Argyrodite Composite Active Material for High-Rate Lithium Batteries
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Solution Overview
Problem
Conventional lithium ion batteries face limitations in achieving higher energy density, capacity, and rate characteristics due to the limitations of sulfide solid electrolytes used as active materials, which hinder further performance improvement.
Innovation Solution
A composite active material is developed comprising a compound with a crystalline phase having an argyrodite-type crystal structure, containing lithium, sulfur, and elements like phosphorus, germanium, or manganese, combined with a conductive material to enhance lithium ion conductivity and battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sulfide solid electrolyte material is used as positive electrode active material, then lithium ion conductivity is improved, but battery capacity and rate characteristics cannot be further improved
Solution Approach 1:
The patent applies composite materials by combining sulfide solid electrolyte (Li7-xPS6-xHa) with conductive material (such as carbon black, graphite, or metal particles) to create a positive electrode active material that exhibits both high lithium ion conductivity and high battery capacity. The composite structure allows the sulfide component to provide ion conductivity while the conductive material enhances electron conductivity and capacity, resolving the contradiction between ion conductivity and battery capacity.
2Reliability
If sulfide solid electrolyte material is used as positive electrode active material, then lithium ion conductivity is improved, but rate characteristics cannot be further improved
Solution Approach 1:
The composite structure combines sulfide solid electrolyte with conductive material to simultaneously achieve high lithium ion conductivity and high rate characteristics. The conductive material network within the composite enables rapid electron transport, while the sulfide phase maintains high lithium ion conductivity, allowing the battery to deliver high capacity at high discharge rates.
Solution Approach 2:
The patent applies local quality by creating a heterogeneous composite where different materials are distributed at different locations within the positive electrode active material. The conductive material is dispersed throughout the sulfide matrix, creating local conductive pathways that enhance both electron and ion transport efficiency, thereby improving rate characteristics while maintaining high lithium ion conductivity.
3Device complexity
If conventional sulfide solid electrolyte is used, then material simplicity is maintained, but energy density and battery performance are limited
Solution Approach 1:
The patent transitions from simple sulfide solid electrolyte to a composite material system combining sulfide with conductive material. This composite approach increases energy density by leveraging the high theoretical capacity of sulfide and the enhanced conductivity of the conductive material, while maintaining relatively simple synthesis procedures and material compatibility.
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 composite active material significantly improves the energy density, capacity, and rate characteristics of lithium ion batteries by enabling efficient lithium ion desorption and absorption, outperforming conventional materials in both initial capacity and discharge rate.
Implementation Method 1
the compound containing lithium (Li) element, sulfur (S) element and an element M, and containing a crystalline phase having an argyrodite-type crystal structure... high lithium ion conductivity
Data Source
AI summary
An active material contains: a compound containing lithium (Li) element, sulfur (S) element, and an element M and containing a crystalline phase having an argyrodite-type crystal structure; and a conductive material dispersed on the surface or in the interior of particles of the compound. The element M represents phosphorus (P) element or the like. The active material is a composite material of the compound and the conductive material. It is preferable that the conductive material is a carbon material or a metallic material. It is also preferable that the content of the lithium element in the active material is from 10 to 25% by mass.