Lithium Dendrite Formation in Li/Poly(ethylene oxide)–Lithium Bis(trifluoromethanesulfonyl)imide and N-Methyl-N-propylpiperidinium Bis(trifluoromethanesulfonyl)imide/Li Cells

Abstract

Lithium metal dendrite growth in Li/poly(ethylene oxide)–lithium bis(trifluoromethanesulfonyl)imide (PEOxLiTFSI) and in an ionic liquid, N -methyl- N -propylpiperidinium bis(trifluoromethanesulfonyl)imide (PP13TFSI) composite solid polymer electrolyte/Li was examined by direct in situ observation. Lithium dendrite formation was observed after 15 h of polarization at 0.5mAcm−2 and at 60°C on PEO18LiTFSI . The onset time was increased to 35 h at 0.5mAcm−2 by the addition of PP13TFSI into PEO18LiTFSI up to 1.44 mol. The dendrite onset time decreased with increasing current density and deviated from Sand’s law in the current density range of 0.1–0.5mAcm−2 at 60°C . The electrical conductivity of PEO18LiTFSI was enhanced, and the interface resistance between Li and PEO18LiTFSI was suppressed by the addition of PP13TFSI. The lithium ion transport number of the composite electrolyte decreased with increasing x in PEO18LiTFSI–xPP13TFSI . The suppression of the lithium dendrite formation could be explained by the low resistance of the interface layer between lithium and the composite polymer electrolyte.

Lithium Dendrite Formation on a Lithium Metal Anode from Liquid, Polymer and Solid Electrolytes

“…Liu et al 10 reported a similar relationship between the lithium dendrite onset time and the current density for a Li/PEO based electrolyte/Li cell at 60°C, where a composite polymer electrolyte of PEO 18 LiTFSI and PP13LiTFSI was used. The log R cc vs. log J curve showed good linearity in the range of 0.1 to 1.0 mA cm ¹1 with a slope of ¹1.25.…”

“…In the last 30 years, lithium dendrite formation on the lithium electrode from liquid electrolytes [4][5][6] and polymer electrolytes [7][8][9][10][11] has been widely studied. Lithium deposition on a lithium electrode from a conventional non-aqueous liquid electrolyte used for lithium-ion batteries resulted in lithium dendrite formation for a short period of polarization.…”

Aqueous Lithium-Air Rechargeable Batteries

“…More attractive results were found for a composite of PEO 18 LiTFSI and a room temperature ionic liquid (RTIL) of N-methyl-N-propylpiperidinium-bis(trifluoromethanesulfonyl)imide (PP13TFSI). 22 The temperature dependence of the electrical conductivity for PEO 18 LiTFSI-xPP13TFSI is shown in Fig. 10.…”

“…We prepared a composite polymer electrolyte consisting of PEO 18 LiTFSI and PP13TFSI and examined the dendrite formation in Li/PEO 18 -LiTFSI-xPP13TFSI/Li using direct in situ observation at various current densities. 22 The relationship between lithium dendrite formation and the ionic transport properties of the composite polymer electrolyte is also discussed. 35 Matsumoto et al 36 reported that the LiTFSI ionic liquid in PP13TFSI enables the reversible plating-stripping of lithium metal.…”

“…Figure 13 shows typical impedance profiles for the Li/ PEO 18 LiTFSI/Li and Li/PEO 18 LiTFSI-1.44PP13TFSI/Li cells at 60°C as a function of the storage time. 22 The Li/PEO 18 LiTFSI/Li cell has high cell impedance that increases with the storage time. The Li/PEO 18 LiTFSI-1.44PP13TFSI/Li cell shows low cell impedance and no change with the storage time.…”