Channelization of cathode/electrolyte interphase to enhance the rate-capability of LiCoO2†

Abstract

The LiCoO₂ cathode material holds great promise for achieving high energy density lithium-ion batteries (LIBs) in electronic products. However, it exhibits structural instability when voltages surpass 4.35 V (vs. Li⁺/Li), particularly under conditions of high current density. Here, we report an in situ surface modification technique for synthesizing a LiCoO₂ composite coated with ZrP₂O₇ (LiCoO₂@ZrP₂O₇) to mitigate these issues. The LiCoO₂@ZrP₂O₇ electrode exhibits a significantly high initial discharge capacity and exceptional long-term cycling stability, with 97.7% capacity retention after 200 cycles at 0.5C with a cutoff voltage of 4.5 V. Additionally, the rate-capability of the modified LiCoO₂ cathode is effectively enhanced by incorporating a ZrP₂O₇ coating layer, resulting in 76.8% capacity retention at 5C compared to the original capacity at 0.1C. Moreover, density functional theory (DFT) calculations reveal that the incorporation of ZrP₂O₇ facilitates Li⁺ migration into LiCoO₂ by reducing the energy barrier. These findings propose a potential approach for preparing layered transition metal oxides with exceptionally stable structure and high interfacial Li⁺ diffusion kinetics, particularly for advancing high-energy density all solid-state batteries.