Silicon is well known as the best material for lithium-ion battery anodes. However, up to 400% Si volume change during lithiation results in anode pulverization and loss of electrical contact. In terms of lithiation-delithiation kinetics, numerous studies indicated importance of formation/stoichiometry of the alloys, degree of lithiation vs. time, electrode potential, charge-discharge,  etc. However, understanding the electrochemical kinetics consistent with materials properties is still in progress since during lithiation-delithiation many of the processes are coupled. Thus, enhancement of the Li-ion anode performance can be achieved by introducing novel materials that meet the requirements for the anode transient behavior.The study is focused on improvement of slow charge-discharge kinetics of Si anode in comparison to carbon-based anodes with emphasis of interface electron transfer, electronic conductivity, and Li-ion transport. The results for the silica hollow microspheres and silica aerogels  reduced to silicon by magnesium reduction and modified with resorcinol-formaldehyde polymeric  precursor forming thin carbon coating will be discussed in regard to transient anode processes. The carbon and silicon porosity, Si content, conductivity, and the carbon film thickness will be adjusted by changing RF-SiO2 ratio, SiO2 sphere diameter and wall thickness, and Mg reduction conditions in Mg vapor phase.Characterization by HRTEM, XRD, Raman, and SEM will be described followed by the discussion of kinetic electrochemical studies. Charge/ discharge, capacity retention, differential capacity, Coulombic efficiency, and internal lithiation behavior of the Si phase will be compared for identification of coupled physicochemical processes on Si-anodes.

Silicon-based anodes for the next generation of lithium-ion batteries

246th National Meeting (2013)

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