Lithium Iron Phosphate Synthesis Using Mixed Ferric Hydroxyphosphate
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Solution Overview
Problem
Existing methods for preparing lithium iron phosphate require high reaction temperatures, long reaction times, harsh conditions, high equipment requirements, and high raw material costs, leading to low production efficiency and impurities that affect product performance.
Innovation Solution
A method using ferrous sulfate, hydrogen peroxide, phosphoric acid, and ammonium dihydrogen phosphate to synthesize ferric hydroxyphosphate, followed by mixing with lithium and carbon sources, and subjecting the mixture to various processing steps to produce lithium iron phosphate with high compaction density and capacity, suitable for large-scale industrial production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high reaction temperature and long reaction time are used for synthesis, then product purity is improved, but production efficiency deteriorates
Solution Approach 1:
The patent changes the reaction parameters by using a sol-gel method with controlled pH (2.0-3.5) and temperature (150-200°C) for a specific duration (30 hours), which optimizes both product purity and production efficiency compared to conventional high-temperature methods
Solution Approach 2:
The patent introduces methyltriethylammonium chloride as a mediator to adjust and control the pH of the reaction system, enabling the hydrothermal synthesis to proceed under optimized conditions that simultaneously achieve high purity and reasonable production efficiency
2Device complexity
If conventional solid phase method is used, then equipment requirements are reduced, but reaction time and temperature requirements increase
Solution Approach 1:
The patent replaces conventional mechanical mixing and high-temperature heating methods with a chemical sol-gel process that uses solution chemistry and controlled hydrothermal conditions, reducing equipment complexity while optimizing reaction time and temperature
3Productivity
If high concentration of raw materials is used, then production efficiency is improved, but impurity content increases
Solution Approach 1:
The patent applies local quality control by adjusting the pH to specific ranges (2.0-3.5) and using controlled concentrations of reagents in different stages of the synthesis, ensuring optimal reaction conditions that maximize productivity while minimizing impurity formation
4Reliability
If multiple synthesis steps are used, then product performance is improved, but process complexity increases
Solution Approach 1:
The patent merges multiple synthesis steps into a unified sol-gel hydrothermal process, where precursor formation, gelation, and crystallization occur in an integrated manner under controlled conditions, reducing process complexity while maintaining product 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 method achieves high production efficiency, low production costs, and improved product performance by producing lithium iron phosphate with enhanced electrochemical properties, suitable for large-scale industrial applications.
Implementation Method 1
adding hydrogen peroxide, phosphoric acid, an ammonium dihydrogen phosphate solution and ammonia water into the ferrous sulfate solution, then reacting to form a mixed slurry
Data Source
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AI summary
The present disclosure provides a method for preparing lithium iron phosphate from ferric hydroxyphosphate, including: purifying ferrous sulfate to form a ferrous sulfate solution, adding hydrogen peroxide, phosphoric acid, an ammonium dihydrogen phosphate solution and ammonia water into the ferrous sulfate solution and then reacting to form a mixed slurry, holding the mixed slurry at a temperature for a period of time, and then washing with water and subjecting to press filtration to form ferric hydroxyphosphate precursors with different iron-phosphorus ratios; then flash drying, sintering at a high temperature, and pulverizing to obtain ferric hydroxyphosphate precursors with different iron-phosphorus ratios and different specific surface areas; pulverizing and mixing the ferric hydroxyphosphate precursors to obtain finished products of ferric hydroxyphosphate, mixing the ferric hydroxyphosphate with a high iron-phosphorus ratio with the ferric hydroxyphosphate with a low iron-phosphorus ratio according to a certain proportion, then proportioning with a lithium source and an iron source according to a certain proportion, and adding a carbon source and an additive to form a mixed material; and subjecting the aforementioned mixed material to ball milling, sanding, spray drying, sintering, pulverizing, sieving, blending, packaging and the like procedures to obtain a finished product of lithium iron phosphate.