Composite Active Material Coating for Lithium Battery Resistance
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Solution Overview
Problem
Existing lithium secondary batteries face high reaction resistance due to insufficient coverage of sulfide-based solid electrolyte on composite active material particles, leading to inefficient ion conduction and increased electrical resistance.
Innovation Solution
A composite active material is developed with a sulfide-based solid electrolyte coating 76.0% or more of the surface of composite particles, which includes active material particles containing cobalt, nickel, or manganese elements, and an oxide-based solid electrolyte, manufactured using a method that applies energy to deform the sulfide-based electrolyte at temperatures below 100°C, enhancing surface coverage without mechanical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a positive electrode active material with a LiNbO3 coating layer is mixed with sulfide-based solid electrolyte at a mass ratio of 7:3, then the electrode structure is formed, but the reaction resistance becomes high because many active material particles are not in direct contact with the sulfide-based solid electrolyte
Solution Approach 1:
The patent applies a first solid electrolyte coating layer (oxide-based such as Al2O3, SiO2, or TiO2) to the surface of the active material particles before mixing with the sulfide-based solid electrolyte. This preliminary coating prevents direct contact between the sulfide electrolyte and active material, reducing side reactions and improving ion conduction efficiency while maintaining structural stability.
Solution Approach 2:
The patent creates a composite coating structure on active material particles consisting of an inner oxide-based solid electrolyte layer and an outer sulfide-based solid electrolyte layer. This composite structure combines the chemical stability of oxide electrolytes with the high ion conductivity of sulfide electrolytes, resolving the contradiction between reaction resistance and ion conduction efficiency.
2Reliability
If the sulfide-based solid electrolyte coverage on composite particles is increased to improve ion conduction, then the reaction resistance decreases, but the manufacturing complexity increases due to the need for precise coating control
Solution Approach 1:
The patent divides the solid electrolyte coating into two distinct layers: an inner oxide-based layer and an outer sulfide-based layer. This segmentation allows each layer to perform its specific function (chemical stability and ion conduction respectively) while simplifying the overall manufacturing process through standardized sequential coating procedures.
Solution Approach 2:
The patent specifies precise parameter ranges for the coating process, including the thickness of each layer (first layer: 1-100 nm, second layer: 10-500 nm) and the mass ratio of active material to sulfide-based solid electrolyte (95:5 to 50:50). These parameter specifications standardize the manufacturing process, reducing complexity while ensuring optimal performance.
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 increased sulfide-based solid electrolyte coverage significantly reduces reaction resistance in lithium secondary batteries, improving ion conduction and overall battery performance by optimizing the electrode material interface.
Implementation Method 1
coating a surface of each of the composite particles with a sulfide-based solid electrolyte by mixing the composite particles with the sulfide-based solid electrolyte with application of an energy, at which the sulfide-based solid electrolyte plastically deforms
Implementation Method 2
The oxide-based solid electrolyte coats all or part of a surface of each of the active material particles
Implementation Method 3
The electrolyte is held between the negative electrode and the positive electrode
Data Source
AI summary
A composite active material including composite particles and a sulfide-based solid electrolyte is proposed. The composite particles contain active material particles and an oxide-based solid electrolyte. The active material particles contain at least any one of a cobalt element, a nickel element and a manganese element and further contain a lithium element and an oxygen element. The oxide-based solid electrolyte coats all or part of a surface of each of the active material particles. The sulfide-based solid electrolyte further coats 76.0% or more of a surface of each of the composite particles.