Extending the Service Life of High‐Ni Layered Oxides by Tuning the Electrode–Electrolyte Interphase

Abstract

As a high‐energy‐density cathode for Li‐ion batteries, high‐Ni layered oxides, especially with ultrahigh Ni‐content, suffer from short lifespans, due in part to their unstable electrode–electrolyte interphase (EEI). Herein, the cycle life of LiNi 0.94 Co 0.06 O 2 is greatly extended by manipulating the EEI with a lithium bis(oxalate) (LiBOB) additive even when operated at a moderately high voltage (4.4 V vs Li/Li+). Impressively, the capacity retention can be increased from 61 to 80% after 500 cycles in a full cell paired with a graphite anode. Additionally, the presence of LiBOB enables a robust boron‐ and oxygen‐enriched EEI that effectively inhibits continual electrolyte decomposition and offers a stable cathode surface. Moreover, the layered architecture of the cathode–electrolyte interphase (CEI) and the anode–electrolyte interphase (AEI) at the nanometer scale is revealed by time‐of‐flight secondary ion mass spectrometry. It is demonstrated that the cathode surface chemistry can significantly influence the AEI both chemically and physically, and AEI is modified from a thick “three‐layer” to a thin “two‐layer” architecture by tuning the cathode surface chemistry with LiBOB. This work presents a correlation between the EEI characteristics and battery performance and highlights the significance of manipulating surface chemistry in developing stable high‐energy‐density Li‐ion batteries.