Abstract: Manganese oxide-based cathodes are attracting great interest owing to their advantages such as low cost, high capacity and energy density. Nevertheless, rapid capacity fading is a critical problem due to the direct contact between cathode and electrolyte, restraining its wide applications. To solve this problem, surface coating becomes a feasible strategy for the cathode material. A carbon coating layer with dopamine was introduced uniformly on the surface of K_0.5Mn₂O_4.3·0.5H₂O by solvothermal process. The coated carbon layer prohibits direct contact of electrode and the electrolyte to effectively hinders side reaction. At a current density of 50 mA/g, the discharge capacity of carbon-coated sample with 10%(wt.)dopamine(C@S-KMO-10%)is still as high as 89.8 mA·h/g with a capacity retention ratio of 63.4% after 100 cycles, showing improved cycling stability and superior rate capability. While the uncoated sample(S-KMO)delivers a discharge capacity of 68.8 mA·h/g - DOI:10.3969/j.issn.1000-1565.2022.05.007碳包覆钾离子电池正极材料K_0.5Mn₂O_4.3·0.5H₂O的研究钱佳琦¹,李小亭¹,雷宇²,张文明²(1.河北大学 质量技术监督学院,河北 保定 071002;2.河北大学 物理科学与技术学院,河北 保定 071002)摘 要:锰基氧化物正极材料具有低成本、高容量和高能量密度等优点,是钾离子电池正极材料研究的热点.然而,由于正极材料与电解液直接接触,发生副反应,导致容量迅速衰减,限制了它的广泛应用.为解决这一问题,对正极材料采用表面包覆的改性策略,以多巴胺为碳源,采用溶剂热法在K_0.5Mn₂O_4.3·0.5H₂O正极材料均匀地包覆碳涂层.碳包覆层阻止了正极材料与电解液的直接接触,有效地抑制了副反应.结果发现:在电流密度为50 mA/g的条件下,添加占正极材料质量10%的多巴胺时,放电容量为89.8 mA·h/g,容量保持率为63.4%,表现出优异的电化学性能,而未包覆的正极材料的放电容量为68.8 mA·h/g, 循环100圈后容量保持率为32%.这种表面涂层策略为提高钾离子电池阴极的循环稳定性提供了一种新的改性方法.关键词:溶剂热法;碳包覆;正极材料;表面改性中图分类号:O646 文献标志码:A 文章编号:1000-1565(2022)05-0494-07Carbon-coated K_0.5Mn₂O_4.3·0.5H₂O as cathode for potassium-ion batteriesQIAN Jiaqi¹, LI Xiaoting¹, LEI Yu², ZHANG Wenming²(1. College of Quality and Technical Supervision, Hebei University, Baoding 071002, China;2. College of Physics Science and Technology, Hebei University, Baoding 071002, China)Abstract: Manganese oxide-based cathodes are attracting great interest owing to their advantages such as low cost, high capacity and energy density. Nevertheless, rapid capacity fading is a critical problem due to the direct contact between cathode and electrolyte, restraining its wide applications. To solve this problem, surface coating becomes a feasible strategy for the cathode material. A carbon coating layer with dopamine was introduced uniformly on the surface of K_0.5Mn₂O_4.3·0.5H₂O by solvothermal process. The coated carbon layer prohibits direct contact of electrode and the electrolyte to effectively hinders side reaction. At a current density of 50 mA/g, the discharge capacity of carbon-coated sample with 10%(wt.)dopamine(C@S-KMO-10%)is still as high as 89.8 mA·h/g with a capacity retention ratio of 63.4% after 100 cycles, showing improved cycling stability and superior rate capability. While the uncoated sample(S-KMO)delivers a discharge capacity of 68.8 mA·h/g - 收稿日期:2022-03-09 基金项目:国家自然科学基金资助项目(52171206) 第一作者:钱佳琦(1995—),女,河北保定人,河北大学在读硕士研究生,主要从事钾离子电池正极材料方向研究. E-mail:qianjiaqi6953@163.com 通信作者:张文明(1982—),男,吉林四平人,河北大学教授,主要从事新型离子电池、电催化锌空气电池、微生物燃料电池、可穿戴柔性传感器件方向研究.E-mail:wmzhang@hbu.edu.cn第5期钱佳琦等:碳包覆钾离子电池正极材料K_0.5Mn₂O_4.3·0.5H₂O的研究with 32% capacity retention after 100 cycles. This surface coating strategy offers a new modification approach to improve the cycling stability of cathodes for potassium ion batteries.

Key words: solvothermal process, carbon coating, cathode, surface modification