Battery Unit Screening by Overpotential for Post-Storage Consistency

The patent applies preliminary action by introducing a pre-storage screening process that is performed before the batteries are stored. The method involves discharging each battery unit at a 6C rate for 40 seconds and evaluating the variation curve of overpotential to identify batteries with consistent characteristics. This preliminary screening ensures that only batteries with good consistency are selected for grouping, and this consistency is maintained even after the storage period, thereby resolving the contradiction between initial consistency and post-storage consistency.

The patent implements preliminary screening of battery units before grouping by discharging each unit at a 6C rate and evaluating the overpotential variation curve. This preliminary action identifies batteries with consistent characteristics, allowing them to be grouped together. This approach maintains high productivity while ensuring good consistency between battery units, as the screening process is efficient and the grouping is based on objectively measured characteristics.

The patent changes the parameter used for screening from traditional indicators (voltage, internal resistance, capacity) to a new parameter: the variation curve of overpotential during 6C discharge. This parameter change provides more sensitive and accurate detection of battery consistency while maintaining screening efficiency. The overpotential variation curve captures dynamic electrochemical characteristics, enabling precise identification of consistent batteries without significantly increasing screening time.