Graphite Anode Composition for Fast Charging and High-Temperature Cycle Life
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Solution Overview
Problem
Existing negative electrode materials in lithium batteries face issues such as volume expansion leading to structural damage, capacity fading, safety concerns, and limitations in energy density and fast-charging capabilities, necessitating the development of a novel active material to enhance performance.
Innovation Solution
A negative electrode active material comprising two types of graphite with controlled depressurization rebound rate, Dn10 ratio, particle size distribution width, and Dv50 particle size, ensuring high particle packing density and electrolyte wetting, thereby addressing lithium plating and enhancing high-temperature cycle life while balancing charging capability and energy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If silicon-based materials are used as negative electrode material to increase capacity, then the theoretical specific capacity increases significantly, but the volume expansion causes severe structural damage and sharp decline in cycle life
Solution Approach 1:
The patent embeds silicon-based active material particles inside hollow graphite shells, creating a nested structure where silicon is contained within graphite. This allows silicon to provide high capacity while graphite maintains structural stability during cycling, resolving the contradiction between capacity and cycle life.
Solution Approach 2:
The patent employs hollow graphite shells as flexible containers that can accommodate silicon's volume expansion during lithiation. The shell structure provides mechanical flexibility to absorb expansion stress while maintaining structural integrity, preventing pulverization and preserving cycle life.
2Quantity of substance
If metal oxides are used as negative electrode material to increase capacity, then the theoretical specific capacity and electron transfer reaction sites increase, but capacity fading and safety concerns occur
Solution Approach 1:
The patent creates composite structures combining metal oxide particles with graphite shells or coatings. The metal oxide provides high capacity while the graphite component provides structural stability and prevents capacity fading, resolving the contradiction between capacity and reliability.
3Reliability
If graphite is used as negative electrode material to ensure high electrical conductivity and stable potential, then the cycle life is good, but the capacity is relatively close to the limit
Solution Approach 1:
The patent merges graphite's structural advantages with silicon's high capacity characteristics. By combining these two materials in a nested or composite structure, the resulting electrode achieves both the cycle life of graphite and the high capacity of silicon, resolving the contradiction between reliability and quantity of substance.
4Speed
If particle size is reduced to improve charging capability, then the charging rate increases, but the particle packing density decreases
Solution Approach 1:
The patent optimizes particle size parameters to achieve a balance between charging capability and packing density. By carefully controlling particle size distribution and using hollow structures, the patent maintains sufficient packing density while ensuring adequate charging rates through optimized diffusion paths.
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 achieves improved electrical contact, increased energy density, and extended cycle life by optimizing graphite particle properties, reducing lithium plating, and enhancing electrolyte penetration, resulting in better performance in secondary batteries, battery modules, and electrical devices.
Implementation Method 1
In lithium batteries, the negative electrode material plays a key role in storing and releasing lithium ions
Implementation Method 2
Graphite is one of the most common negative electrode materials for lithium batteries, which has high electrical conductivity
Data Source
AI summary
A negative electrode active material, and a preparation method therefor and a use thereof. The negative electrode active material comprises a graphite material, and the graphite material comprises first graphite and second graphite. Two types of graphite having a certain pressure-relief rebound rate are selected, and are combined with a Dn10 range controlled and a distribution width limited. A negative electrode sheet can have high particle packing density and compaction level, so that good electrical contact between negative electrode active materials and sufficient infiltration of an electrolyte can both be ensured, thereby prolonging high-temperature cycle life while considering charging capability and energy density.