Boosting the lithium-ion storage performance of perovskite Sr_xVO_3-δ via Sr cation and O anion deficient engineering

Perovskite SrVO₃ has been investigated as a promising lithium storage anode where the V cation plays the role of the redox center, combining excellent cycle stability and safe operating potential versus Li metal plating, with limited capacity. Here, we demonstrate the possibility to boost the lithium storage properties, by reducing the non-redox active Sr cation content and fine-tuning the O anion vacancies while maintaining a non-stoichiometric Sr_xVO_3-δ perovskite structure. Theoretical investigations suggest that Sr vacancy can work as favorable Li⁺ storage sites and preferential transport channels for guest Li⁺ ions, contributing to the increased specific capacity and rate performance. In contrast, inducing O anion vacancy in Sr_xVO_3-δ can improve rate performance while compromising the specific capacity. Our experimental results confirm the enhancement of specific capacities by fine adjusting the Sr and O vacancies, with a maximum capacity of 444 mAh g^-1 achieved with Sr_0.63VO_3-δ, which is a 37% increase versus stoichiometric SrVO₃. Although rich defects have been induced, Sr_xVO_3-δ electrodes maintain a stable perovskite structure during cycling versus a LiFePO₄ cathode, and the full-cell could achieve more than 6000 discharge/charge cycles with 80% capacity retention. This result highlights the possibility to use the cation defective-based engineering approach to design high-capacity perovskite oxide anode materials.