Spent Battery Sorting via High-Temperature Storage
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Solution Overview
Problem
Existing methods for determining the reusability of nonaqueous electrolyte secondary batteries cannot accurately differentiate between degradation caused by salt concentration unevenness and liquid shortage, leading to unnecessary battery disposal.
Innovation Solution
A method involving high-temperature storage of spent batteries between 40° C. to 75° C. for 8 to 48 hours to recover salt concentration unevenness and liquid shortage issues, with pre- and post-storage internal resistance measurements to assess reusability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If internal resistance is used as the sole determination indicator for battery reusability, then the determination process is simple, but reusable batteries are misclassified as unreusable due to salt concentration unevenness or liquid shortage
Solution Approach 1:
The patent applies preliminary action by performing high-temperature storage treatment before the reusability determination. This pre-treatment step restores batteries with salt concentration unevenness or liquid shortage to their proper state, ensuring that subsequent internal resistance measurements accurately reflect the battery's true condition rather than temporary degradation states.
Solution Approach 2:
The patent changes the temperature parameter by storing batteries at high temperature (40°C to 75°C) for a predetermined period. This parameter change facilitates the restoration of salt concentration distribution and liquid levels within the battery, thereby improving the accuracy of reusability determination based on internal resistance measurements.
2Productivity
If spent batteries are immediately evaluated without high-temperature storage, then the evaluation process is fast, but the evaluation accuracy is reduced due to reversible degradation from salt concentration unevenness and liquid shortage
Solution Approach 1:
The patent implements preliminary action by introducing a high-temperature storage step before evaluation. This pre-treatment restores reversible degradation issues, allowing for accurate evaluation while maintaining reasonable processing efficiency through optimized storage conditions and duration.
Solution Approach 2:
The patent utilizes parameter changes by controlling temperature (40°C to 75°C) and time (predetermined period) during high-temperature storage. These parameter optimizations balance the restoration effect on salt concentration and liquid levels with the need for efficient processing, achieving both accuracy and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurately determines battery reusability by recovering input/output characteristics, reducing material degradation, and minimizing the number of steps and costs, while avoiding misclassification of reusable batteries.
Implementation Method 1
the increase in the internal resistance of the battery caused by the salt concentration unevenness or liquid shortage is reversible, and where the salt concentration unevenness or liquid shortage is eliminated or the degree thereof is reduced, the nonaqueous electrolyte secondary battery can be restored to the usable state
Implementation Method 2
an electrolytic solution sometimes flows out from inside of an electrode body under the effect of expansion and contraction of an electrode active material or due to heat generation
Data Source
AI summary
Provided is a method by which the sorting as to whether a spent nonaqueous electrolyte secondary battery with the degraded input/output characteristics can be reused can be realized more accurately by taking into consideration the degradation of the input/output characteristics which is caused by the salt concentration unevenness and liquid shortage in the electrode body. The method for sorting a reusable nonaqueous electrolyte secondary battery, which is disclosed herein, includes: a preparation step of preparing a spent nonaqueous electrolyte secondary battery having a positive electrode and a negative electrode; a high-temperature storage step of storing the prepared nonaqueous electrolyte secondary battery for a predetermined time under a high-temperature condition; and a determination step of determining, on the basis of an internal resistance measured after the high-temperature storage step, whether or not the nonaqueous electrolyte secondary battery which has been stored at a high temperature can be reused.