Reversible Cycling of Graphite Electrodes in Propylene Carbonate Electrolytes Enabled by Ethyl Isothiocyanate

Abstract

As one of the greatest inventions in the history of electrochemistry, the lithium-ion battery (LIB) has radically transformed human beings’ daily life by powering portable electronics and electric vehicles. When we look back upon the long and arduous effort devoted to the development of the LIB technology, it is found that the birth of LIBs could have been even earlier if reversible cycling of the graphite electrode had been realized in the propylene carbonate (PC) electrolyte, one of the few dominating electrolytes extensively used in nonaqueous electrochemistry long before the concept of LIBs. In this work, a functional electrolyte additive, that is, ethyl isothiocyanate, has been identified to enable the reversible Li+ ion intercalation/de-intercalation into/out of the graphite electrode in PC electrolyte by forming a high-quality solid electrolyte interphase (SEI) on the graphite electrode. A wide range of advanced in situ and ex situ spectroscopic characterization techniques coupled with theoretical calculations have been employed to understand the SEI formation mechanism. The results reported here rejuvenate the promise of PC as the primary electrolyte solvent for LIBs by artificially rectifying the interfacial electrochemical processes.

Development, retainment, and assessment of the graphite-electrolyte interphase in Li-ion batteries regarding the functionality of SEI-forming additives

“…Targeting particular elements, NMR spectroscopy could be implemented to characterize the formed SEI on graphite anode; however, a low signal-to-noise ratio of measurement may cause some limitations ( Hall et al., 2017 ; Wang et al., 2019 ). Vibrating spectroscopy including Fourier transform infrared spectroscopy (FT-IR) and Raman analysis could provide valuable surface information in order to investigate SEI composition ( Li et al., 2021 ; Nanda et al., 2019 ) but several shortcomings such as weak vibration signals in thin films, hard peak detection due to the inhomogeneous nature of the SEI, and appearance of similar functional groups from different components may limit the precision of measurement ( Verma et al., 2010 ). Tracking changes among absorption bands in different operating conditions such as temperature ( Saqib et al., 2018 ) and voltage ( Rikka et al., 2018 ) is an approach to study affecting parameters on SEI composition.…”

“…Added to EC-based electrolytes, this type of additive has been used in PC-based electrolytes to protect the graphite against exfoliation and give reversibility to the lithium intercalation process. Introducing ethyl isothiocyanate (EITC) to a PC-based electrolyte has led to the formation of a polymeric structure containing N=C–S units which have improved the cyclability of the electrode by protecting the electrolyte from an extended co-intercalation/decomposition process ( Li et al., 2021 ).…”

Phase Change Materials for Life Science Applications

“…The enhancement of the sensor was due to in situ thermal management derived from its PCM core of the electroactive microcapsule. [ 95 ] In another study, an intelligent glucose biosensor was designed by microencapsulating n ‐docosane in SiO 2 , and depositing polydopamine/carbon nanotube as an electroactive layer to detect glucose at high temperatures. The authors evaluated the thermal characteristics temperature at a maximum degradation rate using a differential thermogravimetric (DTG) thermogram that reflects the thermal stability of a material.…”

Exploring the Effects of Dopamine and DMMP Additives on Improving the Cycle Boosting and Nonflammability of Electrolytes in Full-Cell Lithium-Ion Batteries (18650)

“…LIBs can disperse heat naturally at slower rates using the thermal effect. − Impurities such as chlorine, water, and HF significantly affect the performance (eqs –), dendrite formation, and electrolyte stability, where elevated temperatures mainly produce large amounts of hydrofluoric acid (HF). − Typically, heat is released from the electrolyte when trace impurities in the water initiate the thermal decomposition of the electrolyte. − LiPF 6 ↔ LiF + PF 5 PF 5 + normalH 2 normalO → OPF 3 + 2 HF OPF 3 + 2 x Li + + 2 x normale − → Li x PF 3 − x normalO + x LiF OPF 3 + 3 normalH 2 normalO → PO 4 normalH 3 + 3 HF The instability of the internal components, such as the flammable organic electrolyte, is the immediate cause of thermal runaway issues, resulting in nonflammable, nontoxic, and good interfacial electrode adherence. It inhibits Li dendrite growth, and highly conducting electrolytes can mitigate such risks. − ...…”