Liquid Thermal System for Cell Aging and OCV Testing
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Solution Overview
Problem
The manufacturing of lithium-ion secondary cells is complex, with chemical interactions and mechanical challenges making it difficult to assemble and quality check cells effectively, leading to late-stage defects that are often irreparable and result in cell discarding.
Innovation Solution
A method involving assembling cells with electrodes and electrolytes, storing them in a liquid-based thermal system at varying temperatures, performing open circuit voltage (OCV) tests, and conducting charge/discharge cycles to evaluate and discard or keep cells based on test results, utilizing a liquid-based thermal system for controlled temperature management and accelerated chemical reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cells are fully assembled and conditioned in a formation process before quality checking, then the cell assembly is complete and functional, but defects are detected too late and cells must be discarded
Solution Approach 1:
The patent introduces a preliminary thermal treatment process (aging or forming) that accelerates chemical reactions and stabilizes the cell before final quality checking. This preliminary action allows defects to manifest earlier in the process, enabling detection before the cell is fully assembled and sealed, thereby reducing waste without compromising final product reliability.
Solution Approach 2:
The patent utilizes temperature as a variable parameter, storing cells at elevated temperatures (e.g., 40-80°C) to accelerate chemical reactions and stabilize the cell chemistry. This parameter change enables earlier detection of defects through accelerated aging tests, allowing quality verification to occur before final assembly completion, thus reducing the loss of time in defect detection.
2Productivity
If cells are stored at elevated temperatures to accelerate chemical reactions, then the formation process is accelerated, but energy consumption increases
Solution Approach 1:
The patent employs periodic thermal treatment cycles rather than continuous high-temperature storage. Cells undergo alternating periods of elevated temperature (to accelerate reactions) and ambient temperature (to conserve energy), with the thermal treatment applied only during critical formation stages. This periodic approach maintains productivity while significantly reducing overall energy consumption compared to continuous heating.
3Measurement precision
If multiple OCV tests are performed at different temperatures, then defect detection accuracy is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent integrates multiple OCV testing conditions into a single unified thermal treatment and testing system. The same thermal chamber used for accelerated aging also serves as the testing environment, and the system automatically performs multiple OCV measurements at different temperatures and time points. This multi-functional approach improves defect detection accuracy without proportionally increasing manufacturing process complexity, as the same equipment performs multiple functions.
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
This approach allows for earlier detection of defects, improved accuracy in cell capacity measurement, reduced cell aging time, and energy savings by enabling more efficient thermal treatment and quality evaluation, thereby enhancing the manufacturing process.
Implementation Method 1
storing the cells in contact with a liquid-based thermal system; circulating liquid in the liquid-based thermal system at least while the cells are in contact with the liquid-based thermal system
Implementation Method 2
circulating liquid in the liquid-based thermal system; after storing the cells at the first temperature, and while the cells have at least a partial charge, performing a first open circuit voltage (OCV) test on the cells; after the first OCV test, storing the cells at a second temperature lower than the first temperature
Data Source
AI summary
A method of manufacturing cells includes: assembling cells that include at least electrodes and electrolyte contained in a housing; after assembly, storing the cells in contact with a liquid-based thermal system; circulating liquid in the liquid-based thermal system at least while the cells are in contact with the liquid-based thermal system, the liquid having a first temperature; after storing the cells at the first temperature, and while the cells have at least a partial charge, performing a first open circuit voltage (OCV) test on the cells; after the first OCV test, storing the cells at a second temperature lower than the first temperature; after storing the cells at the second temperature, performing a second OCV test on the cells; and for each of the cells, discarding or keeping the cell based at least in part on the first and second OCV tests.