Mixed Lithium Metal Oxide Composite with Pyrolysis Carbon Coating
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Solution Overview
Problem
Current electrode materials for secondary lithium-ion batteries do not achieve sufficient electrode density, leading to lower battery capacity due to coarse primary particles and impurities produced by high-temperature calcination processes, which also result in reduced powder compaction density.
Innovation Solution
A composite material comprising particles of mixed lithium metal oxide partially coated with non-crystalline pyrolysis carbon and particles of crystalline elemental carbon, where the crystalline elemental carbon is not VGCF, is used to enhance pressing density and electrode performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature calcination processes are used to produce lithium metal oxide particles, then the material achieves crystalline structure and chemical purity, but the primary particles become coarse and powder compaction density is reduced
Solution Approach 1:
The patent introduces a dual-carbon composite structure where fine crystalline carbon particles (average diameter 0.5-2.0 μm) are distributed within and on the surface of pyrolysis carbon coating. This segmentation of carbon forms a hierarchical structure that fills voids between larger oxide particles, enabling higher powder compaction density (≥2.0 g/cm³) while maintaining the crystalline purity of the lithium metal oxide produced by high-temperature calcination
Solution Approach 2:
The patent creates a nested structure where crystalline carbon particles are embedded within the pyrolysis carbon coating that surrounds the lithium metal oxide particles. This nested arrangement allows fine carbon particles to occupy interstitial spaces, increasing the overall packing density of the composite material without compromising the crystalline structure achieved through high-temperature processing
2Manufacturing precision
If high-temperature calcination is used to produce lithium metal oxide, then phase-pure material is obtained, but coarse primary particles are formed reducing electrode density
Solution Approach 1:
The patent applies local quality by creating regions of different carbon types with different functions: pyrolysis carbon provides a continuous coating for conductivity and structural integrity, while discrete crystalline carbon particles in specific size ranges (0.5-2.0 μm) provide dense packing. This localized differentiation allows the material to achieve both phase purity from high-temperature calcination and high electrode density through optimized local structures
Solution Approach 2:
The patent creates a composite material system combining lithium metal oxide with a dual-carbon structure consisting of pyrolysis carbon coating and embedded crystalline carbon particles. This composite approach allows the material to simultaneously achieve phase purity (from high-temperature calcination of the oxide), high electrode density (from fine carbon particle packing), and excellent conductivity (from the carbon network)
3Reliability
If carbon is added to increase conductivity and capacity, then electrode performance improves, but carbon content must be carefully controlled to maintain material properties
Solution Approach 1:
The patent optimizes the carbon content parameter by precisely controlling the amount of crystalline carbon (0.1-5.0 wt.%, preferably 0.5-2.0 wt.%) and the thickness of pyrolysis carbon coating (1-10 nm). This parameter optimization ensures sufficient conductivity and capacity enhancement while preventing excessive carbon from compromising the lithium metal oxide phase purity or creating unwanted graphite formation, thus achieving reliable electrode performance with controlled carbon content
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 composite material achieves a pressing density improvement of at least 10% and a battery capacity increase by a factor of approximately 5%, with improved cycle stability and current carrying capacity, while maintaining a low carbon content and avoiding the formation of ordered synthetic graphite.
Implementation Method 1
particles of a mixed lithium metal oxide which are partially coated with non-crystalline pyrolysis carbon
Implementation Method 2
particles of crystalline elemental carbon
Data Source
AI summary
The present invention relates to a composite material containing particles made of a mixed lithium-metal oxide, which in some regions are provided with a pyrolysis carbon coating, and particles made of elemental carbon, which in some regions are provided with a coating made of pyrolysis carbon. The present invention further relates to a method for producing such a composite material and to an electrode containing the composite material, and to a secondary lithium ion battery containing an electrode comprising the composite material.