Spheronized Graphite Anode Material With Lower Internal Porosity
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Solution Overview
Problem
Existing carbonaceous negative electrode active materials, particularly those derived from spheronized natural graphite, suffer from high internal porosity, reduced density, and poor sphericity, leading to issues such as electrode swelling, irreversible reactions, and degradation of high-temperature storage characteristics.
Innovation Solution
A method involving the spheronization of a mixture of microgranular and macrogranular scaly graphite, followed by carbon coating and disintegration, to produce a carbonaceous negative electrode active material with reduced internal pores and improved sphericity, using a combination of mechanical and chemical processes to enhance particle assembly and coating stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If natural graphite is spheronized to improve processability and reduce irreversible reaction, then sphericity and electrode cycle life are improved, but internal porosity increases and density decreases
Solution Approach 1:
The patent applies the nesting principle by filling internal pores within spheronized graphite particles with fine graphite powder. The fine particles nest into the void spaces of the larger spheronized particles, thereby reducing internal porosity while maintaining the spherical shape and improving density without compromising the benefits of spheronization.
2Reliability
If low-crystalline carbon coating is applied to prevent electrolyte destruction and reduce irreversible reaction, then electrode stability is improved, but coating film breaks during densification and graphite edge surface is exposed
Solution Approach 1:
The patent employs composite materials by combining spheronized graphite particles with fine graphite powder and additional carbon coating materials. This creates a multi-layered composite structure where the fine particles and carbon coating work together to reinforce the coating film, preventing it from breaking during densification while maintaining electrode stability and preventing electrolyte contact with graphite edge surfaces.
3Volume of stationary object
If internal pores are reduced to improve density and prevent gas generation, then high-temperature storage characteristics are improved, but particle packing efficiency may decrease
Solution Approach 1:
The patent applies local quality by selectively filling only the internal pores within particles with fine graphite powder, while maintaining the external spherical shape and surface properties. This localized modification reduces internal porosity and improves density without affecting the overall particle morphology and packing efficiency, thereby improving high-temperature storage characteristics while maintaining productivity.
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 resulting material exhibits improved sphericity, reduced internal stress, enhanced capacity retention during high-temperature storage, and minimized electrode swelling, resulting in a more stable and efficient lithium secondary battery performance.
Implementation Method 1
spheronizing the mixture to prepare spheronized granulated particles
Implementation Method 2
spheronization of natural graphite having a scaly particle shape
Implementation Method 3
when natural graphite is surface coated through the heat treatment of low-crystalline carbon, such as pitch
Implementation Method 4
surface coated through the heat treatment of low-crystalline carbon
Data Source
AI summary
A method for preparing a spheronized carbonaceous negative electrode active material, including the steps of: mixing microgranular scaly graphite with macrogranular scaly graphite, wherein the macrogranular scaly graphite has a larger average particle diameter than the microgranular scaly graphite, to form a mixture, and spheronizing the mixture to prepare spheronized granulated particles; carrying out carbon coating of the spheronized granulated particles; and disintegrating the carbon-coated spheronized granulated particles.