Additive evolved stabilized dual electrode-electrolyte interphases propelling the high-voltage Li||LiCoO2 batteries up to 4.7 V

Elevating the cutoff voltage over 4.65 V notably augments the energy density of LCO batteries, but concomitant irreversible internal structural deterioration and serious side reactions at interface accelerate the capacity decay. The application requirement of high-voltage LCO batteries is still challenging. Triphenylphosphine selenide (TPPSe) served as multi-functional additive is involved in the electrolyte to concurrently construct stabilized solid electrolyte interphase (SEI) and cathode/electrolyte interphase (CEI) films and enhance the durability of high-voltage LCO batteries, benefited from the distinctive SeP group. The specific SeP group in TPPSe could be oxided in priority at cathode side to form SeOx and phosphate to enhance the high-voltage stability of LCO, and reduced at anode side to form Li2Se and Li3P, the lithium (Li) metal anode is well protected. Only 0.2 wt% TPPSe is added into the baseline electrolyte, the discharge capacity of LCO batteries is improved from 44 mAh g−1 to 159 mAh g−1 after 500 cycles at 1 C rate in the voltage range of 3.0–4.65 V. The functioning mechanism is revealed by XPS, TOF-SIMS, STEM, AFM, DEMS, et. al., combining with theoretical calculation. Furthermore, 10 wt% FEC and 1 wt% HTCN are introduced in the TPPSe-containing electrolyte to powerfully heighten the high-voltage stability. As expected, the Li||LCO pouch cell realizes the capacity of 169 mAh g−1 after 100 cycles at ultrahigh cutoff voltage (4.7 V) with low N/P ratio (1.19). Such an effective electrolyte-based strategy provides promising insight into the exploitation of valuable and practical electrolyte additives and realization of high-voltage LCO-based batteries with superior cycling performance.