How to improve the safety of polymer lithium batteries?
With the advancement of the technological age, Grignard battery products have enriched our lives, and the polymer lithium batteries used in these products have higher safety performance requirements. So in what ways can we improve the safety of lithium polymer batteries?
1. The opening pressure and sensitivity of the safety valve safety valve are important factors affecting the safety of the battery, which can reduce the power of the explosion to a certain extent;
2. The principle of the additive: Polymer monomer molecules are added to the electrolyte. When the charging voltage exceeds the limit, the electrode surface polymerizes to form a film. The electrooxidation polymerization reaction seals the electrode surface and blocks the battery reaction to prevent unsafe behavior;
3. The diaphragm PP/PE/PP is better than PE and PP; when the battery is heated, the PE micropores in the middle layer of the internal diaphragm are closed first, blocking the flow of current, thereby playing a safety role;
4. Structural design refers to the internal safety isolation measures of the battery, including positive and negative, pole and diaphragm widths, fixed limit pieces, glue on both ends of the negative pole piece, and glue on the core.
A external short circuit
After the battery is fully charged, use a conductor with a resistance of less than 50mQ to short-circuit the positive and negative electrodes. The test result: the battery does not catch fire or explode after a short circuit.
The battery will not explode or catch fire if the battery is overcharged under the conditions of 3C rate and 5V voltage.
C Thermal Shock
After the battery is fully charged, it is placed in the incubator and heated to 150°C at a rate of 5°C/min, and kept for 30 minutes. The battery is bulging, hot, no fire, no explosion.
Fix the battery on the fixture of the safety device, and use a steel nail with a diameter of 2.5mm to force it down to make the battery completely penetrate. The battery leaks, generates heat, does not catch fire or explode.
E free fall
The six sides of X, Y, and Z are dropped twice at a height of 1000mm. After the drop, the cell voltage, internal resistance, and capacity are normal, and there is no heat. , Drum shell, etc.
Methods to verify the qualification of lithium batteriesHigh-rate battery test methods and requirements