Several factors influencing the performances of lithium ion battery cycle
The cycle life for lithium battery is very important, the long cycle life mean less resource consumption. Thus, The influence factors of lithium ion battery cycle, it is the problem for each lithium electricity industry related personnel have to considered. Here we list some factors which may influence the battery cycle life.
1. Raw Material type: the choice of materials is the primary factor which influence the lithium ion battery performance. Chose the cycle performance of poor material, process made more perfect, more reasonable, the cycle of batteries must also cannot be guaranteed, Choose a good material, even made some follow-up questions, cycle performance may not bad too far. From the Angle of material, a whole battery of cycle performance, is by the positive electrode and the electrolyte circulation performance after the match, the cathode and the electrolyte cycle after the matching performance of the two, with poor person. Material cycle performance is poorer, on the one hand, is likely to be in circulation in the process of crystal structure change too fast to continue to complete the intercalated-li lithium, on the one hand may be due to the active substance and its corresponding electrolyte can't generate dense and uniform SEI film active material and electrolyte premature side reaction and make the electrolyte excessive consumption will affect cycle, in the design of the cell, if one side choose the bad cycle life material, then otherside no need to choose the good cycle life material, it would be waste.
2. Compaction of positive and negative electrode: if Compaction of positive and negative electrode is high, Although can improve the energy density of batteries, but also to a certain extent reduce the material cycle performance, According to the analysis of theory of compaction, the greater the equivalent of the greater the damage to the structure of the material, and the structure of the material is to guarantee the foundation of the lithium ion battery can be recycled, In addition, the anode compaction is high batteries are difficult to ensure higher fluid volume, and protect liquid quantity is to complete a normal cell cycle or the basis of more circulation.
3. Moisture: Too much moisture will with the cathode active material adverse events, and destroying the structure, in turn, affect the circulation, too much water also not conducive to the formation of the SEI film, But it is difficult to remove traces of moisture at the same time, the trace amounts of water can also be a certain extent to ensure the performance of the batteries.
4. Coating film density: Single variable considering membrane density on the influence of the cycle is an almost impossible task. Membrane density inconsistent or bring capacity differences, is either batteries winding or laminated layer of the difference, For the same as material of batteries with capacity, to lower density was equivalent to add a layer or multilayer winding or laminated layers, the corresponding increase of diaphragm can absorb more electrolyte in order to keep the cycle.
5. Too much negative electrode : Negative excess reason except for the first time to consider the influence of the reversible capacity and the density of coating film deviation, the impact on the cycle performance is also a consideration, For cobalt acid lithium and graphite system, negative electrode graphite into circulation in the process of the "short board" is common. If negative excessive insufficient, lithium batteries may before the cycle is not analysis, but the positive structure change little circulation after hundreds of times but the cathode structure is destroyed and cannot receive the positive provide lithium, lithium ion to analyse cause premature capacity decline.
6. The volume of electrolyte: Insufficient amount of electrolyte influence on the cycle there are three main reasons, one is the insufficient amount of filler, 2 it is though filled fluid amount but aging time enough or is negative because of the high compaction immersion is not sufficient, 3 it is inside the loop batteries electrolyte was consumed.
7. The objective conditions of the test: Test in the process of charging and discharging rate, cut-off voltage, charging cut-off current, in the test charge discharge, testing the room temperature, all of a sudden interruption in the process of testing, test points and outside factors, such as batteries, contact resistance will be more or less affect the cycle performance test result. In addition, the sensitive degree of different material to the objective factors each are not identical, unified test standard and knowledge of common and important characteristics of materials should be enough for routine use.
Conclusion: like bucket principle, many of the factors affecting the performance of cell cycle, the final decisive factor, is the shortest board of a number of factors. At the same time, between these influencing factors, also have interactive effects. Under the same material and made into ability, the higher the cycle, often means that the lower energy density, find combination point between just to meet customer demand, to ensure consistency of batteries made from as far as possible, is the most important task.