If a lithium battery pack is placed in an irregular space for a long time without charging and discharging it, what will happen to it? We conducted a small experiment on this, and through observation, we found that the physical and electrochemical performance of the battery pack has decreased (correct storage does not cause these problems).
Lithium ion batteries are a relatively complex electrochemical system. After a long period of storage, the internal balance will gradually change. When accumulated to a certain extent, the following changes often occur in lithium batteries.
1. Physical characteristics
When a lithium battery pack is placed for a long time, its physical characteristics (appearance, size, weight, etc.) will change to some extent, especially its appearance characteristics. When the temperature and humidity of the storage environment are not good, this trend of change is more obvious. The weight of a battery pack stored in a high humidity environment for a long time is higher than that of a battery pack stored in a low humidity environment. For example, the steel shell of a battery is prone to rust under high humidity. Rust does not affect the internal condition of the battery, but it can also increase the weight of the battery, affect product transportation, and may have a negative impact on matching electronic components.
2. Electrochemical characteristics
● In terms of capacity, the capacity change of lithium batteries stored for a long time is mainly reflected in two aspects: first, the reduction of battery capacity, mainly caused by self discharge; The second is the increase in irreversible capacity, which mainly depends on irreversible consumption reactions between the chemical systems inside the battery. Self discharge is inevitable in all lithium ion batteries.
● Internal resistance. For lithium batteries stored for a long time, the resistance tends to increase with the increase of storage time. Exceeding a certain internal resistance can cause internal batteries to be scrapped or degraded, exceeding the reference value. Therefore, it is necessary to pay attention to the resistance changes of batteries during long-term storage.
● Discharge characteristics: The discharge characteristics of lithium ion batteries tend to decline after long-term storage. The low-temperature performance of batteries stored for a long time will significantly decrease.
So, how to properly store lithium battery packs to avoid loss?
The lifetime of lithium batteries is affected by operating temperature and ambient humidity. High temperature and humidity can accelerate the consumption of lithium battery life. It is recommended to store rechargeable batteries in a dry natural environment of 5 ℃ to 40 ℃. Lithium batteries should be charged 50% to 80% when not in use for a long time, and should be removed from the instrument and stored in a dry and cool environment. The battery should be charged every 3 months to avoid excessive storage time and battery self-discharge. Too low can cause irreversible capacity loss. If the lithium battery emits a peculiar smell, heat, discoloration, deformation, or any abnormality during use, storage, or charging, please immediately remove the battery from the instrument or charger and stop using it.
Lithium battery packs can be stored on three-dimensional shelves according to the technical requirements of the product itself, which is conducive to cost control and utilization of storage space.
During storage, deformation caused by stacking and squeezing, or damage or leakage of battery products should be avoided.
Lithium batteries should be stored away from direct sunlight or rain. If the battery becomes damp, the insulation resistance will decrease, and self-discharge and chloride may occur. Elevated temperatures can disrupt the normal functioning of the battery.
4. Use packaging that meets the requirements for safe storage or transportation, such as ordinary wooden boxes, corrugated boxes, PVG boxes, etc., to maximize the safe storage of the goods.
Therefore, in order to give full play to the energy efficiency of lithium batteries, it is necessary to pay attention to the knowledge of lithium battery maintenance and long-term storage during daily use and storage.
