Solid-State Battery Cathode Coating for Faster Ion Transport
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Solution Overview
Problem
The challenge in all-solid-state batteries is to improve the rate capability by densifying the electrode layer while enhancing interfacial bonding between materials, particularly in stacked oxide batteries where co-sintering of positive electrode active materials and conductive agents is difficult.
Innovation Solution
The solution involves incorporating a second solid electrolyte with high lithium ion conductivity on the surface of the electrode active material, specifically a high cobalt-based positive electrode active material, to enhance interfacial bonding and improve ionic conductivity, thereby densifying the electrode layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a sintering agent is added to the positive electrode layer to assist simultaneous sintering and improve interfacial bonding, then the interfacial bonding of the positive electrode layer is improved, but the ionic conductivity of the positive electrode layer decreases resulting in decreased rate capability
Solution Approach 1:
The patent applies local quality by using different sintering agents in different regions of the positive electrode layer. Specifically, a first sintering agent (oxide-based) is used in regions requiring strong interfacial bonding, while a second sintering agent (sulfide-based with higher ionic conductivity) is used in regions where ionic conductivity is critical. This spatial differentiation allows the electrode layer to simultaneously achieve both strong bonding and high ionic conductivity without compromise.
2Stability of the object's composition
If oxide all-solid-state batteries use oxide electrolytes, then stability is superior to sulfide batteries, but ionic conductivity is lower requiring high-temperature firing process
Solution Approach 1:
The patent employs composite materials by combining oxide electrolyte with sulfide-based sintering agents in the positive electrode layer. The oxide electrolyte provides superior stability and chemical inertness, while the sulfide-based sintering agent (such as Li2S-P2S5 system) contributes high ionic conductivity and enables effective sintering at reduced temperatures. This composite approach allows the battery to achieve both stability and high ionic conductivity simultaneously.
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 effectively improves the rate capability of the all-solid-state battery by ensuring better interfacial bonding and higher ionic conductivity within the electrode layer, leading to enhanced performance.
Implementation Method 1
a lithium ion conductivity (25° C.) of the second solid electrolyte may be 1.0×102 times or more than a lithium ion conductivity (25° C.) of the first solid electrolyte
Data Source
AI summary
An embodiment provides an all-solid-state battery including a solid electrolyte layer, and a positive electrode layer and a negative electrode layer disposed with the solid electrolyte layer interposed therebetween, wherein the solid electrolyte layer includes a first solid electrolyte, the positive electrode layer or the negative electrode layer includes an electrode active material and a second solid electrolyte surrounding a part of the surface of the electrode active material with an average thickness of 1 nm to 10 nm, the electrode active material includes a positive electrode active material, the positive electrode active material includes a high cobalt-based positive electrode active material represented by chemical formula 1: LiCoxM1yM21-x-yO2.