Graphite Negative Electrode Material with Metal Oxide Coating for Lithium Ion Battery
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Solution Overview
Problem
Conventional lithium-ion batteries with graphitized carbon negative electrodes suffer from structure degradation and reduced discharge capacity during high current charging-discharging processes due to instability in aqueous electrolytes, leading to poor cycle performance.
Innovation Solution
A method involving a solvothermal reaction of graphite materials with modifier precursors in organic solvents, followed by drying and heat treatment, to form a negative electrode material with improved lithium ion migration and stability, using modifiers like aluminum oxide, titanium oxide, and heat treatment temperatures between 250°C to 900°C.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional graphitized carbon negative electrode materials are used in lithium-ion batteries, then the batteries can achieve low cost and easy control of synthesis processes, but the carbon negative materials react with the electrolyte to form unstable solid-electrolyte interface, leading to structure degradation and poor cycle performance during high current charging-discharging processes
Solution Approach 1:
The patent applies composite materials by combining graphite particles with metal oxide coating layers (such as TiO2, Al2O3, SiO2, ZrO2, or B2O3) to create a composite negative electrode material. The metal oxide coating forms a stable solid-electrolyte interface that prevents structure degradation during high current charging-discharging cycles, while maintaining the low cost and ease of manufacture associated with conventional graphite materials.
Solution Approach 2:
The patent changes the chemical composition parameters of the electrode surface by introducing metal oxide coatings with specific properties. The metal oxide layers have different electrochemical stability, ion conductivity, and surface energy characteristics compared to pure graphite, which modifies the solid-electrolyte interface properties to improve cycle performance while maintaining manufacturing feasibility.
2Reliability
If surface treatment is applied by coating graphite negative material with metal or metal oxide, then the solid-electrolyte interface stability and electrode surface chemical properties are improved, but the interlayer structure of the graphite negative material cannot be improved to increase the migration rate of lithium ions between graphite layers
Solution Approach 1:
The patent applies local quality by creating a metal oxide coating layer with specific thickness and composition on the surface of graphite particles. The coating is designed to be thin enough (controlling the thickness parameter) to allow lithium ion diffusion through the interlayer structure while providing sufficient surface stability. This localized modification at the surface level improves solid-electrolyte interface stability without significantly blocking lithium ion transport pathways.
3Ease of manufacture
If conventional coating methods are used with organic solvent and water mixtures, then the coating process is simple, but the coating uniformity and adhesion are insufficient, leading to poor performance improvement
Solution Approach 1:
The patent changes the solvent system parameters from conventional organic solvent-water mixtures to specific organic solvents (such as N,N-dimethylformamide, N-methyl-2-pyrrolidone, dimethyl sulfoxide, or their mixtures with water). This parameter change in the solvent composition improves the dissolution characteristics of metal oxide precursors and enhances coating uniformity and adhesion to graphite surfaces, while maintaining the simplicity of the dip-coating process.
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 enhances the cycle stability and high current charge-discharge performance of lithium-ion batteries by forming a stable solid-electrolyte interface and increasing interlamellar spacing for faster lithium ion migration, reducing dendrite formation and maintaining capacity over extended cycles.
Implementation Method 1
a solvothermal reaction of a graphite material and a modifier precursor in an organic solvent is conducted to form a reaction product
Implementation Method 2
the reaction product is dried
Implementation Method 3
a heat treatment is applied to the dried reaction product to obtain the negative electrode material
Data Source
AI summary
A method for preparing a negative electrode material of a lithium ion battery is provided. In the method, a solvent-thermal reaction of a graphite material and a modifier precursor in an organic solvent is conducted to form a reaction product. And then, the reaction product is dried. Next, a heat treatment is applied to the dried reaction product to obtain the negative electrode material. The negative electrode material prepared by the method has improved cycle stability and high current performance.