Preparation And Performance Of Lithium-ion Cell With High Specific Energy

In recent years, lightweight requirements of battery for power system is increasingly outstanding. Because of the advantages such as high specific energy, long cycle life, Lithium ion battery has graually became the first choice of energy storage power for lots of power system. However, LiCoO₂/LiC₆ lithium ion battery which is relatively mature and used in engineering in domestic currently, with specific energy in 110wh/kg¹30wh/kg, cannot meet the requirement of use to lithium ion battery.To aim at the actual demand of engineering application, and to adapt to the high rate charge and discharge and the characters of wide working temperature range, the positive and negative electrode and the fluid were studied in this paper, which are the key affecting on the specific energy and the comprehensive performance. Based on study results, the li-ion battery with high specific energy was developed, the battery performance and safety were tested, and the performance characteristics and cycle performance of the battery were verified, analysised and summaried.The designs of the lithium ion battery are closely related to the application requirements such as charging and discharging mode, working temperature and working life and so on. High performance electrode materials plays an important role in lithium ion battery, and is an important approach to improve specific energy of battery. Compared with LiCoO₂ material which is widely used in lithium ion battery, LiNixCoyAlzO₂ materials exhibit more excellent specific capacity, thermal stability and high temperature performance, and mature and stable performance. LiNi_xCo_yAl_zO₂ materials is the ideal anode material for lithium ion battery high specific energy. This paper also studied the effects of type and content of conductive agent and compaction density on the properties of the anode electrode. When three different types of conductive material were mixing used, which are SP, SFG and VGCF, the effects were the best. To achieve the optimal specific energy, both optimal values to content of conductive agent and compaction density of electrode were there.The affects of the morphology and particle size of cathode graphite material on performance of the electrode were studied. Compared with SEM morphologies of random and long elliptic, the electrodes which were prepared with spherical shaped graphite were infiltrated in the shortest time and the battery with the same graphite material was the minimum ac impedance. Compared with material of small particle size, graphite material of large particle size has higher penetration rate. Therefore, graphite cathode materials of large diameter spherical exhibited more excellent specific energy and properties of high rate.Suitability of three different types of electrolyte were studied in this paper, through the compatibility of electrolyte with electrodes, and the ac impedance value of the battery, the battery discharge capacity and discharge voltage under the different working temperature, and the cycle performance. Type B electrolyte was superior to other two kinds of electrolyte in the all four sorts of performanceLithium ion battery with high specific energy has developed, the test results showed that the specific energy achived 170.35Wh/kg?0.5CA, 4.1V?, which was improved significantly compare with LiCO₂ battery. The capacity at 20? was-82.5% of the capacity at 20?, and the discharge capacity rised with temperature, the capacity at 50? was about 110% of the capacity at 20?. The battery showed good temperature characteristic. Discharge voltage of battery after 1235 times cycles in accordance with the working mode was not seen obvious failure. The capacity was still keep at 93.73% of original capacity, which showed the excellent cycle performance. The performance of developed lithium ion battery can meet the requirements of engineering application and had broad application prospects.