Understanding and Engineering Interfacial Adhesion in Solid-State Batteries with Metallic Anodes.

High performance alkali metal anode solid-state batteries require solid/solid interfaces with fast ion transfer that are morphologically and chemically stable upon electrochemical cycling. Void formation at the alkali metal/solid-state electrolyte interface during alkali metal stripping is responsible for constriction resistances and hotspots that can facilitate dendrite propagation and failure. Both externally applied pressures (35-400 MPa) and temperatures above the melting point of the alkali metal have been shown to improve the interfacial contact with the solid electrolyte, preventing the formation of voids.

Toward an Understanding of SEI Formation and Lithium Plating on Copper in Anode-Free Batteries.

"Anode-free" batteries present a significant advantage due to their substantially higher energy density and ease of assembly in a dry air atmosphere. However, issues involving lithium dendrite growth and low cycling Coulombic efficiencies during operation remain to be solved. Solid electrolyte interphase (SEI) formation on Cu and its effect on Li plating are studied here to understand the interplay between the Cu current collector surface chemistry and plated Li morphology.

Establishing Ultralow Activation Energies for Lithium Transport in Garnet Electrolytes.

Garnet-type structured lithium ion conducting ceramics represent a promising alternative to liquid-based electrolytes for all-solid-state batteries. However, their performance is limited by their polycrystalline nature and inherent inhomogeneous current distribution due to different ion dynamics at grains, grain boundaries, and interfaces. In this study, we use a combination of electrochemical impedance spectroscopy, distribution of relaxation time analysis, and solid-state nuclear magnetic resonance (NMR), in order to understand the role that bulk, grain boundary, and interfacial processes play in the ionic transport and electrochemical performance of garnet-based cells.

Thickness-Dependent Characterization of Chemically Exfoliated TiS Nanosheets.

Monolayer TiS is the lightest member of the transition metal dichalcogenide family with promising applications in energy storage and conversion systems. The use of TiS has been limited by the lack of rapid characterization of layer numbers via Raman spectroscopy and its easy oxidation in wet environment. Here, we demonstrate the layer-number-dependent Raman modes for TiS.

Interfacial charge separation in Cu2O/RuO(x) as a visible light driven CO2 reduction catalyst.

We employ transient absorption spectroscopy to record the absorption spectrum of photogenerated charge carriers in Cu2O. We have found that CO2 reduction in Cu2O is limited by fast electron-hole recombination. The deposition of RuOx nanoparticles on Cu2O results in a twofold increased yield of long-lived electrons, indicating partially reduced electron-hole recombination losses.

Efficient Suppression of Electron-Hole Recombination in Oxygen-Deficient Hydrogen-Treated TiO Nanowires for Photoelectrochemical Water Splitting.

There is an increasing level of interest in the use of black TiO prepared by thermal hydrogen treatments (H:TiO) due to the potential to enhance both the photocatalytic and the light-harvesting properties of TiO. Here, we examine oxygen-deficient H:TiO nanotube arrays that have previously achieved very high solar-to-hydrogen (STH) efficiencies due to incident photon-to-current efficiency (IPCE) values of >90% for photoelectrochemical water splitting at only 0.4 V vs RHE under UV illumination.