Solid-State Battery Cathode Coating for Lower Resistance
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Solution Overview
Problem
Conventional all-solid-state batteries exhibit high battery resistance due to oxidation of cathode and solid electrolyte particles, which hinders their performance.
Innovation Solution
A cathode layer is developed containing cathode active material particles and sulfide-based solid electrolyte particles, with a lithium ion conducting oxide coating on the cathode active material particles to suppress reaction and maintain the phosphorus element in an unoxidized state, reducing moisture content to 70 ppm or less, thereby decreasing battery resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional all-solid-state batteries are used, then the battery structure is simple, but the battery resistance remains high due to oxidation of cathode and solid electrolyte particles
Solution Approach 1:
The patent applies composite materials by combining cathode active material particles with a lithium ion conducting oxide coating layer. This composite structure prevents oxidation of the cathode particles while maintaining low battery resistance, as the coating layer acts as a protective barrier that also facilitates lithium ion conduction.
Solution Approach 2:
The lithium ion conducting oxide serves as an intermediary layer between the cathode active material particles and the sulfide-based solid electrolyte particles. This intermediate coating prevents direct contact and oxidation reactions between the cathode particles and the solid electrolyte, thereby reducing battery resistance without requiring complex structural modifications.
2Reliability
If cathode active material particles are coated with lithium ion conducting oxide, then oxidation is suppressed and battery resistance decreases, but manufacturing process becomes more complex
Solution Approach 1:
The patent employs parameter changes by controlling the moisture content of cathode active material particles to 70 ppm or less before coating. This parameter control enables effective coating with lithium ion conducting oxide that suppresses oxidation and reduces battery resistance, while the coating process itself remains relatively simple and manufacturable.
3Reliability
If moisture content of cathode active material particles is reduced to 70 ppm or less, then oxidation is prevented and battery performance improves, but drying process requires more precision
Solution Approach 1:
The patent applies preliminary action by reducing the moisture content of cathode active material particles to 70 ppm or less before the coating process. This preliminary drying step prevents oxidation during subsequent manufacturing steps and improves battery performance, while the required precision is achieved through controlled drying processes performed before assembly.
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 approach results in an all-solid-state battery with lower internal resistance, maintaining high conductivity of the solid electrolyte and improving battery performance by preventing oxidation and moisture-related deterioration.
Implementation Method 1
a lithium ion conducting oxide coating, the lithium ion conducting oxide coating at least part of the surface of the cathode active material particles
Implementation Method 2
solid electrolyte particles as sulfide-based solid electrolyte particles... maintaining high conductivity of the solid electrolyte
Data Source
Figure 1~3
AI summary
Provided is a cathode that is configured to decrease battery resistance when it is used in an all-solid-state battery, and a method for producing the cathode. Disclosed is a cathode comprising a cathode layer for all-solid-state batteries, wherein the cathode layer contains cathode active material particles and solid electrolyte particles; wherein at least one of the cathode active material particles and the solid electrolyte particles contain a phosphorus element; and wherein, in a photoelectron spectrum by X-ray photoelectron spectroscopy measurement of the cathode layer, a P peak intensity ratio (A/B), which is derived from the phosphorus element, of a signal intensity A at a binding energy of 131.6 eV to a signal intensity B at a binding energy of 133.1 eV, is larger than 0.58.