Lithium Cobalt Oxide Cathode with Dual-Layer Silicate Coating
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Solution Overview
Problem
Current cathode active materials for lithium secondary batteries face limitations in high-temperature stability, manufacturing costs, and cycle characteristics, particularly with lithium cobalt oxide having low structural stability and lithium manganese oxide exhibiting low electrical conductivity and rapid electrode degradation.
Innovation Solution
A cathode active material is developed with a lithium-containing transition metal oxide coated uniformly with two or more metal composite oxide layers, formed through a method involving a metal glycolate solution preparation process, including a two-step heating process, mixing, drying, and heat treatment, to enhance conductivity and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If lithium cobalt oxide is used as cathode active material, then charge and discharge efficiency is improved, but structural stability deteriorates and manufacturing cost increases
Solution Approach 1:
The patent applies composite materials by coating lithium cobalt oxide particles with a dual-layer structure consisting of Li2SiO3 inner layer and Li2SiO2 outer layer. This composite structure combines the high charge/discharge efficiency of LiCoO2 with the structural stability and safety benefits of lithium silicate coatings, resolving the contradiction between efficiency and stability.
Solution Approach 2:
The patent implements local quality by creating different coating layers with specific functions: the Li2SiO3 inner layer provides structural support and stability, while the Li2SiO2 outer layer enhances safety and prevents degradation. This localized functional differentiation allows the material to maintain high efficiency while improving overall stability.
2Ease of manufacture
If lithium manganese oxide is used as cathode active material, then manufacturing cost is reduced, but electrical conductivity and cycle characteristics deteriorate
Solution Approach 1:
The patent uses composite materials by forming a dual-layer lithium silicate coating on lithium manganese oxide particles. The Li2SiO3 inner layer and Li2SiO2 outer layer work together to improve electrical conductivity and enhance cycle characteristics, allowing the use of cost-effective lithium manganese oxide while achieving reliable performance.
Solution Approach 2:
The patent applies parameter changes by controlling the coating thickness (0.1-10 μm total) and composition ratios of the dual-layer structure. By optimizing these parameters, the material achieves improved conductivity and cycle life while maintaining low manufacturing costs associated with lithium manganese oxide.
3Quantity of substance
If lithium-containing nickel oxide is used as cathode active material, then discharge capacity is improved, but cycle characteristics deteriorate
Solution Approach 1:
The patent applies composite materials by coating lithium-containing nickel oxide with a dual-layer lithium silicate structure (Li2SiO3 inner layer, Li2SiO2 outer layer). This composite coating protects the high-capacity nickel oxide core, improving cycle characteristics while preserving the high discharge capacity of the underlying material.
4Power
If high temperature operation is performed, then power output is improved, but electrode degradation accelerates
Solution Approach 1:
The patent implements local quality by creating a protective coating layer with specific thermal stability properties on the surface of the cathode particles. This localized protective structure allows high power output during operation while preventing thermal degradation and maintaining electrode stability at elevated temperatures.
Solution Approach 2:
The patent applies beforehand cushioning by pre-coating the cathode particles with thermally stable lithium silicate layers before operation. This protective layer acts as a buffer that prevents direct thermal exposure and chemical degradation during high-temperature operation, allowing sustained power output without accelerated 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 solution improves the cycle characteristics and thermal stability of lithium secondary batteries by ensuring a uniform coating of metal composite oxides, reducing the adverse effects of anions and promoting efficient charge and discharge processes.
Implementation Method 1
a first step of preparing a metal glycolate solution by performing two-steps heating process
Implementation Method 2
a fourth step of performing a heat treatment on the dried mixture
Data Source
AI summary
The present invention relates to a cathode active material including a lithium-containing transition metal oxide and two or more metal composite oxide layers selected from the group consisting of Chemical Formulae 1 to 3 which are coated on the surface of the lithium-containing transition metal oxide, a method of manufacturing the same, and a cathode for a secondary battery including the cathode active material,M(C2H5O2)n [Chemical Formula 1]M(C6H(8-n)O7) [Chemical Formula 2]M(C6H(8-n)O7)(C2H5O2) [Chemical Formula 3](where M, as a metal desorbed from a metal precursor, represents at least one metal selected from the group consisting of Mg, Ca, Sr, Ba, Y, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ir, Ni, Zn, Al, Ga, In, Si, Ge, Sn, La, and Ce, and n is an integer between 1 and 4).