Recycled Cathode Active Material Calcination for Crystal Stability
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Solution Overview
Problem
Recycled cathode active materials from lithium secondary batteries exhibit uneven particle size distribution, unstable crystal structure, and reduced thermal stability, leading to deteriorated battery performance, particularly in high-voltage environments.
Innovation Solution
A method involving desorption and recovery of cathode active materials from waste cathodes, application of a coating agent, and controlled calcination conditions to restore a structure similar to fresh cathode active materials, with a reduced olivine structure compound in the carbon coating layer, using a carbon coating layer and olivine structure compound that satisfies specific carbon content and Raman peak intensity ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If cathode active material is recycled from waste cathode, then resource recovery and cost reduction are achieved, but particle size distribution becomes uneven and crystal structure stability deteriorates
Solution Approach 1:
The patent applies parameter changes by controlling calcination temperature (700-900°C) and atmosphere (nitrogen or argon) to restore the crystal structure of recycled cathode active material. By adjusting these physical and chemical parameters during heat treatment, the olivine structure is stabilized while maintaining resource recovery efficiency.
Solution Approach 2:
The patent uses composite materials by coating the recycled cathode active material with carbon-containing substances (such as sucrose, glucose, or starch) before calcination. This composite approach creates a protective carbon layer that prevents crystal structure degradation and improves particle size distribution uniformity during the recycling process.
2Loss of time
If recycled cathode active material is used directly, then manufacturing time is reduced, but thermal stability and battery lifespan deteriorate
Solution Approach 1:
The patent applies preliminary action by performing calcination treatment on the recycled cathode active material before it is used in battery manufacturing. This pre-treatment step restores thermal stability and crystal structure, ensuring long-term reliability without significantly extending the overall manufacturing timeline.
3Ease of manufacture
If conventional recycling method is used, then processing simplicity is maintained, but olivine structure compound mixes with carbon coating layer reducing battery performance
Solution Approach 1:
The patent uses parameter changes by optimizing calcination temperature (700-900°C) and holding time (5-24 hours) to control the separation of olivine structure compound from the carbon coating layer. These parameter adjustments maintain process simplicity while achieving high coating layer purity and preventing performance degradation.
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 recycled cathode active materials demonstrate improved lifespan characteristics, increased thermal stability, and reduced gas generation during charging and discharging, providing battery performance comparable to fresh materials.
Implementation Method 1
coating a surface of the desorbed cathode active material with a coating agent, performing preliminary milling, and performing spray drying
Implementation Method 2
controlling the calcination conditions of the coating agent-coated cathode active material
Implementation Method 3
Area Ratio LFP corresponds to an intensity of a Raman peak corresponding to the olivine structure compound among intensities of all Raman peaks observed in a Raman spectrum
Data Source
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AI summary
The present invention relates to a cathode active material, a method of recycling a cathode active material, and a secondary battery. According to the present invention, by desorbing and recovering a cathode active material from a waste cathode, applying a coating agent thereto, and controlling the calcination conditions of the coating agent-coated cathode active material, a structure similar to the crystal structure of the fresh cathode active material may be obtained, and the area where an olivine structure compound is mixed within a carbon coating layer on the surface of the cathode active material may be reduced. Accordingly, excellent battery characteristics may be provided.