Cyano Compound Binder for All-Solid Battery Cathode
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Solution Overview
Problem
All-solid lithium-ion batteries face issues with the formation of highly resistive layers at the interface between positive active materials and sulfide-based solid electrolytes, leading to poor charge and discharge characteristics due to the high reactivity of sulfide-based solid electrolytes with the positive active materials.
Innovation Solution
Incorporating a cyano compound represented by Formula M[A(CN)x] into the positive electrode, where M is an alkali metal and A is boron, gallium, aluminum, fluorine, phosphorus, or carbon, to prevent the formation of these resistive layers without the need for coating the positive active materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a sulfide-based solid electrolyte is used in the positive electrode, then lithium-ion conductivity is improved, but a highly resistive layer forms at the interface between the solid electrolyte and positive active material
Solution Approach 1:
The patent introduces a specific binder that acts as an intermediary substance between the sulfide-based solid electrolyte and the positive active material. This binder prevents direct contact and reaction between the sulfide electrolyte and the positive active material, thereby preventing the formation of the highly resistive layer while maintaining lithium-ion conductivity. The binder serves as a protective mediator that resolves the contradiction between high conductivity and low interfacial resistance.
Solution Approach 2:
The patent employs a binder that can be easily incorporated into the positive electrode structure and provides protective function during battery operation. The binder acts as a sacrificial or protective layer that prevents harmful reactions without requiring complex coating processes, making it suitable for commercial production.
2Reliability
If a lithium-ion conductive oxide coating is applied to the positive active material surface, then interfacial resistance is reduced, but the manufacturing process becomes complicated and difficult to scale
Solution Approach 1:
The patent merges the protective function with the existing binder component of the positive electrode. Instead of adding a separate coating layer through complex processes like electro-spraying, the protective function is integrated into the binder material itself. This combination simplifies the manufacturing process while achieving the same protective effect against resistive layer formation.
Solution Approach 2:
The binder in the patent serves multiple functions: it holds the electrode structure together, facilitates electron conduction, and prevents harmful reactions between the sulfide electrolyte and positive active material. This multi-functionality eliminates the need for separate protective coatings and simplifies the overall manufacturing process.
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 approach inhibits the reaction between the positive active material and the solid electrolyte, enhancing the discharge characteristics of the battery by maintaining battery capacity while preventing the formation of highly resistive layers, thus improving the overall performance of the all-solid battery.
Implementation Method 1
the cyano compound... may inhibit a reaction between the sulfide-based solid electrolyte and the positive active material
Data Source
AI summary
A positive electrode for an all-solid battery including a positive active material; a conductive material; and a binder, wherein the positive electrode further includes a cyano compound represented by Formula 1:M[A(CN)x] Formula 1wherein in Formula 1, A is at least one selected from boron, gallium, aluminum, fluorine, phosphorus, and carbon, M is at least one alkali metal, and x is an integer of 1 to 4.