When the polymer lithium battery is overcharged or overdischarged during charging, the charger and the mobile power source do not match easily, and the battery is overcharged, and the possibility of expansion of the polymer lithium ion battery is increased. When the battery is charged and discharged, the inside of the battery continues to rise, the gas generated during the activation process expands, the internal pressure of the battery increases, and the pressure reaches a certain degree. If the outer casing is scratched, it will rupture, causing fire or even explosion.
There is also a problem of edge protection. The interlayer of the aluminum-plastic composite film packaging material of the edge-sealing surface is made of pure aluminum and has good electrical conductivity. It must be reliably insulated and insulated to prevent external elements. The device constitutes a short circuit, which is likely to cause corrosion and flatulence in the cell.
There are two forms of short circuit inside the polymer lithium battery: one is the process of laminating and soft packaging of the battery core, the current collector of the anode and cathode breaks through the electrolyte diaphragm, and physical contact occurs to form a short circuit, called physical short circuit. The other is the local electron conduction caused by the chemical change of the electrode active material and the electrolyte diaphragm material itself during the charge and discharge cycle, which is called chemical short circuit.