Modified Carbon Nanotubes for Battery Conductive Agents
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Solution Overview
Problem
Conventional conductive agents in lithium batteries, such as carbon black and graphene, face issues with conductivity and mechanical stability due to poor contact between active substances, and carbon nanotubes suffer from mechanical weakness and high cost.
Innovation Solution
A method involving multiple acid treatments and reaction with polyethylene glycol forms a 'bridging' structure within carbon nanotubes, enhancing their mechanical properties and conductivity by reducing diameter and forming dedicated lithium ion transport channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional conductive agents (carbon black, conductive graphite) are used, then the contact form is point-to-point which increases contact between active substances, but the conductivity is poor and mechanical stability is insufficient
Solution Approach 1:
The patent changes the physical and chemical parameters of carbon nanotubes through acid treatment (nitric acid, sulfuric acid, hydrochloric acid) and temperature control (65-75°C for 10-14 hours), transforming them into modified carbon nanotubes with improved conductivity and mechanical stability, resolving the contradiction between conductive performance and mechanical strength
Solution Approach 2:
The patent creates a composite structure by combining modified carbon nanotubes with polyethylene glycol through chemical bonding, forming a hybrid material that exhibits both excellent conductivity and enhanced mechanical properties, thereby simultaneously improving reliability and strength
2Reliability
If carbon nanotubes are used as conductive agents, then the conductivity is significantly improved, but the mechanical property is poor and they suffer from mechanical weakness
Solution Approach 1:
The patent applies multiple acid treatments (nitric acid oxidation, sulfuric acid-hydrochloric acid mixed acid treatment) to modify the surface and internal structure of carbon nanotubes, changing their physical and chemical parameters to achieve both high conductivity and improved mechanical strength, eliminating the mechanical weakness while preserving electrical conductivity
Solution Approach 2:
The patent introduces polyethylene glycol as an intermediary substance that chemically bonds with modified carbon nanotubes, acting as a reinforcing agent that enhances mechanical properties while maintaining the conductive network, thus resolving the contradiction between conductivity and mechanical strength
3Reliability
If graphene-based conductive agents are used, then the conductive performance is better due to higher contact area, but the cost is expensive and therefore limited in use
Solution Approach 1:
The patent replaces expensive graphene-based conductive agents with modified carbon nanotubes, which are cheaper alternatives that can be effectively modified through acid treatment and polyethylene glycol bonding to achieve comparable or superior conductive performance, thereby reducing cost while maintaining reliability
Solution Approach 2:
The patent enhances the performance of cost-effective carbon nanotubes through chemical modification (acid treatment and polyethylene glycol grafting), changing their physical and chemical parameters to achieve high conductivity comparable to graphene, thus providing a low-cost solution with excellent conductive performance
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 modified carbon nanotubes exhibit improved tensile strength and conductivity, preventing peeling during battery charging and discharging, thereby optimizing lithium battery performance and cycle stability.
Implementation Method 1
adding carbon nanotubes in a nitric acid solution to react at 65°C to 75°C for 10 h to 14 h, followed by washing and drying to obtain carboxylated carbon nanotubes
Implementation Method 2
adding the carboxylated carbon nanotubes in a first mixed acid solution to react for 10 h to 14 h, followed by washing and drying to obtain first inner wall-carboxylated carbon nanotubes, wherein the first mixed acid solution is a mixed solution of concentrated nitric acid and concentrated hydrochloric acid
Implementation Method 3
mixing the second inner wall-carboxylated carbon nanotubes, a polyethylene glycol, a dispersing agent, and water to obtain a mixed system, controlling a pH of the mixed system to be 1 to 4, and reacting the mixed system under reflux in presence of nitrogen at 78°C to 85°C for 3 h to 5 h
Data Source
Figure 1~2
Figure 3~4
AI summary
Modified carbon nanotubes, A method for preparing the same, a negative electrode slurry, and a battery are provided. The method includes: carboxylating carbon nanotubes; adding the carboxylated carbon nanotubes in a first mixed acid solution to obtain first inner wall-carboxylated carbon nanotubes; adding the first inner wall-carboxylated carbon nanotubes in a second mixed acid solution to obtain second inner wall-carboxylated carbon nanotubes; and mixing the second inner wall-carboxylated carbon nanotubes and a polyethylene glycol to obtain the modified carbon nanotubes.