Porous Graphite Anode Material for Fast-Charging Li-Ion Batteries
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Solution Overview
Problem
Graphite anode materials in lithium ion batteries suffer from limited reactive areas due to poor liquid absorption performance, leading to insufficient electrochemical active sites, which affects rate performance, capacity, and safety, making it difficult to improve these parameters individually.
Innovation Solution
The anode material is designed with controlled oil absorption value, pore volume, specific surface area, and powder porosity within specific ranges, incorporating amorphous carbon, to enhance lithium ion diffusion pathways and electrochemical reaction interfaces, optimizing the synergistic effect of these properties for improved high-rate charging-discharging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If graphite anode material is used in lithium ion battery, then high electronic conductivity and large lithium ion diffusion coefficient are achieved, but poor liquid absorption performance limits reactive area and electrochemical active sites
Solution Approach 1:
The patent applies porous materials by constructing a hierarchical pore structure within the graphite anode material, including micropores (0.003-0.006 μm), mesopores (0.006-0.06 μm), and macropores (0.06-0.6 μm). This porous structure dramatically increases the reactive area and electrochemical active sites while maintaining the inherent high electronic conductivity of graphite, directly resolving the contradiction between conductivity and reactive area.
Solution Approach 2:
The patent transitions from a traditional dense 2D surface structure to a 3D hierarchical pore network, adding dimensional complexity to the graphite structure. This dimensional transformation creates multiple diffusion pathways and increases the effective reactive area without compromising the basal plane conductivity, effectively resolving the area limitation.
2Stability of the object's composition
If graphite anode material with layered structure is used, then small volume change before and after lithium intercalation is achieved, but limited reactive area results in insufficient electrochemical active sites
Solution Approach 1:
The patent segments the graphite structure into multiple hierarchical levels with distinct pore functions: micropores for lithium ion insertion/extraction, mesopores for electrolyte penetration, and macropores for rapid ion transport. This segmentation creates numerous electrochemical active sites throughout the volume while the overall layered structure maintains small volume change during cycling.
Solution Approach 2:
The patent implements a nested pore structure where micropores are embedded within mesopores, which are in turn embedded within macropores. This nested architecture maximizes the number of electrochemical active sites at different scales while maintaining the compact layered graphite structure that ensures minimal volume expansion during lithium intercalation.
3Quantity of substance
If conventional graphite material is used, then high lithium intercalation capacity is achieved, but poor liquid absorption performance deteriorates rate performance and capacity
Solution Approach 1:
The patent employs porous materials with a specific hierarchical pore structure that enhances liquid absorption performance. The macropores (0.06-0.6 μm) and mesopores (0.006-0.06 μm) provide rapid pathways for electrolyte penetration and lithium ion transport, significantly improving rate performance while the micropores (0.003-0.006 μm) maintain high lithium intercalation capacity.
Solution Approach 2:
The patent utilizes hydraulic principles by designing pore structures that facilitate fluid (electrolyte) flow and absorption. The hierarchical pore network enables capillary action and pressure-driven electrolyte penetration, improving liquid absorption performance and ensuring rapid lithium ion transport throughout the electrode, thereby enhancing both capacity and rate performance.
4Temperature
If graphite anode material is used, then low lithium intercalation potential is achieved, but insufficient reactive area forms lithium deposition and limits battery performance
Solution Approach 1:
The patent applies porous materials with optimized pore size distribution that increases reactive area and promotes uniform lithium ion distribution. This uniform distribution prevents localized lithium deposition by providing numerous alternative reaction sites, thereby maintaining low intercalation potential while improving battery safety and preventing dendrite formation.
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 optimized anode material provides sufficient electrochemical reaction space, enhancing lithium ion diffusion and reducing concentration polarization, thereby improving the rate performance and capacity of the battery.
Implementation Method 1
a large pore volume can increase a diffusion pathway of Li+, and a large specific surface area can ensure a sufficient electrochemical reaction interface, promoting the diffusion of lithium ions in a solid-liquid interface and a solid phase
Implementation Method 2
a large specific surface area can ensure a sufficient electrochemical reaction interface, promoting the diffusion of lithium ions in a solid-liquid interface and a solid phase
Implementation Method 3
An infiltration capacity of the electrolyte is usually reflected by the oil absorption value
Implementation Method 4
the anode material is determined by X-ray diffraction, a crystal plane spacing of a plane (002) is d002, where 3.358 Å≤d002≤3.365 Å, and a crystal plane stacking thickness Lc obtained by the X-ray diffraction is 400 Å to 450 Å
Data Source
AI summary
The present disclosure provides an anode material and a battery. The anode material includes graphite, an interior and/or a surface of the graphite has pores, the anode material has an oil absorption value of O mL/100 g, a pore volume of V cm3/kg, a specific surface area of S m2/g, and a powder porosity of Φ%, where 50≤O*V*S≤391, and 40≤Φ≤58. According to the anode material and the battery provided by the present disclosure, a reaction space capable of performing an effective lithium ion de-intercalation in the anode material is relatively sufficient, improving the high-rate charging-discharging performance of the graphite anode material.