Selective Lithium Extraction Using Organic Acid Hydrothermal Leaching
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Solution Overview
Problem
Conventional recycling processes for lithium-ion batteries focus on transition metals rather than lithium, often using high-temperature processes that are energy-intensive and impure, and hydrometallurgical processes that compromise purity, limiting the efficient recovery of high-purity lithium.
Innovation Solution
A low-temperature organic acid-based process using terephthalic acid (TPA) and benzenetetracarboxylic acid (BTCA) under pressure to selectively extract lithium from spent cathode materials, followed by filtration, recrystallization, and sintering to achieve high-purity lithium carbonate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional pyrometallurgical processes are used for battery recycling, then transition metals can be recovered, but energy consumption increases substantially due to high heating requirements
Solution Approach 1:
The patent changes the temperature parameter from high-temperature pyrometallurgical processing to low-temperature hydrothermal processing. The organic acid-based leaching process operates at significantly lower temperatures, reducing energy consumption while maintaining effective lithium recovery from cathode materials.
Solution Approach 2:
The patent replaces the thermal/mechanical pyrometallurgical system with a chemical hydrothermal system. Instead of using high heat to recover metals, the process uses organic acid chemistry in a hydrothermal environment to selectively leach lithium, substituting thermal energy with chemical selectivity.
2Quantity of substance
If conventional hydrometallurgical processes are used for lithium extraction, then lithium can be recovered, but purity is compromised due to transition metal contamination
Solution Approach 1:
The patent introduces organic acids (such as oxalic acid, citric acid, or succinic acid) as intermediary leaching agents that selectively complex with lithium ions. These organic acid intermediaries enable selective lithium extraction while leaving transition metals behind, achieving both recovery and purity simultaneously through selective complexation chemistry.
Solution Approach 2:
The patent segments the recovery process into distinct selective leaching and purification stages. The organic acid-based hydrothermal process selectively extracts lithium in the first stage, and subsequent filtration and crystallization steps further separate lithium from any remaining transition metal contaminants, achieving high purity through process segmentation.
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 process achieves lithium recovery rates exceeding 99.8% with minimal transition metal contamination, establishing a sustainable and efficient method for lithium extraction suitable for recycled lithium-ion batteries.
Implementation Method 1
combining terephthalic acid (TPA) or other organic acid with the recycling stream in a pressure reactor
Implementation Method 2
The pressure reactor is pressurized to a reactor pressure in a range between 1500 kPa-3000 kPa
Implementation Method 3
the resultant solution from the pressure reactor filtered to yield a lithium salt solution
Implementation Method 4
Addition of a crystallizing agent to the lithium salt solution for recrystallizing
Implementation Method 5
Sintering of the crystallized lithium salt recovers a powder including lithium carbonate
Data Source
AI summary
Lithium recycling from expended Li-Ion batteries occurs thought selective recovery of lithium charge materials from a recycling stream including transition metals used for the charge material. Li recovery performed using an organic acid-based approach including terephthalic acid (TPA), benzenetetracarboxylic acid (BTCA), and other organic acids results in highly selective lithium extraction, achieving minimal transition metal contamination in the extracted solution. A recycling stream including cathode materials from spent/end-of-life Li-ion batteries provides a source for recycled Li, as well as other cathode material metals. Combining the organic acid in a hydrothermal reactor followed by filtration separates transition metal oxides from a lithium salt solution. The lithium salt may be recrystallized by acetone and dried to a powder consistency. Lithium carbonate is then recovered by sintering, and further filtered for recovering battery grade recycled Li.