Single-Particle Cathode Precursor for Low-Temperature Layered Oxides
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Solution Overview
Problem
Existing lithium transition metal oxides require high-temperature heat treatment at 830°C or higher to maintain a layered structure, leading to reduced crystallinity, capacity, and lifespan of the positive electrode active material, and high resistance due to phase changes into a rock-salt structure.
Innovation Solution
A positive electrode active material precursor composed of a composite transition metal in the form of a single particle, combined with transition metal hydroxides and oxides, is used to prepare a lithium transition metal oxide at lower temperatures (700°C to 830°C), maintaining the layered structure and improving crystallinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If high-temperature heat treatment at 830°C or higher is performed to prepare a positive electrode active material in the form of a single particle, then the particle form is improved, but the layered structure is not properly maintained and phase change into rock-salt structure occurs, reducing crystallinity and battery performance
Solution Approach 1:
The patent changes the chemical composition parameters of the precursor material by incorporating specific dopants (Al, Ti, Zr, Nb, Ta, Mo, W, Hf, Th, Pa) into the lithium transition metal oxide structure. This compositional modification allows the material to maintain the layered R-3m structure at lower firing temperatures (700-830°C) while forming single particles, avoiding the phase transformation to rock-salt structure that occurs at higher temperatures with conventional materials
Solution Approach 2:
The patent creates a composite precursor material consisting of lithium transition metal oxide combined with specific dopant oxides or hydroxides. This composite structure enables simultaneous achievement of single particle morphology and stable layered structure during heat treatment, as the dopants reinforce the crystal structure and prevent phase transformation while allowing particle consolidation at reduced temperatures
2Shape
If high-temperature heat treatment at 830°C or higher is performed, then a single particle form is achieved, but capacity properties and lifespan properties are reduced due to phase change and reduced crystallinity
Solution Approach 1:
The patent modifies the chemical composition by adding dopants (Al, Ti, Zr, Nb, Ta, Mo, W, Hf, Th, Pa) to the lithium transition metal oxide precursor. This compositional change stabilizes the layered R-3m crystal structure during heat treatment, preventing phase transformation to rock-salt structure and maintaining high crystallinity at lower firing temperatures (700-830°C), thereby preserving battery capacity and lifespan properties while achieving single particle morphology
Solution Approach 2:
The patent prepares a pre-doped precursor material before heat treatment that already contains the stabilizing dopants in the correct stoichiometric ratios. This preliminary doping action ensures that during subsequent low-temperature firing, the layered structure is maintained from the outset, preventing phase transformation before single particle formation can occur, thus preserving battery performance
3Stability of the object's composition
If heat treatment is performed at a temperature lower than 830°C, then phase change is avoided, but the effects of improving lifespan and reducing gas generation do not reach an expected level due to the presence of over-fired secondary particle form
Solution Approach 1:
The patent changes the precursor composition by incorporating dopants (Al, Ti, Zr, Nb, Ta, Mo, W, Hf, Th, Pa) that enhance the reactivity and sintering behavior of the material. This compositional modification enables complete particle consolidation and single particle formation at lower temperatures (700-830°C) without requiring the high temperatures that cause phase transformation, thereby achieving both structure stability and improved battery lifespan effects simultaneously
Solution Approach 2:
The patent creates a composite precursor system combining lithium transition metal oxide with dopant compounds (oxides or hydroxides of Al, Ti, Zr, Nb, Ta, Mo, W, Hf, Th, or Pa). This composite structure facilitates low-temperature sintering and complete particle consolidation while maintaining the layered crystal structure, eliminating secondary particles and achieving expected lifespan improvement effects at reduced temperatures
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 method enables the production of a positive electrode active material with enhanced capacity, lifespan, and reduced resistance by preventing phase changes, while minimizing gas generation.
Implementation Method 1
mixing the lithium transition metal hydroxide, a lithium-containing raw material, and selectively, a doping element-containing raw material, and the like, followed by performing high-temperature heat treatment
Data Source
AI summary
A positive electrode active material precursor includes a first positive electrode active material precursor having a composition represented by Formula 1 described herein and including a composite transition metal in the form of a single particle, and one or more of a second positive electrode active material precursor having a composition represented by Formula 2 described herein or a third positive electrode active material precursor having a composition represented by Formula 3 described herein. The positive electrode active material precursor is capable of implementing a positive electrode active material in the form of a single particle even when heat-treated at a low temperature. Also provided is, a method for preparing a positive electrode active material using the positive electrode active material precursor, and a positive electrode active material prepared by the method.