Guar Gel Binders for Silicon Nanoparticle Anodes: Relating Binder Rheology to Electrode Performance.

Binding agents are a critical component of Si-based anodes for lithium-ion batteries. Herein, we introduce a composite hydrogel binder consisting of carbon black (CB) and guar, which is chemically cross-linked with glutaraldehyde as a means to reinforce the electrode structure during lithiation and improve electronic conductivity. Dynamic rheological measurements are used to monitor the cross-linking reaction and show that rheology plays a significant role in binder performance.

Vacancy-induced manganese vanadates and their potential application to Li-ion batteries.

We report on the synthesis and characterization of a novel manganese vanadate, Mn1.5(H2O)(NH4)V4O12, with rare in situ disorder of Mn(H2O)2(2+)/2NH4(+). We show that vacancies created by ammonium ions and coordinating water molecules within the manganese vanadate crystal structure yield high-charge capacity, favorable rate capability, and long cycle life in Li-ion half-cells.

Hierarchical Graphene-Containing Carbon Nanofibers for Lithium-Ion Battery Anodes.

We present a method to produce composite anodes consisting of thermally reduced graphene oxide-containing carbon nanofibers (TRGO/CNFs) via electrospinning a dispersion of polyacrylonitrile (PAN) and graphene oxide (GO) sheets in dimethylformamide followed by heat treatment at 650 °C. A range of GO (1-20 wt % GO relative to polymer concentration) was added to the polymer solution, with each sample comprising similar polymer chain packing and subsequent CNF microstructure, as assessed by X-ray diffraction. An increase from 0 to 20 wt % GO in the fibers led to carbonized nonwovens with enhanced electronic conductivity, as TRGO sheets conductively connected the CNFs.

Electrospun Ultrafine Fiber Composites Containing Fumed Silica: From Solution Rheology to Materials with Tunable Wetting.

Fumed silica (FS) particles with hydrophobic (R805) or hydrophilic (A150) surface functionalities are incorporated in polyacrylonitrile (PAN) fibers by electrospinning to produce mats with controlled wettability. Rheological measurements are conducted to elucidate the particle-polymer interactions and characterize the system while microscopic and analytic tools are used to examine FS location within both fibers and films to aid in the fundamental understanding of wetting behavior. Unlike traditional polymers, we find these systems to be gel-like, yet electrospinnable; the fumed silica networks break down into smaller aggregates during the electrospinning process and disperse both within and on the surface of the fibers.