Seite - 117 - in Emerging Technologies for Electric and Hybrid Vehicles

Energies 2017,10, 1314 Figure7.Salespriceofbattery I. 3.5.2. Battery II—CostCalculation Thissectionwillquantify the impactofusingsilicon-basedbatteries,withahigherenergydensity, comparedto theclassicalNMCcombinedwithgraphite. Thedifferencebetweenthe twoismainly in thenegativeelectrodewhichusessiliconalloy insteadofgraphite.Manyvarietiesof siliconbased lithium-ionbatteriesareavailable,however theones inwhichsilicon isusedasanalloyare themost promising.Asabaseline the followingpatentWO2016089666A1[50]willbeusedformakingasilicon alloywithhighlifetimeandhighenergydensity. Theexactcalculationof thecompositionof thisactive material composed fromrawmaterials is shown inTable7. Theother components suchasbinder, conductiveagentsarekeptconstant. Inrealitydifferentmaterialsarerequired,however inasimilar quantityandatacomparablecostexplainingwhythesecostarekeptcon. Tocalculate the total costperkWhofbattery II the increasedenergydensityof thepackshould be taken into account. For battery I and battery II receptively the following energydensities are used155Wh/kgand205Wh/kg. This is an increaseof 33%whichcanbeexpected frommaterial calculations. Siliconhasa10 timeshigher theoretical capacity thangraphite, butamixture isused as shownby its composition. The cost breakdown is visualized inFigure 8 inwhich thenegative electrode cost isdecreased from24%forbattery I to 19%forbattery II. Themain impacthowever comesfromthehigherenergydensityexplainingasignificantly lowercostofsiliconbasedbatteries comparedtopNMC.Thismakesa total salespriceof456Dollar/kWhcomparedto431dollar/kWh fromNMC,visualized inFigure9. This is largepricereductionof30%.However it shouldbestated that thisbattery isnotyetacommercialproductandsomeextraresearchshouldbedoneto increase its lifetime. Table7.Anodeactivematerialbattery II—detailed. Material Amount Price in2015(kg) (Dollar) Si73FeI7C10 0.6 2.76 Graphite 0.128 1.25 Carbonnanotubes 0.16 4.17 Carboxymethylcellulose 0.032 2.96 LiPAA 0.08 11.25 Total 1 22.39 117