Experiment method Extrusion test: The test battery was squeezed in two screens, and a squeeze force of about 13 KN was applied by a vise or a piston diameter of 32 mm. Pressing the pressure gauge reading on the hydraulic device reached 17.2 MP, once the maximum pressure , To lift the extrusion. For cylindrical batteries, the long sleeves of the extruded battery should be parallel to the squeeze screen of the extruder, and the pressure on the column should be applied to one of the two axes perpendicular to its long sleeve and then squeezed Press another axis, the button on the battery, squeeze the gas screen. Each test battery is squeezed only once. Acupuncture test: the test should be 20 ℃ ± 5 ℃ ambient temperature, will be connected to the thermocouple battery (thermocouple contact fixed to the battery surface) placed in a fume hood, with a diameter of 2-8mm The stainless steel needle is pierced at the center of the maximum surface of the battery at a speed of 10 mm / s to 40 mm / s and held at any time.