Lithium batteries are batteries made of lithium metal or lithium alloy as the negative electrode material, using non-aqueous electrolyte solutions. Due to the active chemical properties of lithium metal, the processing, storage, and use of lithium metal have high environmental requirements. So, lithium batteries have not been applied for a long time. With the development of science and technology, lithium batteries have become mainstream now.

　　Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium-ion batteries. Lithium ion batteries do not contain metallic lithium and are rechargeable. The fifth generation product of rechargeable batteries, lithium metal batteries, was born in 1996. Their specific capacity, self discharge rate, and performance price are lower than lithium-ion batteries.

　　Lithium ion batteries are now widely used in electric vehicles, energy storage, and digital products.

　　A charging cycle means the process of the battery going from full to empty, and then from empty to full, which is not equivalent to charging once. For example, a lithium battery only uses half of its capacity in a day and then fully charges it. If it continues like this for two days, that is, if you charge half of it and charge it twice in total, it can only be counted as one charging cycle, not two.

　　Therefore, it may usually take several charges to complete a cycle. Every time a charging cycle is completed, the battery capacity will decrease slightly. However, the reduction in battery capacity is relatively small. After multiple cycles of charging, the battery still retains 80% of its original capacity. Many lithium-ion powered products continue to be used as usual after two or three years.

　　Previously, the market believed that the lifespan of lithium batteries was only two to three years, with a cycle count of around 300-500 times. Nowadays, the rapidly developing lithium batteries have greatly increased their lifespan.

　　For example, some car companies can provide lifetime warranty for lithium batteries. In terms of cycle life, lithium iron phosphate batteries have already exceeded 3000-4000 cycles. Some companies are developing automotive grade batteries with a lifespan of 5000 to 6000 cycles. In terms of energy storage batteries, the cycle life is still higher.