Graphite Anode Composite Coating for High-Power Li-Ion Batteries
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Solution Overview
Problem
Existing negative electrode materials, such as artificial graphite and hard carbon, suffer from low energy density and high cost, failing to meet the high-power performance requirements of lithium ion batteries used in 3C products and vehicles, and existing composite coated graphite materials also exhibit low power density and high cost.
Innovation Solution
A composite coating layer is applied to a graphite core, comprising a second graphite inner layer of microcrystals and an amorphous carbon outer layer, leveraging their synergistic effects to enhance capacity and power performance while maintaining low cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If artificial graphite or hard carbon is used as high-power negative electrode material, then power performance is improved, but energy density decreases and cost increases
Solution Approach 1:
The patent applies composite materials by combining graphite microcrystals with amorphous carbon to form a dual-layer coating on natural graphite particles. The graphite microcrystal layer provides high power performance and conductivity, while the amorphous carbon layer contributes to high energy density and capacity, achieving synergistic effects that resolve the contradiction between power performance and energy density
Solution Approach 2:
The patent implements local quality by creating distinct layers with different properties on the surface of natural graphite particles. The graphite microcrystal layer is applied locally to enhance conductivity and power performance at the surface, while the amorphous carbon layer provides bulk energy storage capacity, allowing different regions of the electrode material to optimize for different functions
2Power
If artificial graphite or hard carbon is used as high-power negative electrode material, then power performance is improved, but manufacturing cost increases
Solution Approach 1:
The patent uses natural graphite as the core material, which is abundant and inexpensive compared to artificial graphite or hard carbon. By coating the natural graphite core with relatively thin layers of graphite microcrystals and amorphous carbon, the patent achieves high power performance while keeping the bulk of the material (the core) as a low-cost component
Solution Approach 2:
The composite structure allows the use of inexpensive natural graphite as the primary material (over 90% by mass), combined with smaller amounts of functional coating materials that provide the necessary power performance enhancement at minimal cost increase
3Reliability
If single-layer coating is applied to graphite core, then one performance aspect is improved, but overall power performance and capacity are limited
Solution Approach 1:
The patent segments the coating into two distinct functional layers: an inner graphite microcrystal layer and an outer amorphous carbon layer. Each layer is optimized for specific functions - the graphite microcrystal layer provides conductivity and structural stability, while the amorphous carbon layer enhances capacity and surface reactivity, together achieving superior overall performance that neither layer could provide alone
Solution Approach 2:
The dual-layer composite coating structure combines materials with complementary properties to overcome the limitations of single-layer coatings. The graphite microcrystals provide a crystalline framework for stability and conductivity, while the amorphous carbon provides a disordered structure with high surface area for lithium ion insertion, creating a synergistic system with enhanced power density and capacity
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 composite coating layer achieves high capacity, low irreversible capacity, and excellent power performance, suitable for large-scale industrial production, overcoming the limitations of single-layer coatings.
Implementation Method 1
The graphite microcrystal in the inner layer has a higher gram capacity, which can increase the gram capacity of the coating layer. The amorphous carbon of the outer layer has a low irreversible capacity, which can improve the first-time efficiency of the coating layer.
Data Source
AI summary
The present application provides a negative electrode material, a preparation method thereof, and a lithium ion battery. The negative electrode material comprises a first graphite core and a composite coating layer coated on the first graphite core. The composite coating layer comprises a second graphite inner layer formed on the surface of the first graphite core and an amorphous carbon outer layer formed on the surface of the second graphite inner layer. The second graphite inner layer is graphite microcrystal. The preparation method comprises: mixing the first graphite and the second graphite and performing the coating treatment to obtain the first graphite coated with the second graphite, wherein the second graphite is graphite microcrystals; and making the first graphite coated with the second graphite, coated with carbon, to obtain the negative electrode material. The negative electrode material provided in the present application utilizes the mutual cooperation between the second graphite inner layer and the amorphous carbon outer layer in the composite coating layer to make the negative electrode material have the high capacity, the low irreversible capacity, and the excellent power performance.