Carbon dioxide directly induced oxygen vacancy in the surface of lithium-rich layered oxides for high-energy lithium storage.

Lithium-rich layered oxides are promising cathode materials for lithium-ion batteries due to their high reversible capacities (more than 250 mAh g−1). Nevertheless, in operation, the oxygen lattice would be transformed into O 2 gas with phase transformation. Thus, to suppress O 2 gas, it is necessary to pre-generate the oxygen vacancies in the surface of materials. Herein, for facile and scalable pre-generation of oxygen vacancies, pristine Li 2 MnO 3 ·LiNi 1/3 Co 1/3 Mn 1/3 O 2 oxide (PLR-NCM) is treated directly by CO 2 gas just at the room temperature. The modified material (MLR-NCM), with rich oxygen vacancies in the surface and no obvious structural change inside, shows a discharge capacity of 321 mAh g−1 based on half-cells at 55 °C and 0.1 C (1.0 C = 250 mA g−1), and 240 mAh g−1 as full cells at the room temperature. In addition, it also exhibits high cycling and rate performance owing to the significantly improved lithium ion and electron diffusion efficiencies. Importantly, by real-time monitoring of structural evolution using in situ XRD technique, we find that the O 2 gas release of the modified material is successfully suppressed. This facile method proposed in our work provides a new strategy for greatly improving the performance of lithium-ion batteries. Image 1 • Modified Li-rich layered materials (MLR-NCM) with rich oxygen vacancies are prepared. • Oxygen vacancies in MLR-NCM are formed by facile and scalable direct CO 2 treatments. • MLR-NCM show high Li-storage capacity, cycling and rate performances. • In situ XRD technique is used to confirm that oxygen vacancies suppress O 2 release. • Full cells with MLR-NCM perform excellent Li-storage performance at room temperature. [ABSTRACT FROM AUTHOR]