Tailoring Li <sub>3</sub> N‐Contained Complementary Gradient Solid Electrolyte Interphase in High‐Performance 3.2 V Aqueous Lithium‐Ion Batteries
Fengcheng Tang, Zhuoni Zhao, Fangkun Li, Jun Liu, Qihou Li, Feixiang Wu
Abstract
Abstract Lithium nitride (Li 3 N) as a crucial solid electrolyte interphase (SEI) component to realize high‐voltage non‐aqueous lithium batteries is rarely reported in aqueous lithium‐ion batteries (ALIBs) due to its intense hydrolysis in aqueous solution. To overcome the limited operating voltages (< 3 V) and the unstable electrode/electrolyte interphase in ALIBs, a two‐pronged strategy is presented that includes employing asymmetric amide co‐solvent and overpotential‐driven interfacial engineering. This simple method enables the construction of Li 3 N‐contained complementary gradient SEI in aqueous media unprecedentedly. By adopting the N‐methylformamide (NMF) co‐solvent and an appropriate overpotential (0.3 V), a robust complementary gradient SEI composed of LiF (outer) and stable Li 3 N (inner) via internal self‐protection is established. The potential three‐step formation mechanism of LiF/Li 3 N complementary gradient SEI involving the sequential decomposition of TFSI − , NMF, and H 2 O is proposed. Consequently, the tailored complementary gradient structure synergistically combines chemical stability with rapid formation dynamics, inhibiting the hydrogen evolution reaction in high‐voltage situations. Ultimately, LiMn 2 O 4 ||Li 4 Ti 5 O 12 cells demonstrate excellent cycling stability over 700 and 2000 cycles under 2 and 5C (3.2 V), respectively. This work establishes a span‐new idea for stabilizing the Li 3 N‐contained electrode/electrolyte interphase in aqueous batteries, and offers a distinctive pathway for advancing high‐voltage, long‐term ALIBs.