Study On The Effects Of Key Materials For Lithium-ion Dynamic Battery On Its Low Temperature Performance

Lithium-ion dynamic battery has become the focus of research and has beenmoving toward market replacing the traditional lead-acid, nickel-metal hydride andnickel cadmium battery gradually with the advantages of high energy density, highpower density, long service life and green pollution-free. Compared with other fields,high power and high capacity power supplies have higher requirements on all theaspects of Lithium ion dynamic battery. At present, Lithium ion dynamic battery holdsdefects on functions and cost. For example, to a largely extent, the defect of its lowtemperature performance restricts its wild using in the field of dynamic battery. Theoutput performance of Lithium ion dynamic battery will be affected below0degreesCelsius, the functions of battery will deteriorate significantly below minus20degreesCelsius, and battery will be used only30%of rated capacity below minus40degreesCelsius. The functions and performances of battery materials directly determines theadvantages and defects of battery products, so, it is very important for improving thelow temperature performance of Lithium ion dynamic battery by testing its effects onthe low temperature performance from the materials.This paper mainly studies the key materials of Lithium ion dynamic batterywhich concludes separator, electrolyte, and cathode active material and their effectson the low temperature performance. All the experiments are finished in the powerbattery production lines；so, The purpose of it is to make the research results havereference value and guiding significance on the actual production process. The steamwhich is evaporated when the pole pieces are baked has not any pollution onsurroundings, because in the procedure of making and preparing the Lithium iondynamic batteries, it uses the water-borne binder to make and prepare the positive andnegative pole pieces. Compared with the conditional NMP organic regents, it is moreenvironmentally friendly and the cost is lower.The thermal analysis of separator contrasts to the thermal shrinkage ability of theseparator1and the separator2, and SEM analyzes the changes of separator porestructure at various temperatures. And we get “closed temperature” from it. Comparedwith the separator2, the separator1has better thermal performance and mechanicalstrength by testing and analysis while, the separator2has better circulationperformance and low temperature performance. It is because the making and preparation methods are so different that the morphology of the holes is aslo different.On the whole, the diaphragm materials have little influence on low temperatureperformance.On one hand, this paper also studies the effects of conductivity electrolyte on lowtemperature performance and discovers that the low viscosity solvent can increase theconductivity of electrolyte. The electrolyte3has lowest EC index in these testedelectrolytes and has highest corresponding conductivity. And it also has best lowtemperature performance and its capacity expressed at0degree accounts93%in thenormal temperature. On the other hand, finds that the effect of the low temperatureperformance of batteries is mainly affected by the process of charging at lowtemperature. The elaboration of capacity of electrolytes with additives is better thanthe electrolytes with no additives either at normal temperature or low temperature. Soit can improve the capacity of battery and low temperature performance effectively.The content of additive can affect the function of electrolyte, if it is higher overstandard content, the electrochemical performance will degenerate.This paper also compares the positive materials of these two normal powerbatteries: LiMn2O4and LiFePO4.And it finds that the cycle performance of them haslittle differences. And the low temperature performance of LiMn2O4is better than thatof LiFePO4obviously, the capacity retention rate them keeps86%and69%at lowtemperature. And it also studies how the density of the positive pole of one-sidedaffects low temperature performance, and finds that the density of the reduction offacet can provide the low temperature performance of battery.