Surface Modified Cathode Active Materials for Lithium-Ion Batteries
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Solution Overview
Problem
The presence of basic impurities such as Li2CO3 on the surface of cathode materials in lithium-ion batteries leads to reduced mechanical stability and accelerated performance loss due to parasitic reactions with the electrolyte, necessitating a method to mitigate these effects.
Innovation Solution
A process involving a solution with solvates like H3BO3, H3PO4, or phosphate salts is used to modify the surface chemistry of cathode active materials, converting basic impurities into beneficial coating layers, thereby enhancing electrochemical performance and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If LiNixMnymCo1-x-yO2 cathode material is synthesized through solid-state reaction at high temperature, then the cathode material can be produced, but basic impurities such as LiOH and Li2CO3 deposit on the surface
Solution Approach 1:
The patent applies preliminary action by treating the cathode material surface with acid solution before battery assembly to remove basic impurities. The acid treatment is performed in advance on the synthesized cathode material, converting LiOH and Li2CO3 impurities into soluble salts that can be washed away, preventing subsequent parasitic reactions in the battery
Solution Approach 2:
The patent converts the harmful basic impurities (LiOH, Li2CO3) into beneficial removable substances by reacting them with acid to form soluble lithium salts. The harmful surface deposits are transformed into soluble compounds that can be easily removed by washing, turning a manufacturing defect into a removable issue
2Ease of manufacture
If basic impurities remain on the cathode surface, then manufacturing steps are reduced, but parasitic reactions with electrolyte accelerate performance loss
Solution Approach 1:
The patent introduces acid solution as an intermediary substance to mediate between the cathode material and the electrolyte. The acid treatment creates a clean surface interface that prevents direct parasitic reactions between basic impurities and the electrolyte, acting as a protective intermediary layer through surface modification
3Device complexity
If basic impurities are present on the cathode surface, then no additional treatment steps are needed, but the mechanical stability of the cathode electrode reduces
Solution Approach 1:
The patent extracts the harmful basic impurities from the cathode surface through acid treatment and washing. By removing LiOH and Li2CO3 deposits, the underlying stable cathode material structure is revealed, restoring and maintaining the mechanical stability of the cathode electrode without adding structural 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 surface modification process improves capacity retention and reduces interfacial impedance, enhancing the overall performance and longevity of lithium-ion batteries while minimizing chemical waste and manufacturing steps.
Implementation Method 1
treating the synthesized cathode material with an acid solution can convert the basic impurities into soluble salts, which can be easily removed
Implementation Method 2
washing the treated cathode material with a solvent, filtering the washed cathode material
Implementation Method 3
drying the wet film at an elevated temperature to obtain the final cathode electrode
Data Source
AI summary
A process for modifying a surface chemistry of a cathode active material includes providing a powder of the cathode active material, wetting the powder of cathode active material with an efficient amount of a solution to form a mixture, and baking the mixture to obtain a surface modified cathode active material, wherein: the cathode active material has a formula of LiNixMnyCo1-x-yO2, wherein 0≤x≤1, 0≤y≤1, and 0≤x+y≤1; the solution comprises a solvate and a solvent; and the solvate comprises H3BO3, H3PO4, a phosphate salt, a hydrogenphosphate salt, a dihydrogenphosphate salt, or a combination of any two or more thereof.