Battery Module Buffer Structure for Electrolyte Flow Stability
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Solution Overview
Problem
Secondary battery modules face challenges in maintaining electrical capacity and cycle characteristics due to volume fluctuations of lithium metal or silicon particles during charging and discharging, leading to electrolyte leakage and solution shortages.
Innovation Solution
Incorporating a buffer material with a thick wall part and a thin wall part, where the thin wall part tapers off, is used between secondary batteries or the cell stack and end plates, allowing for adjustable restraining force and electrolyte solution flow management, preventing solution shortages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If lithium metal or silicon particles are used as negative electrode active material to improve electrical capacity, then the electrical capacity is improved, but the volume of negative electrode fluctuates greatly during charging/discharging causing electrolyte leakage and solution shortage
Solution Approach 1:
The buffer material is arranged between the secondary battery and end plate beforehand to provide cushioning during volume fluctuations. The buffer material absorbs expansion forces during charging and prevents compression during discharging, protecting the electrode laminate from damage and preventing electrolyte leakage before problems occur.
Solution Approach 2:
The buffer material's physical parameters (compression modulus, thickness) are optimized to match the volume fluctuation characteristics of lithium metal or silicon particle batteries. By adjusting these parameters, the buffer material can effectively accommodate the large volume changes during charging/discharging cycles while maintaining proper electrolyte levels.
2Reliability
If a buffer material is arranged between secondary batteries to accommodate volume changes, then the cycle characteristic is improved, but the restraining force control becomes insufficient with uniform thickness
Solution Approach 1:
The buffer material features non-uniform thickness with a first thickness in the first region and a second thickness in the second region. This local quality variation allows different regions to provide different restraining forces - the thicker region provides stronger support where greater cushioning is needed, while the thinner region allows more freedom of movement, enabling precise control over the restraining force distribution.
Solution Approach 2:
The buffer material employs asymmetric thickness design rather than uniform thickness. This asymmetry is strategically positioned to match the asymmetric stress distribution in the battery assembly, providing optimized restraining force control that adapts to the specific volume fluctuation patterns of lithium metal or silicon particle batteries.
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 configuration effectively controls the electrolyte solution flow and pressure, ensuring stable cycle characteristics and preventing electrolyte shortages even with volume fluctuations during charge/discharge cycles.
Implementation Method 1
spring elastic bodies such as a leaf spring and liquid spring have been known
Data Source
AI summary
A secondary battery module according to an embodiment of the present invention includes: a battery stack in which a plurality of secondary batteries are laminated, and a pair of end plates disposed at both ends in a lamination direction of the battery stack, further including a buffer material disposed at least between either the secondary batteries which are adjacent, or the battery stack and the end plate, in which, in a first direction that is orthogonal to the lamination direction of the battery stack, one end of the buffer material is established as a thick wall part having a large length in the lamination direction, and the other end is established as a thin wall part having a smaller length in the lamination direction than the thick wall part.