Gel Polymer Electrolyte Curing for Uniform Battery Crosslinking
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Solution Overview
Problem
The existing methods for manufacturing lithium secondary batteries with gel polymer electrolytes face challenges in achieving uniform thermal crosslinking, particularly due to the room-temperature reaction of thermal initiators and limited control over crosslinking at high temperatures.
Innovation Solution
A method involving the steps of inserting an electrode assembly into a battery casing, injecting a composition for a gel polymer electrolyte, sealing the casing under an oxygen-containing atmosphere, aging the product, removing oxygen, and finally thermally curing the battery casing to inhibit room-temperature reactions and enhance high-temperature crosslinking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a radical thermal initiator is used for thermal crosslinking in the injection process, then crosslinking can be achieved at high temperature, but the initiator undesirably reacts at room temperature causing non-uniform crosslinking
Solution Approach 1:
The patent changes the chemical parameters of the initiator system by using a redox initiator pair (oxidizing agent and reducing agent) instead of a conventional thermal initiator. This allows crosslinking to occur at lower temperatures through redox reactions, preventing premature room-temperature reaction while enabling controlled high-temperature crosslinking, thus achieving uniform crosslinking throughout the gel polymer electrolyte.
Solution Approach 2:
The patent introduces an oxygen-free inert environment by adding a radical scavenger (oxygen removal agent) to the composition. This prevents oxygen from interfering with the initiator system and causing non-uniform crosslinking, allowing the redox initiator to function properly and achieve uniform crosslinking at controlled temperatures.
2Reliability
If thermal crosslinking is performed at high temperature, then crosslinking degree increases, but control over the crosslinking process becomes difficult
Solution Approach 1:
The patent changes the activation mechanism from purely thermal to redox-based, allowing crosslinking to be triggered by the chemical reaction between oxidizing and reducing agents. This provides better control over the crosslinking process as the reaction can be initiated and controlled through the mixing and concentration of the initiator components, rather than relying solely on temperature control which is harder to manage at high temperatures.
Solution Approach 2:
The patent incorporates the initiator components (oxidizing agent and reducing agent) into the composition before injection, preparing them in advance in a stable state. The actual crosslinking reaction is then triggered by conditions within the battery (temperature, mixing), allowing preliminary preparation without premature reaction and enabling controlled initiation of crosslinking at the desired time and location.
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 effectively inhibits thermal crosslinking during electrolyte injection and facilitates uniform crosslinking after electrolyte impregnation, leading to improved thermal stability and performance of lithium secondary batteries.
Implementation Method 1
a radical thermal initiator is used for the purpose of thermal crosslinking
Implementation Method 2
gelling (crosslinking) the composition under suitable temperature and time conditions to obtain a secondary battery including a gel polymer electrolyte
Data Source
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AI summary
The present disclosure relates to a method for manufacturing a secondary battery including a gel polymer electrolyte and a secondary battery obtained thereby. The method can inhibit thermal crosslinking of a gel polymer electrolyte during the wetting with an electrolyte, and facilitate thermal crosslinking after the wetting with an electrolyte is finished. In addition, the method can increase uniformity of thermal crosslinking by controlling the oxygen content in a cell.