Fast charging of lithium-ion battery using multistage charging and optimization with Grey relational analysis

Slow charging of batteries is one of the main challenges for the deployment of battery electric vehicles (BEVs) into market. There are multiple concerns with fast charging of lithium-ion batteries, such as rapid rise of surface temperature, accelerated aging, dendrite formation and lower charging efficiency. In order to achieve fast charging without compromising the aging of lithium-ion battery, one of the possible solutions is multistage constant current (MCC) charging. In this study, the charging levels of 5S-CC (five stage-constant current) charging (a type of MCC charging) has been optimized by using a new efficient approach Grey relational analysis (GRA) with Taguchi Design of experiment. It is also the part of the study to investigate CC-CV (Constant current -Constant voltage) charging and provide a comparative analysis with 5S-CC charging for creating an efficient lithium-ion battery charging technique for battery-powered vehicles. Panasonic NCR 18650PF lithium-ion bat-teries with LiNiCoAlO2 as the cathode and graphite as the anode having nominal capacity of 2750mAh were used in this study. The optimized 5S-CC charging takes 48.11 min compared to 73.48 min for CC-CV_0.05C charging, and the maximum temperature in CC-CV charging is 41.02 degrees C while in 5S-CC charging is 40.08 degrees C. The 5S-CC charging, generates significantly lower amount of surface heat up to 93.66 J while CC-CV_0.05C charging, generates 100.11 J, which may address the existing issue of rapid charging while extending battery life.