Cathode Metal Recovery via Two-Step Leaching for High-Purity Separation

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Solution Overview

Problem

The high cost and environmental impact of manufacturing lithium secondary batteries due to the use of expensive transition metals, particularly nickel, cobalt, and manganese, necessitate an efficient and high-purity recovery method for these metals from waste cathode materials.

Innovation Solution

A two-step leaching process using specific amounts of reducing agents in acidic solutions to separate cobalt and nickel in a first leachate and manganese in a second leachate, optimizing the recovery efficiency and purity of each metal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a single-step leaching process is used to recover transition metals from cathode material, then the process is simple and fast, but the purity and recovery efficiency of individual metals is low

Engineering Contradiction:

Improverecovery efficiencyVSAvoidprocess complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent divides the leaching process into two sequential steps: first leaching with a reducing agent to selectively dissolve cobalt and nickel, then second leaching with acid to dissolve manganese. This segmentation allows each step to target specific metals, achieving high purity recovery of individual metals while maintaining reasonable process complexity.

Inventive Principle:

Principle #1Segmentation

2Quantity of substance

If excessive reducing agent is used in the first leaching step, then more cobalt and nickel are extracted, but manganese contamination increases and recovery efficiency decreases

Engineering Contradiction:

Improvecobalt and nickel extractionVSAvoidpurity of leachate

Core Design Contradiction:

Quantity of substanceVSManufacturing precision

Solution Approach 1:

The patent optimizes the reducing agent amount to 0.5-2 equivalents, which is a specific parameter range that maximizes cobalt and nickel extraction while minimizing manganese dissolution. This precise parameter control ensures high purity of the first leachate, eliminating the need for manganese removal steps.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If high purity recovery of transition metals is achieved, then production costs decrease and environmental impact is reduced, but the recovery process becomes more complex and time-consuming

Engineering Contradiction:

Improvepurity of recovered metalsVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent extracts cobalt and nickel in the first leaching step, then separately extracts manganese in the second step. This extraction sequence achieves high purity recovery of each metal without requiring additional purification steps, as the selective leaching inherently produces clean leachates ready for direct metal recovery.

Inventive Principle:

Principle #2Taking out (Extraction)

4Loss of substance

If traditional single-step leaching is used, then the process is cost-effective, but valuable transition metals are lost and purity is low requiring additional processing

Engineering Contradiction:

Improvemetal lossVSAvoidmanufacturing simplicity

Core Design Contradiction:

Loss of substanceVSEase of manufacture

Solution Approach 1:

The patent implements continuous useful action by sequentially performing two leaching steps that together recover all valuable transition metals (cobalt, nickel, and manganese) with high efficiency. The first leaching recovers cobalt and nickel, while the second recovers manganese, ensuring minimal metal loss without requiring complex additional processing steps.

Inventive Principle:

Principle #20Continuity of useful action

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 increases the recovery efficiency and purity of transition metals, particularly cobalt and manganese, by selectively extracting them in separate leachates, thereby reducing waste and lowering production costs.

Implementation Method 1

treating the cathode active material with a first acidic solution containing a reducing agent in an amount smaller than an amount corresponding to a reaction equivalent of the cathode active material

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 2

treating the remaining cathode active material with a second acidic solution containing a reducing agent

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 3

producing a first leachate by treating the cathode active material with a first acidic solution

Methodology Applied

Scientific EffectLeaching: Solvation

Data Source

PatentUS12451533B2Method for reducing waste by recovering transition metals from lithium secondary battery

Publication Date: 2025.10.21 SK INNOVATION CO LTD

AI summary

A method for reducing waste by recovering transition metal of a lithium secondary battery of the present invention includes preparing a cathode active material from a cathode of the lithium secondary battery, producing a first leachate by treating the cathode active material with a first acidic solution containing a reducing agent in an amount smaller than an amount corresponding to a reaction equivalent of the cathode active material, and producing a second leachate by treating the remaining cathode active material, which excludes a fraction contained in the first leachate, with a second acidic solution containing a reducing agent. Accordingly, extraction rate of manganese and purity of cobalt may be improved.