Title: Sustainable layered cathode with suppressed phase transition for long-life sodium-ion batteries

Authors: Yonglin Tang, Qinghua Zhang, Wenhua Zuo, Shiyuan Zhou, Guifan Zeng, Baodan Zhang, Haitang Zhang, Zhongyuan Huang, Lirong Zheng, Juping Xu, Wen Yin, Yongfu Qiu, Yinguo Xiao, Qiaobao Zhang, Tiqing Zhao, Hong-Gang Liao, Inhui Hwang, Cheng-Jun Sun, Khalil Amine, Qingsong Wang*, Yang Sun*, Gui-Liang Xu*, Lin Gu*, Yu Qiao* & Shi-Gang Sun*

Abstract: Sodium-ion batteries are among the most promising alternatives to lithium-based technologies for grid and other energy storage applications due to their cost benefits and sustainable resource supply. For the cathode—the component that largely determines the energy density of a sodium-ion battery cell—one major category of materials is P2-type layered oxides. Unfortunately, at high state-of-charge, such materials tend to undergo a phase transition with a very large volume change and consequent structural degradation during long-term cycling. Here we address this issue by introducing vacancies into the transition metal layer of P2-Na_0.7Fe_0.1Mn_0.75□_0.15O₂ (‘□’ represents a vacancy). The transition metal vacancy serves to suppress migration of neighbouring Na ions and therefore maintain structural and thermal stability in Na-depleted states. Moreover, the specific Na−O−□ configuration triggers a reversible anionic redox reaction and boosts the energy density. As a result, the cathode design here enables pouch cells with energy densities of 170 Wh kg⁻¹ and 120 Wh kg⁻¹ that can operate for over 600 and 1,000 cycles, respectively. Our work not only suggests a feasible strategy for cathode design but also confirms the possibility of developing a battery chemistry that features a reduced need for critical raw materials.

Full-Link: https://www.nature.com/articles/s41893-024-01288-9