Lithium Battery Cathode Recovery via Controlled Dry Reduction
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Solution Overview
Problem
Existing methods for recovering valuable metals from lithium secondary battery cathodes, such as those using strong acids, suffer from low selectivity, long regeneration times, and environmental pollution, and lack efficient dry-based recovery processes.
Innovation Solution
A method involving a dry reductive reaction of a cathode active material mixture with a controlled reductive reaction gas to form a preliminary precursor mixture, followed by controlled reduction degree adjustment, allowing for the recovery of lithium and transition metals with high purity and yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a wet process using strong acid is used to leach waste cathode active material, then valuable metals can be recovered, but the regeneration selectivity is low, regeneration time is long, and environmental pollution occurs
Solution Approach 1:
The patent changes the chemical state parameters by using a dry reductive reaction process instead of wet acid leaching. The cathode active material is reacted with reductive reaction gas at controlled temperatures (400-600°C) to convert transition metals to metallic state, then selectively dissolved in acid to achieve high-purity lithium recovery without environmental pollution
Solution Approach 2:
The patent replaces the wet chemical leaching process with a dry reductive reaction process. Instead of using strong acids to dissolve all metals simultaneously, the method uses controlled thermal reduction followed by selective acid treatment, eliminating the need for large volumes of acid and reducing environmental harm
2Quantity of substance
If a wet process using strong acid is used to leach waste cathode active material, then valuable metals can be recovered, but the regeneration time is long
Solution Approach 1:
The patent performs preliminary reductive reaction on the cathode active material before acid leaching. By pre-converting transition metals to metallic state through controlled reduction with H2-containing gas, the subsequent acid treatment becomes much faster and more selective, significantly reducing total regeneration time
Solution Approach 2:
The patent changes the physical and chemical parameters of the cathode material through controlled reduction at 400-600°C, transforming the transition metal oxides into metallic forms that can be rapidly and selectively dissolved in acid, thereby accelerating the overall recovery process
3Object-affected harmful factors
If a dry reductive reaction is used to recover lithium from waste cathode, then environmental pollution is reduced, but precise control of reaction equipment and conditions is required to increase lithium recovery ratio
Solution Approach 1:
The patent establishes specific parameter ranges for the dry reductive reaction: temperature (400-600°C), hydrogen concentration (10-40 vol%), and reduction degree (0.24-1.6). These controlled parameters enable high lithium recovery ratio (81.1-97.5%) while maintaining environmental friendliness, balancing process complexity with effectiveness
4Productivity
If the reduction degree of transition metal is not precisely controlled, then the lithium recovery ratio decreases, but precise control increases process complexity
Solution Approach 1:
The patent uses XRD analysis to measure the reduction degree of transition metals and provides feedback control to adjust the reductive reaction conditions. By monitoring the phase fractions of MeO, lithium-transition metal oxide, and Me phases, the process maintains optimal reduction degree (0.24-1.6) to maximize lithium recovery ratio
Solution Approach 2:
The patent defines precise parameter ranges for controlling the reduction process: temperature (400-600°C), hydrogen concentration (10-40 vol%), and reduction degree (0.24-1.6). These controlled parameters directly influence lithium recovery efficiency while managing process complexity through established guidelines
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 achieves high-purity and high-yield recovery of lithium and transition metals without environmental harm, reducing the need for wet processes and minimizing by-products.
Implementation Method 1
The cathode active material mixture is reacted with a reductive reaction gas to form a preliminary precursor mixture having a reduction degree of transition metal
Data Source
AI summary
In a method of recovering an active metal of a lithium secondary battery, a cathode active material mixture is prepared from a waste cathode of a lithium secondary. The cathode active material mixture is reacted with a reductive reaction gas to form a preliminary precursor mixture having a reduction degree of transition metal defined by Equation 1 in a range from 0.24 to 1.6. A lithium precursor is recovered from the preliminary precursor mixture. A lithium recovery ration is improved by adjusting the reduction degree of transition metal.