Ultrasonic Signs of Overcharged Lithium-Ion Batteries

Over the past decade, the quest for high-voltage, high-capacity cathode materials have emerged as a central focus in developing next generation high energy density lithium-ion batteries, drawing substantial attention and research efforts. This study leverages the sensitivity of ultrasonic waves to gas to investigate the ideal liquid injection coefficient for LiCoO
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-artificial graphite (LCO-AG) commercial pouch cells and the gas production rate at varying overcharge voltages, all while analyzing the associated failure mechanisms. The findings indicate that the LCO-AG commercial pouch cells maintain stability within a charge and discharge range of 3.0-4.5 V. However, when charged beyond 4.5 V, instability in the LiCoO
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electrode structure arises, leading to violent electrolyte oxidation and decomposition, subsequently compromising battery cycle stability. Ultrasonic imaging reveals an escalating gas production rate with higher overcharge cut-off voltages. This research provides valuable insights for determining the optimal liquid injection volume and understanding battery failure mechanisms. Consequently, it offers crucial guidance for battery design and usage strategies.