Disordered Rocksalt Cathode Particle Architecture for Conductivity
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Solution Overview
Problem
Disordered rocksalt cathode materials for lithium ion batteries face poor conductivity issues, which are mitigated by reducing particle size, but this compromises volumetric energy density, sacrificing some of the benefits of high energy density.
Innovation Solution
A method involving milling a suspension of metal precursors to form primary particles, followed by spray drying to create secondary particles, and annealing to produce disordered rocksalt powder, with specific particle size ranges to achieve high energy density without compromising conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If particle size is reduced to improve conductivity, then electron and ion transport pathways are shortened, but volumetric energy density is limited
Solution Approach 1:
The cathode material is segmented into a hierarchical structure with primary particles (10-100 nm) agglomerated into secondary particles (1-20 μm). This segmentation creates short electron/ion transport pathways within primary particles for good conductivity, while the agglomerated secondary particle structure maintains high volumetric energy density by efficiently packing material in the electrode.
Solution Approach 2:
The patent applies a nested structure where smaller primary particles are contained within larger secondary particles. The primary particles (10-100 nm) are nested within secondary particles (1-20 μm), creating a multi-scale hierarchical architecture that simultaneously achieves short transport distances at the primary particle level and high packing density at the secondary particle level.
2Quantity of substance
If disordered rocksalt structure is used to achieve high energy density, then theoretical energy density increases, but conductivity becomes poor
Solution Approach 1:
The disordered rocksalt material is segmented into a hierarchical structure with primary particles (10-100 nm) agglomerated into secondary particles (1-20 μm). This segmentation creates short electron/ion transport pathways within primary particles for good conductivity, while the agglomerated secondary particle structure maintains high volumetric energy density by efficiently packing material in the electrode.
Solution Approach 2:
The patent changes the particle size parameters of the disordered rocksalt material, creating a specific hierarchical distribution where primary particles range from 10-100 nm and secondary particles range from 1-20 μm. This parameter optimization allows the material to simultaneously achieve the high energy density characteristic of disordered rocksalt structures and the good conductivity required for practical 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 approach results in a cathode with micro-sized secondary particles that are agglomerations of sub-micro-sized primary particles, providing both desirable conductivity and high energy density, as demonstrated by good rate performance in lithium ion batteries.
Implementation Method 1
milling a suspension of precursors via a micromedia mill to form a mixture of primary particles in the suspension
Implementation Method 2
spray drying the suspension after the milling to form secondary particles
Implementation Method 3
annealing the secondary particles to form a disordered rocksalt powder
Data Source
AI summary
A method for forming a cathode includes milling a suspension of precursors via a micromedia mill to form a mixture of primary particles in the suspension. The precursors include one or more metal compounds. The method includes spray drying the suspension after the milling to form secondary particles. The secondary particles are agglomerations of the primary particles. The method also includes annealing the secondary particles to form a disordered rocksalt powder.