Lithium Vanadium Phosphate Synthesis via Precipitation
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Solution Overview
Problem
Conventional methods for producing lithium vanadium phosphate as a positive electrode active material for lithium secondary batteries result in low discharge capacity and complex, industrially non-viable production processes, despite the material's high theoretical capacity.
Innovation Solution
A method involving mixing a vanadium compound, phosphorus source, and reducing sugar in a water solvent, followed by heat treatment, spray drying, and firing at a lower temperature to produce a single-phase lithium vanadium phosphate with enhanced reactivity and crystallinity, facilitating better battery performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional production methods (crushing and mixing, pelletizing, firing) are used to produce lithium vanadium phosphate, then the material can be obtained, but the discharge capacity is low and the process is complex
Solution Approach 1:
The patent applies preliminary action by performing a precipitation reaction before the main firing process. Raw materials (vanadium compound, phosphorus source, lithium source) are first mixed in aqueous solution to form a precipitate, which is then dried and fired. This preliminary precipitation step creates a pre-formed compound structure that reacts more efficiently during firing, achieving high discharge capacity while simplifying the overall process by eliminating complex crushing and pelletizing steps.
2Reliability
If high discharge capacity is achieved through precipitation forming reaction and media mill crushing treatment, then reactivity is improved, but the production process becomes complex and industrially disadvantageous
Solution Approach 1:
The patent replaces mechanical crushing treatment with a chemical precipitation approach. Instead of using media mills to mechanically crush and refine particles, the method uses aqueous solution chemistry to form a precipitate with the desired fine particle structure and high reactivity. This substitution of mechanical processing with chemical processing simplifies the manufacturing process while maintaining high reactivity, making it industrially viable.
3Stability of the object's composition
If lithium vanadium phosphate is produced as a single phase material, then battery performance is enhanced, but conventional methods require complex multi-step processing
Solution Approach 1:
The patent achieves single-phase lithium vanadium phosphate by optimizing chemical parameters in the precipitation and firing processes. Specifically, it controls the molar ratios of raw materials in the aqueous solution, adjusts the pH and temperature during precipitation, and optimizes the firing temperature and atmosphere. These parameter changes ensure complete reaction and formation of a homogeneous single-phase product, eliminating the need for complex multi-step processing while achieving superior phase homogeneity and battery 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 yields a lithium vanadium phosphate with improved reactivity and crystallinity, leading to enhanced battery performance and industrial viability by simplifying the production process while maintaining high discharge capacity.
Implementation Method 1
a heat treatment to carry out a reductive reaction on the vanadium compound
Implementation Method 2
subjecting the raw material mixed liquid to a spray drying treatment to thereby obtain a reaction precursor
Implementation Method 3
firing the obtained reaction precursor in an inert gas atmosphere or a reductive atmosphere at 600 to 1,300°C
Data Source
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AI summary
There is provided a lithium vanadium phosphate of a single phase in terms of X-ray diffractometry, which is useful particularly as a positive electrode active material of a lithium secondary battery and the like, by an industrially advantageous method. The present invention is a method for producing the lithium vanadium phosphate having a NASICON structure, the method comprising a first step of mixing a tetravalent or pentavalent vanadium compound, a phosphorus source and a reducing sugar in a water solvent to thereby prepare a mixed slurry, a second step of subjecting the mixed slurry to a heat treatment to thereby make a solution, a third step of adding a lithium source to the solution to thereby prepare a raw material mixed liquid, a fourth step of subjecting the raw material mixed liquid to a spray drying treatment to thereby obtain a reaction precursor, and a fifth step of firing the reaction precursor in an inert gas atmosphere or a reductive atmosphere at 500 to 1,300°C.