Promoting the performances of P2-type sodium layered cathode by inducing Na site rearrangement

• Published in: Nano energy 2022-09, Vol.100, p.107482, Article 107482
• Main Authors: Zhang, Taolve, Ji, Haocheng, Hou, Xiaohui, Ji, Wenhai, Fang, Hui, Huang, Zhongyuan, Chen, Guojie, Yang, Tingting, Chu, Mihai, Xu, Shenyang, Chen, Ziwei, Wang, Chaoqi, Yang, Wenyun, Yang, Jinbo, Ma, Xiaobai, Sun, Kai, Chen, Dongfeng, Tao, Mingming, Yang, Yong, Zheng, Jiaxin, Pan, Feng, Xiao, Yinguo
• Format: Article
• Language: English
• Subjects: Na site rearrangement; P2-type NiMn-based layered oxides; Smooth kinetic process; Sodium-ion batteries; Structural regulation
• ISSN: 2211-2855
• DOI: 10.1016/j.nanoen.2022.107482

The electrochemical performance and structural stability of sodium-ion battery is substantially dependent on the occupancy and distribution of Na+ in cathode materials. However, it is challenging to simultaneously regulate the occupancy and optimize the distribution of Na+ in cathodes for higher capacity and superior cyclability. Here we attempt to adjust the arrangement of Na+ in layered cathode materials by applying a combination approach, including enhancing the Na content, disrupting transition metal ordering and strengthening Na+-TMn+ electrostatic force. Through detailed structural characterizations on cathodes, it is revealed that the rearrangement of Na+ at two distinct Wyckoff positions can be realized in Li/Ti-codoped Na2/3Ni1/3Mn2/3O2 cathodes, contributing to outstanding rate performance and smooth kinetic process. In addition, the inhibited P2-O2 phase transition and intact lattice structure is closely related to the rearranged Na layer and strengthened transition metal slab, jointly resulting in excellent long cycling performance with 90.2% capacity retention after 200 cycles at 1 C (150 mA/g). This work sheds new light on the role of different Na sites and provides a universal and practical approach to adjusting the Na+ distribution in P2-type cathode materials. [Display omitted] ●Targeted regulation of the arrangement of Na+ at two distinct Wyckoff positions is achieved in P2-type layered cathodes.●The modified material exhibits fast and smooth kinetic process with outstanding rate performance.●The rearranged Na layer ensures stable and robust structure at the whole voltage range of 2.0–4.3 V.●DFT calculation reveals the mechanism of Na+ rearrangement and the role of different Na sites.