Lithium-Ion Battery Diaphragm Annealing for Uniform Roll Heating
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Solution Overview
Problem
The roll core of a diaphragm in a roll-shaped structure experiences non-uniform heating and cooling during annealing, leading to reduced quality or unqualification, and is influenced by external environment changes, especially in varying temperature conditions.
Innovation Solution
A method involving three-layer co-extrusion followed by annealing in a specialized annealing box with controlled heating and cooling mechanisms, including a motor-driven system with interlayer films and adjustable collars, ensures uniform heating and cooling of the diaphragm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the diaphragm is annealed in a roll-shaped structure, then space is saved and handling is easier, but non-uniform heating and cooling occurs leading to reduced quality
Solution Approach 1:
The diaphragm is divided into multiple layers (first diaphragm layer, second diaphragm layer, and intermediate layer) that can be separately controlled during annealing. This segmentation allows different regions to be heated and cooled more uniformly, resolving the non-uniform heating issue while maintaining the roll-shaped structure for easy handling.
Solution Approach 2:
An intermediate layer is introduced between the first and second diaphragm layers. This intermediate layer acts as a thermal mediator that facilitates more uniform heat distribution throughout the roll-shaped diaphragm structure during annealing, preventing the quality degradation caused by non-uniform heating and cooling.
2Device complexity
If purely cooling at room temperature is used, then the process is simple, but it cannot meet the processing requirement for accurate temperature change within a period
Solution Approach 1:
The cooling system is made dynamic and adjustable, allowing the cooling rate to be controlled according to different processing requirements. The system can switch between different cooling modes (fast cooling, slow cooling, or room temperature cooling) to meet various temperature change requirements within specific time periods, rather than relying on fixed room temperature cooling.
3Adaptability or versatility
If external environment changes are not controlled, then the processing environment is open and accessible, but great temperature changes occur in summer or winter greatly influencing production
Solution Approach 1:
The annealing process is conducted in a controlled environment that isolates the diaphragm from external environmental fluctuations. The annealing device creates a stable thermal environment inside, protecting the diaphragm from temperature changes caused by seasonal variations in the external environment, thereby ensuring consistent diaphragm quality throughout the year.
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 method achieves stable and uniform diaphragm quality by controlling annealing temperature, isolating external environment influence, and facilitating large-scale rapid production.
Implementation Method 1
the inner surface of the box body is fixedly connected with heating plates which are uniformly arranged
Implementation Method 2
placing the casting film with the A/B/A three-layer co-extrusion structure in an annealing box to be subjected to annealing at the annealing temperature of 130-150° C. for 1-24 h
Data Source
AI summary
Disclosed is a method for preparing a three-layer-co-extruded diaphragm of a lithium-ion battery, falling into lithium-ion battery diaphragm technical field. The annealing box used comprises: box body, motor and sealing over, with uniformly-arranged heating plates fixedly connected to inner surface of the box body, a driving shaft arranged horizontally within the box body in front-back direction, a first and second driven shafts arranged on the left and right sides of the driving shaft correspondingly within the box body, an interlayer film coiling connected between the driving shaft and the first driven shaft within the box body horizontally; a diaphragm coiling connected between the driving shaft and the second driven shaft within the box body slantwise. Controllable annealing temperature and insulation from external environment avoid influence of external environment on diaphragm and ensure uniform heating of diaphragm. It produces a diaphragm of stable quality and is convenient to be mass-produced.