LED flashlights are a common portable lighting tool in modern life, and lithium batteries are its main power source**.
However, over time, many users may find that the lithium battery capacity of LED flashlights gradually decreases, resulting in a shorter use time.
There are several main reasons for the reduction of the lithium battery capacity of LED flashlight:
During the charge-discharge cycle of lithium-ion batteries, cathode materials (such as lithium cobalt oxide, lithium nickel manganese cobalt oxide, etc.) and.
Anode materials, such as graphite or silicon-based materials, undergo structural changes and wear, resulting in a gradual decrease in their efficiency at intercalation and de-intercalation of lithium ions.
With the increase of service time, the electrolyte will undergo an irreversible chemical reaction with the electrode surface to produce a solid electrolyte boundary** (SEI), which can stabilize the electrode-electrolyte interface, but excessive growth will consume active lithium and increase internal resistance, thus affecting battery performance.
The resistance inside the battery increases with the use of time, resulting in more energy loss and less energy actually available.
When multiple cells are connected in series, the inconsistent self-discharge rate between each cell will lead to an imbalance in power, which will further accelerate the attenuation of the overall battery capacity.
Under certain conditions, the battery may experience vulcanization, where components in the electrolyte react with metal parts to form insoluble sulfates, hindering the migration of lithium ions and reducing battery capacity.
Temperatures that are too high or too low will accelerate the deterioration of the battery's internal chemicals, and may lead to electrolyte deterioration, electrode material structure damage, and loss of active lithium ions, thereby accelerating the degradation of battery capacity.
Rapid charging and discharging will exacerbate the internal temperature rise of the battery, and may not be able to complete the electrochemical reaction sufficiently, which will also lead to a decrease in battery capacity and shortened life in the long run.
Deep discharge below the safe threshold will increase the stress of the electrode material and damage its microstructure, especially for some sensitive cathode materials.
In summary, a variety of internal factors and external use conditions act together on lithium batteries, resulting in a gradual decrease in their capacity over time.
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