed with triisopropanolamine cyclic borate (BON) and LiTFSI (defined as TFBN) to regulate the transport behavior of anions and Li⁺. The electron-deficient boron atom in BON can serve as the Lewis acid site, which anchors the anion to prevent its depletion at the interface. Meanwhile, the electron-rich nitrogen atom can serve as the Lewis base site, which accelerates the transport of Li⁺ to facilitate smooth Li deposition. As a result, BON can effectively dissociate lithium salts and regulate the migration behavior of anions and Li⁺. Using this novel SEI layer, Li||Li symmetric batteries can achieve stable cycling for over 1200 h at 1.0 mA cm⁻². Furthermore, the Li||LFP full cells show 93.7% capacity retention after 2000 cycles at an ultrahigh current of 10 C.