半固态锂电池电极浆料导电性能的评价方法研究

Evaluation method of the conductive property of the electrode slurry in semi-solid lithium battery

半固态锂电池是一种新型电化学储能技术,以电极浆料作为电化学反应的主体材料。电极浆料是将电极活性材料和导电剂分散于电解液中形成的固液混合体系,导电性能的优劣决定其是否能够实现良好的电化学性能。本论文以不同导电添加剂配比的磷酸铁锂电极浆料为研究对象,分别采用直流电导率仪、电化学阻抗谱测试以及固定频率交流电测试的方法进行电导率的测定,并与半电池在不同电流密度下的充放电性能进行了比较。研究认为对电极浆料进行电化学阻抗谱测试是有效的导电性能评价方法,但模型建立和数值模拟的过程较为复杂;通过电化学工作站对样品施加固定频率的交流电亦可得到相应的阻抗,测试结果稳定,操作简单高效,可用于对电极浆料导电性能的初步评价和比较。

The semi-solid lithium battery （SSLB） is a new type of electrochemical energy storage technology. The electrode slurry is the key material to realize electrochemical reaction of SSLB？ which is made by dispersing the electrode active material and conductive agent in the electrolyte to form hybrid system. The conductive per-formance of the electrode slurry is important to determine the electrochemical performance. Taking the LiFeP04 slurry with different ratios of conductive additive as the research target？ three methods？ the direct current conductivity tester,the electrochemical impedance spectra measurement and the alternating current resistance test at fixed frequency,were used to test the conductive property. The charge and discharge performance of the half cell sat different current densities were conducted and compared. The present results indicate that the electrochemical impedance spectra measurement is an effective method for the evaluation of conductive performance？ but the simulation of equivalent circuit reduces the efficiency of this method？ while the method of alternating current resistance test at fixed frequency is simpler and the test results are stable. Therefore,the alternating current resistance test at fixed frequency can be used for the evaluation and comparison of conductive properties of the electrode slurry.