Tin (Ⅳ) Oxide (SnO_2) Modified LiNi_(0.8)Co_(0.2)O_2 Cathode Material For Lithium Ion Batteries

摘要

Synthesis of positive electrode materials for lithium ion batteries (LIB) plays a major role in battery performance. In this study, we first investigated the effect of chelating agents and calcination temperature on the production of LiNi_(0.8)Co_(0.2)O_2 cathode material. Then, by using mechanical mixing and sol-gel methods, tin oxide was introduced in the LiNi_(0.8)Co_(0.2)O_2 powder to enhance the electrochemical performance. The effects of chelating agents (citric acid, oxalic acid, adipic acid), calcination temperature (600-800 ℃, @10 hours) and the tin oxide presence on the LiNi_(0.8)Co_(0.2)O_2 powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer, Emmmett and Teller (BET) analyses. Galvonastatic tests were performed in between 3-4.2 V at various C rates (0.2,0.5, 1C). The powders produced by using adipic acid as chelating agent at 700 ℃ showed higher capacity and better electrochemical properties than those of powders synthesized by oxalic and citric acid. And sol-gel modified powders had higher initial capacity and better capacity retention than the mechanically modified and the bare powders. Sol-gel modified powders had more stable cycle characteristic and they had not shown immediate capacity fall even at higher C rates where they kept their capacity above 140 mAh/g even after 50 cycles.