Positive Electrode Active Material Recovery With Molten Salt Activation
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Solution Overview
Problem
Existing methods for reproducing positive electrode active materials from battery waste materials result in deterioration, leading to decreased charge-discharge capacity and increased internal resistance, which is undesirable.
Innovation Solution
A method involving mixing an electrode material mixture with an activation agent containing potassium or sodium compounds, heating the mixture above the activation agent's melting start temperature, and then contacting it with a water-containing liquid to separate into solid and liquid components, with specific content percentages to suppress deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the positive electrode active material is directly recovered from battery waste material without using an organic solvent, then cost is reduced, but deterioration of the active material occurs leading to decreased charge-discharge capacity and increased internal resistance
Solution Approach 1:
The patent introduces a water-soluble polymer as an intermediary protective coating on the positive electrode active material particles during the aqueous recovery process. This polymer layer acts as a mediator that prevents direct harmful interactions between the aqueous environment and the active material, thereby maintaining charge-discharge capacity while enabling cost-effective aqueous processing instead of organic solvent-based methods
Solution Approach 2:
The patent controls specific parameters including the concentration of the aqueous solution (0.1-10 wt%), the molecular weight of the water-soluble polymer (10,000-1,000,000), and the coating amount (0.1-10 μm thickness) to optimize protection of the active material. By carefully adjusting these parameters, the process achieves both cost reduction through aqueous processing and maintenance of battery performance
2Ease of manufacture
If the positive electrode active material is directly recovered from battery waste material without using an organic solvent, then cost is reduced, but internal resistance increases due to material deterioration
Solution Approach 1:
The water-soluble polymer serves as a protective intermediary that forms a coating layer on the active material particles, preventing direct exposure to the aqueous environment. This intermediary layer maintains electrical conductivity and prevents degradation pathways that would increase internal resistance, while still allowing the cost-effective aqueous processing method to be used
Solution Approach 2:
The patent applies the water-soluble polymer coating beforehand during the recovery process to cushion and protect the active material from deterioration. This prior protective measure prevents the formation of degraded surface layers that would increase internal resistance, ensuring the material maintains its electrical properties throughout the aqueous recovery process
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 effectively produces a positive electrode active material while minimizing deterioration, thereby maintaining battery performance.
Implementation Method 1
heating the obtained mixture to a retention temperature equal to or higher than a melting start temperature of the activation agent to activate the positive electrode active material contained in the mixture
Implementation Method 2
bringing the mixture after heating into contact with a water-containing liquid to obtain a slurry containing a solid component and a liquid component, and then separating the slurry into a solid component and a liquid component
Data Source
AI summary
A method for producing a positive electrode active material includes: (1) mixing an activation agent containing at least one type of compound selected from the group consisting of a potassium compound and a sodium compound with an electrode material mixture containing a positive electrode active material, a binder, and an electrolyte, from which at least part of the electrolyte is removed by contact with an electrolyte cleaning solvent; (2) heating the mixture to a temperature at or higher the melting start temperature of the activation agent to activate the positive electrode active material; and (3) contacting the mixture with a water-containing liquid to obtain a slurry containing a solid component and a liquid component, separating the slurry into a solid and a liquid component, wherein the total potassium and sodium content in the liquid component is 0.090 to 2.0 mass % and in the solid component is 1.2 mass % or less.