ZIF-67原位负载纳米纤维素基锂离子电池隔膜的制备及性能研究

Preparation and Properties of ZIF-67 In-situ Loaded Cellulose Nanofibril-based Separator for Lithium-ion Batteries

本研究以纳米纤维素(CNF)为原料,经乙酰化、原位负载ZIF-67和浸渍电解液制备出一种新型ZIF-67@乙酰化纳米纤维素(ZIF-67@ACNF)锂离子电池隔膜,系统探讨了ZIF-67的粒径对隔膜结构及性能的影响。结果表明,当ZIF-67的粒径从0.46µm(ZIF-67_(4)@ACNF隔膜)减小至0.25µm(ZIF-67_(8)@ACNF隔膜)时,隔膜的孔隙率从74.2%减小至52.1%,离子电导率从0.75 mS/cm下降至0.22 mS/cm,界面电阻从112.5Ω增加至1115.7Ω,锂离子迁移数从0.41减小至0.31,电化学稳定窗口从5.1 V减小至4.5 V。采用ZIF-67_(4)@ACNF隔膜组装电池,在室温、0.5 C的条件下进行电池充/放电测试,初始容量达到159.6 mAh/g,循环200圈后容量保持率达到90%。

In this study,cellulose nanofibril(CNF)was acetylated followed by in-situ loading of ZIF-67 and electrolyte impregnation to pre‐pare a novel ZIF-67@acetylated cellulose nanofibril(ZIF-67@ACNF)separator for lithium-ion batteries.The effects of particle size of ZIF-67 on the structure and performance of the separator were systematically investigated.The results showed that as the particle size of ZIF-67 decreased from 0.46µm(in ZIF-67_(4)@ACNF separator)to 0.25µm(in the ZIF-67_(8)@ACNF separator),the porosity of the separator reduced from 74.2%to 52.1%,the ionic conductivity decreased from 0.75 mS/cm to 0.22 mS/cm,the interfacial resistance increased from 112.5Ωto 1115.7Ω,the lithium-ion transference number declined from 0.41 to 0.31,and the electrochemical stability window went down from 5.1 V to 4.5 V.The initial capacity of assembled cell by ZIF-67_(4)@ACNF separator reached 159.6 mAh/g with a capacity reten‐tion rate of 90%after 200 cycles at 0.5 C under room temperature.