Engineering Na+-layer spacings to stabilize Mn-based layered cathodes for sodium-ion batteries
Wenhua Zuo, Xiangsi Liu, Jimin Qiu, Dexin Zhang, Zhumei Xiao, Jisheng Xie, Fucheng Ren, Jinming Wang, Yixiao Li, Gregorio F. Ortiz, Wen Wen, Shunqing Wu, Ming‐Sheng Wang, Riqiang Fu, Yong Yang
Abstract
Abstract Layered transition metal oxides are the most important cathode materials for Li/Na/K ion batteries. Suppressing undesirable phase transformations during charge-discharge processes is a critical and fundamental challenge towards the rational design of high-performance layered oxide cathodes. Here we report a shale-like Na x MnO 2 (S-NMO) electrode that is derived from a simple but effective water-mediated strategy. This strategy expands the Na + layer spacings of P2-type Na 0.67 MnO 2 and transforms the particles into accordion-like morphology. Therefore, the S-NMO electrode exhibits improved Na + mobility and near-zero-strain property during charge-discharge processes, which leads to outstanding rate capability (100 mAh g −1 at the operation time of 6 min) and cycling stability (>3000 cycles). In addition, the water-mediated strategy is feasible to other layered sodium oxides and the obtained S-NMO electrode has an excellent tolerance to humidity. This work demonstrates that engineering the spacings of alkali-metal layer is an effective strategy to stabilize the structure of layered transition metal oxides.