Lithium-Sulphur Electrode With Crosslinked Binder for Cycle Stability
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Solution Overview
Problem
Lithium-sulphur cells face challenges in maintaining structural integrity and cycle life due to the detachment of charged species from the current collector during charge and discharge cycles, leading to premature fading.
Innovation Solution
A crosslinked polymer network is formed by depositing an electrode mixture comprising an electrically conductive material, electroactive sulphur material, and a binder polymer onto a current collector, where the polymer is crosslinked to create a stable matrix that retains the materials in place, enhancing structural integrity and adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional binder is used to hold electroactive sulphur material and electrically conductive material on the current collector, then the electrode can be assembled and initially functional, but the charged species detach from the current collector during charge and discharge cycles, leading to premature fading and reduced cycle life
Solution Approach 1:
The patent applies parameter changes by transforming the binder polymer from a linear structure to a crosslinked network structure. This chemical structural change creates a three-dimensional network that mechanically interlocks with the electroactive sulphur material and electrically conductive material, preventing their detachment during charge-discharge cycles. The crosslinking degree and network density are optimized parameters that directly influence the electrode's structural stability and cycle life.
Solution Approach 2:
The patent creates a composite material system consisting of four components: crosslinked polymer binder, electroactive sulphur material, electrically conductive material, and current collector. The crosslinked polymer acts as a matrix that binds the sulphur and conductive materials together and to the current collector. This composite structure synergistically combines the adhesive properties of the crosslinked polymer with the electrochemical activity of sulphur and the electrical conductivity of the conductive material, resolving the contradiction between structural integrity and electrochemical performance.
2Reliability
If the electrode materials are held loosely to maintain flexibility, then the electrode can accommodate volume changes during cycling, but the charged species detach from the current collector, reducing reliability and cycle life
Solution Approach 1:
The patent changes the physical and chemical parameters of the binder polymer by introducing crosslinks at controlled densities. This creates a network structure that balances adhesion strength and flexibility. The crosslinking density is optimized to provide sufficient mechanical interlocking for strong adhesion while maintaining enough network flexibility to accommodate volume changes of the electroactive materials during charge-discharge cycles.
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 crosslinked polymer network improves the cycle life of lithium-sulphur cells by maintaining electrical contact and reducing detachment risks, resulting in stable discharge performance over multiple cycles.
Implementation Method 1
a binder comprising a polymer that is crosslinked to form a crosslinked polymer network
Data Source
AI summary
According to the present disclosure, there is an electrode for a lithium sulphur cell. The electrode comprises a matrix deposited on a current collector, wherein the matrix comprises an electrically conductive material, an electroactive sulphur material and a binder comprising a polymer that is crosslinked to form a crosslinked polymer network.