Research On The Relationship Of Performance Between Ternary Cathode Cell And Battery Pack

The ternary cathode battery of LiNi_0.5Co_0.2Mn_0.3O₂ and its battery pack are used as objects of study.First,the performance of ternary cathode material and its battery is analyzed,and then the influences of resistance and temperature on battery pack are studied.Finally,the temperature field generated in the working process of battery is simulated and analyzed.The performance of ternary cathode material and its battery is analyzed.The study found that the battery voltage change rates with specific capacity are 10^-2 and 5.59×10^-2vg/mAh in the stage of SOC=89.85%to SOC=100%and SOC=0%to SOC=6.65%.The phenomenon of overheating and over current is easily caused,because the change rate of battery voltage is very high.Therefore,in order to improve its cycle life,the ternary cathode battery should be used as shallow charge and shallow discharge to avoiding the use of batteries in these two stages.The influences of resistance difference on the parallel battery pack are studied,which is caused by combination.The study found that with the increase of resistance difference,the current of the larger resistance battery would be outside the normal range easily,and the performance of battery is reduced,then the life of battery pack is shortened.The cycle life of battery pack is improved by connecting same length wires at the end of batteries'positive and negative.The paper found that the capacity retention rate of improved process battery pack is increased by 8.92%after 500 cycles.Through the study of influences of temperature factor on the parallel battery pack,the paper found that the difference of parallel branch current is increased or the over current phenomenon of larger resistance battery appears easily,because the temperature changes the capacity and resistance of single battery,and the performance of battery pack is reduced.By analyzing the influences of temperature on the battery,a scheme of improving the performance of battery pack is put forward.It's that putting larger resistance battery in the inner side,where the heat dissipation is difficult,and taking shallow charge and shallow discharge system,to avoiding the phenomenon of over current.The paper found that the capacity retention rate of improved process battery pack is increased by 4.99%after 500cycles.In view of the temperature influences on the battery,the temperature field of ternary cathode battery and battery pack is studied by using simulation software.The paper found that the battery temperature and the temperature difference of battery pack would beyond the normal range,if the working current,working environment and shell material are selected improperly.If the convective heat transfer coefficient is amplified,the temperature of sealed battery pack is reduced,but the temperature difference of battery pack is increased.In order to improve the performance of the single battery and battery pack,a scheme of improving the temperature field is put forward.For example,the distances between the single batteries are increased,and the ventilation holes are added at the center of the battery pack,and the shell is selected,which have strong cooling capacity.