Ultrathin and High‐Modulus LiBO₂ Layer Highly Elevates the Interfacial Dynamics and Stability of Lithium Anode under Wide Temperature Range

Abstract Lithium (Li) metal batteries (LMBs) face huge challenges to achieve long cycling life at wide temperature range owing to the severe dendrite growth at subambient temperature and the intense side reactions with electrolyte at high temperature. Herein, an ultrathin LiBO₂ layer with an extremely high Young's modulus of 8.0 GPa is constructed on Li anode via an in situ reaction between Li metal and 4,4,5,5‐tetramethyl‐1,3,2‐dioxa‐borolane (TDB) to form LiBO₂@Li anode, which presents two times higher exchange current density than pristine Li anode. The LiBO₂ layer presents a strong absorption to Li ions and greatly improves the interfacial dynamics of Li‐ion migration, which induces homogenous lithium nucleation and deposition to form a dense lithium layer. Consequently, the Li dendrite growth during cycling at subambient temperature and the side reactions with electrolyte at high temperature are simultaneously suppressed. The LiBO₂@Li/LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) full batteries with limited Li capacity and high cathode mass loading of 9.9 mg cm^–2 can steadily cycle for 300 cycles with a capacity retention of 86.6%. The LiBO₂@Li/NCM811 full batteries and LiBO₂@Li/LiBO₂@Li symmetric batteries also present excellent cycling performance at both −20 and 60 °C. This work develops a strategy to achieve outstanding performance of LMBs at wide working temperature‐range.