Lithium‐Ion Batteries with Superlong Cycle‐Life in Wide Temperature Range via Interfacial Alkyl‐Chain Sway

Abstract The cathode‐electrolyte interphase directly influences the wide‐temperature performance of lithium‐ion batteries, particularly long‐term cycle performance. However, improving both high‐ and low‐temperature properties of cathode often requires distinct approaches, making it challenging to unify these strategies. In this work, an interfacial‐driven strategy on the cathode surface is designed with nano‐Mg(OH)₂ with Tween80 (nano‐Mg(OH)₂@Tween80). Tween80 serves as the framework of the weak‐linked flexible confined space for preparing ultrafine nano‐Mg(OH)₂ and then adsorbs in situ onto the nano‐Mg(OH)₂. In the cell assembled with nano‐Mg(OH)₂@Tween80 modified LiNi_0.5Co_0.2Mn_0.3O₂, the alkyl‐chain sway of Tween80 molecules accelerates electrolyte diffusion on cathode surface. Hence, both the timely formation of a stable and conductive Mg‐rich interphase layer and rapid lithium‐ion transfer are achieved, leading to the co‐improvement of high/low‐temperature performances. The half‐cell with the addition of nano‐Mg(OH)₂@Tween80, maintains over 70 mAh·g⁻¹ and 90% Coulombic efficiency after 1000 cycles at 60 °C, and keeps 80 mAh·g⁻¹ with 99% Coulombic efficiency after 500 cycles at −5 °C, even still very stable at −15 °C.