表面活性剂辅助制备(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)高熵氧化物及储锂性能

Surfactant assisted synthesis of(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_3O_4high-entropy oxide and its lithium-ion storage performance

为了进一步提高锂离子电池负极材料(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)高熵氧化物(HEO)的倍率性能,以金属硝酸盐为金属源、尿素为沉淀剂、十二烷基三甲基溴化铵(DTAB)为表面活性剂,利用水热法制备了具有单一尖晶石结构的(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)纳米材料(HEO-DTAB)。采用XRD、SEM、EDS、比表面及孔径分析仪对HEO-DTAB进行了表征,并对其制作的电极进行了电化学性能测试。结果表明,与未添加DTAB制备的材料(HEO)相比,HEO-DTAB具有更小的颗粒尺寸(10.8 nm)、更均匀的分散性、更大的比表面积(27.88 m^(2)/g)和均一的孔结构;HEO-DTAB制作的电极在0.2 A/g下展示了较高的初始放电比容量(1308 mA·h/g)和库仑效率(82.5%),循环25圈时放电比容量为1263 mA·h/g;在1 A/g下,循环150圈后的放电比容量高达1053m A·h/g,是HEO制作的电极的8.4倍。HEO-DTAB的纳米结构使其电极材料具有较大的赝电容贡献率(91.1%,扫描速率为1.5 mV/s),大幅度提升了材料的比容量和倍率性能。

In order to further improve the rate performance of anode material(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4)high-entropy oxide(HEO) in lithium-ion batteries,spinel-structured(Co_(0.2)Cr_(0.2)Fe_(0.2)Mn_(0.2)Ni_(0.2))_(3)O_(4) nanocrystalline powder(HEO-DTAB) was synthesized by hydrothermal method using metal nitrate as metal source,urea as precipitant and dodecyl trimethyl ammonium bromide(DTAB) as surfactant.The powders obtained were characterized by XRD,SEM,EDS,specific surface area and pore size analyzer,followed by evaluation on electrode electrochemical performance.The results showed that the HEO-DTAB possessed smaller particle size(10.8 nm),more uniform dispersion,larger specific surface area(27.88 m^(2)/g)and more uniform pore distribution in comparison to HEO without surfactant DTAB.The HEO-DTAB electrode exhibited a higher initial specific capacity(1308 m A·h/g),and an initial coulomb efficiency(82.5%),with a discharge specific capacity of 1263 m A·h/g at 0.2 A/g after 25 cycles.The discharge specific capacity at 1 A/g after 150 cycles was 1053 mA·h/g,which was 8.4 times that of HEO electrode.The nanostructure of HEO-DTAB led to a pronounced pseudocapacitance contribution ratio(91.1% at scan rate of 1.5 mV/s) of the electrode,significantly improving the specific capacity and rate performance of the material.