Cathode Hybrid Electrolyte for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
Current solid secondary batteries face issues with leakage and insufficient wettability due to high viscosity in ionic liquid mixtures, which affects the interface resistance and lithium ion mobility between the cathode and solid electrolyte, especially when using high-voltage stable cathode active materials like lithium cobalt oxide.
Innovation Solution
A cathode hybrid electrolyte is developed, comprising an ion conductor represented by Formula 1 and an ionic liquid with the same anionic moiety, which solidifies to reduce viscosity and improve miscibility, preventing leakage and enhancing lithium ion mobility by forming a solidified structure around the cathode active material layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an ionic liquid is impregnated in the cathode to reduce interfacial resistance, then the wettability with respect to the cathode is improved, but the viscosity increases causing leakage and insufficient wettability
Solution Approach 1:
The patent uses a composite electrolyte system combining ionic liquid with a polymer matrix (forming a gel polymer electrolyte). The ionic liquid provides high ion conductivity and low viscosity characteristics, while the polymer matrix provides structural stability and prevents leakage. This composite approach allows the cathode to benefit from improved wettability and reduced interfacial resistance without suffering from the high viscosity and leakage problems of pure ionic liquids.
2Object-affected harmful factors
If a solid electrolyte is used to prevent fire and explosion, then safety is improved, but the wettability with cathode active material is insufficient leading to high interfacial resistance
Solution Approach 1:
The patent changes the physical and chemical parameters of the electrolyte by incorporating ionic liquid into the solid electrolyte matrix. This creates a gel polymer electrolyte with intermediate properties between solid and liquid electrolytes. The ionic liquid component provides better wettability and lower interfacial resistance compared to conventional solid electrolytes, while the polymer matrix maintains the solid structure for safety. This parameter modification allows the electrolyte to achieve both safety and good interfacial contact.
3Temperature
If high-voltage stable cathode active material is used, then voltage stability is improved, but the wettability of the ionic liquid impregnated cathode is needed to reduce interfacial resistance
Solution Approach 1:
The gel polymer electrolyte acts as an intermediary between the high-voltage stable cathode active material and the solid electrolyte. The ionic liquid component of the gel electrolyte provides excellent wettability that facilitates good contact with the cathode active material surface, reducing interfacial resistance. Meanwhile, the polymer matrix maintains structural integrity. This intermediary solution enables the system to utilize high-voltage stable materials without suffering from poor interfacial contact.
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 cathode hybrid electrolyte reduces interfacial resistance, prevents leakage, and improves lithium ion mobility, leading to enhanced cell performance and cycle characteristics in solid secondary batteries.
Implementation Method 1
A cathode hybrid electrolyte is developed, comprising an ion conductor represented by Formula 1 and an ionic liquid with the same anionic moiety, which solidifies to reduce viscosity and improve miscibility, preventing leakage
Implementation Method 2
which solidifies to reduce viscosity and improve miscibility
Data Source
AI summary
Provided are a cathode hybrid electrolyte for a solid secondary battery, a cathode including the cathode hybrid electrolyte, a method of preparing the cathode, and a solid secondary battery including the cathode hybrid electrolyte, wherein the cathode hybrid electrolyte includes an ion conductor represented by Formula 1, and an ionic liquid, where at least a portion of the anions of the ionic liquid comprise the same anionic moiety —Y− of the ion conductor,where, in Formula 1, X, R1 to R3, Y−, and n are the same as defined in the detailed description.