Composite Current Collector Binder Layer for Cold-Press Stability
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Solution Overview
Problem
Current composite current collectors with a three-layer structure face issues such as electrode plate deformation, cold-pressing strip breakage, and peeling between metal and support layers due to low elastic modulus and poor adhesion, leading to performance and safety concerns in lithium-ion batteries.
Innovation Solution
A composite current collector with a binder layer containing organic binder and inorganic particles, where the binder layer's thickness and particle size are optimized to enhance adhesion and elastic modulus, including large and small particles with specific size ratios, is used between the support and metal layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a composite current collector with a three-layer structure of metal layer-support layer-metal layer is used to thin metal layers, then energy density is improved, but the electrode plate extends much farther during cold pressing and is prone to deformation, leading to cold-pressing strip breakage and electrode plate wrinkling
Solution Approach 1:
The patent applies composite materials by creating a multi-layer structure consisting of metal layers, support layers, and binder layers. This composite structure combines the advantages of thin metal layers (high energy density) with the mechanical stability of support and binder layers, resolving the contradiction between energy density improvement and cold-pressing deformation prevention
Solution Approach 2:
The binder layer acts as an intermediary between the metal layer and support layer. It provides adhesion and mechanical reinforcement to the thin metal layers, preventing deformation during cold pressing while maintaining the energy density benefits of the thinned metal structure
2Reliability
If an organic binder layer is used between the metal layer and the support layer to improve adhesion, then peeling is reduced, but the elastic modulus decreases significantly and elongation during cold pressing becomes excessively large
Solution Approach 1:
The patent uses composite materials by formulating a binder layer containing both organic binder and inorganic particles. The inorganic particles (such as oxides or carbides) provide high elastic modulus and dimensional stability, while the organic binder ensures adhesion between layers, thus resolving the contradiction between improving adhesion and maintaining elastic modulus
Solution Approach 2:
The binder layer exhibits local quality differentiation through its composition: the organic binder component provides adhesion locally at interfaces, while the inorganic particle component provides elastic modulus and dimensional stability locally within the layer, allowing both functions to coexist without compromising overall performance
Data Source
AI summary
This application provides a current collector and a preparation method thereof, a secondary battery containing such current collector, a battery module, a battery pack, and an electric apparatus. The current collector in this application includes a support layer, a binder layer, and a metal layer, where the binder layer is arranged between the support layer and the metal layer, the binder layer includes an organic binder and inorganic particles, a thickness D0 of the binder layer is 1.0-5.0 μm, optionally 1.0-3.0 μm; and the inorganic particles include large particles with a median particle size D50large and small particles with a median particle size D50small, and the median particle sizes of the large particles and the small particles satisfy the following relationships: D50large>D50small; D50large=(0.5-0.9)×D0; and D50small=(0.1-0.4)×D0.