Study On The Influence Of The Preparation Process Upon The Uniformity Of The Power Lithium-ion Batteries

Lithium-ion battery is getting more and more attention in the field of electricvehicles with the development of new energy promotion. Power batteries need thesystem output high power and high capacity which we must pack the single cells.The performance differences between the cells have crucial influence upon thebattery pack. So the study of power lithium-ion battery should not only focus interms of the performance of cell battery, such as the battery materials, auxiliarymaterials, or machinery equipment. Improving the uniformity of single battery isalso very important. While nearly most of the research on the uniformity of the li-ionbattery is considering how to improve the detection technology to improve thesorting results and the battery management system. The relationship between thepreparation production and the uniformity of the li-ion batteries has not reported yet.In this paper, the preparation process was studied. The reason that caused cellperformances difference and the solution were pointed out. This study focus on thoseprocess which have significant impact on the uniformity of cells in batteries,including the slurry mixing, coating, rolling, roll winding or lamination, liquidinjection, and formation. Experiments were carried out to analysis the influence ofevery crucial preparation process.Battery with capacity of5Ah was designed and produced which havehigh-power and high-capacity by using the existing process conditions. The Batteryis using the LiMn2O4as the cathode, graphite as the negative, conductive carbon as aconductive agent, and a new water-based binder. The test shows that these batterieshave a good consistency on the capacity, internal resistance and voltage. Todetermine the relationship between the battery performance and the process, thedifferences of performance under the same process, different compaction density anddifferent liquid injection were analyzed.In this paper, the accurateness of cell classification was promoted by extractingthe discharge capacity, the DC discharge resistance and the rate of time which costby constant current and voltage charging. The result of consistency is good bysorting with these three characteristics. What’s more, it doesn’t need more processsteps and have no destructive to the batteries. The test results of5Ah powerlithium-ion battery classification and evaluation with this method show that themethod is reliable. And it can achieve or surpass the accuracy of sorting by capacity, internal resistance, and voltage. What’s more, it is less of the process of theconventional internal resistance, voltage testing process, and overcome thelimitations of sorting by single points, and it can also ensure that the uniformity ofbatteries of all kinds of performance indicators. So we can say it provides a fast andsimple and reliable method to the actual production of power lithium-ion batterysorting.