Cathode Active Material Residual Lithium Removal
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Solution Overview
Problem
High Ni content cathode active materials for lithium ion secondary batteries form residual lithium, leading to reduced stability due to CO2 generation during charge and discharge, necessitating an improved manufacturing method to minimize residual lithium content.
Innovation Solution
A method involving consecutive washing and surface treatment of lithium transition metal oxides in a Couette-Taylor Reactor, followed by LDH coating and heat treatment, to produce a cathode active material with reduced residual lithium content, using a washing liquid and layered double hydroxide (LDH) in specific ratios and conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high Ni content cathode active material is manufactured, then energy density is improved, but residual lithium forms on the surface leading to reduced stability
Solution Approach 1:
The washing process is performed before the coating process in a sequential manner within the same reactor. The washing liquid removes residual lithium from the surface of the cathode active material particles before they are coated with the protective layer, preventing the formation of unstable compounds during subsequent processing
Solution Approach 2:
A washing liquid is introduced as an intermediary substance to remove residual lithium from the cathode active material surface. The washing liquid acts as a mediator between the high Ni content material and the subsequent coating process, eliminating harmful residues that would otherwise compromise stability
2Manufacturing precision
If washing and coating processes are performed separately, then process control is improved, but manufacturing complexity and time increase
Solution Approach 1:
The washing and coating processes are merged into a single reactor unit, the Couette-Taylor reactor. The reactor is designed to sequentially accommodate both washing liquid introduction and coating material application, combining two separate manufacturing steps into one integrated system, thereby reducing equipment complexity and manufacturing time while maintaining process control
3Ease of manufacture
If residual lithium is not removed, then manufacturing simplicity is maintained, but CO2 generation occurs during charge and discharge reducing battery stability
Solution Approach 1:
The washing process is performed as a preliminary step before the coating and heat treatment processes. By removing residual lithium early in the manufacturing sequence, the subsequent charge and discharge cycles are prevented from generating CO2, eliminating the harmful effect before it can occur during battery operation
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 effectively reduces residual lithium content to less than 750 ppm, enhancing the stability and efficiency of lithium ion secondary batteries by preventing undesirable reactions with the electrolyte and improving charge and discharge performance.
Implementation Method 1
contacting the lithium transition metal oxide with the washing liquid to wash the lithium transition metal oxide
Implementation Method 2
contacting the washed lithium transition metal oxide with the layered double hydroxide to form a coating on a surface of the washed lithium transition metal oxide
Implementation Method 3
heat treating the coated lithium transition metal oxide to form a cathode active material
Data Source
AI summary
A method of manufacturing a cathode active material, according to the inventive concept includes: disposing a lithium transition metal oxide and a washing liquid into a reaction chamber; contacting the lithium transition metal oxide with the washing liquid to wash the lithium transition metal oxide and form a washed lithium transition metal oxide; disposing a layered double hydroxide into the reaction chamber to form a coating of the layered double hydroxide on a surface of the washed lithium transition metal oxide to provide a coated lithium transition metal oxide; and heat treating the coated lithium transition metal oxide to form a cathode active material, wherein the cathode active material comprises a layered double oxide coated lithium transition metal oxide, and wherein the contacting the lithium transition metal oxide with the washing liquid and the forming of the coated lithium transition metal oxide are consecutively performed in a single space.