Ni-Rich Cathode Surface Washing to Prevent Lithium Depletion
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Solution Overview
Problem
Lithium ion batteries, particularly those with Ni-rich electrode active materials, face issues due to undesired reactions on the electrode surface, such as electrolyte decomposition, which current methods like coating with aluminium oxide or removing free LiOH/Li2CO3 do not adequately address, often resulting in poor electrochemical properties.
Innovation Solution
A process involving treating Li1+xTM1−xO2 electrode active materials with an aqueous medium of pH 5-14 for up to 3 minutes, followed by rapid solid-liquid separation, to prevent lithium depletion and enhance electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the electrode active material is washed with water to remove free LiOH or Li2CO3, then the surface is cleaned, but lithium depletion occurs and electrochemical properties deteriorate
Solution Approach 1:
The patent changes the pH parameter of the washing medium from neutral water (pH 7) to alkaline medium (pH 12-14), which prevents lithium depletion while effectively removing LiOH and Li2CO3. This parameter change resolves the contradiction by maintaining lithium content while achieving surface cleaning.
Solution Approach 2:
The patent applies preliminary coating with aluminium oxide or calcium oxide before washing to protect the surface during the washing process. This preliminary protective action prevents harmful interactions between water and the electrode material, allowing effective removal of LiOH/Li2CO3 without lithium depletion.
2Object-generated harmful factors
If coating is applied to protect the surface, then electrolyte decomposition is reduced, but lithium exchange during charging and discharging is hindered
Solution Approach 1:
The patent uses a thin coating layer that provides sufficient protection against electrolyte decomposition while maintaining adequate lithium ion conductivity. The coating is applied at controlled amounts to achieve partial protection without excessive barrier effect that would hinder lithium exchange.
Solution Approach 2:
The patent modifies the coating parameters by selecting specific materials (aluminium oxide or calcium oxide) and controlling coating thickness to optimize the balance between protection and lithium ion transport. The coating is designed with specific physical and chemical properties that allow lithium exchange while preventing electrolyte decomposition.
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 electrode active materials with improved electrochemical properties, including reduced resistance and prolonged cycling stability, suitable for high-capacity lithium ion batteries.
Implementation Method 1
treating Li1+xTM1−xO2 with an aqueous medium with a pH value in the range of from 5 to 14
Implementation Method 2
removing said aqueous medium from treated Li1+xTM1−xO2 by way of a solid-liquid separation
Data Source
AI summary
Process for modifying an electrode active material according to general formula Li1+xTM1−xO2, wherein TM contains a combination of Ni and at least one transition metal selected from Co and Mn, and, optionally, at least one metal selected from Al, Ba, and Mg and, optionally, one or more transition metals other than Ni, Co, and Mn, wherein at least 75 mole-% of TM is Ni, and x is in the range of from −0.05 to 0.2, said process comprising the steps of (a) treating said Li1+xTM1−xO2 with an aqueous medium with a pH value of at least 5 and up to 14, (b) removing said aqueous medium from treated Li1+xTM1−xO2 by way of a solid-liquid separation, wherein steps (a) and (b) are commenced with a maximum time difference of 3 minutes. In addition, the present invention is directed towards Ni-rich electrode active materials.