Positive-Electrode Particle Distribution for Higher Compacted Density

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Solution Overview

Problem

Existing sodium iron phosphate pyrophosphate Na4Fe3(PO4)2(P2O7) materials exhibit low compacted density and poor energy density due to inefficient packing, despite their potential as a positive electrode material in sodium-ion batteries.

Innovation Solution

A method for producing a positive-electrode active material comprising first and second active particles with specific particle size ratios and distributions, optimized to enhance compacted density and energy density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single particle size of Na4Fe3(PO4)2(P2O7) is used, then the material structure is simple and easy to manufacture, but the compacted density is low due to inefficient packing

Engineering Contradiction:

Improveease of manufactureVSAvoidcompacted density

Core Design Contradiction:

Ease of manufactureVSVolume of stationary object

Solution Approach 1:

The patent divides the particle population into multiple size segments (first active particles with smaller size and second active particles with larger size) to improve packing efficiency. This segmentation allows smaller particles to fill voids between larger particles, increasing compacted density while maintaining manufacturing simplicity through separate preparation of each size fraction

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies the nesting principle by having smaller first active particles nested within the voids and spaces between larger second active particles. This hierarchical arrangement maximizes space utilization and achieves higher compacted density, similar to how nested dolls occupy space efficiently

Inventive Principle:

Principle #7Nested doll (Nesting)

2Speed

If smaller particles are used to increase surface area and reactivity, then the reaction rate improves, but the compacted density decreases due to poor packing efficiency

Engineering Contradiction:

Improvereaction rateVSAvoidcompacted density

Core Design Contradiction:

SpeedVSVolume of stationary object

Solution Approach 1:

The patent merges two particle size populations (small first active particles and large second active particles) into a composite distribution. This combination allows the system to simultaneously benefit from the high reactivity of small particles and the efficient packing of large particles, resolving the contradiction between reaction rate and compacted density

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250388483A1Positive-electrode active material, preparing method thereof, and battery

Publication Date: 2025.12.25 HITHIUM TECH HK LTD

AI summary

Provided are a positive-electrode active material, a preparing method thereof, and a battery. The positive-electrode active material of the present disclosure includes first active particles and second active particles. An average particle size of the first active particles is smaller than an average particle size of the second active particles; in a particle size distribution curve of the positive-electrode active material, the first active particles have a first peak, the second active particles have a second peak, and a ratio r1 of a value of a peak top of the first peak to a value of a peak top of the second peak satisfies: 0.3≤r1≤0.8.