Improved Cycling Performance of a Si Nanoparticle Anode Utilizing Citric Acid as a Surface-Modifying Agent.

Citric acid and its analogues have been investigated as surface-modifying agents for Si nanoparticle anodes using electrochemical cycling, attenuated total reflectance infrared (ATR IR), and X-ray photoelectron spectroscopy (XPS). A Si nanoparticle anode prepared with citric acid (CA) has better capacity retention than one containing 1,2,3,4-butanetetracarboxylic acid (BA), but both electrodes outperform Si-PVDF. The Si-CA anode has an initial specific capacity of 3530 mA h/g and a first cycle efficiency of 82%.

Systematic Investigation of Binders for Silicon Anodes: Interactions of Binder with Silicon Particles and Electrolytes and Effects of Binders on Solid Electrolyte Interphase Formation.

The effects of different binders, polyvinylidene difluoride (PVdF), poly(acrylic acid) (PAA), sodium carboxymethyl cellulose (CMC), and cross-linked PAA-CMC (c-PAA-CMC), on the cycling performance and solid electrolyte interphase (SEI) formation on silicon nanoparticle electrodes have been investigated. Electrodes composed of Si-PAA, Si-CMC, and Si-PAA-CMC exhibit a specific capacity ≥3000 mAh/g after 20 cycles while Si-PVdF electrodes have a rapid capacity fade to 1000 mAh/g after just 10 cycles. Infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS) reveal that PAA and CMC react with the surface of the Si nanoparticles during electrode fabrication.

Solvate structures and spectroscopic characterization of LiTFSI electrolytes.

A Raman spectroscopic evaluation of numerous crystalline solvates with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI or LiN(SO2CF3)2) has been conducted over a wide temperature range. Four new crystalline solvate structures-(PHEN)3:LiTFSI, (2,9-DMPHEN)2:LiTFSI, (G3)1:LiTFSI and (2,6-DMPy)1/2:LiTFSI with phenanthroline, 2,9-dimethyl[1,10]phenanthroline, triglyme, and 2,6-dimethylpyridine, respectively-have been determined to aid in this study. The spectroscopic data have been correlated with varying modes of TFSI(-)···Li(+) cation coordination within the solvate structures to create an electrolyte characterization tool to facilitate the Raman band deconvolution assignments for the determination of ionic association interactions within electrolytes containing LiTFSI.

Tetra-kis(acetonitrile-κN)lithium hexa-fluoridophosphate acetonitrile monosolvate.

In the title compound, [Li(CH(3)CN)(4)]PF(6)·CH(3)CN, the asymmetric unit consists of three independent tetra-hedral [Li(CH(3)CN)(4)](+) cations, three uncoordinated PF(6) (-) anions and three uncoordinated CH(3)CN solvent mol-ecules. The three anions are disordered over two sites through a rotation along one of the F-P-F axes. The relative occupancies of the two sites for the F atoms are 0.

Poly[[(acetonitrile)-lithium(I)]-μ(3)-tetra-fluoridoborato].

The structure of the title compound, [Li(BF(4))(CH(3)CN)](n), consists of a layered arrangement parallel to (100) in which the Li(+) cations are coordinated by three F atoms from three tetra-fluoridoborate (BF(4) (-)) anions and an N atom from an acetonitrile mol-ecule. The BF(4) (-) anion is coordinated to three different Li(+) cations though three F atoms. The structure can be described as being built from vertex-shared BF(4) and LiF(3)(NCCH(3)) tetra-hedra.

Poly[bis-(acetonitrile-κN)bis-[μ(3)-bis(tri-fluoro-methane-sulfonyl)-imido-κO,O':O'':O''']dilithium].

In the title compound, [Li(2)(CF(3)SO(2)NSO(2)CF(3))(2)(CH(3)CN)(2)](n), two Li(+) cations reside on crystallographic inversion centers, each coordinated by six O atoms from bis(trifluoromethanesulfonyl)imide (TFSI(-)) anions. The third Li(+) cation on a general position is four-coordinated by two anion O atoms and two N atoms from acetonitrile mol-ecules in a tetra-hedral geometry.