Partial Cathode Coating for Low-Resistance Li-Ion Cycling
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Solution Overview
Problem
Lithium ion batteries face issues with undesired reactions on the surface of cathode active materials, leading to resistance build-up during repeated cycling, which current coating methods do not adequately address, especially concerning particle agglomeration and efficiency.
Innovation Solution
A process involving treating electrode active materials with metal alkoxides or metal halides, followed by moisture treatment, repeated multiple times, with ozone substitution in the final cycle, to achieve a partially coated surface with acidic oxides, reducing resistance and improving cycling performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional coating methods are used to protect cathode active material surface, then surface protection is achieved, but particle agglomeration occurs and coating efficiency is insufficient
Solution Approach 1:
The patent changes the chemical parameters of the coating process by using metal alkoxides or metal halides that react with surface hydroxyl groups to form metal oxide coatings. The controlled reaction conditions and stoichiometry enable efficient coating without particle agglomeration, resolving the contradiction between surface protection and coating efficiency
Solution Approach 2:
The patent introduces metal alkoxides or metal halides as intermediary substances that mediate between the cathode active material surface and the desired metal oxide coating. These intermediaries react with surface hydroxyl groups to form stable metal oxide layers, achieving effective surface protection while maintaining particle dispersion and high coating efficiency
2Reliability
If coating is applied to protect surface, then resistance build-up is reduced, but coating uniformity and coverage are insufficient
Solution Approach 1:
The patent employs partial coating rather than attempting complete surface coverage, recognizing that uniform distribution of coating material at optimal concentration provides better performance than thick or non-uniform coatings. The controlled reaction conditions ensure sufficient coating uniformity where needed, achieving resistance stability without requiring perfect overall coverage
Solution Approach 2:
The patent optimizes reaction parameters including temperature, time, and metal alkoxide/halide concentration to achieve uniform coating distribution. By controlling these parameters, the process ensures consistent coating thickness and composition across particle surfaces, improving manufacturing precision while maintaining resistance stability
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 process results in a cathode active material with low resistance build-up during repeated cycling, enhancing discharge behavior and cycle stability, particularly suited for lithium ion batteries.
Implementation Method 1
treating said electrode active material with a metal alkoxide or metal halide or metal amide or alkyl metal compound
Implementation Method 2
treating the material obtained in step (b) with moisture
Implementation Method 3
in the last sequence of steps (b) and (c), moisture is at least partially substituted by ozone
Data Source
AI summary
A process for making a partially coated electrode active material may involve: (a) providing an electrode active material of the formula Li1+xTM1−xO2, wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one metal selected from Al, Ti, Mo, W, and Zr, and x is in the range of from zero to 0.2, wherein at least 60 mole-% of the transition metal of TM is Ni, and wherein the electrode active material has a residual moisture content in the range of from 50 to 1,000 ppm; (b) treating the electrode active material with a metal alkoxide or metal halide or metal amide or alkyl metal compound; (c) treating the material obtained in (b) with moisture; and (d) repeating the sequence of (b) and (c) twice to 4 times, wherein, in the last sequence of (b) and (c), moisture is at least partially substituted by ozone.