Experimental investigation of the influence of electrolyte loss and replenishment on the critical performances of cylindrical lithium-ion cells

The loss of electrolytes is a non-negligible aging mode that could lead to the performance degradation of lithium-ion batteries, and electrolyte replenishment may be a potential scheme for battery performance recovery. In this study, a series of cylindrical 18,650 cells with different electrolyte losses and replenishments are prepared, and then the relationship between electrolyte residuals and battery performances is experimentally investigated. The results show that the capacity reduction will be significant when the electrolyte residual is less than 70%, and the solid electrolyte interphase, ohmic impedance, and reaction impedance increase suddenly. Severe capacity fading (rollover failure) can be clearly observed when the electrolyte residual is less than 50%. Moreover, the feasibility of restoring battery performance by refilling electrolytes is investigated experimentally. The results show that the capacity and impedance of the cells with different electrolyte losses are extensively restored after electrolyte replenishment, and the rollover failure is disappeared. This study provides a valuable reference for understanding the mechanism of battery aging and rollover failure, and proposes a new idea for the secondary utilization of the aged cells.