Functionalized Silicon Particles for Enhanced Half- and Full-Cell Cycling of Si-Based Li-Ion Batteries.

Vinylene carbonate (VC) and polyethylene oxide (PEO) have been investigated as functional agents that mimic the solid electrolyte interphase (SEI) chemistry of silicon (Si). VC and PEO are known to contribute to the stability of Si-based lithium-ion batteries as an electrolyte additive and as a SEI component, respectively. In this work, covalent surface functionalization was achieved via a facile route, which involves ball-milling the Si particles with sacrificial VC and PEO.

Additive manufacturing of LiNiMnCoO battery electrode material via vat photopolymerization precursor approach.

Additive manufacturing, also called 3D printing, has the potential to enable the development of flexible, wearable and customizable batteries of any shape, maximizing energy storage while also reducing dead-weight and volume. In this work, for the first time, three-dimensional complex electrode structures of high-energy density LiNiMnCoO (NMC 111) material are developed by means of a vat photopolymerization (VPP) process combined with an innovative precursor approach. This innovative approach involves the solubilization of metal precursor salts into a UV-photopolymerizable resin, so that detrimental light scattering and increased viscosity are minimized, followed by the in-situ synthesis of NMC 111 during thermal post-processing of the printed item.

Understanding the Solution Dynamics and Binding of a PVDF Binder with Silicon, Graphite, and NMC Materials and the Influence on Cycling Performance.

The impact of the binding, solution structure, and solution dynamics of poly(vinylidene fluoride) (PVDF) with silicon on its performance as compared to traditional graphite and LiNiMnCoO (NMC) electrode materials was explored. Through refractive index (RI) measurements, the concentration of the binder adsorbed on the surface of electrode materials during electrode processing was determined to be less than half of the potentially available material resulting in excessive free binder in solution. Using ultrasmall-angle neutron scattering (USANS) and small-angle neutron scattering (SANS), it was found that PVDF forms a conformal coating over the entirety of the silicon particle.

Structure and dynamics of small polyimide oligomers with silicon as a function of aging.

The effect of UV curing and shearing on the structure and behavior of a polyimide (PI) binder as it disperses silicon particles in a battery electrode slurry was investigated. PI dispersant effectiveness increases with UV curing time, which controls the overall binder molecular weight. The shear force during electrode casting causes higher molecular weight PI to agglomerate, resulting in battery anodes with poorly dispersed Si particles that do not cycle well.

LaZrO Nanoparticle-Mediated Synthesis of Porous Al-Doped LiLaZrO Garnet.

In this work, we modified the reaction pathway to quickly (minutes) incorporate lithium and stabilize the ionic conducting garnet phase by decoupling the formation of a La-Zr-O network from the addition of lithium. To do this, we synthesized LaZrO (LZO) nanoparticles to which LiNO was added. This method is a departure from typical solid-state synthesis methods that require high-energy milling to promote mixing and intimate particle-particle contact and from sol-gel syntheses as a unique porous microstructure is obtained.

Role of Low Molecular Weight Polymers on the Dynamics of Silicon Anodes During Casting.

This work probes the slurry architecture of a high silicon content electrode slurry with and without low molecular weight polymeric dispersants as a function of shear rate to mimic electrode casting conditions for poly(acrylic acid) (PAA) and lithium neutralized poly(acrylic acid) (LiPAA) based electrodes. Rheology coupled ultra-small angle neutron scattering (rheo-USANS) was used to examine the aggregation and agglomeration behavior of each slurry as well as the overall shape of the aggregates. The addition of dispersant has opposing effects on slurries made with PAA or LiPAA binder.

XPCS Microrheology and Rheology of Sterically Stabilized Nanoparticle Dispersions in Aprotic Solvents.

X-ray photon correlation spectroscopy (XPCS) microrheology and conventional bulk rheology were performed on silica nanoparticle dispersions associated with battery electrolyte applications to probe the properties of these specific complex materials and to explore the utility of XPCS microrheology in characterizing nanoparticle dispersions. Sterically stabilized shear-thickening electrolytes were synthesized by grafting poly(methyl methacrylate) chains onto silica nanoparticles. Coated silica dispersions containing 5-30 wt % nanoparticles dispersed in propylene carbonate were studied.

Probing clustering dynamics between silicon and PAA or LiPAA slurries under processing conditions.

This work explores the complex interplay between slurry aggregation, agglomeration, and conformation (i.e. shape) of poly(acrylic acid) (PAA) and lithiated poly(acrylic acid) (LiPAA) based silicon slurries as a function of shear rate, and the resulting slurry homogeneity.

Direct Measure of Electrode Spatial Heterogeneity: Influence of Processing Conditions on Anode Architecture and Performance.

In this work, the spatial (in)homogeneity of aqueous processed silicon electrodes using standard poly(acrylic acid)-based binders and slurry preparation conditions is demonstrated. X-ray nanotomography shows segregation of materials into submicron-thick layers depending on the mixing method and starting binder molecular weights. Using a dispersant, or production of dispersant from the cleavage of the binder into smaller molecular weight species, increases the resulting lateral homogeneity while drastically decreasing the vertical homogeneity as a result of sedimentation and separation due to gravitational forces.

Role of Surface Acidity in the Surface Stabilization of the High-Voltage Cathode LiNiMnCoO.

Metal oxide coatings have been reported to be an effective approach for stabilizing cathode interfaces, but the associated chemistry is unclear. In this work, thin films of TiO, ZnO, and CrO, which have different surface acidities/basicities, were used to modify the surface chemistry of LiNiMnCoO and study the acidity's role in the cathode/electrolyte interphase composition and impedance under high-voltage cycling (4.5 V Li/Li).

Palladium Nanoparticle-Enabled Ultrathick Tribofilm with Unique Composition.

There is a consensus that savings of 1.0-1.4% of a country's gross domestic product may be achieved through lubrication R&D.

Improved ZnS nanoparticle properties through sequential NanoFermentation.

Sequential NanoFermentation (SNF) is a novel process which entails sparging microbially produced gas containing HS from a primary reactor through a concentrated metal-acetate solution contained in a secondary reactor, thereby precipitating metallic sulfide nanoparticles (e.g., ZnS, CuS, or SnS).

Shear Thickening Electrolyte Built from Sterically Stabilized Colloidal Particles.

We present a method to prepare shear thickening electrolytes consisting of silica nanoparticles in conventional liquid electrolytes with limited flocculation. These electrolytes rapidly and reversibly stiffen to solidlike behaviors in the presence of external shear or high impact, which is promising for improved lithium ion battery safety, especially in electric vehicles. However, in initial chemistries the silica nanoparticles aggregate and/or sediment in solution over time.

Manufacturing demonstration of microbially mediated zinc sulfide nanoparticles in pilot-plant scale reactors.

The thermophilic anaerobic metal-reducing bacterium Thermoanaerobacter sp. X513 efficiently produces zinc sulfide (ZnS) nanoparticles (NPs) in laboratory-scale (≤ 24-L) reactors. To determine whether this process can be up-scaled and adapted for pilot-plant production while maintaining NP yield and quality, a series of pilot-plant scale experiments were performed using 100-L and 900-L reactors.

In situ capping for size control of monochalcogenide (ZnS, CdS and SnS) nanocrystals produced by anaerobic metal-reducing bacteria.

Metal monochalcogenide quantum dot nanocrystals of ZnS, CdS and SnS were prepared by anaerobic, metal-reducing bacteria using in situ capping by oleic acid or oleylamine. The capping agent preferentially adsorbs on the surface of the nanocrystal, suppressing the growth process in the early stages, thus leading to production of nanocrystals with a diameter of less than 5 nm.

Large-scale delamination of multi-layers transition metal carbides and carbonitrides "MXenes".

Herein we report on a general approach to delaminate multi-layered MXenes using an organic base to induce swelling that in turn weakens the bonds between the MX layers. Simple agitation or mild sonication of the swollen MXene in water resulted in the large-scale delamination of the MXene layers. The delamination method is demonstrated for vanadium carbide and titanium carbonitride MXenes.

Scalable production of microbially mediated zinc sulfide nanoparticles and application to functional thin films.

A series of semiconducting zinc sulfide (ZnS) nanoparticles were scalably, reproducibly, controllably and economically synthesized with anaerobic metal-reducing Thermoanaerobacter species. These bacteria reduced partially oxidized sulfur sources to sulfides that extracellularly and thermodynamically incorporated with zinc ions to produce sparingly soluble ZnS nanoparticles with ∼5nm crystallites at yields of ∼5gl(-1)month(-1). A predominant sphalerite formation was facilitated by rapid precipitation kinetics, a low cation/anion ratio and a higher zinc concentration compared to background to produce a naturally occurring hexagonal form at the low temperature, and/or water adsorption in aqueous conditions.

Optimization of multicomponent aqueous suspensions of lithium iron phosphate (LiFePO4) nanoparticles and carbon black for lithium-ion battery cathodes.

Addition of polyethyleneimine (PEI) to aqueous LiFePO4 nanoparticle suspensions improves stability and reduces agglomerate size, which is beneficial to lithium-ion battery cathode manufacturing. This research examines the effect of both PEI concentration and molecular weight (MW) on dispersing LiFePO4 and Super P C45 in multicomponent aqueous suspensions. It is demonstrated that the optimal conditions for obtaining stable suspensions with minimal agglomerate size are 1.

Optimization of LiFePO4 nanoparticle suspensions with polyethyleneimine for aqueous processing.

Addition of dispersants to aqueous based lithium-ion battery electrode formulations containing LiFePO(4) is critical to obtaining a stable suspension. The resulting colloidal suspensions enable dramatically improved coating deposition when processing electrodes. This research examines the colloidal chemistry modifications based on polyethyleneimine (PEI) addition and dispersion characterization required to produce high quality electrode formulations and coatings for LiFePO(4) active cathode material.