Polyanion Cathode Recycling via Chlorination and Solvent Separation
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Solution Overview
Problem
Conventional recycling methods for polyanion-based lithium secondary battery cathode materials, such as LiFePO4, are inefficient and environmentally hazardous due to the use of toxic acidic substances and complex processes, limiting their economic feasibility and safety.
Innovation Solution
A method involving chlorination with chlorine-containing gases to form lithium chloride, followed by solvent separation and subsequent reactions to obtain lithium carbonate and hydroxide, allowing for safe and efficient recovery of high-value materials without additional purification steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If conventional recycling methods using toxic acidic substances are applied to polyanion-based cathode materials, then lithium and metal compounds can be recovered, but the process generates harmful waste and requires complex purification steps
Solution Approach 1:
The invention changes the chemical parameters of the recycling process by replacing toxic acidic substances with chlorine-containing gases. This parameter change transforms the chemical reaction mechanism from acid dissolution to chlorination, enabling lithium to be converted into lithium chloride which can be easily separated through solvent extraction without generating harmful waste
Solution Approach 2:
The invention converts potentially harmful chlorine-containing gases into beneficial reagents for selective chlorination. By controlling the chlorination process, lithium is transformed into lithium chloride which readily dissolves in solvents, while metal phosphates remain insoluble. This converts what could be a hazardous process into an environmentally friendly separation method that eliminates the need for complex purification steps
2Adaptability or versatility
If conventional NCM-based recycling processes are applied to polyanion-based cathode materials, then recycling can proceed using established methods, but the crystal structure difference causes extremely reduced recycling efficiency
Solution Approach 1:
The invention applies local quality by designing a recycling process specifically tailored to the crystal structure characteristics of polyanion-based cathode materials. The chlorination process exploits the specific structural features of materials like LiFePO4, targeting the lithium sites for selective conversion to lithium chloride while leaving the metal phosphate framework intact. This localized chemical transformation achieves high recycling efficiency for polyanion materials without requiring adaptation of conventional NCM methods
3Loss of substance
If complex recycling processes are used for LFP batteries, then complete material recovery can be achieved, but the process becomes economically infeasible due to excessive complexity
Solution Approach 1:
The invention segments the recycling process into two simple, distinct stages: (1) chlorination of the cathode material with chlorine-containing gases to convert lithium into lithium chloride, and (2) solvent extraction to separate lithium chloride from metal phosphates. This segmentation achieves complete material recovery through straightforward steps that can be easily implemented and scaled, eliminating the economic barriers associated with complex multi-step processes
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 safely separates lithium and polyanion compounds, reducing social and economic costs by avoiding toxic chemicals and simplifying the process, while maintaining high recovery efficiency and eco-friendliness.
Implementation Method 1
forming a first mixture including a compound containing polyanions and lithium chloride by chlorinating a polyanion-based lithium secondary battery cathode material separated from a battery with a gas containing chlorine
Implementation Method 2
separating and obtaining the compound containing polyanions and a second mixture including the lithium chloride and a solvent by contacting the first mixture with the solvent
Data Source
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AI summary
The present disclosure relates to a method and device for recycling a polyanion-based lithium cathode material for a lithium secondary battery, and more particularly, to a method and device for recycling a polyanion-based lithium cathode material capable of simply and efficiently separating high-value substances of a secondary battery cathode material without generating toxic byproducts such as acid waste.