Molten Salt Relithiation of Nickel-Based Cathodes for Ni-Rich Upcycling
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Solution Overview
Problem
Current recycling technologies for lithium-based battery cathode materials, particularly nickel-based cathodes, face challenges in efficiently and cost-effectively recycling and upcycling spent materials to next-generation cathodes due to harsh conditions required, such as high temperatures, and the destruction of the cathode particle structure.
Innovation Solution
A method involving a molten salt system with lithium and nickel cations and chloride or bromide anions is used to relithiate and upcycle spent nickel-based cathode materials at relatively mild temperatures (700° C. to 900° C.), allowing for the production of Ni-rich NMC cathodes with a pure α-NaFeO2 type layered structure and excellent electrochemical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional high-temperature processes (above 600°C) are used for upcycling NMC 111 to NMC 622, then the α-NaFeO2 type layered structure can be constructed, but the process requires harsh conditions and significant energy input
Solution Approach 1:
The patent changes the chemical composition parameters of the molten salt system by incorporating lithium chloride, nickel chloride, and aluminum chloride in specific ratios. This compositional modification allows the molten salt to facilitate lattice reconstruction at lower temperatures (700-900°C) compared to conventional processes requiring temperatures above 600°C, thereby resolving the contradiction between structural integrity and processing temperature
Solution Approach 2:
The molten salt system acts as an intermediary medium that enables lithium and nickel incorporation into the cathode material structure. The molten salt facilitates mass transport and chemical reactions at reduced temperatures, serving as a mediator that allows structural reconstruction without requiring harsh high-temperature conditions, thus resolving the temperature-structure contradiction
2Quantity of substance
If upcycling process inserts Li, Ni, and O to transform NMC 111 to NMC 622, then the nickel content and capacity increase, but the weight of NMC almost doubles requiring high temperature above 600°C
Solution Approach 1:
The patent modifies the stoichiometric parameters of the molten salt system containing lithium chloride, nickel chloride, and aluminum chloride. By optimizing the concentration ratios of these salts, the process enables efficient nickel incorporation and lattice reconstruction at lower temperatures (700-900°C), resolving the contradiction between increasing nickel content and reducing processing temperature
Solution Approach 2:
The molten salt system serves as an intermediary that facilitates the insertion of lithium and nickel atoms into the cathode structure during upcycling. This intermediary mechanism enables controlled compositional changes and structural reconstruction at reduced temperatures, allowing nickel content increase without requiring temperatures above 600°C
3Quantity of substance
If conventional recycling technologies use pyrometallurgy or hydrometallurgy, then valuable metals can be returned to production chain, but the complete destruction of cathode particles reduces the highly added value of the compound structure
Solution Approach 1:
The molten salt system acts as a gentle intermediary that enables metal recovery while preserving cathode structure. Unlike pyrometallurgy or hydrometallurgy that completely destroy particles, the molten salt facilitates controlled dissolution and reprecipitation, allowing metal extraction and recovery while maintaining the layered cathode structure intact, thus resolving the contradiction between metal recovery and structure preservation
Solution Approach 2:
The patent optimizes the chemical composition parameters of the molten salt system to enable selective dissolution of metals while preserving the cathode framework. By controlling the chemical environment and temperature parameters, the process achieves effective metal recovery without complete structural destruction, resolving the contradiction between quantity recovery and composition stability
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 the efficient recycling and upcycling of spent NMC 111 to NMC 622 or NMC 811, restoring lithium content and achieving electrochemical performance comparable to pristine NMC 622, while being environmentally friendly and scalable.
Implementation Method 1
heating the initial mixture to a temperature of 700° C. to 900° C. for at least 1 hour to promote lithium cation incorporation from the molten salt into the spent cathode material
Data Source
AI summary
A method for processing spent nickel-based cathode material useful in lithium-based batteries, the method comprising: (i) producing an initial mixture containing the spent nickel-based cathode material and a molten salt system comprising cations and anions, wherein the cations comprise lithium cations; (ii) heating the initial mixture to a temperature of 700° C. to 900° C. for at least 1 hour to produce a relithiated cathode material; and (iii) washing the relithiated cathode material to remove any residual salt. In a further method, the cations comprise nickel and lithium cations and the anions comprise chloride or bromide anion in combination with at least one of nitrate, sulfate, and carbonate anions in further combination with hydroxide anion, wherein the method results in upcycling of the nickel-based cathode material to produce a version of said relithiated cathode material having a greater nickel content.