Reduction of Voltage Delay in the Li / SOCl2 System via Suitable Choice of Electrolyte Salts

Abstract

New electrolyte salts based on the reaction between NbCl5 and either Li2S or Li2O in SOCl2 substantially reduce voltage delay in laboratory half‐cells. The maximum effect was obtained with the NbCl5/Li2S combination. The conductivity of both electrolytes is 13.2×10−3 mho cm−1 at 26°C. Observations with scanning electron microscopy (SEM) show that the anode film formed in the new electrolyte has a different morphology and appears less dense than the film formed in control LiAlCl4 electrolyte. The anodic rate capability of Li is slightly greater, over a range of over‐potentials, in the normalNbCl/Li2S electrolyte than in LiAlCl4 . Atomic absorption, infrared, and x‐ray photoelectron spectroscopy and electrochemical analysis suggest that the salt formed by reacting NbCl5 with Li2S in SOCl2 is either Li2Nb2Cl10S or Li2Nb2Cl12 . The mechanism for reducing voltage delay and affecting anode film morphology is thought to be associated with the nature of the salt's anion, or possibly the SO2 produced when Li2S is combined with the NbCl5 in SOCl2 .

Rechargeable Na/Cl2 and Li/Cl2 batteries

“…We found NaCl coating on Na metal due to reaction with SOCl 2 in both samples, analogous to LiCl formed on Li in Li -SOCl 2 primary batteries (Extended Data Fig. S6a, d) [34][35][36] . Abundant elements of F, N and S, assigned to NaF, Na 2 SO 4 , Na 2 S 2 O 3 , Na 2 SO 3 were observed only on Na in the uoride containing electrolyte, suggesting reactions between Na and anions FSIand TFSIforming a more protective SEI layer on Na (Extended Data Fig.…”

A Rechargeable Na/Cl Battery

“…We found NaCl coating on Na metal due to reaction with SOCl 2 in both samples, analogous to LiCl formed on Li in Li -SOCl 2 primary batteries (Extended Data Fig. S6a, d) [34][35][36] Fig. S6a, b, c) [37][38][39][40] .…”

Microelectrode Studies of the Li/Li+ Couple in SOCl2 / LiAlCl4

“…Several reviews have discussed the Li/SOC12 interface (1-3) and the presence of a "solid electrolyte interphase (SEI)" is generally accepted. The evidence for this model of the interface results mainly from battery discharge experiments (4)(5)(6)(7)(8)(9), particularly the voltage delay phenomenon, as well as small amplitude ac and galvanostatic pulse techniques (10)(11)(12)(13).…”

“…nyl chloride, they have not been used extensively for the investigation of the negative electrode reaction. Interestingly, however, Fleischer et al (9) have shown a cyclic voltammogram which would suggest that the Li/Li ~ couple is rapid in thionyl chloride. One reason for the absence of such studies is the experimental problems resulting from iR drop in solvents such as thionyl chloride (dielectric constant, 9).…”