Silicon Anode Plate Structure to Prevent Wrinkling and Detachment
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Solution Overview
Problem
Silicon-based materials in batteries experience significant expansion during charging, leading to wrinkling and detachment of the electrode plate, which adversely affects cycling performance.
Innovation Solution
A negative electrode plate design featuring a negative electrode current collector with a tensile strength of ≥800 MPa and a base coating comprising a conductive agent and a first binder, which improves bonding and reduces wrinkling and detachment risks by maintaining conductivity and enhancing the fitting between the current collector and the silicon-based active layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as active materials to increase energy density, then the gram capacity and energy density of the battery are improved, but the expansion rate of the material increases, causing wrinkling of the electrode plate and detachment of the active layer
Solution Approach 1:
The negative electrode film layer is divided into two distinct parts: a base coating layer and a negative electrode active layer. This segmentation allows the base coating to provide structural stability and accommodate expansion, while the active layer contains the silicon-based material for high capacity, thus resolving the contradiction between energy density and structural stability.
Solution Approach 2:
The base coating acts as an intermediary layer between the current collector and the silicon-based active layer. It mediates the expansion stress by providing a buffer zone that can deform without causing wrinkling or detachment, thereby protecting the overall electrode structure while allowing the use of high-capacity silicon materials.
2Strength
If the tensile strength of the current collector is increased to ≥800 MPa, then the risk of wrinkling during charging is reduced, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The negative electrode film layer is designed as a composite structure with a base coating and an active layer. This composite design allows the base coating to bear the mechanical stress and prevent wrinkling, while the active layer maintains the electrochemical function, thus achieving high strength requirements without excessively complicating the manufacturing process.
3Reliability
If a base coating comprising conductive agent and binder is added to improve bonding force, then the peel strength is improved to ≥30 N/m, but the device complexity increases
Solution Approach 1:
The base coating is designed to perform multiple functions simultaneously: it provides mechanical bonding between the current collector and active layer, maintains electrical conductivity through the conductive agent, and accommodates volume expansion. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.
Data Source
AI summary
A negative electrode plate comprises a negative electrode current collector and a negative electrode film layer located on at least one surface of the negative electrode current collector. The negative electrode film layer comprises a base coating and a negative electrode active layer. The base coating is located between the negative electrode current collector and the negative electrode active layer. The base coating comprises a conductive agent and a first binder. The negative electrode active layer comprises a silicon-based material. The tensile strength of the negative electrode current collector is ≥800 MPa, and the peel strength of the negative electrode film layer is ≥28 N/m.