Comparison of Safety of Four Polymer Lithium Batteries

Lithium nickel-cobalt manganese acid(ternary) battery

The theory available in practice is greatly improved in terms of energy. Compared with lithium cobalt acid batteries, it can better play a high-capacity role. However, from the material point of view, ternary batteries use lithium nickel cobalt manganese acid and organic electrolytes., The safety problem has not been fundamentally solved. If the battery has a short circuit, it will generate too much current, which will cause safety hazards.

lithium iron phosphate battery

The theoretical capacity is 170mAh/g, and the actual reachable capacity of the material is 160mAh/g. In terms of safety, the heat stability of lithium iron phosphate is high, and the oxidation ability of electrolytes is low, so the safety is high; However, the defect is that the conductivity is low, the volume is too large, and the amount of electrolytes is large. Due to the large capacity, the consistency of the battery is poor.

Lithium cobalt acid battery

The biggest feature in preparation is that after being fully charged, there are still a large number of lithium ions remaining at the positive pole, that is, there are no more lithium ions attached to the positive pole at the negative pole, but in the supercharged state. Under, The excess lithium ions on the positive pole will still swim toward the negative pole, because they can not completely accommodate the change back to the metal lithium on the negative pole. Since the metal lithium is a dendritic crystal, it is called dendritic crystal. Once the dendritic crystal is formed, it will be pierced. The diaphragm provides an opportunity, The diaphragm puncture will form an internal short circuit. Since the main component of the electrolyte is carbonate, the flash point and boiling point are low, and they will burn or even explode at higher temperatures. Controlling the formation of lithium dendrites is relatively easy on small-capacity lithium batteries. Therefore, lithium cobalt acid batteries are currently limited to small-capacity batteries such as portable electronic devices and can not be used for power batteries.

Lithium manganate battery

The material of lithium manganate battery has a certain point. It can ensure that under the full state, the positive lithium ion can be completely embedded in the negative carbon hole, instead of having a certain residual at the positive pole like lithium cobalt acid. This basically avoids the production of dendritic crystals. Theoretically, in fact, if lithium manganese acid batteries encounter strong external forces or lose material during preparation, they may cause the battery to form lithium ions in the process of charging and discharging cycles. Fast movement. Dendritic crystals are formed when the negative pole does not fully receive lithium ions. Avoidance of this consequence is guaranteed by the test at the factory of the battery. In short, qualified lithium manganese acid batteries generally do not have safety accidents. The solid structure of lithium manganese acid makes its oxidation performance much lower than that of lithium cobalt acid. Even if the external short circuit is basically avoided, the combustion and explosion caused by metallic lithium can be basically avoided.

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