Study On The Multi-Component Safe Electrolyte For Lithium Ion Battery

Lithium-ion battery (LIB) is a new energy resources, and has been widely used owing to its long-term cycle performance, moderate rate capability, and higher gravimetric and volumetric energy. But lithium ion battery contains flammable organic electrolyte and under certain abuse conditions, flame or explosion may be caused. The safety has always been an issue for lithium ion battery, especially for the larger size lithium ion batteries. Therefore, it’s meaningful to research and development the safety electrolyte.In this paper, we research and analyze a multi-component safety electrolyte, and the 1.0 mol/L LiPF6/EC+DEC(1:1 wt.%) is the baseline electrolyte. The flammability and conductivity of the two electrolytes were tested, and the results show that compared to the baseline electrolyte, the burning rate of the multi-component safety electrolyte decreased to some extent, and its conductivity increased by 20.8%. The thermal stability of the two electrolytes was tested by C80 micro calorimeter. The results indicate that multi-component safety electrolyte releases much less heat than that of baseline electrolyte, which decreases by 45.6%. The main exothermic peak temperature is delayed from 201.4℃ to 244.2℃.The two electrolytes and LTO anode are assembled as the half cells:Li/baseline electrolyte/LTO and Li/multi-component safety electrolyte/LTO. The cyclic performance indicates that from the first cycle to the 35th cycle, the specific capacity of Li/multi-component safety electrolyte/LTO is higher than that of Li/baseline electrolyte/LTOhalf cells, and their cycle efficiency are nearly equal. From the results of cyclic voltammetry, it was found that multi-component safety electrolyte has a good stability and compatibility on the LTO electrode. The results of thermal stability show that Li/multi-component safety electrolyte/LTO system released less heat apparently, decreased by 35.4%. Moreover, the activation energy of the Li/baseline electrolyte/LTO system is bigger, which indicates more stable chemical stability.The two electrolytes and NCM cathode are assembled as the half cells: Li/baseline electrolyte/NCM and Li/multi-component safety electrolyte/NCM. The cyclic performance indicates that from the first cycle to the 65th cycle, the specific capacity and cycle efficiency of the two half cells are nearly equal. From the results of cyclic voltammetry, it was found that multi-component safety electrolyte has a good stability and compatibility on the NCM electrode. The results of thermal stability show that Li/multi-component safety electrolyte/NCM system released less heat, and the sharp peak value reduces from 594.2 mW/g to 352.7 mW/g, with a reduction of 40.6%. Moreover, the activation energy of the Li/multi-component safety electrolyte/NCM system is bigger, which indicates more stable chemical stability.The two electrolytes and LFP cathode are assembled as the half cells:Li/baseline electrolyte/LFP and Li/multi-component safety electrolyte/LFP. The average specific capacity of Li/multi-component safety electrolyte/LFP half cells is 8% higher than that of Li/baseline electrolyte/LFP half cells at the 0.1 C rate, and at the 0.5 C rate, their specific capacity are nearly equal. From the results of cyclic voltammetry, it was found that multi-component safety electrolyte has a good stability and compatibility on the LFP electrode. The results of thermal stability show that LFP/multi-component safety electrolyte/Li system released less heat apparently, decreased by 39.5%. Moreover, the activation energy of the LFP/multi-component safety electrolyte/Li system is bigger, which indicates more stable chemical stability.