Quasi-Solid Li-Ion Cathode Composition for Low-Resistance Interfaces
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Solution Overview
Problem
Existing quasi-solid-state Li-ion batteries face challenges in achieving sufficient ion conductivity at ambient temperature and maintaining low resistivity at interfaces between the cathode and solid-state or quasi-solid-state electrolytes, requiring complex manufacturing processes and high-pressure steps.
Innovation Solution
A cathode composition is developed with a catholyte intrinsically mixed with the electrode material, comprising a mixture of fluoropolymers and a lithium salt, which enhances ion conductivity and adhesion without the need for additional coating or high-pressure steps, maintaining cohesion and adhesion to the current collector.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high pressure or additional coating steps are applied to improve cathode-catholyte interfaces, then interface resistivity is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent incorporates the catholyte-forming binder directly into the cathode structure during the electrode manufacturing process, before battery assembly. The PVDF and P(VDF-HFP) binder mixture is applied to the cathode substrate along with active material and conductive additive, and upon contact with electrolyte solvent, the binder swells to form the catholyte layer in situ, eliminating the need for subsequent coating or high-pressure treatment steps
Solution Approach 2:
The patent merges the functions of the binder and the catholyte into a single integrated component. The same PVDF/P(VDF-HFP) binder material that provides structural cohesion to the cathode also serves as the catholyte source when swollen with electrolyte solvent, thereby simplifying the overall battery structure and manufacturing process while ensuring good cathode-catholyte interface contact
2Reliability
If P(VDF-co-HFP) copolymer is used to increase swelling and ion conductivity, then ion conductivity is improved, but structural cohesion may be compromised
Solution Approach 1:
The patent applies different binder materials to different functional requirements within the cathode structure. PVDF provides the primary structural framework and cohesion due to its high crystallinity and mechanical strength, while P(VDF-HFP) is incorporated specifically in optimized amounts (10-40 mass% HFP content) to provide localized swelling and ion conductivity enhancement at the cathode-catholyte interface, with each binder component performing its specialized function
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
This solution provides improved ambient-temperature ion conductivity, maintaining the cathode's capacity and flexibility, and simplifies the manufacturing process, ensuring safety by eliminating electrolyte leakage and flammability risks.
Implementation Method 1
The advantage of these P(VDF-co-HFP) copolymers is that they produce greater swelling in the electrolyte solvents and so promote ion conductivity in a quasi-solid-state Li-ion battery cathode
Implementation Method 2
maintaining cohesion and adhesion to the current collector
Implementation Method 3
The electrolyte consists of a lithium salt, generally lithium hexafluorophosphate, mixed with a solvent which is a mixture of organic carbonates, which are selected so as to optimize the transportation and the dissociation of the ions
Data Source
AI summary
The invention concerns a cathode composition comprising an intrinsically incorporated catholyte. The invention also concerns a quasi-solid-state Li-ion battery comprising said cathode, an anode and a separator, and a method for manufacturing said Li-ion battery.