A multifunctional zeolite film enables stable high-voltage operation of a LiCoO2 cathode

Abstract

Increasing the upper cut-off voltage is a useful way to enhance the specific capacity of the LiCoO₂ (LCO) cathode and the energy density of the corresponding lithium-ion batteries (LIBs), while the main challenge is concurrent phase transition associated with the oxygen evolution reaction that results in a quick decay in electrochemical performance. Here, we report a significant improvement in both capacity and durability at high voltage by simply growing an AlPO₄-5 zeolite protecting layer over LCO, with good crystallinity, ordered porous channels and full surface coverage. Such a coating, realized by using triethylamine as a template, acts multifunctionally to remarkably alleviative phase transition via suppressing the oxygen release at high voltage, enable fast Li⁺ diffusion through its nanoporous structure, accelerate the Li⁺-desolvation on the cathode/electrolyte interface, and boost the redox kinetics, as supported by various in situ and ex situ measurements of the LCO@AlPO₄-5 zeolite (LCO@Z) cathode at a high cut-off voltage of 4.6 V (vs. Li/Li⁺) and density functional theory (DFT) calculations. As a result, the surface engineered LCO@Z electrode exhibits outstanding cycling stability (capacity retention of 90.3% after 200 cycles) and high-rate capability (108.2 mA h g⁻¹ at 10C). Such a zeolite coating strategy provides a new way for developing high-energy-density LIBs with great application potential.