Compressible Battery Pack Insulators for Uniform Cell Pressure
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Solution Overview
Problem
Batteries with multiple electrochemical cells face challenges in managing dimensional changes during charging and discharging, leading to uneven pressure distributions and potential battery pack failures, particularly with lithium metal cells, which can result in dendrite formation and safety hazards.
Innovation Solution
The use of thermally insulating compressible solid articles with specific mechanical properties, such as low compression set and high resilience, to mitigate dimensional changes and apply uniform anisotropic forces to electrochemical cells, while also facilitating thermal management and alignment of active regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If electrochemical cells are used with high energy density, then battery capacity is improved, but dimensional changes during charging and discharging cause uneven pressure distribution and potential failures
Solution Approach 1:
The patent introduces a compressible component with specific mechanical properties (compression set between 5-20%, resilient modulus between 0.5-5 MPa) that changes its physical state during cell expansion/contraction. This parameter-based approach allows the component to adapt to dimensional changes while maintaining uniform pressure distribution, resolving the contradiction between high capacity cells and battery reliability
Solution Approach 2:
The compressible component acts as an intermediary between electrochemical cells, absorbing dimensional changes and distributing forces uniformly. This mediator prevents direct stress concentration between cells, eliminating the reliability issues caused by uneven pressure distribution while maintaining high energy density
2Productivity
If force is applied to electrochemical cells to improve performance, then current density is improved, but thermal management becomes challenging
Solution Approach 1:
The compressible component is designed with specific local properties: thermally insulating (effective thermal conductivity ≤ 0.5 W/m·K) in the thickness direction to manage heat locally between cells, while maintaining mechanical compliance for force application. This localized quality differentiation resolves the contradiction between improving current density through force application and managing thermal effects
3Stability of the object's composition
If compressible components are used to mitigate dimensional changes, then pressure distribution is improved, but thermal insulation may hinder heat transfer
Solution Approach 1:
The compressible component exhibits direction-dependent thermal properties: thermally insulating (effective thermal conductivity ≤ 0.5 W/m·K) in the thickness direction to provide thermal management between cells, while allowing lateral heat dissipation. This anisotropic local quality resolves the contradiction between maintaining uniform pressure distribution and enabling necessary heat transfer
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 approach reduces dendrite formation, improves current density, and maintains battery performance by minimizing expansion and contraction of the battery pack, even with high energy density and low pack burden, while ensuring efficient heat transfer and uniform pressure distribution.
Implementation Method 1
a thermally insulating compressible solid article portion between the first electrochemical cell and the second electrochemical cell; wherein the thermally insulating compressible solid article portion has an effective thermal conductivity of less than or equal to 0.5 W m−1 K−1 in a thickness direction
Implementation Method 2
a compression set less than or equal to 15% as determined by a constant force measurement
Implementation Method 3
a resilience of at least 60%, and wherein: at a compressive stress of 12 kgf/cm2, the percent compression of the thermally insulating compressible solid article portion is at least 30%
Data Source
AI summary
Batteries including electrochemical cells, associated components, and arrangements thereof are generally described. In some aspects, batteries with housings that undergo relatively little expansion and contraction even in cases where electrochemical cells in the battery undergo a relatively high degree of expansion and contraction during charging and discharging are provided. Batteries configured to apply relatively high magnitudes and uniform force to electrochemical cells in the battery, while in some cases having high energy densities and a relatively low pack burden, are also provided. In certain aspects, arrangements of electrochemical cells and associated components are generally described. In some aspects, thermally conductive solid articles that can be used for aligning components of the battery are described. In some aspects, thermally insulating and compressible components for battery packs are generally described.