Insulating Electrode Layer With Cross-Linked Resin for Thin-Separator Safety
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Solution Overview
Problem
Conventional electrodes with insulating layers face challenges in achieving both high output and safety due to issues with viscosity and uniformity of the binder solution, leading to limitations in energy density and safety improvements in electrochemical elements.
Innovation Solution
An electrode design incorporating a current collector, an electrode mixture layer with active materials, and an insulating layer featuring a cross-linked resin with specific structural units, which improves binding and uniformity, and includes an insulating material like α-alumina to enhance safety and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a separator is made thinner to improve volumetric energy density, then energy density is improved, but safety becomes more difficult to ensure
Solution Approach 1:
An insulating layer is introduced as an intermediary component between the electrode mixture layer and the separator. This layer acts as a mediator that prevents direct contact and potential short circuits while maintaining the thin separator structure needed for high energy density. The insulating layer includes inorganic particles (such as alumina, silica, or boehmite) dispersed in a binder solution, creating a protective barrier that ensures safety without compromising volumetric energy density.
Solution Approach 2:
The insulating layer is constructed as a composite material system combining inorganic insulating particles with a polymer binder matrix. This composite structure provides both the electrical insulation needed for safety and the mechanical adhesion required for structural integrity. The inorganic particles (alumina, silica, boehmite) provide insulation and thermal stability, while the binder (polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber) provides cohesion and bonding to the electrode surface.
2Reliability
If an insulating layer is disposed on the separator, then safety is improved, but the electrode structure becomes more complex
Solution Approach 1:
The insulating layer is merged with the electrode mixture layer to form an integrated electrode structure. Instead of treating the insulating layer as a separate component between the electrode and separator, it is applied directly to the electrode mixture layer surface, combining the functional layers into a unified structure. This integration reduces assembly complexity while maintaining the safety benefits of electrical insulation.
3Ease of manufacture
If conventional binder solutions are used for the insulating layer, then manufacturing is simpler, but binding uniformity and performance are insufficient
Solution Approach 1:
The binder solution is formulated as a composite system containing multiple polymer components (polyvinylidene fluoride, carboxymethyl cellulose, styrene-butadiene rubber) in specific proportions. This composite binder formulation provides both ease of application and superior binding uniformity, achieving homogeneous adhesion of the insulating layer to the electrode mixture layer while maintaining manufacturing simplicity.
Solution Approach 2:
The binder solution parameters are optimized by controlling the concentration ratios of different polymer components and adjusting the solvent composition (N-methyl-2-pyrrolidone and water). By adjusting these parameters, the solution achieves optimal viscosity and drying characteristics that enable uniform coating and binding, bridging the gap between manufacturing simplicity and binding precision.
Data Source
AI summary
An electrode is provided that includes a current collector, an electrode mixture layer on the current collector, and an insulating layer on the electrode mixture layer. The electrode mixture layer includes an active material. The insulating layer includes an insulating material and a resin having a repeating structural unit represented by a specific general formula.