Study On High And Low Temperature Performance Of Lithium - Ion Battery For Lithium - Ion Battery

The lithium-rich manganese-based material has a stable structure, good cycle performance, inexpensive.It has been researched by lithium-ion battery workers and was expected to become one of the cathode materials for lithium-ion battery. With the lithium-rich manganese-based material as the cathode material, artificial graphite as the anode material, the electrochemical properties of the batteries were tested, including the low-temperature discharge performance, the high temperature cycle performance and high-temperature storage performance.The lithium-ion battery pole piece surface morphology was observed by scanning electron microscopy(SEM) after discharging at the high and low temperature,the content of elements on the surface of the pole piece can be measured by energy dispersive spectroscopy(EDS).The results showed that the lithium-ion batteries charge-discharge performance and polarization getting worse and worse as the temperature decrease under the conditions of low temperature.The formation voltage,the type and use of the conductive agent, the compaction ratio have an effect on the low temperature performance of the lithium-ion battery,0.1C forming current is beneficial to the form of the SEI film on the negative electrode surface.Using more conductive agent can’t effectively improve the low temperature(-20℃) discharge performance of the battery,but on the contrary to hinder the low diffusion of the lithium ion,and the addition of4%of the conductive agent SP has good low temperature discharge performance. In the other under the same conditions,the low temperature performance was better when the cathode compaction ratio was larger,among the four kinds compaction ratios,the largest compaction ratio (3.2g/cm3) discharging at-20℃had a specific discharge capacity55.1mAh/g,and was the highest specific capacity.For the high temperature(55℃) cycle performance of lithium-ion battery, the lithium-rich manganese-based material has better cycle performance than Lithium manganese oxide spinel and Ternary materials,its capacity retention rate is106.6%after100cycles. Surface density and the compaction density of the cathode material have a great influence.The small surface density (270g/m2) improve the high temperature cycle performance in three different surface density (270g/m2、315g/m2、360g/m2); the cycle performance of lithium-ion battery of high temperature55°C showed a certain degree of downward trend as the compaction ratio increases. Although the lithium-rich manganese-based material increase the discharge grams capacity at high cut-off voltage under high temperature(55℃),the discharge threshold voltage may decrease,this means that the battery pack needs more single battery and the risks also arising.The lithium ion battery should not be storaged at60℃or higher temperature,integrated all aspects of performance,the batteries can effectively be activated when they had been storaged at45℃for three days.