Coated Cathode Composite Particles for Low-Resistance Solid-State Batteries
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Solution Overview
Problem
Existing all solid-state batteries face high internal resistance and inadequate charge-discharge characteristics at temperatures near room temperature due to insufficient interface formation between the solid electrolyte and positive electrode active material, leading to lithium ion deficiency and increased charge transfer resistance.
Innovation Solution
A positive electrode active material composite particle with a core-shell structure, where the core is a lithium composite oxide and the shell is a coating layer composed of a multiple oxide, lithium compound, and oxoacid compound, which promotes adhesion and forms a lithium-containing solid electrolyte at low temperatures, reducing internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid electrolyte and positive electrode active material are used in an all solid-state battery, then safety and rapid charging/discharging capabilities are improved, but internal resistance increases and charge-discharge characteristics deteriorate at temperatures near room temperature
Solution Approach 1:
The patent introduces a coating layer as an intermediary substance between the solid electrolyte and positive electrode active material. This coating layer mediates the interface interaction, improving adhesion and facilitating lithium ion transport. The coating layer acts as a bridge that resolves the incompatibility between the solid electrolyte and active material, reducing charge transfer resistance while maintaining the safety benefits of solid electrolytes.
Solution Approach 2:
The patent creates a composite structure consisting of the solid electrolyte, positive electrode active material, and coating layer. This composite material approach combines the advantages of each component: the safety of solid electrolyte, the electrochemical activity of the active material, and the interface-improving properties of the coating layer. The composite structure enables both high safety and low internal resistance at room temperature.
2Object-generated harmful factors
If interface formation techniques are applied to decrease charge transfer resistance, then charge-discharge characteristics improve, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent applies preliminary action by forming the coating layer on the positive electrode active material before assembling the battery. This pre-coating process ensures that the interface is optimized for lithium ion transport from the outset, eliminating the need for complex post-assembly interface formation techniques. The coating layer is applied in advance to prevent interface issues before they occur.
Solution Approach 2:
The patent changes the physical and chemical parameters of the interface by introducing the coating layer with specific properties (composition, thickness, structure). This parameter modification transforms the interface characteristics, reducing charge transfer resistance without requiring complex process changes. The coating layer's parameters are optimized to achieve low resistance while maintaining manufacturing simplicity.
3Object-generated harmful factors
If the positive electrode composite material is molded thin to decrease resistance value, then internal resistance decreases, but the structural integrity and manufacturing difficulty are affected
Solution Approach 1:
The coating layer serves as a mediator that enables the use of thin positive electrode composite materials. By improving adhesion and ion transport at the interface, the coating layer allows the electrode to be made thinner without compromising performance or manufacturability. The intermediary layer compensates for the reduced bulk material, maintaining effectiveness even at thin dimensions.
4Object-generated harmful factors
If oxygen constituting the positive electrode active material is substituted with nitrogen to increase electron conduction property, then electrical resistance decreases, but the chemical stability and composition control become more difficult
Solution Approach 1:
The coating layer acts as an intermediary that improves overall electrical conductivity without requiring substitution of oxygen with nitrogen in the active material. The coating layer provides alternative conduction pathways at the interface, achieving low electrical resistance while preserving the chemical stability of the original active material composition.
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 particle design significantly decreases internal resistance and enhances charge-discharge characteristics, enabling all solid-state batteries to operate effectively at room temperature with improved ion conductivity and capacity.
Implementation Method 1
improving the adhesion between a solid electrolyte and an active material
Implementation Method 2
decrease a charge transfer resistance between a solid electrolyte and a positive electrode active material
Implementation Method 3
mix a material having a low melting point such as SiO2 or an amorphous material and sinter the resulting mixture at a high temperature for rigidly coupling an ion conductor to a positive electrode active material
Data Source
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AI summary
A positive electrode active material composite particle according to the present disclosure includes a base particle constituted by a positive electrode active material containing a lithium composite oxide having a layered crystal structure, and a coating layer that is constituted by a material containing a multiple oxide different from the positive electrode active material, a lithium compound, and an oxoacid compound, and that at least partially coats a surface of the base particle. The oxoacid compound preferably contains at least one of a nitrate ion and a sulfate ion as an oxoanion.