In the 1970s, MS Whittingham began researching lithium-ion batteries. He was later known as the "father of lithium-ion batteries" and was awarded the Nobel Prize in Chemistry in 2019.
Because lithium metal is chemically highly reactive and prone to chemical reactions, its processing, storage, and use require very strict environmental conditions. Furthermore, lithium batteries contain a complex chemical reaction system, necessitating stringent storage environmental requirements.
So what factors actually affect the performance and lifespan of lithium batteries? And how can we extend their lifespan in daily use?
I. Depth of discharge and number of rechargeable cycles
The number of rechargeable cycles is related to the depth of discharge; the deeper the battery discharges, the fewer the number of rechargeable cycles. Number of rechargeable cycles * Depth of discharge = Total number of complete charge cycles. A higher total number of complete charge cycles indicates a longer battery lifespan. In other words: Number of rechargeable cycles * Depth of discharge = Actual battery lifespan.
II. Overcharging, over-discharging, and large charging and discharging currents.
Any form of overcharging will severely damage the performance of lithium batteries, or even cause them to explode. Overcharging should be avoided.
At the same time, deep discharge below 2V or 2.5V should be avoided, as this will rapidly and permanently damage the lithium-ion battery and may also cause internal metal plating to short-circuit, rendering the battery unusable or unsafe. Furthermore, large charging and discharging currents should be avoided, as high currents place excessive stress on the battery.
III. Overheated or overcooled environments
Temperature has a significant impact on lithium battery life. Sub-zero temperatures can potentially burn out lithium batteries the moment electronic devices are turned on, while overheating will reduce battery capacity. In direct sunlight or in a hot, stuffy car, it's advisable to turn off digital devices, as lithium-ion batteries age faster once the operating temperature exceeds 60°C. Lithium battery charging temperature range: 0-45°C; lithium-ion discharging temperature range: 0-60°C.
IV. Long-term fully charged or no-power state
Both excessively high and low charge levels are detrimental to the lifespan of lithium batteries. When a lithium battery is in a state of no or low charge for an extended period, the resistance to electron movement within the battery increases, leading to a reduction in battery capacity. Ideally, a lithium battery should be in a mid-range charge state, i.e., at 50% charge, for the longest battery life. Generally, maintaining a charge level between 10% and 90% is beneficial for battery protection.
