Molecular Design Of Humic Acid And Electrochemical Behavior Research

Lead-acid batteries have a long history of 150 years, but are stillreplaceable in the whole storage battery industry for theirparticular advantages. Pushed by a boost of electric vehicles,research on lead-acid battery is becoming a hot topic, since it maybring great significance to the industry development. A commonproblem is low utilization ratio of active substances, especiallythose in negative electrodes, whose performance determinesbattery capacity, although lead-acid battery technology is quitemature. This study is to improve performance of negativeelectrodes by adding humic acid to original negative additives.Electrochemical behavior of humic acid (a new synthetic organicadditive) in charge-discharge course was investigated adopting acyclic voltammetry method, and effects of humic acids withdifferent molecular structures on electrode reaction were observed.The purpose of this study is to provide theoretical basis forselecting novel organic additives by studying effects of molecular structures and active groups of humic acid on electrode structures.This study contained 3 sections as follows:1、Concentration of active substances and functional groupswas determined after purification of humic acids of differentorigins.2、Chemical modification of original humic acid was undergone,then carboxyl contents and molecular weights of original andpost-modification samples were compared, next electrochemicalperformances of sample-based small batteries were determined.3、Humic acids were classified according to their solubility inorganic solvents, and electrochemical performances of differentclassed were determined.This study suggested:Electrochemical performances of humic acids were closelyrelated to their molecular weights and carboxyl contents.Electrochemical performances of batteries were positivelycorrelated to carboxyl contents of humic acids. Charge acceptanceand discharge capacity of batteries increased as carboxyl contentsrose.Electrochemical performances of batteries were positivelycorrelated to molecular weights of humic acids. Charge acceptanceand discharge capacity of batteries increased as molecular weights rose.