Battery Pack Cell Chemistry for Thermal Capacity Balancing
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Solution Overview
Problem
Lithium-ion batteries experience capacity loss and performance degradation due to temperature differences within battery packs, leading to imbalance and poor overall performance, especially at low temperatures.
Innovation Solution
A battery pack design where first and second battery cells have different lithium replenishing agent contents based on their heat dissipation capabilities, with higher contents in cells with better heat dissipation to compensate for lithium loss and maintain capacity balance without external balancing interventions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of secondary batteries in the battery pack is increased, then the power and volume of the battery pack are improved, but the temperature difference between the interior and exterior regions increases, leading to capacity imbalance
Solution Approach 1:
The patent applies local quality by differentiating the lithium replenishing agent content based on the spatial position of battery cells within the pack. Cells in the interior region (with poorer heat dissipation) receive a greater amount of lithium replenishing agent compared to cells in the exterior region (with better heat dissipation). This localized differentiation compensates for the temperature-induced capacity loss in interior cells, thereby maintaining overall capacity balance while allowing increased battery pack power.
2Adaptability or versatility
If battery cells are arranged in positions with different heat dissipation capabilities, then the battery pack design flexibility is improved, but the capacity balance between cells deteriorates due to temperature differences
Solution Approach 1:
The patent implements local quality by tailoring the lithium replenishing agent content to the specific thermal environment of each battery cell position. Cells located in regions with poorer heat dissipation (such as the interior region) are assigned a higher lithium replenishing agent content, while cells in regions with better heat dissipation (such as the exterior region) receive a lower content. This position-dependent differentiation compensates for thermal effects and maintains capacity consistency across the battery pack.
Solution Approach 2:
The patent applies parameter changes by modifying the chemical composition parameter (lithium replenishing agent content) of battery cells based on their thermal environment. By adjusting the amount of lithium replenishing agent according to the heat dissipation capability of each position, the patent compensates for temperature-induced capacity variations and maintains reliable capacity consistency across all cells.
3Reliability
If lithium replenishing agent content is increased in all battery cells, then the capacity loss compensation is improved, but the overall lithium content and potential side reactions increase
Solution Approach 1:
The patent applies local quality by selectively increasing the lithium replenishing agent content only in battery cells that require it (interior region cells with poorer heat dissipation), rather than uniformly increasing it in all cells. This targeted approach compensates for capacity loss in thermally disadvantaged cells while avoiding excessive lithium content in cells that already have adequate heat dissipation, thereby minimizing unnecessary side reactions and material waste.
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 achieves capacity self-balancing and maintains consistent discharging capacity across battery cells at various temperatures, enhancing the overall performance of the battery pack by compensating for lithium losses through targeted lithium replenishment.
Implementation Method 1
an addition amount W1 of a lithium replenishing agent in the first battery cell is greater than an addition amount W2 of the lithium replenishing agent in the second battery cell
Implementation Method 2
a heat dissipation capability at a position where the first battery cell is located is greater than a heat dissipation capability at a position where the second battery cell is located
Implementation Method 3
the temperature of the first battery cell is lower than the temperature of the second battery cell due to a heat dissipation difference in the battery box
Data Source
AI summary
A battery pack comprises a battery box and a first battery cell and a second battery cell disposed in the battery box, wherein a heat dissipation capability at a position where the first battery cell is located is greater than a heat dissipation capability at a position where the second battery cell is located, an addition amount W1 of a lithium replenishing agent in the first battery cell is greater than an addition amount W2 of the lithium replenishing agent in the second battery cell, W1>0, and W2≥0.