The Study On The Effect Of Mixing Li LiNi_0.4Co_0.2Mn_0.4O₂ With LiMn₂O₄ And Ceramic Separator On The Performances Of The Battery

As the global population,traditional energy such as coal and oil consumption and air pollution is increasing,as well as urban traffic congestion,the development of new energy car will be a important strategy of national policy in the world,China is no exception,it strongly advocates the development of new energy car in a lithium-ion motive power type.NCM has become the preferred positive material for lithium-ion battery applied in electric power-assisted with its outstanding comprehensive performances,such as high specific energy,good cycle performance and etc..To do the research,we mix the LiNi_0.4Co_0.2Mn_0.4O₂ which has higher specific capacity with the LiMn₂O₄ which is more stable at different ratios,then study the cycle performance,high and low temperature performance and safety property.Cycling tests with button cell were investigated,and the performance of LiMn₂O₄ and LiNi_0.4Co_0.2Mn_0.4O₂ in button cell is best when its voltage range is 3.0-4.2V and 2.8V-4.2V,respectively,was confirmed.Based on the cycling,high and low temperature and safety test of four different proportion matched material,we come to a conclusion that the material with a ratio of 7:3 has the best electrochemical performances in the 3.0-4.2V charge and discharge potential range,and its specific capacity is around 135mAh/g.Even under the temperature of-20??-10?and 55?,the battery still have about 60%?80%and 105%capacity retention,respectively,which conform to the electrochemistry requirements of New Energy Car,but its safety performance improvement still have a long way to go.Rial on its different process combination of activation,formation and high-temperature aging,we found that if we do the process of amalgamative activation and simplified formation before high-temperature aging process,the capacity retention can be increased by4%even after 350 cycles in room temperature,and its high-temperature charge retention and high-temperature capacity restoration rate can be improved by 0.9%and 1.6%,respectively.Meanwhile,the 3C rate can be fully upgraded by 6.3%comparing with the82.7%of the original scheme.What's more,it shorten the production time so as to greatly improve the equipment utilization and productivity.From the study on the ceramic separator,which is shaped by coating the Al₂O₃ on the common separator surface,we found that the coated Al₂O₃ ceramic material enhances its tensile strength,thermal contraction and electrolyte absorption as well as the electrolyte retention ability,so as to significantly improves the puncture-resistant performances of the battery.