Pitch-Coated Graphite Negative Electrode for High-Temperature Lithium Batteries
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Solution Overview
Problem
Rechargeable lithium batteries face challenges in achieving high temperature performance, high current density, and high active mass density due to limitations in negative active materials, particularly in terms of specific surface area and Raman spectrum ratios, which affect stability and cycle-life characteristics.
Innovation Solution
A negative active material with a specific surface area of less than or equal to 1 m2/g and a Raman spectrum area ratio (D/G) of less than or equal to 0.3, composed of a pitch-coated crystalline carbon-based material, including artificial graphite, is developed, which is heat-treated under inert conditions to enhance stability and reduce reactivity at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the specific surface area of negative active material is increased to improve capacity, then the active mass density increases, but the high temperature performance and cycle-life characteristics deteriorate due to increased reactivity and side reactions
Solution Approach 1:
The patent applies local quality by creating a heterogeneous surface structure where the negative active material has different properties at different locations: the core maintains high capacity characteristics while the surface develops a stabilized layer with reduced reactivity. This allows the bulk material to provide high active mass density while the surface layer protects against high temperature degradation and side reactions.
Solution Approach 2:
The patent utilizes parameter changes by controlling the specific surface area within an optimized range (0.01-1.0 m²/g) and adjusting the Raman spectrum D/G ratio (0.1-0.3) to achieve the desired balance between capacity and stability. These parameter optimizations ensure that the material maintains high active mass density while exhibiting improved high temperature performance and cycle-life characteristics.
2Quantity of substance
If the specific surface area of negative active material is increased to improve capacity, then the active mass density increases, but the stability and cycle-life characteristics deteriorate due to increased side reactions
Solution Approach 1:
The patent applies local quality by creating a heterogeneous surface structure where the negative active material has different properties at different locations: the core maintains high capacity characteristics while the surface develops a stabilized layer with reduced reactivity. This allows the bulk material to provide high active mass density while the surface layer protects against high temperature degradation and side reactions.
Solution Approach 2:
The patent utilizes parameter changes by controlling the specific surface area within an optimized range (0.01-1.0 m²/g) and adjusting the Raman spectrum D/G ratio (0.1-0.3) to achieve the desired balance between capacity and stability. These parameter optimizations ensure that the material maintains high active mass density while exhibiting improved high temperature performance and cycle-life characteristics.
3Quantity of substance
If conventional carbon-based materials are used with higher specific surface area, then the capacity is improved, but the high temperature cycle-life characteristics deteriorate
Solution Approach 1:
The patent utilizes parameter changes by controlling the specific surface area within an optimized range (0.01-1.0 m²/g) and adjusting the Raman spectrum D/G ratio (0.1-0.3) to achieve the desired balance between capacity and stability. These parameter optimizations ensure that the material maintains high active mass density while exhibiting improved high temperature performance and cycle-life characteristics.
Solution Approach 2:
The patent applies composite materials by combining negative active material with specific surface area of 0.01-1.0 m²/g with conventional carbon-based materials or coatings to create a composite structure that maintains high capacity while improving high temperature cycle-life characteristics through the synergistic effects of the different components.
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 developed negative active material exhibits excellent high temperature cycle-life characteristics, maintaining capacity retention and stability, outperforming comparative examples in high temperature applications.
Implementation Method 1
a lithium-transition metal oxide having a structure being capable of intercalating lithium ions
Implementation Method 2
heat-treated under inert conditions to enhance stability and reduce reactivity at high temperatures
Data Source
AI summary
A negative active material for a rechargeable lithium battery includes a carbon-based material and has a specific surface area of less than or equal to about 1 m2/g, and an area ratio D/G of a ID peak at about 1350 cm−1 to about 1370 cm−1 and a G peak at about 1570 cm−1 to about 1620 cm−1 of less than or equal to about 0.3 in a Raman spectrum analysis and includes a carbon-based material.