Effect of stirring environment humidity on electrochemical performance of nickel-rich cathode materials as lithium ion batteries

The effect of moisture absorption of the nickel-rich cathode material during the stirring process on electrochemical performance was studied. Studies have shown that the sample stirred in low humidity has better electrochemical performance. At 0.2 C, the initial discharge specific capacity is 199.6 mAh·g−1. The capacity retention rate after 50 cycles is 91.4% at 1 C rate, which is 5% higher than the sample stirred in room temperature and humidity. The CV, EIS curves, and SEM images of different samples were analyzed before and after cycle. It indicates that the material will absorb moisture in room temperature and humidity, which can lower amount of lithium, resulting in reduction of initial discharge specific capacity. In cycle, the electrolyte can react with moisture and decompose in the battery, which can be proven from the XPS spectrum. It causes the transportation of lithium ions’ difficulty, the material structure collapsing, and the capacity attenuation.