Mixed-Cell Battery Module Layout for Expansion Force Control
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Solution Overview
Problem
High-energy-density battery modules experience rapid capacity fading and reduced cycle life due to excessive expansion forces during charge and discharge cycles, leading to decreased performance and safety concerns.
Innovation Solution
Combining first-type battery cells with higher volumetric energy density and expansion force change rate with second-type battery cells of lower volumetric energy density and expansion force change rate, arranged to satisfy specific relationships, to reduce average expansion force and enhance ion transport stability within the battery module.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If battery cells with high volumetric energy density are used to increase energy density of the battery module, then the volumetric energy density is improved, but the expansion force change rate increases leading to reduced cycle life
Solution Approach 1:
The patent applies parameter changes by selecting battery cells with specific volumetric energy density values (VED1 ≥ 400 Wh/L for first-type cells and VED2 < 400 Wh/L for second-type cells) and controlling their expansion force change rates (ΔF1 and ΔF2) to satisfy the relationship (ΔF1 × n + ΔF2 × m)/(n + m) ≤ 0.8 × ΔF1. This parameter optimization allows the battery module to achieve high energy density while maintaining acceptable cycle life through mathematical control of expansion characteristics.
Solution Approach 2:
The patent employs a composite structure by combining two different types of battery cells with distinct properties: first-type battery cells with high volumetric energy density and higher expansion force change rate, and second-type battery cells with lower volumetric energy density and lower expansion force change rate. This composite arrangement allows the battery module to balance energy density and cycle life by leveraging the complementary characteristics of different cell types.
2Quantity of substance
If more battery cells are assembled in limited space to increase energy density, then the volumetric energy density is improved, but the expansion force during charge and discharge cycles increases causing capacity fading
Solution Approach 1:
The patent controls the expansion force change rate parameter by selecting and arranging battery cells to satisfy the mathematical relationship (ΔF1 × n + ΔF2 × m)/(n + m) ≤ 0.8 × ΔF1. This parameter control ensures that even with increased cell density in limited space, the overall expansion force remains within acceptable limits, preventing capacity fading and maintaining reliability.
Solution Approach 2:
The patent uses a composite arrangement of two types of battery cells with different expansion characteristics. The second-type battery cells with lower expansion force change rate act as buffers among the first-type cells, reducing the cumulative expansion force effect and preventing the capacity fading that would otherwise result from high cell density packing.
3Quantity of substance
If battery cells with high expansion force change rate are used to achieve high energy density, then the volumetric energy density is improved, but the stability of ion transport interfaces deteriorates
Solution Approach 1:
The patent optimizes the expansion force change rate parameter by controlling it to satisfy (ΔF1 × n + ΔF2 × m)/(n + m) ≤ 0.8 × ΔF1. This parameter control prevents excessive expansion forces that would destabilize ion transport interfaces between electrode plates and separators, thereby maintaining interface stability while achieving high energy density.
Solution Approach 2:
The patent employs a composite cell arrangement where second-type battery cells with lower expansion force change rate are interspersed among first-type cells. This composite structure provides a stabilizing effect on ion transport interfaces by reducing the overall expansion stress, preventing interface degradation while maintaining high energy density through the inclusion of high-density first-type cells.
Data Source
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AI summary
The present application discloses a battery module, a battery pack, an apparatus, and a method and device for manufacturing a battery module. The battery module includes n first-type battery cells and m second-type battery cells, n ≥ 1, m ≥ 1, and the n first-type battery cells and the m second-type battery cells are arranged and satisfy: VED1 > VED2, ΔF1 > ΔF2, and (ΔF1 × n + ΔF2 × m)/(n + m) ≤ 0.8 × ΔF1, where VED1, VED2, ΔF1 and ΔF2 are respectively defined in the description.