Research On The Synthesis And Performances Of LiCo_xNi_1-xO₂ Of Lithium-Ion Battery

Compared with traditional secondary batteries, e.g., Pb-PbO₂ battery, Ni-Cd battery. Ni-MH battery and so on. Lithium-Ion Battery (LIB) shows greater advantages at the aspect of rate capability, energy density, and charge-discharge performance. Moreover, LIB also shows the advantages of long cycling life, low self-discharge rate, and amity to the environment. Now LIB has been broadly used in portable electrics, and actively used in space technology, national defence industry, electric vehicles (EV), UPS, etc. As we know, the key to the commercialization of LIB is the successful development of the intercalated electrode materials. This thesis introduced the cathode materials of LIB in detail, especially in the development status of LiCoO₂, and a summary of the LIB development about technology status and development tendency was also given. The effect mechanism of LiCoO₂ on the performance of the LIB was discussed from the viewpoint of the primary principle of electrochemistry. Further more, the fabrication technique and performance of LIB were studied, and LIB for EV was also studied primarily.The condition of synthesis about LiNi_xCo_1-xO₂ was tested, different material was used to rectangle batteries to tested the capability of the material. The capability of the circulation, the capability of charging and discharging in different rate was tested, The result showed that the condition of synthesis affect the material deeply. The result showed that:The temperature of synthesis should be about 800 ℃ ,the time of synthesis is about 60h, The proportion about n(Li):n(Co):n(Ni) in the material was n(Li):n(Co): n(Ni)=1.05:0.7:0:3 was best. The result of the capability of charging and discharging, the condition of circulation was good. The recharge capacity was high when recharge rate was0.1C .A new quasi solid-state method was used to make a stable Al₂O₃ film on the surface of Co₃O₄.The structure of the cathode material was characterized by XRD. The charge-discharge performance of the material was tested, Results show that materials have the advantage of uniform size-distribution and better electrochemical performance. For example :LiCo_0.98Al_0.02O₂ can yield 137.5 mAhg^-1 in it initial discharge and maintained at 130.29mAhg^-1 after being cycled 50 times at room temperature. The results of the experiment of overcharge performance show a satisfied result.