College of Materials Science and Engineering, Taiyuan University of Technology

【目的】探索具有优异电化学性能的负极材料对于提高钠离子电池的性能至关重要。高熵氧化物(HEO)因具有高结构稳定性和高的本征电导率,成为一种非常有前景的二次电池电极材料。然而,HEO直接作为电极材料,其电化学性能往往受制于电极材料的团聚。而碳纳米管(CNT)因其所具有的高导电性、良好的机械稳定性常常被用来优化电池性能。【方法】通过水热法将碳纳米管和尖晶石型高熵氧化物耦合,制备了(FeCoNiCuMn)3O4/CNT复合材料(HEO/CNT),并将其应用于钠离子电池负极。【结果】电化学测试表明,HEO/CNT展现出优异的储钠性能:高可逆比容量和长循环稳定性(在0.5A/g电流密度下,循环200圈后的可逆容量为231mAh/g,具有67%的容量保持率);优异的倍率性能(在电流密度为2A/g时,提供了290.2mAh/g的可逆容量,当电流密度回到0.1A/g时,容量恢复到了440mAh/g).同时,原位XRD测试表明HEO/CNT的储钠过程是插层和转换反应的结果。【结论】HEO/CNT优异的电化学性能归因于纳米尺寸的高熵氧化物(FeCoNiCuMn)3O4具有较大的比表面积和较高的表面活性,增加了电解液的接触面积,缩短了离子扩散路径;其次碳纳米管缓冲了高熵氧化物在充放电过程中的体积变化,这种思路将为设计高倍率和长寿命的电极材料提供思路,也为高熵材料应用于电化学领域提供了一种新的发展策略。

【Purposes】 Exploration of anode materials with excellent electrochemical properties is essential to improve the performance of sodium ion batteries (SIBs). High-entropy oxides (HEO), with their unique structural characteristics, tailorable chemical composition, and tuna- ble functional properties, have drawn increasing interest in the fields of environmental science and renewable energy technology. However, when HEO are directly used as anode materials for SIBs, a problem of agglomeration limits the electrochemical performance. In general, carbon nanotubes (CNT) are used to optimize battery performance because of their high electrical con- ductivity and good mechanical stability. 【Methods】 Spinel-type high-entropy oxide (FeCoNi- CuMn)3O4/CNT composites (HEO/CNT) with space group Fd-3m have been synthesized through hydrothermal treatment followed by annealing method. 【Findings】 As the anode material in SIBs, at a current density of 0.5 A/g, HEO/CNT has a reversible capacity of mAh/g after cycles. Additionally, the HEO/CNT exhibits high reversible capacities of 363.3, 350, 341.1, 310.2, and 290.2 mAh/g at the current densities 0.1, 0.2, 0.5, 1, and A/g, respec- tively. In situ X-ray diffraction analysis has been employed to reveal that the sodium ion storage process is a result of a combined Na intercalation and conversion reaction between Na and HEO/CNT. 【Conclusions】 Thanks to the “high entropy effect” of the high entropy oxide/carbon material, the volume change of the active material is mitigated during the charge/discharge process. Therefore, HEO/CNT is expected to be an electrode material with good sodium storage performance. This work provides a new template strategy for the application of high entropy ma- terials.

国家自然科学基金资助项目(52072256)

肖泽华,李慧君,田勤,等.基于高熵氧化物(FeCoNiCuMn)3O4/CNT钠离子电池负极材料的储钠性能研究[J].太原理工大学学报,2024,55(3):445-454.

XIAO Zehua,LI Huijun,TIAN Qin,et al.Research on sodium storage mechanism of sodium ion batteries with high entropy oxide (FeCoNiCuMn)3O4/CNT as anode[J].Journal of Taiyuan University of Technology,2024,55(3):445-454.