Revealing the Impact of Slight Electrical Abuse on the Thermal Safety Characteristics for Lithium-Ion Batteries

Electrical abuse has a severe impact on the safety of lithium-ion batteries. The effect of electrical abuse, including slight overcharge and slight over-discharge, on the battery thermal characteristics is deeply investigated in this work. The heat generation under adiabatic conditions increases after the cell suffers from slight electrical abuse, and self-heating temperature during thermal runaway decreases, indicating that slight electrical abuse has an apparent negative impact on the battery thermal characteristics. Furthermore, slight over-discharge decreases the battery thermal characteristics more than slight overcharge under the same degree of slight electrical abuse. The postmortem characterization analysis is carried out to reveal the mechanisms of the change of thermal characteristics for both slight overcharge and slight over-discharge, in which the evolution of morphology, crystal structure, and composition for the anode and cathode are investigated by multiple characterization analyses, including scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. It is proved that the intrinsic essence of the thermal characteristics change is lithium plating for slight overcharge and is copper plating for slight over-discharge, which leads to the decrease of battery thermal stability and the different degree between slight overcharge and slight over-discharge.