Micro-Oxidized Graphite Anodes for Fast-Charging Batteries
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Solution Overview
Problem
Graphite-based secondary batteries exhibit poor fast charge performance due to high active ion diffusion resistance and limited kinetic performance, leading to rapid capacity fade during high-rate charging.
Innovation Solution
A modified graphite is prepared by heat-treating a graphite substrate in a micro-oxidizing atmosphere containing CO2, O2, or O3, which increases active ion diffusion channels and reduces diffusion resistance, and a carbon-coated negative active material is produced by concurrent carbonization and micro-oxidization, enhancing fast charge performance and cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite is used as negative active material, then the secondary battery can be manufactured with conventional processes, but the fast charge performance is poor due to high active ion diffusion resistance
Solution Approach 1:
The patent applies porous materials by creating a porous carbon coating layer on the graphite surface through heat treatment in a micro-oxidizing atmosphere. This porous structure increases the number of active ion diffusion channels and reduces diffusion resistance, directly addressing the harmful factor of high diffusion resistance while maintaining the beneficial graphite base material.
Solution Approach 2:
The patent applies local quality by modifying only the surface layer of the graphite particles with a carbon coating, while keeping the bulk graphite structure intact. This localized modification approach preserves the good electrochemical properties of graphite in the interior while improving fast charge performance at the surface where ion diffusion occurs.
2Reliability
If the graphite substrate is heat-treated in a micro-oxidizing atmosphere, then the active ion diffusion channels increase and diffusion resistance decreases, but the process complexity increases
Solution Approach 1:
The patent merges the carbonization process with the micro-oxidation process by conducting both simultaneously in a single heat treatment step. This combines multiple functions (carbon coating formation and surface modification) into one operation, reducing process complexity while achieving the desired porous structure and improved performance.
Solution Approach 2:
The patent applies parameter changes by optimizing the heat treatment conditions (temperature range of 600-1400°C, specific atmosphere composition with controlled oxygen partial pressure) to achieve the desired porous carbon coating. By carefully controlling these parameters, the process becomes more predictable and easier to implement industrially.
3Reliability
If the heat treatment temperature is increased to improve the degree of isotropy and nanopore formation, then the fast charge performance improves, but the yield rate of modified graphite decreases
Solution Approach 1:
The patent applies parameter changes by identifying and optimizing the heat treatment temperature range (600-1400°C) to achieve a balance between forming sufficient nanopores for good fast charge performance and maintaining an acceptable yield rate. This optimized parameter range allows adequate porous structure development without excessive material loss.
Solution Approach 2:
The patent applies partial action by using a micro-oxidizing atmosphere with controlled oxygen concentration rather than full oxidation conditions. This partial oxidation approach is sufficient to create the needed porous structure while avoiding excessive material consumption that would occur under more aggressive oxidation conditions.
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 modified graphite and carbon-coated materials improve fast charge performance, achieve high first-cycle Coulombic efficiency, and extend cycle life, making them suitable for large-scale batch production and high-energy density applications.
Implementation Method 1
heat-treating the graphite substrate in a micro-oxidizing atmosphere
Implementation Method 2
heat-treating the graphite substrate in a micro-oxidizing atmosphere containing CO2, O2, or O3
Implementation Method 3
heat-treating the graphite substrate in a micro-oxidizing atmosphere where the reactive gas is one or more selected from CO2, O2, and O3
Data Source
AI summary
Provided are a modified graphite and a preparation method thereof, a carbon-coated negative active material and a preparation method thereof, a negative electrode plate, a secondary battery, a battery module, a battery pack, and an electrical device. The preparation method of a modified graphite includes the following steps: (S10) providing a graphite substrate; and (S20) heat-treating the graphite substrate in a micro-oxidizing atmosphere to obtain the modified graphite, where the micro-oxidizing atmosphere includes a reactive gas, and the reactive gas is one or more selected from CO2, O2, and O3. The preparation method of a carbon-coated negative active material includes the following steps: (S100) providing a negative active material substrate; and (S200) heat-treating the negative active material substrate and a carbonaceous precursor in a micro-oxidizing atmosphere to obtain the carbon-coated negative active material, where the micro-oxidizing atmosphere includes a reactive gas.