Interface stabilization via lithium bis(fluorosulfonyl)imide additive as a key for promoted performance of graphite‖LiCoO2 pouch cell under -20 ○C.

The effects of lithium bis(fluorosulfonyl)imide, Li[N(SO2F)2] (LiFSI), as an additive on the low-temperature performance of graphite‖LiCoO2 pouch cells are investigated. The cell, which includes 0.2M LiFSI salt additive in the 1M lithium hexafluorophosphate (LiPF6)-based conventional electrolyte, outperforms the one without additive under -20 °C and high charge cutoff voltage of 4.3 V, delivering higher discharge capacity and promoted rate performance and cycling stability with the reduced change in interfacial resistance. Surface analysis results on the cycled LiCoO2 cathodes and cycled graphite anodes extracted from the cells provide evidence that a LiFSI-induced improvement of high-voltage cycling stability at low temperature originates from the formation of a less resistive solid electrolyte interphase layer, which contains plenty of LiFSI-derived organic compounds mixed with inorganics that passivate and protect the surface of the cathode and anode from further electrolyte decomposition and promotes Li+ ion-transport kinetics despite the low temperature, inhibiting Li metal-plating at the anode. The results demonstrate the beneficial effects of the LiFSI additive on the performance of a lithium-ion battery for use in battery-powered electric vehicles and energy storage systems in cold climates and regions.

Approaching the maximum capacity of nickel-rich LiNi0.8Co0.1Mn0.1O2 cathodes by charging to high-voltage in a non-flammable electrolyte of propylene carbonate and fluorinated linear carbonates.

We report a promising approach to achieve the maximum capacity (>230 mA h g-1) and high capacity retention (95% during 100 cycles) of a nickel-rich cathode of LiNi0.8Co0.1Mn0.1O2 (NCM811) by charging to 4.5 V in a non-flammable electrolyte of propylene carbonate and fluorinated linear carbonates. Our electrolyte permits the stabilization of the cathode-electrolyte interface and cathode structure at high-voltage, enabling stable and safe operation of the Ni-rich cathode for high-energy density and high-safety lithium-ion and lithium metal batteries.

Encapsulation and Functionalization of Nanoparticles in Crosslinked Resorcinarene Shells.

Two resorcinarene-derived tetrathiols with terminal alkene sidechains (tetraarylthiol cavitand 3 and tetrabenzylthiol cavitand 4) were determined to be efficient at extracting colloidal gold nanoparticles from aqueous solutions and stabilizing their dispersion in organic solvents. Treatment of these nanoparticle dispersions with the Grubbs olefin metathesis catalyst resulted in crosslinked resorcinarene shells that were highly resistant to alkanethiol-induced desorption at high temperatures. Nanoparticles in crosslinked shells of tetrabenzylthiol cavitand 4 were particularly robust, and could be precipitated and redispersed many times with minimal attrition. These shells could also withstand oxidative conditions and were amenable to synthetic modifications involving epoxidation and dihydroxylation.