NCM Cathode MnO2 Coating for Surface Defect Repair
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Solution Overview
Problem
Lithium nickel cobalt manganese oxide cathode materials with high Ni content face issues such as residual lithium on the surface, surface defects, and increased reactivity with the electrolyte, leading to decreased cycling performance and side reactions.
Innovation Solution
A method involving the mixing of lithium nickel cobalt manganese oxide cathode material with a potassium permanganate solution and introducing an olefin, which reacts to form a manganese-dioxide-coated layer on the surface defects, ensuring uniform coating and preventing excessive thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating methods are used to form a coating layer on the cathode material surface, then some surface defects can be repaired and side reactions can be alleviated, but the coating uniformity is poor and coating agent distribution is insufficient, leaving some defect areas uncoated
Solution Approach 1:
The patent introduces olefin gas as an intermediary carrier that transports coating agent precursors to the cathode material surface. The olefin bubbles act as mediators that deliver coating agents uniformly across the surface, including defect areas, solving the non-uniform coating problem while maintaining defect protection
Solution Approach 2:
The patent uses gas-phase olefin introduction and bubble formation to achieve coating agent delivery. The pneumatic process of gas bubbling through the slurry ensures uniform distribution of coating agents on the cathode material surface, improving coating uniformity while maintaining comprehensive coverage
2Manufacturing precision
If the amount of coating agent is increased to ensure complete coverage of surface defects, then all defect areas can be coated, but the coating becomes excessively thick, decreasing specific capacity and increasing impedance
Solution Approach 1:
The patent enables local quality control by allowing coating agents to deposit preferentially on surface defect areas through the olefin bubble mechanism. The coating thickness is locally optimized - thicker at defect sites for protection, thinner on already-sound surfaces - thereby achieving complete coverage without excessive overall thickness that would harm cycling performance
Solution Approach 2:
The patent uses controlled olefin gas introduction to deliver precisely the amount of coating agent needed. Rather than adding excessive coating agent that would create uniformly thick coating, the partial action of bubble-mediated delivery ensures coating is applied only where needed (at defect areas), avoiding over-coating and its negative effects on capacity and impedance
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 method achieves directed coating of surface defects, reducing side reactions with the electrolyte and maintaining high cycling performance by forming a uniform MnO2-enriched layer, thus enhancing the cathode material's stability and capacity retention.
Implementation Method 1
the adhered gas can react with potassium permanganate in the solution in the defect areas to form MnO2 precipitate to make up for the defects
Implementation Method 2
the adhered gas can react with potassium permanganate in the solution in the defect areas to form MnO2 precipitate
Data Source
AI summary
The present disclosure discloses a method for coating a lithium nickel cobalt manganese oxide cathode material, and relates to the technical field of the synthesis of cathode materials. The present disclosure provides a method for coating a lithium nickel cobalt manganese oxide cathode material, comprising the following steps: (1) mixing the lithium nickel cobalt manganese oxide cathode material with a potassium permanganate solution, and introducing an olefin; and (2) after a reaction is completed, a reaction product is dried and calcinated to obtain a manganese-dioxide-coated lithium nickel cobalt manganese oxide cathode material; wherein the number of carbon atoms in the olefin is ≤10, and the number of carbon-carbon double bonds in the olefin is 1. By introducing an olefin when mixing a lithium nickel cobalt manganese oxide cathode material with a potassium permanganate solution, directed coating of surface defects is realized.