Influence of Electrolyte on the Electrode/Electrolyte Interface Formation on InSb Electrode in Mg-Ion Batteries

Abstract

Achieving the full potential of magnesium-ion batteries (MIBs) is still a challenge due to the lack of adequate electrodes or electrolytes. Grignard-based electrolytes show excellent Mg plating/stripping, but their incompatibility with oxide cathodes restricts their use. Conventional electrolytes like bis(trifluoromethanesulfonyl)imide ((Mg(TFSI)2) solutions are incompatible with Mg metal, which hinders their application in high-energy Mg batteries. In this regard, alloys can be game changers. The insertion/extraction of Mg2+ in alloys is possible in conventional electrolytes, suggesting the absence of a passivation layer or the formation of a conductive surface layer. Yet, the role and influence of this layer on the alloys performance have been studied only scarcely. To evaluate the reactivity of alloys, we studied InSb as a model material. Ex situ X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy were used to investigate the surface behavior of InSb in both Grignard and conventional Mg(TFSI)2/DME electrolytes. For the Grignard electrolyte, we discovered an intrinsic instability of both solvent and salt against InSb. XPS showed the formation of a thick surface layer consisting of hydrocarbon species and degradation products from the solvent (THF) and salt (C2H5MgCl−(C2H5)2AlCl). On the contrary, this study highlighted the stability of InSb in Mg(TFSI)2 electrolyte.

Unveiling the electronic properties of native solid electrolyte interphase layers on Mg metal electrodes using local electrochemistry

“…C 1s and O 1s spectra reveal the presence of inorganic (MgCO 3 , MgO and Al 2 O 3 ) 10,34 and organic (tetrahydrofuran decomposition products) compounds. 32,35 Furthermore, the Mg 1s spectrum was fitted with two separate peaks for inorganic Mg-based moieties (MgCO 3 , MgO) and traces of APC species (C–Mg–Cl). 36…”

“…The Cl doublet (198.5 and 200.2 eV) was assigned to metal chloride moieties such as C-Mg-Cl and AlCl 3, which fall in the same binding energy range. 32,33 These peaks can be attributed to the presence of residual electrolyte species. However, Tutusaus et al did not report Cl-species aer soaking Mg metal samples in APC for 12 h. 11 The Al 2p spectrum is dominated by Al 2 O 3 , which cannot be associated with residual APC electrolyte.…”

“…† C 1s and O 1s spectra reveal the presence of inorganic (MgCO 3 , MgO and Al 2 O 3 ) 10,34 and organic (tetrahydrofuran decomposition products) compounds. 32,35 Furthermore, the Mg 1s spectrum was tted with two separate peaks for inorganic Mg-based moieties (MgCO 3 , MgO) and traces of APC species (C-Mg-Cl). 36 Considering the Mg/TFSI and Mg/BOR samples, the deconvolution of F 1s spectra showed a peak at 1305.4 eV which indicates the formation of MgF 2 on the surface of the Mg disks (blue area in Fig.…”

“…It is plausible that Al-containing anions in the electrolyte are reduced in contact with Mg metal to Al 0 , which is further oxidised to Al 2 O 3 during sample preparation for the characterisation. 25,32 XPS spectra for C, O and Mg were collected as shown in Fig. S4 † with a detailed peak assignment described in Section S5 in the ESI.…”

InSb: A Stable Cycling Anode Material Enables Fast Charging of Li-Ion Batteries at Sub-zero Temperatures

“…It can be further lithiated at low potential (below 0.6 V), thus providing more capacity. However, the specific lithium storage mechanism is not clear so far, and the volume effect and temperature effect on the InSb anode have not yet been reported. − …”