Battery Separator and Electrolyte Balance for Low-Swelling Cycling
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Solution Overview
Problem
Secondary batteries face cycling performance degradation due to insufficient electrolyte wetting and interfacial side reactions caused by high binding forces between electrode plates, leading to electrolyte loss and electrode swelling.
Innovation Solution
A secondary battery design with a porous separator having binding layers and a specific electrolyte composition, including a compound represented by formula I, with controlled mass percentage and binding forces, enhances electrolyte oxidation resistance and interfacial stability to reduce electrolyte consumption and swelling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separators with high binding force are disposed between positive electrode plates and negative electrode plates to reduce interfacial side reactions, then interfacial side reactions are reduced, but storage space of electrolytes is reduced causing cycling performance degradation
Solution Approach 1:
The patent optimizes the binding force parameters of the separator to specific ranges (10-15 N/m for positive electrode, 18-25 N/m for negative electrode) to achieve the right balance between reducing interfacial side reactions and maintaining sufficient electrolyte storage space. This parameter optimization resolves the contradiction by finding the optimal binding force values that satisfy both requirements simultaneously.
2Reliability
If separators with high binding force are used to reduce interfacial side reactions, then interfacial stability is improved, but electrolyte loss increases causing cycling performance degradation
Solution Approach 1:
The patent introduces a specific compound (formula I) into the electrolyte with controlled mass percentage (5-30%) to improve oxidation resistance and reduce electrolyte loss. This chemical modification of the electrolyte composition compensates for the electrolyte loss caused by high binding force separators, thereby resolving the contradiction between interfacial stability and electrolyte conservation.
3Reliability
If separators with high binding force are used to reduce interfacial side reactions, then interfacial stability is improved, but electrode swelling increases due to electrolyte loss
Solution Approach 1:
The patent uses the compound of formula I as an intermediary substance in the electrolyte that mediates between the separator and electrode plates. This compound improves oxidation resistance and reduces electrolyte decomposition, thereby preventing the formation of by-products that cause electrode swelling. The intermediary compound enables the system to maintain both high binding force benefits and reduced electrode swelling.
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
Improves cycling performance and swelling performance by reducing electrolyte loss and interfacial reactions, maintaining effective ion transmission and electrode stability.
Implementation Method 1
The electrolyte including the compound represented by formula I and controlling the value of A within the above range can improve the oxidation resistance of the electrolyte to reduce interfacial side reactions between the positive electrode plate and the electrolyte and between the negative electrode plate and the electrolyte
Implementation Method 2
the separator includes a porous substrate layer and binding layers disposed on two surfaces of the porous substrate layer, the binding layer includes a polymer, a binding force between the separator and the positive electrode plate is F1 N/m, where 10 ≤ F1 ≤ 15, and a binding force between the separator and the negative electrode plate is F2 N/m, where 18 ≤ F2 ≤ 25
Data Source
AI summary
A secondary battery includes a positive electrode plate, a negative electrode plate, a separator, and an electrolyte. The electrolyte includes a compound represented by formula I. R11 and R12 are each independently selected from halogen-substituted or unsubstituted C1 to C6 alkyl, at least one of R11 or R12 is substituted with halogen, and based on a mass of the electrolyte, a mass percentage of the compound represented by formula I is A%, where 30 ≤ A ≤ 80. The separator includes a porous substrate layer and binding layers disposed on two surfaces of the porous substrate layer, the binding layer includes a polymer, a binding force between the separator and the positive electrode plate is F1 N/m, where 10 ≤ F1 ≤ 15, and a binding force between the separator and the negative electrode plate is F2 N/m, where 18 ≤ F2 ≤ 25.