Shen, Brian H. | Search NASA

DOE OSTI2019

Shear activated impact resistant electrolyte

A passively impact resistant composite electrolyte composition includes an electrolyte solvent, up to 6M of an electrolyte salt, and shear thickening ceramic particles having an outer surface. The shear thickening ceramic particles have an absolute zeta potential of greater than ±40 mV. The shear thickening ceramic particles have a polydispersity index of no greater than 0.1, and an average particle size of in a range of 50 nm to 1 um. The ceramic particles have bonded to the outer surface steric stabilizing polymers. The steric stabilizing polymers have a chain length of from 0.5 nm to 100 nm. A passively impact resistant laminated battery and a method of making the electrolyte composition are also disclosed.

Veith, Gabriel M.↗

DOE OSTI2018

Silicon Surface Tethered Polymer as Artificial Solid Electrolyte Interface

Here, we have developed a proof of concept electrode design to covalently graft poly(methyl methacrylate) brushes directly to silicon thin film electrodes via surface-initiated atom transfer radical polymerization. This polymer layer acts as a stable artificial solid electrolyte interface that enables surface passivation despite large volume changes during cycling. Thin polymer layers (75 nm) improve average first cycle coulombic efficiency from 62.4% in bare silicon electrodes to 76.3%. Average first cycle reversible capacity was improved from 3157 to 3935 mAh g -1 , and average irreversible capacity was reduced from 2011 to 1020 mAh g -1 . Electrochemical impedance spectroscopy performed on silicon electrodes showed that resistance from solid electrolyte interface formation increased from 79 to 1508 Ω in untreated silicon thin films over 26 cycles, while resistance growth was lower – from 98 to 498 Ω – in silicon films functionalized with PMMA brushes. The lower increase suggests enhanced surface passivation and lower electrolyte degradation. This work provides a pathway to develop artificial solid electrolyte interfaces synthesized under controlled reaction conditions.

36 MATERIALS SCIENCE↗