摘要
Sc and Zn were introduced into O3-NaMn_(0.5)Ni_(0.5)O_(2)(NaMN)using the combination of solution combustion and solid-state method.The effect of Sc and Zn dual-substitution on Na^(+) diffusion dynamics and structural stability of NaMN was investigated.The physicochemical characterizations suggest that the introduction of Sc and Zn broaden Na^(+) diffusion channels and weaken the Na—O bonds,thereby facilitating the diffusion of sodium ions.Simulations indicate that the Sc and Zn dual-substitution decreases the diffusion barrier of Na-ions and improves the conductivity of the material.The dual-substituted NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(Na MNSZ44)cathode delivers impressive cycle stability with capacity retention of 71.2%after 200 cycles at 1C and 54.8%after 400 cycles at 5C.Additionally,the full cell paired with hard carbon anode exhibits a remarkable long-term cycling stability,showing capacity retention of 64.1%after 250 cycles at 1C.These results demonstrate that Sc and Zn dual-substitution is an effective strategy to improve the Na^(+) diffusion dynamics and structural stability of NaMN.
采用溶液燃烧和固态相结合的方法将Sc和Zn引入O3-NaMn_(0.5)Ni_(0.5)O_(2)(Na MN),研究Sc和Zn双取代对NaMN的Na^(+)扩散动力学和结构稳定性的影响。物理化学表征表明,Sc和Zn的引入拓宽Na^(+)的扩散通道,削弱Na—O键,从而促进Na^(+)的扩散。理论计算结果表明,Sc和Zn双取代降低Na^(+)的扩散势垒,提高材料的电导率。双取代的NaMn_(0.5)Ni_(0.4)Sc_(0.04)Zn_(0.04)O_(2)(NaMNSZ44)正极具有高的循环稳定性,在1C下进行200次循环后,容量保持率为71.2%,在5C下进行400次循环后,容量保持率为54.8%。此外,与硬碳负极匹配组装的全电池具有显著的长期循环稳定性,在1C下进行250次循环后容量保持64.1%。这些结果表明,Sc和Zn双取代是一种改善NaMN的Na^(+)扩散动力学和结构稳定性的有效策略。
基金
financial support from the National Natural Science Foundation of China(No.52377220)
the Natural Science Foundation of Hunan Province,China(No.kq2208265)。
