LiFePO 4 单颗粒电化学本征性能的快速精确评测

Abstract

Single particle microelectrode enables to evaluate the electrochemical responses for single particle of active material without binder and conductive agent. Thus, the influences of additive and electrode structure on the electrochemical performance of active materials can be ignored. Furthermore, this technology can be used to evaluate active materials fast. Therefore, single particle microelectrode allows fast and accurate determination of the intrinsic performance of active material. Cyclic voltammogram(CV),cycle performance, and kinetic behavior of LiFePO_4 cathode materials were evaluated by the single particle microelectrode. CV curve of LiFePO_4 particle with a pair of oxidation and reduction peaks was obtained with scan rates of 20 m V·s~(-1), which is 400 times larger than that of composite electrode. Besides, it is found that Li+diffusion in LiFePO_4 particle is the bottleneck of electrochemical process, and the Li+diffusion coefficient in LiFePO_4 particle is about 2.4 ~ 3.2 × 10~(11)cm~2·s~(-1). Excellent cycle performance was also proved to be the intrinsic properties of LiFePO_4 cathode materials by single particle microelectrode. Therefore, single particle microelectrode is an effective method for evaluation of active materials for lithium ion batteries.