Square Secondary Battery Pressing Structure for Gas Discharge
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Solution Overview
Problem
In rectangular secondary batteries, gas generated during charging and discharging accumulates at the center portion of the electrode body, leading to capacity/power decline and lithium deposition due to the expansion of the negative electrode plate, especially in larger batteries with longer gas discharge paths.
Innovation Solution
A rectangular secondary battery design that includes a flat electrode body housed in a rectangular case with a pressing member arranged between the sealing plate and the electrode body, pressing the center portion perpendicular to the winding axis, ensuring gas is discharged from the end portions, reducing accumulation at the center.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the electrode body is housed with the winding axis parallel to the sealing plate longitudinal direction, then the battery structure is simplified and manufacturing is easier, but gas accumulates at the center portion of the electrode body causing capacity/power decline and lithium deposition
Solution Approach 1:
A gas discharge guide member is introduced as an intermediary component between the sealing plate and the electrode body. This guide member has a gas discharge guide groove that directs gas from the center portion of the electrode body toward the end portions, enabling gas to be discharged effectively without changing the overall winding axis orientation or complicating the manufacturing process
Solution Approach 2:
The solution introduces a new spatial dimension for gas discharge by creating a groove structure that provides an additional gas flow path. The groove extends in the winding axis direction and provides a designated channel for gas to move from the center to the ends, adding a dimensional pathway without altering the fundamental electrode structure
2Quantity of substance
If the battery size is increased to provide higher capacity, then more energy is stored, but the gas discharge path becomes longer causing greater gas accumulation and more prominent capacity/power decline
Solution Approach 1:
The gas discharge guide member serves as a mediator that creates an efficient gas transport pathway. The guide groove structure provides a direct route for gas to travel from the center to the ends, reducing the effective discharge path length and preventing gas accumulation even in larger battery configurations with higher capacity
3Quantity of substance
If the negative electrode plate volume expands during charging, then more lithium is stored, but the center portion of the electrode body moves upward causing gas discharge obstruction and lithium deposition
Solution Approach 1:
The gas discharge guide member acts as a structural intermediary that maintains the electrode body's positional stability. The guide groove structure constrains the electrode body, preventing excessive upward movement of the center portion during charging while still allowing gas to discharge through the groove pathway
Solution Approach 2:
The invention changes the physical parameters of the electrode body configuration by introducing the guide groove structure. This creates a constrained geometry that limits the range of motion of the electrode body during volume expansion, maintaining stability while accommodating the necessary dimensional changes during charging cycles
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
Reduces capacity/power decline and lithium deposition by effectively discharging gas from the center portion to the end portions, maintaining electrode functionality and performance.
Implementation Method 1
an insulating pressing member contacting the sealing plate and the electrode body is arranged between the sealing plate and the electrode body. The pressing member presses the electrode body in a direction perpendicular to the winding axis of the electrode body
Implementation Method 2
gas generated by reaction with an electrolytic solution in the electrode body moves along the winding axis, and is discharged from the end portions of the electrode body
Data Source
AI summary
A secondary battery includes a battery case housing a flat electrode body and a sealing plate. The electrode body is housed in the battery case such that a winding axis thereof is parallel with a longitudinal direction of the sealing plate. At an end portion of the electrode body in a winding axis direction thereof, an edge of a positive or negative electrode plate is connected to an external terminal fixed to the sealing plate through a current collector. An insulating pressing member is arranged between the sealing plate and the electrode body. The pressing member presses the electrode body in a direction perpendicular to the winding axis such that a distance between a portion of the electrode body contacting the pressing member and the sealing plate is longer than a distance between the end portion of the electrode body in the winding axis direction thereof and the sealing plate.