Coated Positive Electrode Material for Low-Resistance Solid-State Interfaces
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Solution Overview
Problem
Current all-solid-state batteries suffer from high resistance and insufficient high voltage tolerance due to the formation of a high-resistance layer at the interface between the solid electrolyte and the positive electrode active material, limiting their output characteristics and energy density.
Innovation Solution
A coated positive electrode active material is developed, comprising a positive electrode active material with a coating layer containing cobalt (Co), lithium (Li), phosphorus (P), and a pentavalent transition metal element (M) such as vanadium (V), niobium (Nb), or tantalum (Ta), which forms an interfacial layer to inhibit the formation of high-resistance layers and enhance lithium ion conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is formed on the positive electrode active material to improve output characteristics and high voltage tolerance, then the resistance decreases and voltage tolerance improves, but the manufacturing complexity increases and manufacturing precision requirements increase
Solution Approach 1:
A coating layer comprising Li-P glass and Li-M glass is applied as an intermediary between the positive electrode active material and the solid electrolyte. This coating layer serves as a mediator that improves Li ion conductivity at the interface, reduces resistance, and enhances high voltage tolerance without requiring complex manufacturing processes
Solution Approach 2:
The coating layer is formed as a composite material combining Li-P glass (lithium phosphate glass) and Li-M glass (lithium metasilicate glass) in specific ratios. This composite structure provides synergistic effects that optimize both Li ion conductivity and high voltage tolerance while maintaining manufacturability
2Reliability
If the coating layer contains lithium and phosphorus to enhance Li ion conductivity, then the resistance decreases, but the manufacturing precision requirements increase
Solution Approach 1:
The coating layer composition is optimized by controlling the molar ratio of Li to (P+M) between 0.8 and 1.2, and the ratio of P to (P+M) between 0.1 and 0.9. These parameter specifications ensure high Li ion conductivity while providing clear manufacturing guidelines that balance precision requirements with practical manufacturability
3Productivity
If a coating layer is applied to inhibit high-resistance layer formation at the solid electrolyte interface, then output characteristics improve, but the device complexity increases
Solution Approach 1:
The Li-P glass and Li-M glass coating serves as an intermediary layer at the solid electrolyte interface, preventing direct contact between the solid electrolyte and positive electrode active material. This intermediary coating inhibits high-resistance layer formation and improves output characteristics while maintaining relatively simple device structure
Solution Approach 2:
The coating layer is applied specifically at the critical interface region between the solid electrolyte and positive electrode active material, where it locally improves Li ion conductivity and prevents resistance formation. This localized application optimizes performance without unnecessarily complicating the entire battery structure
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 coated positive electrode active material achieves low resistance, high energy density, and high voltage tolerance, improving the performance of lithium secondary batteries.
Implementation Method 1
the coating layer contains at least lithium (Li), phosphorus (P), an element M, and oxygen (O), and the element M is a pentavalent transition metal element
Implementation Method 2
the coating layer... forms an interfacial layer to inhibit the formation of high-resistance layers
Data Source
Figure 1~2
AI summary
A coated positive electrode active material for a lithium secondary battery includes a positive electrode active material and a coating layer disposed on the surface of the positive electrode active material. The positive electrode active material contains cobalt (Co). The coating layer contains at least lithium (Li), phosphorus (P), an element M, and oxygen (O). The element M is a pentavalent transition metal element.