Pitch-Coated Graphite Composite for Stable Li-Ion Anodes
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Solution Overview
Problem
Existing graphite-based negative electrode materials in lithium-ion batteries face issues with incomplete coating, agglomeration, and complex preparation processes, leading to poor cycle stability and rate performance, which are not adequately addressed by current carbon coating methods.
Innovation Solution
A method involving mixing graphite with a surfactant and alkali liquor, followed by precipitation with water-soluble mesophase pitch and alcohol solvent, and sequential pyrolysis to form a pitch-based graphite composite with a core-shell structure, ensuring uniform coating and improved compatibility with electrolytes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If solid phase coating method is used to coat pitch on graphite, then the process is simple and cost is low, but the coating is incomplete
Solution Approach 1:
The patent introduces an alkaline solution as an intermediary medium to facilitate the coating process. The pitch is dissolved or dispersed in the alkaline solution, which then penetrates into the graphite particle gaps more effectively than direct solid-phase mixing, enabling complete and uniform coating while maintaining process simplicity
Solution Approach 2:
The patent changes the physical state of pitch from solid to dissolved/dispersed state in alkaline solution. This parameter change allows the pitch to flow into and coat the graphite particle surfaces and gaps more effectively, achieving complete coverage without requiring complex processing equipment
2Manufacturing precision
If CVD method is used to prepare pyrolytic carbon-coated graphite, then coating completeness is improved, but cost becomes too high
Solution Approach 1:
The patent replaces the expensive CVD process with a simple liquid-phase coating method using alkaline solution and pitch. This disposable, low-cost chemical approach achieves comparable or better coating completeness without requiring expensive CVD equipment or complex process control
Solution Approach 2:
The patent substitutes the mechanical/thermal CVD process with a chemical solution-based approach. Instead of using high-temperature vapor deposition, the pitch is delivered dissolved in alkaline solution, allowing coating to occur through chemical interaction and simple drying, dramatically reducing equipment and operational costs
3Manufacturing precision
If liquid phase coating method is used to coat pitch on graphite, then coating penetration is improved, but agglomeration occurs after heat treatment
Solution Approach 1:
The patent performs preliminary uniform mixing of pitch with alkaline solution before coating the graphite particles. This pre-dispersion ensures that pitch is evenly distributed in the coating solution, preventing localized concentration that would lead to agglomeration during subsequent heat treatment
Solution Approach 2:
The patent controls the concentration and pH parameters of the alkaline solution to optimize pitch dissolution and coating uniformity. By adjusting these parameters, the pitch forms a thin, even coating that dries uniformly without agglomerating during heat treatment
4Reliability
If amorphous carbon is used as coating material, then protective shell is formed, but electrochemical performance is low requiring additional conductive agents
Solution Approach 1:
The patent changes the structural parameters of the carbon coating by using pitch as precursor, which upon heat treatment forms a more ordered carbon structure compared to amorphous carbon. This structural transformation inherently improves electrical conductivity, eliminating the need for additional conductive agents while maintaining protective function
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 method results in a composite material with enhanced cycle stability and rate capability, reducing stripping and cracking risks, and improving conductivity and reversible capacity, making it suitable for lithium-ion batteries.
Implementation Method 1
mixing graphite, a surfactant and alkali liquor to obtain dispersion
Implementation Method 2
mixing the dispersion, water-soluble mesophase pitch and an alcohol solvent, performing precipitation reaction
Implementation Method 3
sequentially performing first pyrolysis and second pyrolysis on the precursor in a protective gas to obtain the pitch-based graphite composite material
Data Source
AI summary
A pitch-based graphite composite material, a preparation method therefor and an application thereof are provided. The graphite is coated with pitch gel spheres, and a core-shell composite structure of pitch carbon microsphere coated graphite is obtained through pyrolysis and carbonization, so that the contact between a graphite surface and an electrolyte can be effectively reduced, a stable SEI film can be generated, and the SEI film has good rate and cycle performance. In addition, a porous structure formed by gas generated by pyrolysis and carbonization is beneficial to the transportation of lithium ions, the conductivity and reversible capacity of the material can be significantly improved, the material is more stable in the charging and discharging processes of the lithium-ion battery, the risks of stripping and cracking are effectively reduced, and the cycle stability and the rate capability of the battery are improved.