Analysis And Study On The Effects Of The Low Temperature Performance For Lithium-ion Battery

As a new generation of clean and renewable energy system, lithium-ion batteries have manyadvantages such as high energy density, long life, reproducible and clean et al. It has been afocus of research in energy, and will gradually replace the traditional nickel-metal hydride,nickel cadmium and lead-acid batteries. It has been widely applied to mobile phones, digitalcameras, laptop computers and many other fields. Of course, lithium-ion batteries still havemany faults such as weak low-temperature performance, heavy load discharge performanceand security issue except for it advantages which restrict in wide range of applications in manyother fields.This paper had a research on the factors of affecting the low-temperature performances,there are conductive agents, electrolyte, cathode material which are applied to the batteriesmade process, The research content are as follows:(1)Firstly I had a research on how the conductive agent, electrolyte to have an influenceto low-temperature performance of lithium-ion batteries. Using CNT and SP as conductiveagent make two teams of batteries. First inject common electrolyte to two kinds of batteries.The result display that injected CNT batteries has a good low-temperature performance. At thesurroundings of0℃, the rate of low-temperature discharge capacity/normal temperaturedischarge capacity are95.39%and69.36%. Then inject dynamical electrolyte to two kinds ofbatteries, the result show that at0℃to-10℃low temperature surroundings, no matter whichkinds of conductive agent used, injecting dynamical electrolyte batteries have a goodlow-temperature performance, at the surroundings of0℃, the rate of low-temperaturedischarge capacity/normal temperature discharge capacity are95.98%and95.86%, whichmostly have any difference between this two kinds of batteries making with conductive agentCNT and SP. But when temperature drop to-5℃, this two kinds of batteries made with CNTand SP, injected with dynamical electrolyte have a better low-temperature performance thanthe batteries injected with common electrolyte.(2)Secondly I mainly had a research on lithium manganite, containing three element ofcobalt, nickel, manganese, lithium iron phosphate material, the result demonstrated thatdynamical lithium manganite cathode material have a better low-temperature performancethan the common lithium manganite cathode material, at the surroundings of0℃, the rate oflow-temperature discharge capacity/normal temperature discharge capacity are94.28%and78.64%, three element material have a good low-temperature performance as well as common lithium manganite cathode material, at the surroundings of0℃, the rate oflow-temperature discharge capacity/normal temperature discharge capacity is78.79%, lithiumiron phosphate material has a more inferior low-temperature performance than others material,at the0℃, the rate of low-temperature discharge capacity/normal temperature dischargecapacity is71.82%.(3)Thirdly I analyzed the effect that the caking agent and the compacted density have onlow-temperature performance to lithium iron phosphate batteries, the result show that usingthree different kinds of caking agents batteries have different rate, the rate of low-temperaturedischarge capacity/normal temperature discharge capacity are71.82%,77.88%and78.85%.In this experiment we made three different batteries with three different compacted densities,which are1.7g/cm~3,1.8g/cm~3,1.9g/cm~3, the result show that the batteries have bestlow-temperature performance with1.8g/cm~3.(4)In the end, analyzed the effect of constant current and multistep formation to thelow-temperature performance, as the result show, varies current have little effect on theperformance but the formation have some effect on the low-temperature performance,constantcurrent formation is better.