Thio-Coated Cathode Active Material for Lithium Salt Residue Control
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Solution Overview
Problem
Lithium secondary batteries face challenges with non-uniform chemical structures in lithium metal oxide cathode active materials, leading to reduced capacity and stability due to lithium precipitation and surface damage during charging and discharging, and existing washing methods fail to effectively remove lithium salt impurities.
Innovation Solution
A cathode active material is developed with a lithium metal oxide particle coated with a thio-based compound containing sulfur, such as thioamide, tri-thiocarbonate, or thiosulfate compounds, which forms a protective layer on the surface, enhancing structural and crystalline stability and preventing side reactions with the electrolyte.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If water washing is used to remove lithium salt impurities, then some impurities are removed, but lithium salt impurities remain and surface damages occur
Solution Approach 1:
The patent changes the chemical parameters of the washing solution by using organic solvents (acetonitrile, dimethyl carbonate, ethyl methyl carbonate) instead of water, and controls the lithium salt concentration within 1-100 ppm to achieve effective impurity removal without surface damage
Solution Approach 2:
The patent introduces a coating layer as an intermediary substance between the lithium metal oxide surface and the washing solution. This coating layer protects the surface from direct contact with the washing solution, preventing surface damage while allowing impurity removal through the coating
2Use of energy by moving object
If lithium metal oxide is used as cathode active material, then high operational voltage and energy density are achieved, but non-uniform chemical structure and lithium precipitation occur
Solution Approach 1:
The patent applies local quality improvement by coating only the surface of the lithium metal oxide particles with a protective layer. This coating is applied locally at the particle surfaces where lithium precipitation and chemical non-uniformity occur during charging-discharging cycles, without altering the bulk composition
Solution Approach 2:
The patent creates a composite structure by combining lithium metal oxide with a coating layer formed from compounds containing sulfur, nitrogen, or phosphorus. This composite structure maintains the high energy density of lithium metal oxide while adding surface stability to prevent chemical non-uniformity
3Duration of action of moving object
If lithium metal oxide structure is subjected to repeated charging and discharging, then battery operation is maintained, but structure transformation and damage occur
Solution Approach 1:
The patent applies preliminary action by pre-coating the lithium metal oxide particles before battery assembly. The coating layer is formed in advance to prevent structural transformation and damage during subsequent repeated charging-discharging operations, rather than attempting to repair damage after it occurs
4Ease of manufacture
If conventional washing methods are used, then processing is simple, but lithium salt impurities are not sufficiently removed
Solution Approach 1:
The patent changes the chemical parameters of the washing solution by using specific organic solvents (acetonitrile, dimethyl carbonate, ethyl methyl carbonate) and controlling lithium salt concentration within 1-100 ppm, achieving effective impurity removal while maintaining a relatively simple washing process
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 thio-coating improves the operational stability and electrical properties of lithium secondary batteries by maintaining capacity retention and preventing surface damage, while effectively removing lithium salt impurities and maintaining structural integrity.
Implementation Method 1
a thin-based compound formed on at least portion of a surface of the lithium metal oxide particle
Implementation Method 2
the thio-based compound having a double bond that contains a sulfur atom
Data Source
AI summary
A cathode active material for a lithium secondary battery includes a lithium metal oxide particle and a thio-based compound formed on at least portion of a surface of the lithium metal oxide particle. The thio-based compound has a double bond that contains a sulfur atom. Chemical stability of the lithium metal oxide particle may be improved and surface residues may be reduced by the thio-based compound.