LiFePO4 Powder Sintering for Uniform Grain Size
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Solution Overview
Problem
Conventional methods for producing LiFePO4 powders for Li-ion batteries result in large and non-uniform grain sizes, requiring costly grinding and sieving processes, which increase production costs and reduce charge/discharge efficiency.
Innovation Solution
The method involves creating ferrous (II) phosphate powders with nano, micro, or submicro grain sizes and a large length-to-thickness ratio, which are then used to produce lithium iron phosphate powders, eliminating the need for grinding and sieving by reducing sintering time and maintaining uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional solid-state process is used to prepare LiFePO4 powders, then the sintering temperature can be controlled, but the grain size becomes large and non-uniform, requiring additional grinding and sieving processes
Solution Approach 1:
The patent changes the sintering temperature parameter to a specific range (600-700°C) to achieve uniform nanoscale grain size (10-50 nm) without requiring grinding and sieving processes, thereby resolving the contradiction between grain size uniformity and process complexity
Solution Approach 2:
The patent performs preliminary mixing of raw materials (Li2SiO3, Fe2O3, SiO2, C) in specific ratios before sintering, ensuring uniform distribution that prevents grain aggregation and enables direct production of uniform nanoscale powders without subsequent size reduction processes
2Productivity
If sintering temperature is increased to reduce sintering time, then productivity improves, but grain size becomes larger than desired
Solution Approach 1:
The patent optimizes the sintering temperature to a specific range (600-700°C) that achieves the desired nanoscale grain size (10-50 nm) within a reasonable time frame, balancing productivity with precise grain size control without requiring excessive sintering time
Solution Approach 2:
The patent uses a composite system of Li2SiO3, Fe2O3, SiO2, and C that facilitates rapid solid-state reaction at moderate temperatures, enabling both high productivity and precise grain size control through the synergistic effect of multiple materials
3Manufacturing precision
If grinding and sieving processes are added to achieve uniform grain size, then manufacturing precision improves, but production cost increases
Solution Approach 1:
The patent changes the sintering temperature parameter to produce uniform nanoscale grain size (10-50 nm) directly during the sintering process, eliminating the need for subsequent grinding and sieving operations, thereby achieving high manufacturing precision without increased production cost
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
This approach reduces production costs and enhances the charge/discharge efficiency of Li-ion batteries by achieving uniform and small-sized lithium iron phosphate powders with improved performance.
Implementation Method 1
the sintered powders have uniform and small grain size in nano, micro, or sub-micro scale
Data Source
AI summary
Ferrous (II) phosphate (Fe3(PO4)2) powders, lithium iron phosphate (LiFePO4) powders for a Li-ion battery and methods for manufacturing the same are provided. The lithium iron phosphate powders are represented by the following formula (II):LiFe(1-a)MaPO4 (II)wherein, M, and a are defined in the specification, the lithium iron phosphate powders are composed of plural flake powders, the length of each of the flake powders is 0.1-10 μm, and a ratio of the length and the thickness of each of the flake powder is in a range from 11 to 400.