Separator Heating in Cell Winding to Prevent Electrode Gaps
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Solution Overview
Problem
The issue of gaps forming between the cathode and anode electrode plates in wound lithium-ion batteries during high-pressure winding, leading to lithium precipitation and safety hazards such as short circuits, is addressed.
Innovation Solution
A cell winding process where a separator layer with a polycarbosilane (PCS) polymer is heated and melted to bond the cathode and anode electrode plates, eliminating the need for additional bonding structures and simplifying the cell structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high pressure winding is applied to form wound battery, then energy density and output power are improved, but gaps occur between electrode plates causing lithium precipitation
Solution Approach 1:
The separator layer is pre-heated to melt the polycarbosilane polymer before the winding process begins. This preliminary heating action ensures that the separator is already in a bonding-ready state when winding starts, preventing gap formation between electrode plates during the high-pressure winding process that improves energy density
Solution Approach 2:
The physical state of the separator layer is changed from solid to melted state through heating. This parameter change (temperature increase) transforms the separator's properties to enable it to fill gaps and bond electrode plates together during winding, preventing lithium precipitation while maintaining the high energy density achieved through high-pressure winding
2Reliability
If additional bonding structures are added to prevent gaps, then reliability is improved, but device complexity and cell volume increase
Solution Approach 1:
The separator layer serves dual functions: it acts as both the traditional separator and as a bonding agent. By incorporating polycarbosilane polymer that melts upon heating, the separator self-bonds the cathode and anode electrode plates together, eliminating the need for additional bonding structures and reducing cell complexity while maintaining reliability
Solution Approach 2:
The separator layer is designed to perform multiple functions simultaneously: electrical insulation between electrodes, ion conduction, and mechanical bonding. This multi-functionality eliminates the need for separate bonding components, reducing device complexity while ensuring reliable bonding between electrode plates during high-pressure winding
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 method ensures a secure bond between the electrode plates, preventing lithium precipitation and enhancing safety by reducing the cell's volume and improving performance.
Implementation Method 1
a heating step in which a heating portion is arranged on the winding device, and the heating portion heats heated regions on two surfaces of the separator layer that are respectively attached to the cathode electrode plate and the anode electrode plate
Implementation Method 2
the heated regions on the two surfaces of the separator layer that respectively face the cathode electrode plate and the anode electrode plate are heated, so that a polycarbosilane (PCS) polymer of the separator layer is melted and then wound
Data Source
AI summary
A cell winding process, a cell winding device, a cell, a battery, and a power consuming device. A heating portion is arranged to heat a separator layer, such that a PCS polymer of the separator layer is melted at a high temperature, to bond a cathode electrode plate to an anode electrode plate, and the cathode electrode plate is thus closely bonded and fixed to the anode electrode plate, thereby preventing the electrode plates from being retracted due to stress release after winding, which otherwise results in a gap.