Surround-Cell Battery Pack Layout for Thermal Spread Suppression
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Solution Overview
Problem
In battery packs composed of secondary battery cells, thermal runaway can occur due to overcharge, overdischarge, or mechanical collision, leading to potential safety hazards as the thermal runaway can quickly spread across adjacent cells, compromising the safety performance of the battery pack.
Innovation Solution
A battery pack design where first battery cells surround second battery cells, with a thermal stability factor μ=(D1×R1)/(D2×R2) between 0.2 and 1, and specific ratios for capacity and extrusion force, to suppress thermal spread and enhance collision safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If multiple secondary battery cells are closely arranged to pursue high energy density, then energy density is improved, but thermal runaway can quickly spread to adjacent cells causing safety hazards
Solution Approach 1:
The patent divides the battery pack into multiple unit structures, where each unit structure contains N1 first battery cells surrounding N2 second battery cells. This segmentation creates isolated thermal zones that prevent thermal runaway from spreading across the entire battery pack, while maintaining high energy density through close arrangement within each unit.
Solution Approach 2:
The patent introduces a thermal stability factor μ=(D1×R1)/(D2×R2) as a mediator to control thermal interactions between battery cells. By designing the unit structure with specific combinations of battery cells that satisfy 0.2≤μ≤1, the system mediates heat transfer between cells to prevent thermal runaway propagation while maintaining energy density.
2Object-affected harmful factors
If battery cells are arranged in a unit structure with first battery cells surrounding second battery cells, then thermal spread is suppressed, but device complexity increases
Solution Approach 1:
The patent employs a nested arrangement where N1 first battery cells surround N2 second battery cells within each unit structure. This nested configuration efficiently suppresses thermal spread by creating protective layers around central cells, while maintaining compact geometry that minimizes overall structural complexity.
Solution Approach 2:
The patent controls thermal stability through parameter optimization, specifically designing the unit structure to satisfy 0.2≤μ≤1 where μ=(D1×R1)/(D2×R2). By adjusting the parameters D1, R1, D2, and R2 of the surrounding and central battery cells, the system achieves thermal spread suppression without requiring complex additional components or structures.
3Object-affected harmful factors
If the thermal stability factor μ=(D1×R1)/(D2×R2) is controlled within 0.2≤μ≤1, then thermal spread is suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines a specific parameter range 0.2≤μ≤1 for the thermal stability factor μ=(D1×R1)/(D2×R2) that balances thermal safety and manufacturing feasibility. This parameter range is wide enough to accommodate normal manufacturing variations while still achieving effective thermal spread suppression, avoiding overly stringent precision requirements.
Solution Approach 2:
The patent applies different battery cell configurations locally within the unit structure, where N1 first battery cells with specific D1 and R1 parameters surround N2 second battery cells with D2 and R2 parameters. This local differentiation allows precise control of thermal interactions at the unit level while maintaining overall system manufacturability through standardized unit replication.
Data Source
AI summary
Provided are a battery pack and an electric apparatus. The battery pack of this application includes multiple battery cells arranged repeatedly in a unit structure, where the unit structure includes N1 first battery cells and N2 second battery cells, the N1 first battery cells surrounding the N2 second battery cells, N1 and N2 being integers greater than or equal to 1, and N1>N2. Given that the first battery cell has a volumetric energy density denoted as D1 and a direct current impedance denoted as R1, and that the second battery cell has a volumetric energy density denoted as D2 and a direct current impedance denoted as R2, the unit structure has a thermal stability factor μ=(D1×R1)/(D2×R2) satisfying 0.2≤μ≤1.