Match!
Aaron Michael Chockla
University of Texas at Austin
Inorganic chemistryChemistryMaterials scienceLithium-ion batteryGermanium
19Publications
15H-index
1,123Citations
What is this?
Publications 17
Newest
#1Kyle C. Klavetter (University of Texas at Austin)H-Index: 17
#2Sean M. Wood (University of Texas at Austin)H-Index: 7
Last. C. Buddie MullinsH-Index: 53
view all 11 authors...
Abstract We report stable, high capacity cycling performance over 2500 deep cycles at variable C -rates (1 C , 5 C and 10 C ) for slurry-cast Li-ion battery anodes made using commercially-available germanium nanopowder. The determining factor in cycling performance was the use of fluoroethylene carbonate (FEC) rather than ethylene carbonate (EC) as a co-solvent in the electrolyte. Cycling tests for the FEC-based electrode showed stable performance close to 700 mAh g −1 through 500 cycles at 10 C...
76 CitationsSource
#1Timothy D. Bogart (University of Texas at Austin)H-Index: 12
#2Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 3 authors...
Lithium ion batteries with significantly higher energy and power density desired for new personal electronic devices, electric vehicles, and large-scale energy storage, require new materials. This review focuses on the replacement of the graphite anode with silicon or germanium. Si and Ge both have significantly higher Li storage capacities than graphite, but also undergo significant volumetric expansion and contraction during lithiation and delithiation. Si and Ge nanomaterials can tolerate the...
46 CitationsSource
#1Xiaotang Lu (University of Texas at Austin)H-Index: 15
#2Justin T. Harris (University of Texas at Austin)H-Index: 11
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 5 authors...
Germanium (Ge) nanowires can be grown using either gold (Au) or nickel (Ni) seeds in a supercritical solvent; however, the quality and yield of the nanowires is much higher using Au seeds and diphenyl germane (DPG) as a reactant under typical reaction conditions. We find that the addition of monophenylsilane (MPS) dramatically improves the yield and quality of Ni-seeded Ge nanowires, producing straight nanowires with relatively uniform diameter and nearly 100% conversion of DPG to Ge. MPS partic...
19 CitationsSource
#1Paul R. Abel (University of Texas at Austin)H-Index: 10
#2Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
Last. C. Buddie Mullins (University of Texas at Austin)H-Index: 53
view all 8 authors...
Both silicon and germanium are leading candidates to replace the carbon anode of lithium ions batteries. Silicon is attractive because of its high lithium storage capacity while germanium, a superior electronic and ionic conductor, can support much higher charge/discharge rates. Here we investigate the electronic, electrochemical and optical properties of Si(1-x)Gex thin films with x = 0, 0.25, 0.5, 0.75, and 1. Glancing angle deposition provided amorphous films of reproducible nanostructure and...
88 CitationsSource
#1Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
#2Vincent C. Holmberg (University of Texas at Austin)H-Index: 14
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 3 authors...
Optical extinction spectra were measured for dispersions of germanium (Ge) nanorods produced by arrested solution–liquid–solid (SLS) growth using bismuth (Bi) seeds. Peaks in the real (n) and imaginary (k) parts of the complex index of refraction of Ge give rise to an absorbance peak at ∼600 nm, which shifts to slightly longer wavelengths with increased aspect ratio. Discrete dipole approximation calculations of absorption and scattering cross sections reveal that the length-dependent optical pr...
7 CitationsSource
#1Vincent C. Holmberg (University of Texas at Austin)H-Index: 14
#2Timothy D. Bogart (University of Texas at Austin)H-Index: 12
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 5 authors...
The optical properties of free-standing nonwoven silicon (Si) and germanium (Ge) nanowire fabrics, including diffuse and specular reflectance, diffuse and direct transmittance, and absorptance spectra, were measured using an integrating sphere to account fully for all incident photons. Very thin, 50 μm thick, sheets with ∼90% void volume have extremely high optical densities. They are optically opaque across nearly all wavelengths from ultraviolet to near-infrared, and only minimal light penetra...
21 CitationsSource
#1Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
#2Kyle C. Klavetter (University of Texas at Austin)H-Index: 17
Last. Brian A. KorgelH-Index: 76
view all 4 authors...
A tin (Sn)-seeded supercritical fluid–liquid–solid (SFLS) synthesis of silicon (Si) nanowires with trisilane reactant was developed. When used as anodes in lithium ion (Li-ion) batteries, films of the nanowires with poly(vinylidene) fluoride (PVdF) or sodium alginate (NaAlg) binder, carbon conductor, and fluoroethylene carbonate (FEC)-containing electrolyte gave reversible, high charge storage capacities of 1,800 mA h g–1. The nanowires also exhibited relatively good rate capability, with capaci...
82 CitationsSource
#1Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
#2Kyle C. Klavetter (University of Texas at Austin)H-Index: 17
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 4 authors...
Solution-grown germanium (Ge) nanowires were tested as high capacity anodes in lithium ion (Li-ion) batteries. Nanowire films were formulated and cast as slurries with conductive carbon (7:1 Ge:C w/w), PVdF binder and 1.0 M LiPF6 dissolved in various solvents as electrolyte. The addition of fluorethylene carbonate (FEC) to the electrolyte was critical to achieving stable battery cycling and reversible capacities as high as 1248 mA h g–1 after 100 cycles, which is close to the theoretical capacit...
124 CitationsSource
#1Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
#2Timothy D. Bogart (University of Texas at Austin)H-Index: 12
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 6 authors...
The effects of binder, electrolyte, and presence of gold (Au) seeds on the performance of silicon (Si) nanowire anodes in Lithium (Li)-ion batteries were systematically examined. Large irreversible capacity loss, poor performance at cycle rates of C/5 and faster, and significant capacity fade were observed when excess Au was not removed from the Si nanowires. Battery stability was very poor when poly (vinylidene fluoride) (PVdF) binder and common carbonate electrolytes, ethylene carbonate, dimet...
61 CitationsSource
#1Aaron Michael Chockla (University of Texas at Austin)H-Index: 15
#2Matthew G. Panthani (University of Texas at Austin)H-Index: 22
Last. Brian A. Korgel (University of Texas at Austin)H-Index: 76
view all 9 authors...
Binder-free graphene-supported Ge nanowires, Si nanowires, and Si nanocrystals were studied for use as negative electrode materials in rechargeable lithium ion batteries (LIBs). Graphene obtained from reduced graphene oxide (RGO) helped stabilize electrochemical cycling of all of the nanomaterials. However, differential capacity plots revealed competition between RGO and Si/Ge lithiation. At high Si/Ge loading (>50% w/w) and low cycle rates ( C/10), RGO lithiation begins to dominate. Under those...
71 CitationsSource
12