Bimodal Pyrite Cathode Particle Distribution

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Solution Overview

Problem

Lithium-iron disulfide batteries face challenges due to inconsistencies in particle size distribution, impurities in natural pyrite, and volumetric expansion issues, leading to reduced electrochemical performance and manufacturing difficulties.

Innovation Solution

A bimodal or multi-modal particle size distribution of pyrite is achieved by combining different pyrite sources with distinct particle size distributions, optimizing electrochemical performance and manufacturing processability, and reducing voids and stress in the cathode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If natural pyrite is crushed and dry milled to reduce particle size, then electrochemical activity is improved, but particle size consistency deteriorates and weathering susceptibility increases

Engineering Contradiction:

Improveelectrochemical activityVSAvoidparticle size consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent segments the particle size distribution into two distinct modes: a first mode (5-20 microns) from natural pyrite and a second mode (0.1-5 microns) from synthetic pyrite. This segmentation allows each particle size range to fulfill specific functional requirements, resolving the contradiction between maintaining electrochemical activity and achieving particle size consistency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a composite particle size distribution by combining natural pyrite and synthetic pyrite in a bimodal mixture. This composite approach leverages the advantages of both materials: natural pyrite provides cost-effectiveness and adequate electrochemical activity, while synthetic pyrite provides fine particle size consistency and prevents weathering.

Inventive Principle:

Principle #40Composite materials

2Reliability

If particle size is reduced to improve electrochemical performance, then surface area increases, but susceptibility to weathering and oxidation increases

Engineering Contradiction:

Improveelectrochemical performanceVSAvoidweathering susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent segments the particle population into two size groups, with the finer synthetic pyrite particles (0.1-5 microns) providing high surface area for electrochemical performance, while the coarser natural pyrite particles (5-20 microns) providing weathering resistance. This segmentation resolves the contradiction between electrochemical performance and weathering susceptibility.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If natural pyrite is used as raw material, then manufacturing cost is reduced, but impurity content increases

Engineering Contradiction:

Improvemanufacturing costVSAvoidelectrochemical performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent segments the pyrite source into two components: natural pyrite (5-20 microns) providing cost advantages and synthetic pyrite (0.1-5 microns) providing high purity. This segmentation allows the system to achieve both cost-effectiveness and high electrochemical performance by assigning different functional roles to each component.

Inventive Principle:

Principle #1Segmentation

4Reliability

If synthetic pyrite is used to reduce impurities, then electrochemical performance is improved, but manufacturing cost increases

Engineering Contradiction:

Improveelectrochemical performanceVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent segments the pyrite usage by function: synthetic pyrite (0.1-5 microns) is used specifically for its high purity and fine particle size to enhance electrochemical performance, while natural pyrite (5-20 microns) is used for its cost-effectiveness. This functional segmentation optimizes both performance and cost.

Inventive Principle:

Principle #1Segmentation

5Device complexity

If single particle size profile is used from media milling, then manufacturing process is simplified, but particle distribution uniformity is limited

Engineering Contradiction:

Improvemanufacturing process complexityVSAvoidparticle distribution uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent segments the particle size distribution into two distinct modes produced by different processes: natural pyrite crushed and dry milled (5-20 microns) and synthetic pyrite produced via controlled synthesis (0.1-5 microns). This segmentation achieves superior particle distribution uniformity while maintaining manageable manufacturing complexity.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9099741B2Particle size distribution variations in iron disulfide cathodes

Publication Date: 2015.08.04 ENERGIZER BRANDS LLC

AI summary

A cathode, electrochemical cell and process for making either is disclosed. The cathode includes iron disulfide which exhibits multiple peaks representing distinct maxima of mean diameters for the volume-based particle size distribution. All of the maxima are less than 20 microns. A combination of natural pyrite ore and synthetic iron disulfide may be mixed to achieve the desired distribution, or a combination of natural pyrite ores may be processed in different manners to achieve the desired characteristics.