Cathode Oxide Separation Using Ammonia Complexation in NMC Recycling
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Solution Overview
Problem
Current battery recycling methods face challenges in efficiently separating metal oxides from NMC cathode active material, particularly due to co-precipitation issues with transition metals and the need for complex chemical processes, which complicates the recovery of high-purity metals and requires additional disassembly steps.
Innovation Solution
A novel recycling method that leaches NMC material with sulphuric or citric acid, followed by precipitation with excess ammonia to form ammine complexes, allowing for the separation of lithium and manganese hydroxides, and subsequent oxidation and refinement of metals using hydrogen peroxide or heating, enabling a single-step recovery and separation without shredding batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If precipitation is used to separate transition metals from leach liquor, then metal recovery is achieved, but co-precipitation occurs causing low purity and requiring complicated reaction control
Solution Approach 1:
The patent introduces an organic solvent extraction system as an intermediary between the leach liquor and final metal products. The organic solvent selectively complexes with transition metals (Ni, Co, Mn) to form extractable complexes, separating them from lithium in the aqueous phase. This intermediary extraction step prevents co-precipitation issues and enables high-purity metal recovery through controlled phase separation rather than direct precipitation.
2Productivity
If shredding is used to disassemble batteries, then disassembly speed increases, but physical separation of cathode material becomes challenging and requires complicated chemical processes
Solution Approach 1:
The patent extracts and isolates the cathode material from the battery assembly before chemical processing, using manual or mechanical disassembly to remove only the cathode component. This extracted cathode material is then processed through a simplified chemical circuit designed specifically for cathode materials, avoiding the need for complex separation processes that would be required if anode and cathode materials were processed together after shredding.
3Quantity of substance
If conventional precipitation with base titration is used, then metal hydroxides precipitate in order of electromotive potential, but transition metals precipitate at similar pH ranges requiring complicated control
Solution Approach 1:
The patent changes the chemical parameters of the system by introducing organic solvents with specific complexing agents that have different extraction constants for different transition metals. Instead of relying on pH-based precipitation sequences, the system uses solvent composition, organic-to-aqueous phase ratio, and complexing agent concentration as controllable parameters to achieve selective metal extraction and separation.
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 provides a simple, efficient, and versatile closed-loop recycling process capable of handling various cathode compositions, achieving high-purity metal oxide recovery and reuse as cathode active material, thereby addressing supply chain gaps and reducing the need for mining precious metals.
Implementation Method 1
NMC material is leached in sulphuric or citric acid before precipitating it with excess ammonia
Implementation Method 2
precipitating it with excess ammonia. During precipitation, the aqueous cobalt and nickel ions are reduced to hydroxides before undergoing a ligand substitution to form the ammine complexes
Implementation Method 3
aqueous cobalt and nickel ions are reduced to hydroxides before undergoing a ligand substitution to form the ammine complexes
Implementation Method 4
The separated metals are then oxidized by reacting with a reducing agent like hydrogen peroxide or by heating in a furnace
Data Source
AI summary
Disclosed herein is a method and chemical process for separating the cathode metal oxides of lithium-ion batteries. The main utility of this method is in recycling the cathode active material of used batteries to effectively offer a closed route supply chain solution for battery manufacturers. The invention acts on transition metal solubility in a unique way by using excess ammonia to separate transition metal compounds from lithium as hexammines through a ligand substitution reaction. It is tailored for recycling NMC cathodes and can adjust to process various chemistries depending on future demand.