1,2,3,4-Tetrakis(2-cyanoethoxy)butane (TCEB)-Assisted Construction of Self-Repair Electrode Interface Films to Improve the Performance of 4.5 V Pouch LiCoO2/Artificial Graphite Full Cells Operating at 45 °C

1,2,3,4-Tetrakis(2-cyanoethoxy)butane (TCEB) is first evaluated as a functional electrolyte additive to increase the charge cutoff voltage and energy density of pouch LiCO2 (LCO)/ artificial graphite (AG) lithium-ion batteries (LIBs) at a high temperature of 45 degrees C. The charge (0.7 C) and discharge (1 C) tests show that TCEB effectively improves the cycle stability of cells under a high charge cutoff voltage of 4.5 V. At 25 degrees C, the capacity retention of the cells with TCEB increases from 0.0% to 72.1% after 1200 cycles. At 45 degrees C, the capacity retention of the cells without TCEB after 50 cycles is close to 0.0%, while the capacity retention of the cells with TCEB is still 81.6%, even after 350 cycles. The spectroscopic characterization results demonstrate that the TCEB electrolyte additive participates in the construction of a self-repair electrode/electrolyte interface film. Subsequently, low impedance and strong protective layers are formed on the two electrode surfaces. The quantitative analysis results and a theoretical calculation also show that TCEB effectively inhibits the dissolution of Co3+ and maintains the structural integrity of electrode materials. These results indicate that TCEB endows LIBs with excellent cycle stability and is a promising electrolyte additive for the high-voltage and high-temperature conditions of LCO-based LIBs.

Automated summary

TCEB is a promising electrolyte additive that effectively improves cycle stability and energy density of LIBs. Experimental tests and spectroscopic characterization show that TCEB enhances cycle life and forms strong protective layers on electrode surfaces.