Carbon Nanotube Masterbatch Dispersion in Li-Ion Electrodes
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Solution Overview
Problem
The introduction of carbon nanotubes into liquid formulations for Li-ion battery electrodes is hindered by high viscosity and low stability, limiting their practical use due to aggregation, and they pose safety concerns as agglomerated powders with unknown toxicological properties.
Innovation Solution
A masterbatch in agglomerated solid form containing 15-40% carbon nanotubes or nanofibers and 1-40% polymer binder, with a binder/carbonaceous filler mass ratio less than 2, is developed for efficient dispersion and integration into electrodes, allowing for higher carbon nanotube content and improved safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carbon nanotubes are dispersed directly in liquid formulations, then electrical conductivity is improved, but viscosity increases and stability decreases
Solution Approach 1:
The patent uses a masterbatch as an intermediary carrier containing pre-dispersed carbon nanotubes in a polymer matrix. This masterbatch serves as a mediator between the carbon nanotubes and the liquid formulation, allowing indirect introduction of CNTs that avoids direct aggregation issues while maintaining electrical conductivity benefits
Solution Approach 2:
The carbon nanotubes are pre-dispersed and pre-mixed with the polymer binder in the masterbatch before being introduced to the liquid formulation. This preliminary dispersion action prevents aggregation that would occur if CNTs were added directly to the liquid formulation, thereby improving both stability and conductivity
2Reliability
If carbon nanotubes are dispersed directly in liquid formulations, then electrical conductivity is improved, but the formulation becomes highly viscous
Solution Approach 1:
The masterbatch acts as an intermediary that encapsulates carbon nanotubes within a polymer matrix, preventing direct interaction between CNTs and the liquid formulation that would cause high viscosity. This indirect introduction method maintains conductivity while minimizing viscosity increase
Solution Approach 2:
Carbon nanotubes are pre-mixed with the polymer binder in the masterbatch before formulation. This preliminary mixing distributes CNTs uniformly within the polymer matrix, preventing clumping and excessive viscosity when the masterbatch is incorporated into the liquid formulation
3Ease of manufacture
If carbon nanotubes are used in agglomerated powder form, then handling is simplified, but toxicological safety becomes uncertain
Solution Approach 1:
The patent embeds carbon nanotubes within a polymer matrix to create a composite masterbatch material. This composite structure maintains the handling advantages of solid material while encapsulating the CNTs, potentially reducing toxicological risks associated with exposed nanotube surfaces and agglomerated powder forms
4Reliability
If carbon nanotubes are added at higher concentrations, then electrical conductivity improves, but aggregation increases
Solution Approach 1:
The polymer matrix in the masterbatch serves as a protective intermediary that separates and stabilizes carbon nanotubes at higher concentrations. This prevents direct CNT-CNT contact that would lead to aggregation, allowing higher CNT loading while maintaining dispersion stability
Solution Approach 2:
Carbon nanotubes are pre-dispersed in the polymer matrix at the desired high concentration before the masterbatch is incorporated into the liquid formulation. This preliminary dispersion at high concentration prevents aggregation from occurring during subsequent formulation steps, enabling higher CNT content without stability loss
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 masterbatch enables effective and homogeneous dispersion of carbon nanotubes, enhancing electrical conductivity and mechanical support, while reducing safety risks and improving cycling capacity and electrochemical performance of electrodes.
Implementation Method 1
dissolving a powder of the binder polymer in the solvent, to form a solution
Implementation Method 2
efficient and homogeneous dispersion of the carbon nanotubes within the masterbatch and around the active electrode material
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
The present invention relates to a masterbatch in agglomerated solid form comprising: a) carbon nanofibres and/or nanotubes and/or carbon black, the content of which is between 15 wt% and 40 wt%, preferably between 20 wt% and 35 wt%, relative to the total weight of the masterbatch; b) at least one solvent; c) at least one polymer binder, which represents from 1 wt% to 40 wt%, preferably from 2 wt% to 30 wt% relative to the total weight of the masterbatch. The present invention also relates to a concentrated masterbatch, characterized in that it is obtained by eliminating all or part of the solvent from the masterbatch described previously. It also relates to a process for preparing said masterbatches and to the uses of the latter, especially in the manufacture of an electrode or of a composite material for an electrode.