Designing Low‐Concentration Propylene Carbonate‐based Electrolyte by Manipulating Lithium⁺‐Solvation Structure for Graphite Anode

Abstract

We systematically study the correlation between Li+‐solvation structure, interfacial stability, and electrochemical behavior in the system of graphite anode with low‐concentration (0.5 M) propylene carbonate (PC)‐based electrolyte (LCPE). 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropylether (TTE) [or 1,1,2,2‐tetrafluoroethyl‐2,2,2‐trifluoroethyl ether (HFE)] is used to manipulate the solvation structures of Li+ in the LCPEs. Varying Li+‐solvation structures are realized by changing the volume ratios of PC to TTE (or HFE) in the LCPEs. With the increase of TTE (or HFE) dosages, the relative contents of LiF and LixPOyFz in SEI derived from normalPnormalF6- increase, while the decomposition products of PC reduce. With enough TTE (or HFE) in the LCPE, the Li||graphite cell exhibits reversible (de)lithiation without PC co‐intercalation and continuous electrolyte decomposition due to the shield of a compact SEI rich in LiF and LixPOyFz. Our work proves it is practicable to achieve LiF‐riched SEIs on graphite anodes and realize reversible (de)lithiation in LCPEs by regulating the Li+‐solvation structures with inert cosolvents.

Tuning the Electrolyte and Interphasial Chemistry for All‐Climate Sodium‐ion Batteries

“…[20] The finding is further supported by the Raman spectroscopic study. The EC/PC/EP electrolyte shows two distinct Raman peaks in the solvent band that unambiguously correspond to the solvated PC (852 cm −1 ) and solvated EP (864 cm −1 ) [21] (Figure 1e). The moderate Na + ‐solvation resulted from the low‐polarity EP solvent can lead to reduced Na + ‐desolvation energy and facilitate reaction kinetics at low temperatures [18] .…”

Rational Design of the Li+-Solvation Structure Contributes to Constructing a Robust Cathode-Electrolyte Interphase for a 5 V High-Voltage LiNi0.5Mn1.5O4 Cathode

“…42 With the addition of TTE, the signals of LiF and Li x PO y F z strengthen, suggesting that the addition of TTE promotes the involvement of anions in the CEI formation process. 43 It has been demonstrated that a LiFrich CEI can effectively restrain parasitic reactions between the cathode and the electrolyte, thereby improving the cycle stability and rate performance of LIBs. 38,44,45 In addition, the signal of lattice oxygen in the O 1s spectrum increases as TTE content grows.…”

Does Salt Concentration Matter? New Insights on the Intercalation Behavior of PF6−${\rm{PF}}_6^ - $ into Graphite Cathode for the Dual‐Ion Battery

“…The inert cosolvent 1,1,2,2‐tetrafluoroethyl‐2,2,3,3‐tetrafluoropropyl ether (TTE) was utilized to manipulate the solution structure as we mentioned in previous works. [ 10,11 ] The solution structures in the 1M‐ET11 and 1M‐ET12 electrolyte should be similar with the 2M‐E and 3M‐E electrolyte, respectively. The onset potential for $${\rm{PF}}_6^ - $$ intercalation within the graphite cathode, the cycle and rate performances of Li||graphite and graphite||graphite cells, and the evolution of graphite intercalation compounds (GICs) in each electrolyte were systematically investigated.…”