Composite Cathode Material With Extended Solid Electrolyte Interface
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Solution Overview
Problem
Existing composite positive electrode active materials have a high resistance due to a short contact interface between the positive electrode active material and the solid electrolyte, despite a high area percentage of the solid electrolyte, leading to increased battery resistance.
Innovation Solution
A composite positive electrode active material is developed with a specific interface length value A (μm−1) of 1.326 or more, achieved by coating the positive electrode active material with a lithium-ion conducting oxide containing elemental B and P, followed by a solid electrolyte coating, to enhance the contact interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the area percentage of solid electrolyte is increased, then the solid electrolyte coverage is improved, but the contact interface length between positive electrode active material and solid electrolyte remains short
Solution Approach 1:
The patent applies a nested structure where solid electrolyte particles are positioned within the porous interior of positive electrode active material particles, and lithium-ion conducting oxide coats the exterior surface. This nested arrangement allows the solid electrolyte to be embedded inside the active material, maximizing the contact interface area without increasing the overall particle size, thereby resolving the contradiction between area coverage and interface length.
Solution Approach 2:
The patent utilizes porous positive electrode active material particles that can accommodate solid electrolyte particles within their internal porous structure. This porous architecture enables the solid electrolyte to be distributed throughout the interior volume, significantly increasing the contact interface length between the active material and solid electrolyte while maintaining a compact particle size.
2Reliability
If the contact interface length is increased, then the battery resistance is reduced, but the manufacturing complexity increases
Solution Approach 1:
The patent employs preliminary action by pre-forming porous positive electrode active material particles with controlled pore structures before introducing solid electrolyte particles. This pre-prepared porous framework facilitates subsequent uniform distribution and embedding of solid electrolyte, simplifying the manufacturing process while achieving extended contact interface length and reduced battery resistance.
Solution Approach 2:
The patent creates a composite material system consisting of porous positive electrode active material, embedded solid electrolyte particles, and exterior lithium-ion conducting oxide coating. This composite structure integrates multiple functional components into a unified particle system, where each component contributes to reducing battery resistance through synergistic effects, thereby achieving performance improvement without proportionally increasing manufacturing complexity.
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 interface length value reduces battery resistance, improving the lithium ion insertion/desorption reaction and overall battery performance.
Implementation Method 1
a lithium-ion conducting oxide containing at least one element of elemental B and elemental P
Implementation Method 2
improving the lithium ion insertion/desorption reaction
Data Source
AI summary
A composite positive electrode active material including a positive electrode active material and a lithium-ion conducting oxide containing at least one element of elemental B and elemental P on at least a part of the surface of the positive electrode active material, wherein the composite positive electrode active material contains a solid electrolyte on at least a part of the surface of the lithium-ion conducting oxide, and wherein the interface length value A (μm−1) obtained by dividing the length (μm) of the interface between the positive electrode active material and the solid electrolyte confirmed from an SEM image of a cross section of the composite positive electrode active material by the area (μm2) of the positive electrode active material in the SEM image is 1.326 or more.