Primer-Coated Electrode Plate for Silicon Anode Film Stability
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Solution Overview
Problem
Lithium-ion batteries face issues with film fall-off and decreased cycling performance due to severe volume changes in silicon-based negative electrode materials, leading to poor adhesion between the active material and the current collector.
Innovation Solution
An electrode plate with a primer layer containing a binder and conductive agent on the current collector, enhancing adhesion to above 20 N/m, and an electrolyte with a S═O double bond-containing compound to improve cycling stability and rate performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If silicon-based negative electrode materials are used to meet high energy density requirements, then energy density is improved, but volume changes during lithium ion intercalation and deintercalation become more dramatic, causing severe film fall-off on the current collector surface
Solution Approach 1:
The electrode structure is segmented into three distinct layers: current collector, primer layer, and active substance layer. This segmentation allows the primer layer to specifically address adhesion issues while the active substance layer maintains high energy density silicon-based materials, resolving the contradiction between energy density and film stability.
Solution Approach 2:
A primer layer comprising a binder and conductive agent is introduced as an intermediary between the current collector and the active substance layer. This primer layer acts as a mediator that accommodates volume changes of silicon-based materials during lithium ion intercalation and deintercalation, preventing film fall-off while maintaining electrical conductivity and adhesion.
2Reliability
If the active material layer is made thin to reduce volume swelling impact, then film fall-off is reduced, but adhesion between the active material and current collector becomes insufficient
Solution Approach 1:
The primer layer serves as an intermediary that specifically enhances adhesion between the active material layer and current collector. It provides strong bonding interfaces while accommodating volume changes, resolving the contradiction between film stability and adhesion strength.
Solution Approach 2:
The primer layer is designed as a composite material system comprising a binder and a conductive agent in specific proportions. This composite structure provides both mechanical adhesion and electrical conductivity, simultaneously improving film stability and adhesion strength.
3Reliability
If a primer layer with high adhesion is created to prevent film fall-off, then cycling performance is improved, but the complexity of the electrode structure increases
Solution Approach 1:
The primer layer is applied locally at the critical interface between the current collector and active substance layer, where adhesion is most needed. This localized approach improves cycling performance by preventing film fall-off at the vulnerable interface without unnecessarily complicating the entire electrode structure.
Solution Approach 2:
The adhesion and conductivity functions are extracted from the active substance layer and assigned to the dedicated primer layer. This functional extraction simplifies the design by separating concerns, allowing each layer to be optimized for its specific function while improving overall cycling performance.
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 enhanced adhesion between the membrane and current collector prevents film fall-off and improves cycling stability and rate performance by buffering volume changes during lithium ion intercalation and deintercalation.
Implementation Method 1
With intercalation and deintercalation of lithium ions, active materials swell and shrink accordingly. A negative electrode active material (such as graphite and a silicon-based material) experiences severe volume swelling and shrinkage.
Implementation Method 2
As cycling proceeds, lithium ions repeatedly intercalate into and deintercalate from positive and negative electrodes of a lithium-ion battery.
Implementation Method 3
the primer layer includes a first binder and a first conductive agent, where adhesion between the membrane and the current collector is greater than or equal to 20 N/m
Data Source
AI summary
An electrode plate includes a current collector and a membrane, where the membrane includes a primer layer provided on a surface of the current collector and an active substance layer provided on a surface of the primer layer, and the primer layer includes a first binder and a first conductive agent; where adhesion between the membrane and the current collector is greater than or equal to 20 N/m. This electrode plate can alleviate problems in the prior art such as easy film fall-off of the electrode plate due to low adhesion of part of the active material close to the surface of the electrode current collector.