Lithium-ion batteries because of the high life, high capacity is widely used, but with longer duration of use, the existence of ballooning, safety performance is not ideal and loop attenuation speed problem is increasingly serious, causing the depth analysis and inhibiting the lithium electricity industry According to experimental research and development experience, the author will lithium battery ballooning reasons fall into two categories, one is the thickness of the battery pole piece ballooning change; The second is due to electrolysis melt oxidation decomposition gas ballooning.