Positive Electrode Solvent Retention for Low-Resistance Li-Ion Batteries
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Solution Overview
Problem
Non-aqueous rechargeable batteries experience performance deterioration due to increased DC internal resistance from repeated charging and discharging, which affects high rate characteristics.
Innovation Solution
The battery design includes a positive electrode plate with a mixture layer formed by applying a paste containing a positive electrode active material and organic solvent, where a larger amount of organic solvent remains in the end regions compared to the middle region, allowing for controlled vaporization and increased internal pressure to prevent electrolyte displacement during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the positive electrode mixture paste is dried to remove organic solvent, then the electrode structure becomes stable, but electrolyte displacement occurs during charging causing performance deterioration
Solution Approach 1:
The organic solvent is intentionally left in the positive electrode mixture layer before charging, serving as a preliminary buffer that prevents electrolyte displacement during subsequent charging operations. This preliminary presence of solvent resolves the contradiction by preparing the electrode structure to accommodate electrolyte volume changes without causing displacement.
Solution Approach 2:
The drying process parameters are adjusted to achieve partial rather than complete removal of organic solvent. By controlling the drying conditions (temperature, time, atmosphere), the solvent content is optimized to maintain electrode structural stability while retaining sufficient solvent to prevent electrolyte displacement during charging.
2Stability of the object's composition
If organic solvent is removed from the positive electrode mixture layer, then the electrode plate becomes more stable, but DC internal resistance increases due to electrolyte displacement
Solution Approach 1:
The organic solvent is retained in the positive electrode mixture layer as a preliminary measure to prevent electrolyte displacement during charging. This preliminary retention of solvent directly addresses the harmful effect of DC internal resistance increase by ensuring adequate electrolyte remains in contact with the electrode active material.
Solution Approach 2:
The solvent content parameter in the positive electrode mixture layer is optimized to a specific range that balances electrode stability with sufficient electrolyte retention. By controlling the solvent content parameter, the harmful effect of DC internal resistance is mitigated while maintaining necessary electrode stability.
3Ease of manufacture
If the positive electrode mixture layer is completely dried, then manufacturing is simplified, but high rate characteristics deteriorate due to electrolyte displacement
Solution Approach 1:
The organic solvent is intentionally left in the positive electrode mixture layer as a preliminary buffer before high-rate charging operations. This preliminary retention of solvent prevents electrolyte displacement that would otherwise occur during high-rate charging, thereby preserving high rate characteristics while maintaining manufacturing simplicity.
Solution Approach 2:
The drying process parameters are adjusted to achieve optimal solvent retention rather than complete removal. By modifying the drying parameters (temperature, time, humidity control), the process maintains simplicity while achieving the desired solvent content that preserves high rate charging performance.
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 design limits performance deterioration by preventing electrolyte displacement and maintaining balanced salt concentration, reducing DC internal resistance and enhancing high rate characteristics.
Implementation Method 1
When the non-aqueous rechargeable battery is charged, the organic solvent vaporizes and forms bubbles
Data Source
AI summary
A non-aqueous rechargeable battery includes an electrode body, a non-aqueous electrolyte solution, and a battery case. The electrode body includes a negative electrode plate, a positive electrode plate, and a separator arranged between the negative and positive electrode plates. The battery case accommodates the electrode body and the non-aqueous electrolyte solution. The positive electrode plate includes a positive electrode substrate and a positive electrode mixture layer arranged on the positive electrode substrate. The positive electrode mixture layer is formed by applying a positive electrode mixture paste, containing at least a positive electrode active material and an organic solvent, to the positive electrode substrate and drying the positive electrode mixture paste so that the organic solvent remains in the positive electrode mixture layer. The non-aqueous rechargeable battery is charged in a state in which the electrode body and the non-aqueous electrolyte solution are accommodated in the battery case.