Recycled Cathode Active Material With LiF Surface and No-Wash Recovery
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Solution Overview
Problem
Current methods for recycling positive electrode active materials from waste lithium secondary batteries are inefficient, often resulting in degraded battery characteristics, environmental pollution, and high costs due to the use of acids and organic solvents.
Innovation Solution
A method involving the firing of waste positive electrodes at a predetermined temperature, followed by the addition of a lithium precursor without washing, and subsequent annealing to incorporate crystalline LiF on the surface of the recycled positive electrode active material, while controlling residual lithium levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If acid dissolution method is used to extract rare metals from waste positive electrodes, then rare metals can be recovered, but neutralization and wastewater treatment processes are required which greatly increase process costs
Solution Approach 1:
The patent converts the harmful acid dissolution process into a beneficial direct recycling process. Instead of using acids to dissolve and extract metals (which creates waste requiring neutralization), the invention directly fires the waste positive electrode to recover the active material, transforming a harmful process into an environmentally friendly one that eliminates wastewater treatment needs
Solution Approach 2:
The patent extracts and recycles the positive electrode active material directly from waste positive electrodes through firing, removing it from the waste stream and transforming it into reusable material without requiring acid dissolution and neutralization processes
2Manufacturing precision
If washing process is performed after firing to remove residual lithium, then product purity is improved, but productivity and economic feasibility are reduced
Solution Approach 1:
The patent applies self-service by using the firing process itself to control residual lithium levels. The firing conditions (temperature, atmosphere, time) are optimized to directly achieve the desired residual lithium content without requiring subsequent washing steps, making the process self-sufficient and eliminating additional processing stages
Solution Approach 2:
The patent performs preliminary action by controlling the firing process parameters in advance to achieve the desired residual lithium content before any washing could occur. The firing step is designed to produce the target product specifications directly, preventing the need for corrective washing operations
3Quantity of substance
If organic solvent is used in the recycling process, then extraction efficiency is improved, but the risk of toxic gas generation or explosion increases
Solution Approach 1:
The patent eliminates the use of organic solvents entirely by using direct firing of the waste positive electrode. This converts a process that would require hazardous chemical extraction into a thermal processing method that recovers the active material directly, transforming a high-risk process into a safe one
Solution Approach 2:
The patent replaces the chemical extraction system (using organic solvents) with a thermal processing system (firing). This substitution eliminates the need for solvent handling, extraction, and disposal operations, removing the associated risks of toxic gas generation and explosion
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 approach results in a recycled positive electrode active material with excellent initial discharge capacity, rate performance, capacity characteristics, and resistance characteristics, while also ensuring eco-friendliness, reducing process costs, and improving economic feasibility and productivity by omitting the washing process.
Implementation Method 1
heat-treating a waste positive electrode having a positive electrode active material layer to thermally decompose a binder and a conductive material in the positive electrode active material layer
Implementation Method 2
adding a lithium precursor immediately after the firing without a washing process, and performing annealing so that predetermined crystalline LiF is contained on the surface
Data Source
AI summary
The present disclosure relates to a recycled positive electrode active material, a method of producing the recycled positive electrode active material, and a secondary battery including the same. The recycled positive electrode active material, including: 60 mol % or more of Ni; and crystalline LiF, or 0.24% by weight or less of residual Li2CO3, where the recycled positive electrode active material is one or more selected from the group consisting of a lithium nickel oxide (LNO)-based positive electrode active material, a nickel·cobalt·manganese (NCM)-based positive electrode active material, a nickel·cobalt·aluminum (NCA)-based positive electrode active material, and a nickel·cobalt·manganese·aluminum (NCMA)-based positive electrode active material.