Phosphate Framework Electrode Material with Integrated Carbon Matrix
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Solution Overview
Problem
Phosphate framework materials for rechargeable sodium ion batteries face challenges due to poor electronic and ionic conductivity in their bulk form, which limits their suitability despite having thermal stability and high voltage capabilities.
Innovation Solution
A phosphate framework electrode material with a carbon matrix integrated into Na-transitional metal-Phosphate nanoparticles, synthesized using a method involving surfactants and precursors to enhance electronic conductivity and prevent particle agglomeration, allowing for improved sodium intercalation and electron transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If phosphate framework material is used in bulk form, then thermal stability and high voltage capability are achieved, but electronic and ionic conductivity remains poor
Solution Approach 1:
The patent creates a composite material system consisting of phosphate framework nanoparticles dispersed in a carbon matrix. The carbon matrix serves as a conductive network that compensates for the poor electronic conductivity of the phosphate material, while the nanoparticle structure maintains thermal stability. This composite approach allows simultaneous achievement of both thermal stability and improved electronic conductivity.
Solution Approach 2:
The patent utilizes a porous carbon matrix structure that provides pathways for ion transport while maintaining structural integrity. The porous nature of the carbon matrix enhances ionic conductivity by creating diffusion channels, while the overall composite structure preserves the thermal stability characteristics of the phosphate framework material.
2Speed
If material is downsized to enhance sodium intercalation/de-intercalation, then diffusion length for Na+ ions is reduced, but particle-to-particle boundaries increase causing sluggish electron transportation
Solution Approach 1:
The carbon matrix acts as an intermediary conductive network that bridges the nanoparticle boundaries. Instead of relying on direct particle-to-particle contact for electron transport, the carbon matrix provides continuous conductive pathways that mediate electron transportation across the downsized particle structure, eliminating the sluggishness caused by increased particle boundaries.
Solution Approach 2:
The patent applies different functional qualities to different parts of the composite: the phosphate framework nanoparticles provide local sites for fast sodium intercalation/de-intercalation due to their small size, while the carbon matrix provides the conductive quality needed for electron transportation. This spatial differentiation of functions allows simultaneous optimization of both sodium ion diffusion and electron transport.
3Power
If phosphate framework material is used for high voltage capability, then voltage profiles are achieved, but electronic conductivity limits overall performance
Solution Approach 1:
The composite structure combines high-voltage phosphate framework material with a conductive carbon matrix. The carbon matrix forms a percolating network that provides electronic conductivity pathways, enabling the high-voltage phosphate material to effectively transport electrons to current collectors, thus realizing the voltage capability that would otherwise be limited by poor conductivity.
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 integrated carbon matrix significantly enhances electrical conductivity and sodium storage capacity, making the material suitable for rechargeable sodium ion batteries with improved cyclability and voltage profiles.
Implementation Method 1
the surfactant remaining on the particles is decomposed to form a carbon network between the crystallized particles
Implementation Method 2
the remaining precipitate is dried and sintered to crystallize the particles. In the meantime, the surfactant remaining on the particles is decomposed to form a carbon network between the crystallized particles, and the crystallized particles and the carbon matrix are integrated to form the electrode material in bulk form
Data Source
AI summary
The present disclosure provides a phosphate framework electrode material for sodium ion battery and a method for synthesizing such electrode material. A surfactant and precursors including a sodium precursor, a phosphate precursor, a transition metal precursor are dissolved in a solvent and stirred for sufficient mixing and reaction. The precursors are reacted to yield a precipitate of particles of NaxAbMy(PO4)zXn compound and with the surfactant attached to the particles. The solvent is then removed and the remaining precipitate is sintered to crystallize the particles. During sintering, the surfactant is decomposed to form a carbon network between the crystallized particles and the crystallized particles and the carbon matrix are integrated to form the electrode material.