Meaning
Environmental control and state-of-charge management of packaged batteries before installation prevents irreversible chemical degradation and capacity loss. Standard practice for lithium-ion cell storage requires maintaining a cool, dry environment with the cells held at a partial state of charge to minimize side reactions. This procedure ensures that cells remain safe and functional when kept in warehouse inventories.
Storage Condition
Temperature is the most critical variable affecting the self-discharge and degradation rate of stored batteries. Elevated temperatures accelerate the growth of the solid electrolyte interphase and lead to a permanent loss of active lithium. For long-term lithium-ion cell storage, maintaining a temperature between ten and twenty degrees Celsius with low relative humidity is recommended to slow these aging reactions.
Capacity Recovery
When cells are retrieved after storage, they undergo testing to evaluate both reversible and irreversible capacity losses. The reversible capacity is restored after a full charge and discharge cycle, whereas irreversible loss represents a permanent loss of active material. If lithium-ion cell storage occurs at too high a state of charge, the elevated electrode potential accelerates oxidation and electrolyte decomposition, resulting in higher irreversible loss.
Conversely, keeping the cells at a very low state of charge can cause the copper current collector to dissolve if the cell potential drops below two volts, rendering the cell permanently unusable and dangerously unsafe to recharge.
Commercial Strategy
Procurement agreements often define the maximum allowed storage duration and acceptable state of charge upon delivery. Ensuring adherence to the guidelines of lithium-ion cell storage helps distributors manage risk and avoid financial losses from dead or degraded inventory. Buyers use these guidelines to establish receipt inspection protocols that verify the health of the incoming batches.
