Tris (trifluoroethyl) phosphate (TFP):
1. Introducing 5%-20% concentration of TFP in the electrolyte, the flame retardant performance is significantly improved; when the TFP content reaches 20%, the electrolyte is almost incombustible;
2. TFP has good electrochemical stability on MCMB anode material and LiCOO2 cathode material; it has poor electrochemical performance in graphite/LiCOO2 full battery;
3. The conductivity of the electrolyte decreases with the increase of TFP concentration, which may be caused by the low dielectric constant of TFP, which inhibits the dissociation of the lithium salt electrolyte LiPF6;
4. The electrochemical stability of TFP in the electrolyte of MCMB/LiCOO2 battery is good, and it has little effect on its cycle performance.
5. 1% FEC and 20% TFP+1.0mol/L LiPF6/EC+DEC flame retardant-negative electrode film-forming additive compound electrolyte system shows excellent electrochemical performance in graphite/LiFePO4 full battery.
Bis (trifluoroethyl) carbonate (DTFEC):
1. When 1%-5% TFEC is added, the conductivity will increase, when it exceeds 10%, the conductivity will decrease, and 5% of the conductivity will be the highest;
2. The higher the TFEC concentration, the better the flame retardant effect;
3. The higher the TFEC concentration, the lower the battery capacity, and when it exceeds 5%, there will be a significant drop;
4. The addition of TFEC will aggravate the attenuation of battery capacity, but the attenuation rate is very low. Even if the mass ratio of TFEC reaches 20%, the attenuation rate will not exceed 3%;
5. The addition ratio of TFEC ranges from 0%-20%, and the capacity retention rate is maintained above 99.9%. Therefore, TFEC has no negative impact on the cycle performance of the battery when the battery is charged and discharged at a low rate (0.5C);
6. As the content of TFEC increases, the internal resistance of the battery shows a trend of first decreasing and then increasing, and it is the smallest when the addition amount is 5%.
7. Appropriate amount of TFEC can improve the reversible performance of battery materials. Excessive amount is not conducive to the reduction of electrode polarization and the improvement of reversible performance. When the content is 5%, the electrode polarization is the smallest, and the reversibility and circulation are the best;
8. The addition of TFEC increases the oxidation potential of the battery. As the concentration increases, the voltage rise rate under overcharge conditions is significantly reduced, and the withstand voltage and overcharge performance are significantly enhanced;
9. The addition of TFEC can improve the safety of the battery under internal short-circuit conditions;
10. The addition of TFEC can extend the endurance time (the time from when the temperature of the hot box reaches 150°C until the battery explodes).
Methyl trifluoroethyl carbonate MTFEC:
1. Adding a certain amount of methyl trifluoroethyl carbonate can increase the conductivity of the solution;
2. Methyl trifluoroethyl carbonate has certain flame retardancy;
3. Methyl trifluoroethyl carbonate slightly reduces the battery capacity, but its impact is much smaller than TFEC;
4. Methyl trifluoroethyl carbonate has little effect on the cycle performance of the battery;
5. Methyl trifluoroethyl carbonate increases the oxidation potential of the battery;
6. The addition of methyl trifluoroethyl carbonate can improve the safety of the battery under internal short-circuit conditions;
7. Methyl trifluoroethyl carbonate can prolong the battery endurance time.