Cathode Active Material Coating via Fluidized-Bed Heat Treatment
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Solution Overview
Problem
Lithium ion batteries face issues with undesired reactions on the surface of cathode active materials, leading to instability and inefficiency, despite existing coating methods like aluminum oxide or calcium oxide, which still require process improvements for uniformity and effectiveness.
Innovation Solution
A process involving particulate electrode active materials coated with compounds like Al, B, Mg, or transition metals, treated in a fluidized bed at elevated temperatures to achieve a stable and uniform coating that protects against surface reactions without hindering lithium exchange.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cathode active material surface is left unprotected, then lithium exchange efficiency is maintained, but undesired surface reactions occur leading to instability
Solution Approach 1:
A coating layer comprising compounds of M1 (where M1 is selected from Li, Al, B, Mg, Si, Sn, transition metals, or combinations thereof) is applied to the cathode active material surface. This intermediary layer protects the surface from undesired reactions with the electrolyte and solvent while maintaining lithium ion conductivity, thus resolving the contradiction between stability and harmful surface reactions.
Solution Approach 2:
The patent specifies particular parameter ranges for the coating: M1 compound selection from specific metallic elements, coating thickness control, and post-treatment temperature range of 250-950°C. These parameter optimizations ensure the coating provides sufficient protection while maintaining lithium exchange capability, addressing the stability-harmful reactions contradiction.
2Reliability
If a coating is applied to protect the cathode surface, then stability against surface reactions is improved, but manufacturing efficiency decreases
Solution Approach 1:
The patent replaces complex multi-step coating mechanisms with a simplified process: treating the cathode active material with M1 compounds followed by a single post-treatment heating step at 250-950°C. This substitution of complex processes with a streamlined approach maintains protective functionality while significantly improving manufacturing efficiency.
Solution Approach 2:
By optimizing the post-treatment temperature range to 250-950°C and specifying appropriate M1 compounds, the patent achieves effective coating activation and stabilization in a single step, eliminating the need for multiple sequential treatments and thereby improving manufacturing productivity.
3Reliability
If a coating is applied to protect the cathode surface, then stability is improved, but coating uniformity is insufficient
Solution Approach 1:
The patent replaces complex multi-step coating procedures with a simplified treatment process involving M1 compounds and a single post-treatment heating step. This substitution ensures more uniform coating distribution across the cathode particle surfaces while maintaining the protective function, thereby improving manufacturing precision.
Solution Approach 2:
The specification of post-treatment temperature range (250-950°C) and the selection of specific M1 compounds facilitate uniform coating formation and activation. These optimized parameters ensure consistent coating quality across batches, addressing the stability-uniformity contradiction.
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 coated electrode active materials with enhanced stability, reduced impedance growth, improved cycle life, and low agglomeration of secondary particles, leading to better electrochemical performance.
Implementation Method 1
treating in a fluidized bed at elevated temperatures
Implementation Method 2
heating the material obtained after the step (b) or (c), if applicable, at a temperature from 250 to 950° C. in a fluidized bed
Implementation Method 3
treating said electrode active material with a compound of M1... to achieve a stable and uniform coating that protects against surface reactions
Data Source
AI summary
Process for making a coated electrode active material wherein said process comprises the following steps: (a) providing a particulate electrode active material according to general formula Li1+xTM1−xO2, wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one metal selected from Mg, Al, Ba, Ti and Zr, and x is in the range of from zero to 0.2, wherein at least 15 mole-% of the transition metal of TM is Ni, (b) treating said electrode active material with a compound of M1, wherein M1 is selected from Li, Al, B, Mg, Si, Sn, and from transition metals, or a combination of at least two of the foregoing, with or without a solvent, wherein said compound of M1 does not act as a cathode active material on its own, (c) optionally, removing compound of M1 which is not deposited on said particulate electrode active material, (d) performing a post-treatment by heating the material obtained after the step (b) or (c), if applicable, at a temperature from 250 to 950° C. in a fluidized bed.