尖晶石型无钴(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)X_(0.2))_(3)O_(4)高熵氧化物的制备及其储锂性能

Preparation and Lithium Storage Performance of Spineltype Cobalt-free(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)X_(0.2))_(3)O_(4) High-entropy Oxide

用溶液燃烧法合成一系列尖晶石型无钴(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)X_(0.2))_(3)O_(4)(X=K、Mg、Zn和Co)高熵氧化物粉体,对其表征并研究了电化学性能。结果表明:上述高熵氧化物粉体均为单相尖晶石结构,形貌为多孔网状结构且组成元素分布均匀。其中(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)Zn_(0.2))_(3)O_(4)的储锂性能最优异,电流密度为200 m A·g^-(1)循环150圈后可逆比容量高达1303 m Ah·g^-(1);即使电流密度提高到1000 m A·g^-(1)循环380圈后其可逆比容量仍达到1190 m Ah·g^-(1)(高于理论比容量908 m Ah·g^-(1))。4MZn电极优异的储锂性能归因于其较大的比表面积、介孔结构以及丰富的表面氧空位,使其具有较高的电导率(12.2 S·m^(-1))和较大的赝电容贡献率;同时,活性元素Zn的加入使4MZn电极在还原过程中生成Li-Zn合金使其比容量提高。

High-entropy oxides(HEOs)have attracted widespread attention as the next-generation anode materials for lithium-ion batteries(LIBs)due to their low cost and high theoretical capacity.In this work,for the first time,a series of spinel-type cobalt-free(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)X_(0.2))_(3)O_(4)(X=K,Mg,Zn)highentropy oxide powders as anode materials for LIBs were synthesized via a solution combustion method.The microstructural features and electrochemical performance of the powders were systematically investigated in comparison with cobalt containing powders of(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)X_(0.2))_(3)O_(4).The results indicate that the prepared high-entropy oxide powders are all single-phase of spinel structures,with a porous reticular morphology and uniform distribution of constituent elements.When used as anode materials for LIBs,cobalt-free(Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2)X_(0.2))_(3)O_(4) exhibits excellent lithium storage performance.After 150 cycles at a current density of 200 mA·g^-(1),its reversible specific capacity is up to 1303 mAh·g^-(1).Furthermore,after 380 cycles at a high current density of 1000 mA·g^-(1),the reversible capacity can still reach 1190 mAh·g^-(1)(both are higher than its theoretical capacity of 908 mAh·g^-(1)).The reasons for the excellent lithium storage performance of 4MZn electrode are:high specific surface area,mesoporous structure,and abundant oxygen vacancies on the surface make it a high conductivity(12.2 S·m^(-1))and a large pseudo-capacitance contribution rate;At the same time,the addition of active element Zn causes the formation of Li-Zn alloy in the reduction process of 4MZn electrode,thereby increasing its specific capacity.This work provides a new design approach for exploring cobalt free high entropy energy storage materials with low cost and excellent electrochemical performance.