Cathode Surface Solid Electrolyte Coating for Low-Impedance Li-Ion Batteries
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Solution Overview
Problem
Current lithium-ion batteries face challenges in improving charge and discharge rate performance, high- and low-temperature performance, and safety performance due to complex and costly processes like perforation processing and coating separators, which also lead to a loss in energy density.
Innovation Solution
A secondary battery design incorporating a positive electrode plate with a positive electrode active material substrate and a solid electrolyte material, where the solid electrolyte material is selectively distributed on the surface of the substrate, optimizing weight percentages and particle sizes to enhance lithium-ion conduction, reduce impedance, and improve safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If perforation processing is performed on electrode plates to improve lithium-ion conduction, then wettability and ionic conduction are enhanced, but manufacturing complexity and cost increase
Solution Approach 1:
The invention applies local quality by coating only the surface of the positive electrode active material particles with solid electrolyte material, rather than processing the entire electrode plate structure. This localized approach improves ionic conduction at the critical particle surfaces where lithium-ion exchange occurs, without requiring complex perforation processing of the whole electrode plate, thus resolving the contradiction between improving conduction and reducing manufacturing complexity
Solution Approach 2:
The invention uses composite materials by combining the positive electrode active material substrate with solid electrolyte material coating. This composite structure provides both the electrochemical activity of the substrate and the ionic conduction benefits of the solid electrolyte coating, achieving improved lithium-ion conduction without the need for complex perforation processing
2Reliability
If coating separators with coatings is performed to improve safety performance, then safety is enhanced, but process complexity and cost increase
Solution Approach 1:
The invention extracts the safety-enhancing coating function from the separator and relocates it to the positive electrode active material particles. By coating the solid electrolyte material directly on the electrode particles, the safety function is achieved at the source of lithium-ion exchange, eliminating the need for complex separator coating processes while maintaining safety performance
Solution Approach 2:
The solid electrolyte material coating acts as an intermediary between the positive electrode active material and the liquid electrolyte. This intermediate layer prevents direct contact between the liquid electrolyte and the active material surface, reducing side reactions and improving safety, while simplifying the overall battery structure by eliminating the need for separately coated separators
3Reliability
If surface coating with solid electrolyte material is applied to improve ionic conduction, then impedance is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The invention controls the weight percentage of the second element (solid electrolyte material) in the surface region to be 1000 ppm to 20000 ppm, and in the internal region to be less than 500 ppm. By specifying quantitative parameter ranges rather than requiring perfect uniformity, the patent achieves improved ionic conduction while maintaining feasible manufacturing precision requirements
Solution Approach 2:
The invention requires that at least part of the solid electrolyte material be disposed on the surface of the positive electrode active material substrate, but does not require complete or uniform coverage. This partial action approach ensures sufficient ionic conduction improvement at critical sites without demanding excessive manufacturing precision for complete surface coverage
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 design reduces impedance, enhances rate and cycling performance, and improves safety by improving lithium-ion conduction and reducing side reactions, while maintaining energy density.
Implementation Method 1
coating surfaces of positive electrode active materials and negative electrode active materials with materials exhibiting excellent ionic conduction to increase the ionic conduction at interfaces
Implementation Method 2
coating separators with coatings is typically used to improve the safety performance of lithium-ion batteries
Data Source
AI summary
A secondary battery comprising positive electrode active material. The positive electrode active material includes a positive electrode active material substrate and a solid electrolyte material. The positive electrode active material substrate includes a first element, and the solid electrolyte material includes a second element. A weight percentage of any one of the second element in a surface region of particles of the positive electrode active material is 1000 ppm to 20000 ppm, and a weight percentage of any one of the second element in an internal region of particles of the positive electrode active material is less than 500 ppm.