Lithium Transition Metal Oxide Surface Coating for Residual Alkali Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Residual alkali on the surface of lithium transition metal oxide cathode materials in lithium-ion batteries leads to instability, reduced cycle performance, and safety hazards due to reactions with electrolytic solutions, and existing coating methods either fail to adequately address these issues or compromise electronic conductivity and capacity.
Innovation Solution
A method involving a liquid-phase surface modification process using lithium-containing phosphate and acidic or alkaline solutions of Y3+, Al3+, TiO2+, or ZrO2+ salts to form a uniform coating layer, reducing residual alkali content and enhancing structural stability and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water washing is used to remove residual lithium, then residual alkali content is reduced, but drying time increases and lattice lithium may be lost leading to structure deterioration
Solution Approach 1:
The patent extracts and removes residual alkali from the cathode material surface through water washing, then quickly removes the washing water through centrifugal separation. This extraction approach effectively reduces residual alkali content while minimizing the time the material is exposed to water, thereby preventing excessive drying time and lattice lithium loss.
Solution Approach 2:
The patent introduces an organic solvent as an intermediary substance to replace water for the final drying step. The organic solvent has lower surface tension and evaporates more quickly than water, enabling rapid removal of remaining moisture without requiring prolonged heating that would cause lattice lithium loss and structure deterioration.
2Object-affected harmful factors
If water washing is used to remove residual lithium, then residual alkali content is reduced, but lattice lithium may be lost leading to structure deterioration and performance degradation
Solution Approach 1:
The patent rushes through the water removal process by immediately following water washing with centrifugal separation. This rapid transition minimizes the contact time between water and the cathode material, preventing water from penetrating deep into the lattice structure and causing lithium loss. The quick processing ensures residual alkali removal while protecting lattice stability.
Solution Approach 2:
The patent uses organic solvent as an intermediary replacement for water in the drying stage. The organic solvent's different chemical properties allow it to remove surface moisture without the same harmful effects as water, thus protecting lattice lithium from dissolution while completing the drying process.
3Object-affected harmful factors
If coating materials are applied to reduce residual alkali, then gas generation is reduced, but electronic conductivity may be compromised
Solution Approach 1:
The patent takes out and removes residual alkali directly through water washing and centrifugal separation, rather than attempting to cover it with coating materials. This extraction approach eliminates the source of gas generation without introducing any coating layer that would block electronic conductivity pathways.
Solution Approach 2:
The patent uses organic solvent as an intermediary drying agent that does not leave residual deposits on the material surface. Unlike some coating materials that may form insulating layers, the organic solvent evaporates completely, maintaining the surface's electronic conductivity while still achieving the goal of reducing residual alkali and preventing gas generation.
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 method effectively reduces residual alkali, stabilizes the surface structure, improves cycle performance, and increases energy density while maintaining electronic conductivity, thereby enhancing the safety and efficiency of lithium-ion batteries.
Implementation Method 1
A method involving a liquid-phase surface modification process using lithium-containing phosphate and acidic or alkaline solutions of Y3+, Al3+, TiO2+, or ZrO2+ salts to form a uniform coating layer
Implementation Method 2
The method effectively reduces residual alkali, stabilizes the surface structure
Data Source
AI summary
Disclosed in the present invention is a method for surface modification of a lithium transition metal oxide positive electrode material, including: adding a first additive, a second additive, and a lithium transition metal oxide to water to obtain a first slurry, the first additive being a lithium-containing phosphate, and the second additive being an acidic solution of a Y3+ or Al3+ salt; dropwise adding a third additive to the firs slurry to obtain a second slurry, the third additive being an acidic solution of a TiO2+ or ZrO2+ salt; dropwise adding a fourth additive to the second slurry to obtain a third slurry, the fourth additive being an acidic solution of a AlO2− salt; and performing centrifugation and drying on the third slurry to obtain an intermediate product, mixing the intermediate product with a large-particle positive electrode material, and performing sintering to obtain a surface-modified lithium transition metal oxide material.