Graphene-Coated Positive Electrode Material With Controlled Sintering
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Solution Overview
Problem
The conventional preparation process for graphene composite positive electrode materials is complex and costly, and high-temperature baking leads to particle size growth and impurity formation, degrading electrochemical performance.
Innovation Solution
A one-step method is used to prepare a polyanion-type positive electrode material with a carbon material containing graphene, where the sintering temperature is controlled between 750° C.-840° C., forming a carbon coating layer on the polyanion-type positive electrode material and dispersing graphene between its particles, using a carbon graphitization catalyst to enhance conductivity and density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional high-temperature baking is used to prepare graphene composite positive electrode material, then graphene can be formed, but particle size grows significantly and impurity phases form, leading to degradation in electrochemical performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the sintering temperature within a narrow range of 750-840°C and adjusting the carbon-to-catalyst ratio. This optimization prevents excessive particle growth and impurity formation while ensuring adequate graphene formation, thereby resolving the contradiction between achieving graphene composite formation and maintaining particle size control and electrochemical performance.
2Reliability
If conventional two-step preparation method is used (first prepare graphene, then mix with positive electrode material precursor), then graphene composite can be formed, but the process becomes complex and costly
Solution Approach 1:
The patent merges the graphene formation process with the positive electrode material synthesis into a single one-step sintering process. By incorporating carbon sources and catalysts directly into the precursor mixture and sintering them together at 750-840°C, the method simultaneously produces the polyanion-type positive electrode material and the graphene composite, eliminating the need for separate graphene preparation and mixing steps, thus simplifying the overall process while ensuring reliable graphene composite formation.
3Volume of stationary object
If higher sintering temperature is used to improve material density, then particle size grows larger, but if lower temperature is used, then density is insufficient
Solution Approach 1:
The patent optimizes the sintering temperature parameter to a specific range of 750-840°C, which is lower than conventional high-temperature baking but sufficient to achieve adequate powder compacted density (≥2.42 g/cm³). This controlled temperature parameter change prevents excessive particle growth while ensuring proper densification, resolving the contradiction between achieving high density and controlling particle size.
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 simplifies the preparation process, increases the powder compacted density of the composite positive electrode material to greater than 2.42 g/cm³, improving energy density and conductivity while reducing costs.
Implementation Method 1
using a carbon graphitization catalyst to enhance conductivity and density
Implementation Method 2
sintering the mixed dry substance to obtain the composite positive electrode material, a sintering temperature being 750° C.-840° C.
Data Source
AI summary
This application provides a composite positive electrode material and preparation method thereof, a positive electrode plate, a secondary battery, and an electric apparatus. The preparation method includes: mixing a lithium source, a phosphorus source, an iron source, a carbon source, and a carbon graphitization catalyst in a predetermined ratio with a solvent to form a mixed slurry; grinding and drying the mixed slurry to obtain a mixed dry substance; and sintering the mixed dry substance to obtain the composite positive electrode material, a sintering temperature being 750° C.-840° C.