Sulfur-Containing Cathode Structure to Prevent Electrolyte Dissolution
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Solution Overview
Problem
Sulfur-based cathode materials face issues with sulfur dissolution in the electrolyte due to unsuitable structural properties, leading to reduced performance and increased production costs.
Innovation Solution
A cathode material structure is designed with a central area of lithium oxide and a surface layer containing lithium oxide and elemental sulfur, featuring pores that allow sulfur to be filled within, preventing dissolution and maintaining compaction density, thereby enhancing volume energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If sulfur is added to increase lithium binding capacity and energy density, then the battery achieves higher theoretical specific capacity, but sulfur dissolves in the electrolyte due to unsuitable structural properties, leading to reduced performance
Solution Approach 1:
The patent utilizes a porous carbon coating layer on the cathode material surface that contains and anchors sulfur species, preventing their dissolution into the electrolyte. The porous structure provides sufficient surface area and binding sites for sulfur while maintaining structural integrity, thus achieving both high lithium binding capacity and performance stability.
Solution Approach 2:
The patent creates a composite cathode material structure combining lithium-rich layered oxide core with a carbon-sulfur composite shell. This composite design allows the core to provide high capacity while the shell prevents sulfur dissolution, resolving the contradiction between quantity of substance and reliability.
2Quantity of substance
If sulfur is added to increase energy density, then the battery achieves higher overall energy density, but production costs increase
Solution Approach 1:
The patent merges the sulfur addition process with the existing carbon coating step in a single manufacturing operation. By combining these functions into one process stage, the patent achieves high energy density while avoiding the need for separate, costly sulfur incorporation steps, thus improving ease of manufacture.
3Reliability
If a surface layer with elemental sulfur is created to prevent dissolution, then sulfur dissolution is prevented, but the structural integrity and mechanical strength may be compromised
Solution Approach 1:
The patent employs a thin film carbon coating layer that is flexible yet structurally sound. This thin film encapsulates the sulfur-containing surface layer, preventing sulfur dissolution while maintaining sufficient mechanical strength through the cohesive properties of the carbon matrix and its strong bonding to the underlying cathode material.
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 cathode material effectively prevents sulfur dissolution, increasing energy density and cycle life of lithium ion batteries without compromising mechanical strength.
Implementation Method 1
the cathode material particles comprising a central area, and a surface layer area, where the central area comprises lithium oxide, and the surface layer area comprises lithium oxide and elemental sulfur
Data Source
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AI summary
A cathode material, a preparation method thereof, a lithium ion battery and a vehicle are provided. The cathode material comprises cathode material particles comprising a central area, and a surface layer area, wherein the central area comprises lithium oxide, and the surface layer area comprises lithium oxide and elemental sulfur, in which the lithium oxide comprises δLiNimConX(1-m-n)O2·(1-δ)Li2MO3, where 0≤δ≤1, X comprises at least one selected from Mn, Al, Nb, and Fe, M comprises at least one selected from Mn, Al, Nb, Fe, Co, and Ni, 0≤m<1, and 0≤n<1.