All-solid-state battery cathode with unoxidized sulfur
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Solution Overview
Problem
Conventional all-solid-state batteries suffer from high battery resistance due to oxidation of cathode and solid electrolyte particles, which affects their performance.
Innovation Solution
A cathode layer for all-solid-state batteries is developed, comprising cathode active material particles and solid electrolyte particles with a sulfur element, where a P-S or Li-S bond is present, and the moisture content is kept below 402 ppm, ensuring the sulfur element remains unoxidized, as indicated by a specific S peak intensity ratio in X-ray photoelectron spectroscopy measurements. The cathode layer may include lithium ion conducting oxides like lithium niobate and sulfide-based solid electrolyte particles to reduce resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional all-solid-state batteries are used with cathode active material particles and solid electrolyte particles, then the battery structure is formed, but the battery resistance remains high due to oxidation of sulfur elements
Solution Approach 1:
The patent changes the chemical state parameter of the sulfur element from oxidized to unoxidized form. By controlling the sulfur element to form P-S or Li-S bonds instead of oxidized sulfur compounds, the battery resistance is significantly reduced while maintaining the battery structure
Solution Approach 2:
The patent creates an inert environment by using phosphorus or lithium as protective elements that form bonds with sulfur, preventing oxidation. The unoxidized sulfur element surrounded by P-S or Li-S bonds acts as a protective configuration that eliminates harmful oxidation reactions
2Reliability
If the sulfur element is present in cathode or solid electrolyte particles, then conductivity can be enhanced, but oxidation of sulfur occurs leading to increased battery resistance
Solution Approach 1:
The patent introduces phosphorus or lithium as intermediary elements that form bonds with sulfur (P-S or Li-S bonds). These intermediaries protect the sulfur element from oxidation while maintaining its conductivity-enhancing properties, acting as a protective mediator between sulfur and oxygen
Solution Approach 2:
The patent creates composite particles where sulfur-containing materials are combined with phosphorus or lithium-containing materials. This composite structure allows the sulfur to provide conductivity while the phosphorus or lithium prevents oxidation, achieving both conductivity enhancement and compositional stability
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 significantly decreases battery resistance in all-solid-state batteries by maintaining the sulfur element in an unoxidized state, enhancing conductivity and overall battery performance.
Implementation Method 1
a P-S bond is present between the sulfur element and a phosphorus element, or a Li-S bond is present between the sulfur element and a lithium element
Implementation Method 2
in a photoelectron spectrum by a X-ray photoelectron spectroscopy measurement of the cathode layer, an S peak intensity ratio (C/D), which is derived from the sulfur element, of a signal intensity C at a binding energy of 161.6 eV to a signal intensity D at a binding energy of 163.1 eV
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 sulfur element; and wherein, in a photoelectron spectrum by X-ray photoelectron spectroscopy measurement of the cathode layer, an S peak intensity ratio (C/D), which is derived from the sulfur element, of a signal intensity C at a binding energy of 161.6 eV to a signal intensity D at a binding energy of 163.1 eV, is larger than 0.78.