Carbon-Coated Spherical Graphite Anode With Pre-Densified Particles
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Solution Overview
Problem
Existing carbonaceous negative electrode 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 spheronization of scaly graphite, followed by cold isostatic pressing, disintegration, and carbon coating at controlled temperatures to produce a carbonaceous negative electrode active material with reduced internal pores and improved sphericity, characterized by specific particle size and density ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If natural graphite is spheronized to improve processability and reduce irreversible reaction, then spherical shape is achieved, but internal pores are generated reducing density
Solution Approach 1:
The patent applies cold isostatic pressing to change the density parameter of spheronized graphite particles from 1.8-2.0 g/cc to 2.5-2.7 g/cc, thereby increasing the quantity of substance while maintaining the spherical shape and processability benefits
2Reliability
If low-crystalline carbon coating is applied to prevent electrolyte destruction, then edge surface protection is achieved, but coating film breaks during densification exposing graphite edges
Solution Approach 1:
The patent performs cold isostatic pressing before carbon coating, pre-densifying the graphite particles to 2.5-2.7 g/cc. This preliminary densification prevents coating film breakage during subsequent electrode manufacturing processes, maintaining coating integrity and continuous protection of graphite edges
3Quantity of substance
If internal pores are reduced by densification to improve capacity, then density increases, but coating film breaks and graphite edges are exposed
Solution Approach 1:
The patent performs cold isostatic pressing before carbon coating, pre-densifying the graphite particles to 2.5-2.7 g/cc. This preliminary densification prevents coating film breakage during subsequent electrode manufacturing processes, maintaining coating integrity and continuous protection of graphite edges
4Reliability
If spheronization is performed to reduce irreversible reaction, then spherical shape is achieved, but internal pores cause gas generation and high-temperature degradation
Solution Approach 1:
The patent applies cold isostatic pressing to change the density parameter from 1.8-2.0 g/cc to 2.5-2.7 g/cc, significantly reducing internal pore volume. This eliminates the harmful effects of gas generation and high-temperature degradation while preserving the spherical shape and low irreversible reaction characteristics
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 solution results in a negative electrode with enhanced capacity retention, reduced swelling, and improved high-temperature storage characteristics, facilitating rapid charge/discharge cycles and minimizing internal stress.
Implementation Method 1
spheronization of scaly graphite
Implementation Method 2
cold isostatic pressing
Implementation Method 3
carbonizing the mixture at a temperature ranging from 1,400° C. to 600° C. to form a carbon coating
Data Source
AI summary
A spheronized carbonaceous negative electrode active material and a method of preparing a spheronized carbonaceous negative electrode active material, which has an average particle diameter (D50) of 8.5-10.5 μm, a minimum particle diameter (Dmin) of 2.3 μm or more, and a tap density of 1.00-1.20 g/cc.