Battery Pack Spacer With Dual-Height Projections
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Solution Overview
Problem
High-rate deterioration in secondary batteries occurs due to electrolyte solution leakage when the wound electrode body is inhibited from expanding, leading to stress concentration on the casing and potential damage during high-rate charging and discharging.
Innovation Solution
A battery pack design with first and second projections on spacers allows for controlled expansion of the casing and wound electrode body, preventing electrolyte solution leakage and alleviating stress on the casing, using first projections to press the ends of the wound electrode body and second projections to accommodate expansion and reduce stress concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the entire power storage element is pressed by the plural ribs evenly, then the wound electrode body expansion is inhibited and uniform cell reaction is induced, but the electrolyte solution is likely to be leaked and high-rate deterioration occurs
Solution Approach 1:
The spacer is divided into multiple regions (first region, second region, third region) with different projection configurations. The first projections are located at the ends of the spacer to press the wound electrode body ends, while the second projections are located at the central portion to provide solution holding space, allowing different parts of the electrode body to experience different pressure conditions appropriate for their function.
Solution Approach 2:
Different regions of the spacer are given different local properties through the varying projection configurations. The end regions have first projections for pressing, while the central region has second projections for solution holding. This local differentiation allows the electrode body to be pressed uniformly overall while maintaining expansion capability in specific areas to prevent electrolyte leakage.
2Reliability
If the number of ribs is reduced or ribs are shortened to allow electrolyte solution expansion space, then high-rate deterioration is inhibited, but stress is concentrated on the ribs and casing damage occurs
Solution Approach 1:
The pressing function is segmented between first projections at the ends and second projections at the center. The first projections maintain pressing force on the electrode body ends to prevent stress concentration, while the second projections create expansion space for the electrolyte solution, thus preventing both leakage and casing damage.
Solution Approach 2:
The projections are designed with different heights as a parameter change. The first projections have a first height for pressing, while the second projections have a second height that creates solution holding space. This parameter differentiation allows the spacer to simultaneously provide pressing force and expansion space without concentrating stress on single points.
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
The design effectively inhibits high-rate deterioration by allowing the wound electrode body to expand with the electrolyte solution, preventing leakage and reducing stress on the casing, thus protecting the battery pack from damage.
Implementation Method 1
both ends of the wound electrode body in the second direction are pressed through the casing
Implementation Method 2
expansion of the casing for the specified volume means the greater expansion of the casing than that during normal charging, and the greater expansion of the casing is associated with high-rate charging
Data Source
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AI summary
A battery pack (1) includes a first unit battery (2A), a second unit battery (2B), and a spacer (3; 3A; 3B; 3C). The first unit battery (2A) includes a wound electrode body (10) and a casing (20) that accommodates an electrolyte solution. The spacer (3; 3A; 3B; 3C) includes: a primary surface (31) that faces the first unit battery (2A); and plural projections (35, 36), each of which is projected from the primary surface (31). The plural projections (35, 36) include: a first projection (35) that abuts the casing (20) in a state where the casing (20) is not expanded; and a second projection (36), a height of which is lower than a height of the first projection (35).