Density functional theory research on the reduction mechanism for the solvent/additive in sodium ion battery.
Liu Q1, Mu D2, Wu B, Wang L, Gai L, Wu F.
ChemSusChem. 2016 Nov 29. doi: 10.1002/cssc.201601356. [Epub ahead of print]
Solid electrolyte interface (SEI) film in Na-ion battery is closely related to capacity fading and cycling stability of the battery. However, there is less study on SEI film of Na-ion battery and the mechanism of SEI film formation is unclear. The mechanism for the reduction of ethylene carbonate (EC), propylene carbonate (PC), vinylene carbonate (VC), ethylene sulfite (ES), 1,3-propylene sulfite (PS) and fluorinated ethylene carbonate (FEC) is studied by density functional theory (DFT) method. The reaction activation energy, Gibbs free energies and enthalpies, structures of the transition states etc. are calculated. It is indicated that VC, ES and PS additives in the electrolyte are all easier to form organic components in anode SEI film by one electron reduction. It is exhibited that the priority of one electron reduction to produce organic SEI components is in order: VC>PC>EC, two-electron to produce inorganic Na2CO3 component is different in order: EC>PC>VC. The two-electron reduction for sulfites ES and PS to form inorganic Na2SO3 is harder than that of carbonate esters reduction. It is also suggested that one electron and two electrons reductive decomposition path for FEC is more possible to produce inorganic NaF components.© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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