A Novel Bifunctional Self‐Stabilized Strategy Enabling 4.6 V LiCoO₂ with Excellent Long‐Term Cyclability and High‐Rate Capability

Abstract

Abstract Although the theoretical specific capacity of LiCoO 2 is as high as 274 mAh g −1 , the superior electrochemical performances of LiCoO 2 can be barely achieved due to the issues of severe structure destruction and LiCoO 2 /electrolyte interface side reactions when the upper cutoff voltage exceeds 4.5 V. Here, a bifunctional self‐stabilized strategy involving Al+Ti bulk codoping and gradient surface Mg doping is first proposed to synchronously enhance the high‐voltage (4.6 V) performances of LiCoO 2 . The comodified LiCoO 2 (CMLCO) shows an initial discharge capacity of 224.9 mAh g −1 and 78% capacity retention after 200 cycles between 3.0 and 4.6 V. Excitingly, the CMLCO also exhibits a specific capacity of up to 142 mAh g −1 even at 10 C. Moreover, the long‐term cyclability of CMLCO/mesocarbon microbeads full cells is also enhanced significantly even at high temperature of 60 °C. The synergistic effects of this bifunctional self‐stabilized strategy on structural reversibility and interfacial stability are demonstrated by investigating the phase transitions and interface characteristics of cycled LiCoO 2 . This work will be a milestone breakthrough in the development of high‐voltage LiCoO 2 . It will also present an instructive contribution for resolving the big structural and interfacial challenges in other high‐energy‐density rechargeable batteries.