Preparation And Performance Study Of Three-dimensional Tree-like Microporous Layer In The Passive Micro Direct Methanol Fuel Cell

Micro direct methanol fuel cell(μDMFC)has the unique advantages of high specific energy density,environmental friendliness and small volume,which meets the strong demand of intelligent microelectronics for the rapid change of power and volume.However,with the continuous improvement of the integration and miniaturization of micro-energy systems,the management of reaction products in μDMFC electrodes is facing more Strict technical challenges.The microporous layer is the only way for substances to exchange from the inside of the electrode to the outside,and its microstructure has a significant influence on the material transfer and electron migration in the electrode.At present,conductive carbon black is generally used in the microporous layer of commercial μDMFC,and its structure and function are relatively simple,which limits the comprehensive performance of the electrode.Therefore,this paper proposes a tree-like microporous layer based on the three-dimensional carbon nanotube framework,and conducts a systematic study on the design and manufacture of threedimensional tree-like carbon nanostructures,the test and evaluation of the electrode characteristics of the tree-like microporous layer,and the impact on the electrochemical performance of μDMFC.Through magnetron sputtering technology and medium temperature chemical vapor deposition technology,carbon nanotubes were deposited on the surface of pre-formed Fe nanoparticles to prepare a carbon nanotube structure with three-dimensional micropores.According to AFM,SEM,RAMAN and TEM characterization methods,the microscopic morphology and phase composition of Fe nano-particles and tree-like carbon nanotube framework structure were identified to reveal the mechanism of the formation of the tree-like carbon nanotube microstructure.Elemental analysis showed that tree-like carbon nanotubes were mainly formed by the bottom growth pattern.The chemical vapor deposition process parameters were adjusted to prepare tree-like microporous layers with different structural characteristics.Through the SEM test,the fourprobe resistivity test,and the surface contact angle test,the microscopic morphology,porosity,conductivity,hydrophobicity and other key electrode characteristics of the tree-like microporous layer were systematically studied,and the excellent role of the tree-like microstructure in promoting the electrode function was analyzed.Through the transfer and ultrasonic spraying process,the membrane electrode based on the three-dimensional tree-like microporous layer were prepared.By comparing the difference in electrode characteristics between the tree-like microporous layer and the traditional microporous layer,we focused on analyzing the unique characteristics of the membrane electrode in terms of power performance,EIS characteristics,dynamic response characteristics,electrode product management,etc.Eventually,we revealed the influence and mechanism of the three-dimensional tree-like microporous layer on the electrochemical performance of the battery.At low methanol concentration,the maximum power density of the three-dimensional tree-like microporous layer battery was increased by 19.5% compared to the ordinary battery,and it exhibited better dynamic response characteristics due to its lower cathode charge Transfer impedance.