Spent Graphite Solvent Washing for Selective SEI Removal
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Solution Overview
Problem
The recycling of graphite from spent lithium-ion batteries has been overlooked due to its perceived low value, despite its potential for valuable passivating properties, leading to challenges in responsible disposal and resource strain.
Innovation Solution
A method involving the use of tailored solvent washes, particularly polar protic solvents like water, methanol, and ethanol, to selectively remove adverse SEI components from end-of-life graphite, retaining beneficial passivating properties and enhancing its value for reuse in lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite is recovered from spent LIBs without treatment, then recovery process is simple, but graphite has excessive SEI that degrades electrochemical performance
Solution Approach 1:
The patent applies extraction by removing the excessive SEI layer from recycled graphite through solvent treatment. The solvent selectively dissolves and removes the harmful SEI components while leaving the beneficial passivating properties intact, thereby improving electrochemical performance without requiring complete SEI removal or graphite synthesis
Solution Approach 2:
The patent changes the chemical environment parameters by introducing specific solvents that alter the SEI layer composition. By controlling solvent type, temperature, and treatment duration, the process optimizes SEI removal while preserving graphite integrity, resolving the contradiction between performance improvement and processing complexity
2Reliability
If graphite is treated with solvent to remove SEI, then electrochemical performance is improved, but processing time and steps increase
Solution Approach 1:
The patent applies preliminary action by performing solvent treatment on graphite immediately after battery disassembly and before other recycling steps. This early treatment removes excessive SEI upfront, preventing subsequent processing issues and reducing total processing time despite adding an initial treatment step
3Productivity
If graphite is used directly from spent batteries, then resource recovery is efficient, but capacity loss occurs due to SEI
Solution Approach 1:
The patent converts the harmful excessive SEI layer into a beneficial thin passivating layer through selective solvent removal. The process transforms the SEI from a capacity-degrading component into a controlled protective layer, enabling direct reuse of graphite with improved capacity retention while maintaining high resource recovery efficiency
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 value of recycled graphite by reducing lithiation requirements, minimizing cell formation processes, and improving electrochemical performance, making it suitable for reuse as battery-grade material.
Implementation Method 1
the solvent includes a protic solvent... the solvent removed the inorganic species, resulting in the graphite
Implementation Method 2
the agitating includes at least one of sonicating or stirring
Data Source
AI summary
Recognizing the significance of the solid-electrolyte-interface (SEI) formed on the surface of a graphite anode during battery operation, the methods described herein may selectively remove SEI components using specifically-selected solvents. Water, methanol, ethanol, and/or isopropanol may be used as solvents to remove specific SEI components such as lithium fluorophosphates and carbonate derived organics. These methods may recover the electrochemical performance of the recycled EOL graphite to near that of pristine graphite. By harnessing the beneficial aspects of SEI, this present disclosure may pave the way for advancing lithium-ion battery recycling.