Surface modification of carbon fibers by electroless tungsten deposition for enhanced electrochemical stability of Lead-Carbon interface

摘要

Energy storage plays a key role in the power management and broader use of renewable energy.The Electrochemical battery owns quick charge/discharge ability and high storage capacity is common used to store electric power.According to the report by the Sandia US national laboratory,a new battery design,known as the hybrid lead carbon battery formed by electronically connecting in parallel a traditional lead-acid battery and an asymmetric electrochemical supercapacitor,which provides a viable and economical method for energy storage.However,metals can't be well wetted on the carbon surfaces.Thus the metal contact of carbon electrode of hybrid lead carbon battery is usually assembled mechanically and gives rise to high contact resistance in use and eventually results in the battery will fail.In this study,we present an easy and facile method to form electrochemically stable lead-carbon interface by using Tungsten carbides as a buffer layer to enhance the wetting of the lead on carbon materials.Luthin etc.found that carbon films on tungsten substrates could form small amount of WC at 870 k,therefore if Tungsten(W)could be deposited on the surface of Carbon fibers,which will act as an anchor for catching Pb.In our experiments,the carbon fibers after Pb electroplating were modified by electroless W plating,and then were heated at vacuum to form chemical bonding at lead-carbon interface.The experimental results reveal there are many Pb particles with 100-200 nrn size uniformly dispersed on the surface of carbon fibers.Fig.1 and 2 are the SEM photos and SEM/EDS analysis of Pb/W/Carbon,separately.The SEM morphology shows that most Pb particles were tiny and did not agglomerate on the surface of carbon fibers,the results confirm that Pb-C interface has good adhesion.The chemical composition of Pb/W/Carbon Fibers lists at Fig.2,including Pb and W,the others like Sn,P and Na came from electroless plating,C and O should be Carbon fiber and Oxidation of carbon or lead.