Asymmetric Battery Pack Tab Placement for Parallel C-Rate Balancing
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Solution Overview
Problem
Conventional asymmetric battery packs with jelly rolls of different capacities and designs connected in parallel experience impedance imbalances, leading to uneven charging and discharging currents, which can result in poor performance due to higher capacity jelly rolls having increased impedance and differing electrode shapes.
Innovation Solution
The solution involves repositioning and increasing the number of cathode and anode tabs on higher capacity battery cells to reduce impedance, allowing for C-Rate balancing by positioning tabs away from the proximal end or distributing them along the length of the electrodes, thereby equalizing the capacity-specific impedance of connected battery cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If higher capacity battery cells are connected in parallel with lower capacity cells, then the battery pack capacity increases, but the impedance imbalance causes uneven charging and discharging currents
Solution Approach 1:
The patent applies local quality by positioning cathode and anode tabs at specific locations along the electrode layers rather than uniformly distributed. The tabs are strategically placed at distances of 10-30mm from electrode ends to create localized current collection zones that compensate for the higher impedance in higher capacity cells, enabling balanced current distribution across cells of different capacities.
2Ease of manufacture
If tabs are positioned at the proximal end of electrodes in higher capacity battery cells, then the manufacturing process is simplified, but the impedance increases causing C-Rate imbalance
Solution Approach 1:
The patent changes the positional parameter of the tabs from the conventional proximal end location to a specific distance (10-30mm) from the electrode ends. This parameter change optimizes the electrical connection geometry to reduce impedance in higher capacity cells while maintaining manufacturing feasibility through standardized positioning guidelines.
Data Source
AI summary
Battery packs having jelly roll battery cells of different capacities may have an imbalance in the charging and/or discharging current supplied to and provided by each jelly roll due to differences in capacity specific impedance between the battery cells of the battery pack. A C-rate (i.e., current relative to rated capacity) of a lower capacity first battery cell and a higher capacity second battery cell connected in parallel may be balanced by repositioning and/or increasing the number of cathode tabs and anode tabs of the second jelly roll battery cell to reduce an impedance of the second battery cell.