Li-Ion Battery Recycling pH Control Without Sodium Separation
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Solution Overview
Problem
The existing methods for recovering lithium from lithium ion secondary batteries require an operation to separate sodium, which reduces efficiency and generates wastewater.
Innovation Solution
A method that includes crushing and sorting the battery, leaching with acid, pH adjustment using lithium hydroxide, metal recovery, and lithium hydroxide recovery, where lithium hydroxide is reused as a pH adjuster, eliminating the need for sodium separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If sodium hydroxide or sodium carbonate is used as a pH adjuster for leachate, then the pH adjustment is easy to perform and the materials are odorless, but a subsequent sodium separation step is required to recover lithium at high purity, which reduces work efficiency and generates wastewater
Solution Approach 1:
Lithium hydroxide recovered from the lithium-containing liquid is reused as the pH adjuster in subsequent processing steps. This self-service approach eliminates the need for external sodium-based alkalis, avoiding sodium contamination and the associated separation steps, thereby improving work efficiency while maintaining ease of operation
Solution Approach 2:
Instead of discarding lithium hydroxide as a byproduct, the invention recovers it from the lithium-containing liquid and reuses it as a pH adjuster. This recovery approach eliminates sodium separation steps and wastewater generation, resolving the contradiction between ease of operation and productivity
2Ease of operation
If sodium hydroxide or sodium carbonate is used as a pH adjuster, then the pH adjustment is simple, but lithium recovery requires additional sodium removal steps and generates wastewater, increasing processing complexity
Solution Approach 1:
The recovered lithium hydroxide serves the dual purpose of being both a recovery product and a pH adjuster for subsequent batches. This self-service system simplifies the overall process by eliminating sodium separation equipment and wastewater treatment steps, reducing process complexity while maintaining operational simplicity
Solution Approach 2:
The invention changes the chemical parameter of the pH adjuster from sodium-based (NaOH, Na2CO3) to lithium-based (LiOH). This parameter change eliminates sodium contamination issues and the associated separation complexity, while LiOH maintains the same ease of pH adjustment properties
3Ease of operation
If conventional pH adjusters like sodium hydroxide are used, then the initial pH adjustment is straightforward, but the need for sodium separation and wastewater treatment increases chemical solution costs
Solution Approach 1:
The invention recovers lithium hydroxide from the lithium-containing liquid that would otherwise be discarded or require expensive treatment. This recovered LiOH is reused as pH adjuster, eliminating the need to continuously purchase fresh alkali and reducing chemical solution costs while maintaining ease of operation
Solution Approach 2:
The system generates its own pH adjuster (lithium hydroxide) from the processing of lithium-containing liquid, making it self-sufficient. This eliminates external chemical purchases and associated costs, while the recovered LiOH maintains the same operational ease as conventional pH adjusters
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 enables efficient recovery of lithium at high purity without the need for sodium separation, improving work efficiency, reducing chemical solution costs, and minimizing wastewater generation.
Implementation Method 1
a pH adjustment step of adding lithium hydroxide to the leachate to adjust a pH
Implementation Method 2
the lithium-containing liquid may be separated into a solution containing lithium hydroxide and a solution containing an acid to be recovered by using an electrodialysis method
Data Source
AI summary
A method for processing a lithium ion secondary battery includes: a crushing and sorting step (S02) of crushing and classifying a lithium ion secondary battery to obtain an electrode material containing at least lithium; a leaching step (S03) of immersing the electrode material in an acid to obtain a leachate; a pH adjustment step (S04) of adding lithium hydroxide to the leachate to adjust a pH; a metal recovery step (S05) of recovering a metal other than lithium in the leachate to obtain a lithium-containing liquid; and a lithium hydroxide recovery step (S06) of recovering lithium in the lithium-containing liquid as lithium hydroxide, in which the lithium hydroxide recovered in the lithium hydroxide recovery step (S06) is used in the pH adjustment step (S04).