Cathode Active Material Coating for Stable Lithium Exchange
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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 specific 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 at least one compound of formula M1[formula content in patent] is applied to the cathode active material surface. This coating acts as an intermediary between the electrolyte and the cathode material, preventing direct harmful interactions while allowing beneficial lithium ion exchange to proceed through the coating structure.
2Reliability
If a coating is applied to protect the cathode surface, then stability against surface reactions is improved, but manufacturing uniformity and efficiency decrease
Solution Approach 1:
The patent specifies precise compositional parameters for the coating compounds (formula M1[formula content in patent] where M1, M2, M3 are specific metals and x, y, z are stoichiometric ratios). By controlling these chemical parameters and the coating application process, uniform coatings with consistent protective properties are achieved across all cathode particles.
3Reliability
If existing coating methods are used, then some protection is achieved, but process efficiency and manufacturing ease require improvement
Solution Approach 1:
The coating layer is applied to the cathode active material particles before assembly into the complete battery cell. This preliminary coating step ensures that all particles are protected before they undergo subsequent processing and assembly operations, preventing surface reactions during manufacturing and eliminating the need for post-assembly protection steps.
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 rate capability, and extended cycle life, while minimizing agglomeration of secondary particles, thus addressing the surface reaction issues in lithium ion batteries.
Implementation Method 1
A process involving particulate electrode active materials coated with compounds like Al, B, Mg, or transition metals, treated in a fluidized bed at specific temperatures to achieve a stable and uniform coating
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.