Analysis of the causes and effects of electrode cracking in lithium batteries.lithium trolling motor battery

　　In the actual use of lithium batteries, active particles often undergo many irreversible physical, chemical, and mechanical processes, such as local overcharging and discharging, surface structure collapse, uneven electrode/electrolyte interface, metal dissolution/precipitation, volume expansion/contraction, local temperature fluctuations, etc. The interaction between these side reactions can lead to the accumulation of mechanical or thermal stress, electrochemical stress, and further induce the generation of cracks within the active particles. This type of crack mainly occurs at stress concentration and weak points of particles, such as particle surfaces, SEI films, grain boundaries, etc.

　　Especially for silicon-based negative electrodes, when lithium is inserted and removed during the charging/discharging cycle, the volume change reaches 270%. This huge volume expansion will cause the crushing of silicon particles and the separation of the coating from the copper collector. Especially, the SEI membrane undergoes a continuous process of fracture and regeneration, constantly consuming lithium ions and active substances, resulting in continuous capacity decay and poor cycling stability.

　　The cracks generated inside the particles can lead to poor contact between particles, damage to particle integrity, and changes in electron and ion transport paths, leading to limited diffusion. The results indicate that the diffusion length of electrons and ions in the solid phase increases with the generation of cracks. This will further affect the electrochemical reaction, which may cause uneven local charging and discharging, leading to secondary cracks in the particles.

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