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Stickle, William F.

Publications and source records attributed to Stickle, William F..

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The Role of Alkalis in Orchestrating Uranyl-Peroxide Reactivity Leading to Direct Air Capture of Carbon Dioxide

Spectator ions have known and emerging roles in aqueous metal-cation chemistry, respectively directing solubility, speciation, and reactivity. Here, in this work, we isolate and structurally characterize the last two metastable members of the alkali uranyl triperoxide series, the Rb + and Cs + salts (Cs-U 1 and Rb-U 1 ). We document their rapid solution polymerization via small-angle X-ray scattering, which is compared to the more stable Li + , Na + and K + analogues. To understand the role of the alkalis, we also quantify alkali-hydroxide promoted peroxide deprotonation and decomposition, which generally exhibits increasing reactivity with increasing alkali size. Cs-U 1 , the most unstable of the uranyl triperoxide monomers, undergoes ambient direct air capture of CO 2 in the solid-state, converting to Cs 4 [U VI O 2 (CO 3 ) 3 ], evidenced by single-crystal X-ray diffraction, transmission electron microscopy, and Raman spectroscopy. We have attempted to benchmark the evolution of Cs-U 1 to uranyl tricarbonate, which involves a transient, unstable hygroscopic solid that contains predominantly pentavalent uranium, quantified by X-ray photoelectron spectroscopy. Powder X-ray diffraction suggests this intermediate state contains a hydrous derivative of CsU V O 3 , where the parent phase has been computationally predicted, but not yet synthesized.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Reversible Cl/Cl - redox in a spinel Mn 3 O 4 electrode

A unique prospect of using halides as charge carriers is the possibility of the halides undergoing anodic redox behaviors when serving as charge carriers for the charge-neutrality compensation of electrodes. However, the anodic conversion of halides to neutral halogen species has often been irreversible at room temperature due to the emergence of diatomic halogen gaseous products. Here, we report that chloride ions can be reversibly converted to near-neutral atomic chlorine species in the Mn 3 O 4 electrode at room temperature in a highly concentrated chloride-based aqueous electrolyte. Notably, the Zn 2+ cations inserted in the first discharge and trapped in the Mn 3 O 4 structure create an environment to stabilize the converted chlorine atoms within the structure. Characterization results suggest that the Cl/Cl - redox is responsible for the observed large capacity, as the oxidation state of Mn barely changes upon charging. Computation results corroborate that the converted chlorine species exist as polychloride monoanions, e.g., [Cl 3 ] - and [Cl 5 ] - , inside the Zn 2+ -trapped Mn 3 O 4 , and the presence of polychloride species is confirmed experimentally. Our results point to the halogen plating inside electrode lattices as a new charge-storage mechanism.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Bismuth-Polyoxocation Coordination Networks: Controlling Nuclearity and Dimension-Dependent Photocatalysis

Bismuth-oxocluster nodes for metal–organic frameworks (MOFs) and coordination networks/polymers are less prolific than other families featuring zinc, zirconium, titanium, lanthanides, etc. However, Bi 3+ is non-toxic, it readily forms polyoxocations, and its oxides are exploited in photocatalysis. This family of compounds provides opportunity in medicinal and energy applications. Here, we show that Bi node nuclearity depends on solvent polarity, leading to a family of Bi x -sulfonate/carboxylate coordination networks with x = 1–38. Larger nuclearity-node networks were obtained from polar and strongly coordinating solvents, and we attribute the solvent’s ability to stabilize larger species in solution. Here, the strong role of the solvent and the lesser role of the linker in defining node topologies differ from other MOF syntheses, and this is due to the Bi 3+ intrinsic lone pair that leads to weak node–linker interactions. We describe this family by single-crystal X-ray diffraction (eleven structures), obtained in pure forms and high yields. Ditopic linkers include NDS (1,5-naphthalenedisulfonate), DDBS (2,2'-[biphenyl-4,4'-diylchethane-2,1-diyl] dibenzenesulphonate), and NH 2 -benzendicarboxylate (BDC). While the BDC and NDS linkers yield more open-framework topologies that resemble those obtained by carboxylate linkers, topologies with DDBS linkers appear to be in part driven by association between DDBS molecules. An in situ small-angle X-ray scattering study of Bi 38 -DDBS reveals stepwise formation, including Bi 38 -assembly, pre-organization in solution, followed by crystallization, confirming the less important role of the linker. We demonstrate photocatalytic hydrogen (H 2 ) generation with select members of the synthesized materials without the benefit of a co-catalyst. Band gap determination from X-ray photoelectron spectroscopy (XPS) and UV–vis data suggest the DDBS linker effectively absorbs in the visible range with ligand-to-Bi-node charge transfer. In addition, materials containing more Bi (larger Bi 38 -nodes or Bi 6 inorganic chains) exhibit strong UV absorption, also contributing to effective photocatalysis by a different mechanism. All tested materials became black with extensive UV–vis exposure, and XPS, transmission electron microscopy, and X-ray scattering of the black Bi 38 -framework suggest that Bi o is formed in situ, without phase segregation. This evolution leads to enhanced photocatalytic performance, perhaps due to increased light absorption.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Chloride electrolyte enabled practical zinc metal battery with a near-unity Coulombic efficiency

Rechargeable aqueous zinc batteries are finding their niche in stationary storage applications where safety, cost, scalability and carbon footprint matter most. However, harnessing this reversible two-electron redox chemistry is plagued by major technical issues, notably hydrogen evolution reaction (HER) at the zinc surface, whose impacts are often not revealed under typical measurement conditions. Here we report a concentrated electrolyte design that eliminates this parasitic reaction and enables a Coulombic efficiency (CE) of 99.95% for Zn plating/stripping measured at a low current density of 0.2 mA cm -2 . With extra chloride salts and dimethyl carbonate in concentrated ZnCl 2 electrolyte, the hybrid electrolyte with a unique chemical environment features low Hammett acidity and facilitates the in situ formation of a dual-layered solid electrolyte interphase, protecting zinc anodes from HER and dendrite growth. Benefiting from the near-unity CE, the pouch cell with a VOPO 4 ·2H 2 O cathode sustains 500 deep cycles without swelling or leaking and delivers an energy density of 100 Wh kg -1 under practical conditions. Finally, our work represents a critical step forward in accelerating the market adoption of zinc batteries as an energy storage system with higher sustainability.

25 ENERGY STORAGE↗
DOE OSTI2020

Fluorinated co-solvent promises Li-S batteries under lean-electrolyte conditions

Practical lithium-sulfur batteries stipulate the use of a lean-electrolyte and a high Coulombic efficiency of the lithium metal anode. In this work, we employ 1,1,2,2-tetrafluoroethyl 2,2,2-trifluoroethyl ether as a co-solvent in the electrolyte of Li-S batteries to meet the demands. The co-solvent fosters the formation of a LiF-rich solid electrolyte interphase on lithium metal anode, as revealed by Ab initio molecular dynamics and Femtosecond Stimulated Raman spectroscopy. The co-solvent results in an average Coulombic efficiency of 99.4% for lithium plating/stripping cycles. Full cells with a capacity ratio of 2 between lithium anode and the S@PAN cathode (3 gs cm –2 ) exhibited a stable cycle life over 100 cycles at an electrolyte/sulfur ratio of 2 µL mg –1 , validating the high Coulombic efficiency of the lithium anode and demonstrating the compatibility of the electrolyte with both electrodes. To enhance the energy density, we prepared a hybrid cathode composed of 45 wt.% VS 2 mixed with ZnS-coated Li 2 S@graphene as the cathode. Based on the mass of both electrodes and the electrolyte, the full cell delivers an energy density of 483 Wh kg –1 , which demonstrates viable Li-S batteries with the lean-electrolyte.

25 ENERGY STORAGE↗
DOE OSTI2020

A High-Rate Aqueous Proton Battery Delivering Power Below -78 °C via an Unfrozen Phosphoric Acid

Lithium-sulfur batteries are attractive for automobile and grid applications due to their high theoretical energy density and the abundance of sulfur. Despite the significant progress in cathode development, lithium metal degradation and the polysulfide shuttle remain two critical challenges in the practical application of Li-S batteries. Development of advanced electrolytes has become a promising strategy to simultaneously suppress lithium dendrite formation and prevent polysulfide dissolution. Here, a new class of concentrated siloxane-based electrolytes, demonstrating significantly improved performance over the widely investigated ether-based electrolytes are reported in terms of stabilizing the sulfur cathode and Li metal anode as well as minimizing flammability. Through a combination of experimental and computational investigation, it is found that siloxane solvents can effectively regulate a hidden solvation-ion-exchange process in the concentrated electrolytes that results from the interactions between cations/anions and solvents. As a result, it could invoke a quasi-solid-solid lithiation and enable reversible Li plating/stripping and robust solid-electrolyte interphase chemistries. The solvation-ion-exchange process in the concentrated electrolytes is a key factor in understanding and designing electrolytes for other high-energy lithium metal batteries.

25 ENERGY STORAGE↗