LiCoPO4 Cathode Conductivity via Molybdenum Coating
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Solution Overview
Problem
Conventional olivine LiCoPO4 cathode materials for lithium-ion batteries suffer from low electrical and ionic conductivity, leading to rapid degradation and limited energy density, and the use of carbon coatings introduces additional mass and potential phase formation issues, while also amorphizing in lithium-free states.
Innovation Solution
A cathode material comprising a substrate with a granular conductive surface layer of a mixture of LiCoPO4 and LiCo2P3O10 phases, coated with molybdenum oxide, which increases conductivity and stability, eliminating the need for carbon and maintaining polycrystallinity at high charge states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional olivine LiCoPO4 is used as cathode material, then high discharge potential (4.8V) and theoretical energy density (816 Wh/kg) are achieved, but electrical conductivity and lithium diffusion are insufficient leading to rapid degradation
Solution Approach 1:
The patent creates a composite cathode material consisting of LiCoPO4 olivine particles embedded in a LiCo2P3O10 matrix. This composite structure combines the high energy density advantage of LiCoPO4 with the superior conductivity and stability of LiCo2P3O10, resolving the contradiction between energy density and operational stability.
Solution Approach 2:
The patent modifies the chemical composition parameters by incorporating LiCo2P3O10 phase into the LiCoPO4 structure. This parameter change (adding a secondary phase) transforms the material properties to achieve both high energy density and improved electrical conductivity with enhanced stability during cycling.
2Reliability
If carbon coating is applied to olivine nanoparticles to improve conductivity, then electrical conductivity increases, but carbon represents 10-20% of total mass reducing battery capacity and causes reducing atmosphere leading to phase formation at grain boundaries
Solution Approach 1:
The patent extracts and eliminates the carbon coating component from the composite structure. By using LiCo2P3O10 as the matrix material instead of carbon, the invention removes the harmful effects of carbon (mass penalty and reducing atmosphere) while maintaining the necessary electrical conductivity function.
Solution Approach 2:
The patent changes the compositional parameter by replacing carbon-based conductive material with LiCo2P3O10 phase. This substitution eliminates the mass penalty associated with carbon coatings while providing inherent conductivity through the olivine structure itself.
3Use of energy by moving object
If conventional olivine LCP is used in completely lithium-free state (5.1V), then high charge state is achieved, but amorphization occurs in the presence of air
Solution Approach 1:
The patent provides beforehand protection by embedding LiCoPO4 particles in a LiCo2P3O10 matrix that acts as a stabilizing environment. This matrix prevents the amorphization that would otherwise occur when LiCoPO4 is in its lithium-free state at 5.1V, allowing high charge states to be achieved while maintaining crystalline structure stability.
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 enhances electrical conductivity, increases energy density by up to 30%, and stabilizes the cathode material at high charge potentials, preventing amorphization, thus improving the performance and longevity of lithium-ion batteries and enabling efficient electrolytic water splitting.
Implementation Method 1
molybdenum coating or doping of the granular surface layer
Implementation Method 2
redox active material with a discharge potential of about 4.8V
Data Source
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AI summary
A cathode for an energy storage device or for an electrolysis device is disclosed. The cathode comprises a substrate (110); a granular surface layer (120) on the substrate (110), wherein the granular surface layer (120) has a mixture of LiCoPO4-LiCo2-P3O10 (LCP-LCPO); and a molybdenum coating (130) or doping of the LCP-LCPO.