Regenerating Graphite from Mixed Battery Waste
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for recycling lithium-ion battery waste focus primarily on recovering metal elements from positive electrode materials, neglecting the recycling of graphite from negative electrode materials, which results in resource waste and environmental contamination.
Innovation Solution
A method involving low-temperature roasting surface modification, flotation separation, weak acid washing, and high-temperature graphitization is employed to efficiently recover and regenerate battery-grade graphite from mixed waste of positive and negative electrode materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If acid leaching method is used to recover graphite, then graphite can be separated from mixed waste, but acid consumption increases and waste acid is produced which is harmful to the environment
Solution Approach 1:
The invention changes the chemical parameters of the leaching process by using weak acid (acetic acid or hydrofluoric acid with concentration 0.5-5 mol/L) instead of strong acid, and controls the leaching temperature (20-80°C) and time (1-12 hours) to achieve effective graphite separation while minimizing environmental harm. The weak acid concentration and contact time are optimized to balance recovery efficiency and environmental protection.
Solution Approach 2:
The invention uses cheap, readily available weak acids (acetic acid or hydrofluoric acid) that can be easily neutralized and disposed of without causing severe environmental damage. These weak acids serve as disposable leaching agents that can be neutralized with alkali after use, converting harmful waste into harmless salts and water, thus eliminating the need for complex acid regeneration systems.
2Manufacturing precision
If organic acid reductive leaching is used to obtain high-purity graphite powder, then graphite purity is improved, but interlayer spacing increases and degree of graphitization decreases, affecting electrochemical properties
Solution Approach 1:
The invention optimizes the leaching parameters by using weak acid with controlled concentration (0.5-5 mol/L) and limited contact time (1-12 hours), which removes impurities from graphite surface without causing excessive interlayer spacing expansion. The weak acid gently etches the graphite surface, achieving purification while preserving the intact layered structure necessary for good electrochemical performance.
Solution Approach 2:
The invention applies partial leaching action by controlling the process conditions to achieve just enough purification without over-leaching. The weak acid treatment is designed to remove surface impurities and loosely bound contaminants while leaving the core graphite structure and interlayer spacing largely unchanged, thus maintaining electrochemical properties while improving purity.
3Ease of manufacture
If careful disassembly is used to obtain negative electrode plate, then graphite recovery process can be simplified, but recovery rate of waste graphite decreases
Solution Approach 1:
The invention segments the graphite recovery process into two independent stages: (1) simple mechanical disassembly to separate negative electrode plates from battery components, and (2) weak acid leaching to separate graphite from copper foil and other contaminants. This segmentation allows the use of simple mechanical methods for initial separation while using chemical treatment only for the critical graphite purification step, thereby maintaining both process simplicity and high recovery rate.
Solution Approach 2:
The weak acid solution acts as an intermediary agent that facilitates the separation of graphite from copper foil and other contaminants without requiring complex mechanical disassembly. The weak acid selectively dissolves or loosens the adhesive and contaminant layers between graphite and copper foil, allowing easy mechanical separation while preserving graphite integrity and maximizing recovery rate.
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
This method achieves clean and effective separation of lithium-ion battery electrodes, reduces acid consumption, and produces graphite with excellent electrochemical properties, suitable for industrial-scale production.
Implementation Method 1
placing mixed waste of positive and negative electrode materials of a failed lithium-ion battery in a muffle furnace, and performing low-temperature roasting surface modification in an air atmosphere
Implementation Method 2
performing low-temperature roasting surface modification to obtain powder
Implementation Method 3
placing the slurry in a flotation machine, and after stirring the slurry, adding a collector and a foaming agent to the slurry, and obtaining a foam product (a body rich in negative electrode graphite) and an ore slurry product (a body rich in positive electrode material) by flotation separation
Implementation Method 4
placing the negative electrode graphite in a high-temperature graphitization furnace and performing oxygen-free heating, to obtain a regenerated graphite product
Implementation Method 5
converting an organic component in the graphite into amorphous carbon... converting amorphous carbon produced by roasting an organic component into a graphite structure with good electrochemical properties
Data Source
Figure 1(A1)~2(B2)
Figure 3(A1)~4(B2)
Figure 5(A1)~6
AI summary
The present invention discloses a method for preparing battery-grade graphite by using mixed waste of positive and negative electrode materials of a failed lithium-ion battery as a raw material, the method comprising: placing mixed waste of positive and negative electrode materials of a failed lithium-ion battery in a muffle furnace, and performing low-temperature roasting surface modification, which removes adhesive and residual electrolyte from the surfaces of the electrode materials, to obtain a powder; placing the powder in a flotation machine, adding clean water and stirring the slurry, improving a subsequent flotation separation effect of positive and negative electrode materials; on the basis of a difference in hydrophilic and hydrophobic properties of the positive and negative electrode materials, separating the positive electrode material from negative electrode graphite by means of flotation to obtain a foam product (a body rich in negative electrode graphite) and an ore slurry product (a body rich in positive electrode material); and after the foam product has undergone weak acid washing and been filtered and dried, performing repair at a high temperature to obtain a graphite product which has excellent electrochemical properties. By means of performing low-temperature roasting surface modification, flotation separation, weak acid washing and high-temperature graphitization repair on mixed waste of positive and negative electrode materials of a failed lithium-ion battery, the present invention recycles negative electrode graphite in the mixed waste of positive and negative electrode materials.