LiFePO4 Particle Aggregation Control for Battery Packing Density
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Solution Overview
Problem
Current methods fail to produce olivine type LiFePO4 particles with high packing properties and low amorphous content at low costs and with minimal environmental burden, while existing techniques either lack effective control over secondary aggregation or result in insufficient solid state reactivity or high ion diffusion efficiency.
Innovation Solution
A process involving the mixing of iron oxide or iron oxide hydroxide with specific additives, followed by sintering in an inert or reducing gas atmosphere, to produce lithium iron phosphate particles with controlled agglomerate diameters and reduced impurity phases, enhancing packing density and charge/discharge characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional methods are used to produce olivine type LiFePO4 particles, then production cost is reduced, but packing properties and charge/discharge cycle characteristics deteriorate
Solution Approach 1:
The patent applies preliminary action by controlling the aggregating condition of primary particles during the sintering process. By pre-establishing the aggregation state of primary particles before final sintering, the method achieves high packing density without requiring complex post-processing or expensive raw materials, thus resolving the contradiction between low production cost and high packing properties
Solution Approach 2:
The patent employs parameter changes by optimizing the sintering temperature range (450-550°C) and controlling the aggregation state of primary particles. These parameter adjustments enable the formation of high-density aggregates with improved packing properties while maintaining cost-effective production processes, addressing the contradiction between manufacturing precision and ease of manufacture
2Reliability
If primary particle diameter is reduced to improve charge/discharge characteristics, then electric resistance decreases, but packing density deteriorates
Solution Approach 1:
The patent applies merging by forming aggregates of primary particles with controlled aggregating conditions. Small primary particles (0.3-3 μm) are merged into compact aggregates with diameters of 3-30 μm, maintaining the low electric resistance benefits of small particles while achieving high packing density through optimized aggregation structure, thus resolving the contradiction between charge/discharge characteristics and packing density
Solution Approach 2:
The patent employs local quality by creating a hierarchical structure where small primary particles with excellent electrochemical properties are localized within compact aggregates. This local optimization allows different regions to serve different functions: small particles provide low electric resistance while the compact aggregate structure provides high packing density, resolving the contradiction between reliability and volume
3Reliability
If carbon content is increased to improve conductivity, then electric resistance decreases, but packing density deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the carbon content range (1-10 wt%) and controlling the aggregation state of particles. This balanced approach ensures adequate conductivity through sufficient carbon while maintaining high packing density through controlled aggregation, resolving the contradiction between electric resistance and packing density without requiring excessive carbon addition
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 process achieves high packing properties and energy density per unit volume, enabling efficient use in secondary batteries with improved charge and discharge cycle performance and reduced environmental impact.
Implementation Method 1
sintering in an inert or reducing gas atmosphere, to produce lithium iron phosphate particles with controlled agglomerate diameters and reduced impurity phases
Implementation Method 2
sintering in an inert or reducing gas atmosphere
Data Source
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AI summary
The present invention relates to a process for producing lithium iron phosphate particles having an olivine type structure, comprising a first step of mixing an iron oxide or an iron oxide hydroxide as an iron raw material which comprises at least one element selected from the group consisting of Na, Mg, Al, Si, Cr, Mn and Ni in an amount of 0.1 to 2 mol% for each element based on Fe, and a carbon element C in an amount of 5 to 10 mol% based on Fe, and has a content of Fe2+ of not more than 40 mol% based on an amount of Fe and an average primary particle diameter of 5 to 300 nm, with a lithium raw material and a phosphorus raw material; a second step of controlling agglomerates diameter in the resulting mixture is 0.3 to 5.0 µm; and a third step of sintering the mixture obtained in the second step in an inert gas or reducing gas atmosphere having an oxygen concentration of not more than 0.1% at a temperature of 250 to 750°C.