Carbon Nanotube-Graphite Composite Anode for Lithium-Ion Batteries
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Solution Overview
Problem
Lithium ion batteries face issues with the expansion and contraction of lithium alloys during charging/discharging cycles, leading to cracking and delamination of the anode material, which reduces the battery's lifespan.
Innovation Solution
A composite anode material is created by bonding carbon nanotubes to graphite via graphitization, forming a carbon-carbon composite that enhances mechanical strength and electrical conductivity, thereby preventing delamination and increasing cycle life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional graphite anode is used, then the battery structure is simple and manufacturing is easy, but the anode cracks and delaminates during charging/discharging cycles due to expansion and contraction
Solution Approach 1:
The patent applies composite materials by combining carbon nanotubes with graphite particles to form a hybrid anode structure. The carbon nanotubes are dispersed in a binder material and mixed with graphite particles, creating a composite that leverages the mechanical strength and flexibility of nanotubes while maintaining the electrochemical performance of graphite, thereby preventing cracking and delamination during cycling
Solution Approach 2:
The patent employs carbon nanotubes as flexible structural elements that can accommodate the expansion and contraction of lithium alloy during charging and discharging. The nanotubes act as flexible reinforcement within the anode matrix, allowing the structure to deform elastically without cracking, thus maintaining structural integrity throughout battery cycles
2Duration of action of stationary object
If carbon nanotubes are added to graphite to form composite, then mechanical strength and cycle life are improved, but manufacturing process becomes more complex
Solution Approach 1:
The patent applies preliminary action by pre-dispersing carbon nanotubes in a binder material before mixing with graphite particles. This pre-dispersion step ensures uniform distribution of nanotubes throughout the binder, preventing agglomeration and simplifying subsequent processing steps, thereby making the overall manufacturing process more manageable despite the added complexity of the composite formulation
3Quantity of substance
If lithium alloy expansion is allowed during charging, then battery capacity is maximized, but anode material cracks and loses electrical contact
Solution Approach 1:
The patent applies parameter changes by modifying the mechanical properties of the anode material through the addition of carbon nanotubes. The nanotubes change the stress-strain characteristics of the anode, enabling it to withstand the volumetric expansion and contraction associated with lithium insertion and extraction, thus maintaining both high capacity and structural integrity throughout the battery lifecycle
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 carbon-carbon composite anode material significantly reduces cracking and delamination, resulting in improved cycle life and extended battery lifespan with less than 5% capacity loss after 500 charging and discharging cycles.
Implementation Method 1
graphitizing the carbon nanotubes and the graphite particles to form a carbon-carbon composite in which the carbon nanotubes are bonded to the graphite particles
Implementation Method 2
the expansion and contraction of the lithium alloy during a charging/discharging cycle
Data Source
AI summary
An improved anode material for a lithium ion battery is disclosed. The improved anode material can improve both electric conductivity and the mechanical resilience of the anode, thus drastically increasing the lifetime of lithium ion batteries.