Tuning Solvation Structure Via Inductive and Steric Hindrance Effects for High‐Voltage LiCoO ₂ Batteries

Abstract

Abstract High‐voltage lithium cobalt oxide (LiCoO 2 ) has a high specific capacity and energy density, making it a promising cathode material for next‐generation lithium‐ion batteries (LIBs). However, stabilizing LiCoO 2 at elevated charging cut‐off voltages remains challenging due to the severe interfacial degradation, particularly the instability of the cathode–electrolyte interphase (CEI) under oxidative conditions. Herein, we propose a novel push–pull electrolyte design strategy by incorporating a non‐coordinating diluent, 1H,1H,5H‐perfluoropentyl‐1,1,2,2‐tetrafluoroethylether (HFE), which modulates the Li + solvation structure through strong inductive and steric hindrance effects, thereby enabling the formation of a robust CEI on the LiCoO 2 surface. Guided by molecular electrostatic potential analysis and nuclear magnetic resonance characterizations, the optimized electrolyte creates a tailored solvation environment that suppresses parasitic interfacial reactions and facilitates the formation of a bilayer interphase. As a result, the LiCoO 2 cathode exhibits excellent electrochemical stability with the HFE‐containing electrolyte, delivering over 300 stable cycles at 4.6 V in high‐loading LiCoO 2 //Li cells (∼11 mg cm −2 ) and retaining 77% capacity after 200 cycles in LiCoO 2 //Graphite full‐cells at 4.5 V. This solvation engineering strategy provides a promising pathway toward next‐generation high‐voltage LiCoO 2 ‐based batteries.