LiCoO2 Cathode Coating and Doping for High-Voltage Stability
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Solution Overview
Problem
Lithium cobalt oxide-based positive electrode materials for secondary batteries face limitations in structural stability at high voltages, leading to reduced cycle characteristics and potential fire risks due to unstable crystal structures and reactions with electrolyte solutions, and excessive metal doping or coating reduces energy capacity.
Innovation Solution
A positive electrode active material with a lithium cobalt oxide substrate, a coating layer containing element A (such as aluminum, titanium, or magnesium) and a dopant element B, where the molar ratio of element A to element B in the coating layer is greater than 1:1 to 10:1, providing enhanced structural and surface stability by preferential oxidation over cobalt under high voltage conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high voltage is applied to LiCoO2 to increase capacity, then energy density is improved, but structural stability deteriorates leading to reduced cycle life and fire risk
Solution Approach 1:
The patent applies composite materials by combining LiCoO2 with metal oxide coatings (such as Al2O3, TiO2, MgO, ZrO2) and doping elements (such as Al, Ti, Mg, Zr) to create a composite structure. This composite approach maintains the high energy density of LiCoO2 while the coating and doping components provide structural stability at high voltages, preventing crystal structure collapse and reducing fire risk.
Solution Approach 2:
The patent changes physical and chemical parameters by controlling the doping concentration (0.01-0.1 mol ratio) and coating thickness to optimize performance. By adjusting these parameters, the material achieves both high voltage operation capability and structural stability, resolving the contradiction between energy density and reliability.
2Reliability
If metal coating or doping is performed on LiCoO2 to secure high-voltage stability, then structural stability is improved, but energy capacity is significantly reduced
Solution Approach 1:
The patent applies local quality by concentrating the stabilizing elements (metal oxides and dopants) at specific locations - the surface coating and crystal lattice substitution sites - rather than uniformly distributing them throughout the bulk material. This localized approach provides high-voltage stability where needed while preserving the energy capacity of the bulk LiCoO2 structure.
Solution Approach 2:
The patent optimizes the concentration parameters of doping elements and coating thickness to achieve the minimum effective amount needed for stability. By controlling doping at 0.01-0.1 mol ratio and using thin coating layers, the patent maintains high energy capacity while sufficient structural stability is achieved.
3Reliability
If excessive metal doping or coating is performed to secure high-voltage stability, then structural stability is improved, but battery performance is significantly reduced due to property variation
Solution Approach 1:
The patent systematically optimizes multiple parameters including doping concentration (0.01-0.1 mol), coating thickness, and metal oxide composition ratios. By finding the optimal parameter range, the patent achieves high-voltage stability while maintaining excellent battery performance, avoiding the degradation that occurs with excessive doping or coating.
Solution Approach 2:
The patent employs feedback by characterizing the material properties (cycle life, capacity retention, structural stability) at different doping and coating levels, then using this information to optimize the formulation. This iterative optimization ensures the best balance between stability and performance.
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 solution maintains structural stability and prevents reduction in cycle characteristics of secondary batteries at high voltages, ensuring optimal performance and reducing the risk of surface instability and fire hazards.
Implementation Method 1
a dopant containing element B which is substituted in the lithium cobalt oxide
Implementation Method 2
preferential oxidation over cobalt under high voltage conditions
Implementation Method 3
a coating layer including element A and formed on a surface of particles of the lithium cobalt oxide
Data Source
AI summary
Provided are positive electrode active material particles for a secondary battery which include a lithium cobalt oxide, a coating layer including element A and formed on a surface of particles of the lithium cobalt oxide, and a dopant containing element B which is substituted in the lithium cobalt oxide, wherein the element A and the element B are each independently at least one selected from the group consisting of aluminum (Al), titanium (Ti), magnesium (Mg), zirconium (Zr), barium (Ba), calcium (Ca), tantalum (Ta), niobium (Nb), and molybdenum (Mo), and a molar ratio of the element A in the coating layer:the element B of the dopant is greater than 1:1 to 10:1.