Mauro Pasta
Associate Professor of Materials
+44 1865 283324
My research interests lie in electrochemical energy storage and conversion, with an emphasis on:
1) Energy storage: Li and Na-ion batteries, grid-scale energy storage.
2) Energy conversion: power from salinity gradients (blue energy), seawater desalination and delithiation.
3) Electrocatalysis: organic molecules electroxidation, ORR and HER reactions, carbon dioxide sequestration and electroreduction.
Research Group website https://www.pastagroup.org
New Postgraduate Research Projects Available
Selected Publications
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Paving the Way toward Highly Efficient, High-Energy Potassium-Ion Batteries with Ionic Liquid Electrolytes
2020|Journal article|Chemistry of Materials -
Outlook on K-ion Batteries
2020|Journal article|Chem -
2020 roadmap on solid-state batteries
2020|Journal article|Journal of Physics: Energy -
Filling vacancies in a Prussian blue analogue using mechanochemical post-synthetic modification.
2020|Journal article|Chem Commun (Camb)Mechanochemical grinding of polycrystalline powders of the Prussian blue analogue (PBA) Mn[Co(CN)6]2/3□1/3·xH2O and K3Co(CN)6 consumes the latter and chemically modifies the former. A combination of inductively-coupled plasma and X-ray powder diffraction measurements suggests the hexacyanometallate vacancy fraction in this modified PBA is reduced by approximately one third under the specific conditions we explore. We infer the mechanochemically-driven incorporation of [Co(CN)6]3- ions onto the initially-vacant sites, coupled with intercalation of charge-balancing K+ ions within the PBA framework cavities. Our results offer a new methodology for the synthesis of low-vacancy PBAs. -
Understanding the conversion mechanism and performance of monodisperse FeF2 nanocrystal cathodes.
2020|Journal article|Nature materialsThe application of transition metal fluorides as energy-dense cathode materials for lithium ion batteries has been hindered by inadequate understanding of their electrochemical capabilities and limitations. Here, we present an ideal system for mechanistic study through the colloidal synthesis of single-crystalline, monodisperse iron(II) fluoride nanorods. Near theoretical capacity (570 mA h g-1) and extraordinary cycling stability (>90% capacity retention after 50 cycles at C/20) is achieved solely through the use of an ionic liquid electrolyte (1 m LiFSI/Pyr1,3FSI), which forms a stable solid electrolyte interphase and prevents the fusing of particles. This stability extends over 200 cycles at much higher rates (C/2) and temperatures (50 °C). High-resolution analytical transmission electron microscopy reveals intricate morphological features, lattice orientation relationships and oxidation state changes that comprehensively describe the conversion mechanism. Phase evolution, diffusion kinetics and cell failure are critically influenced by surface-specific reactions. The reversibility of the conversion reaction is governed by topotactic cation diffusion through an invariant lattice of fluoride anions and the nucleation of metallic particles on semicoherent interfaces. This new understanding is used to showcase the inherently high discharge rate capability of FeF2. -
Quantifying the Search for Solid Li-Ion Electrolyte Materials by Anion: A Data-Driven Perspective
2020|Journal article|JOURNAL OF PHYSICAL CHEMISTRY C -
Observation of Interfacial Degradation of Li6PS5Cl against Lithium Metal and LiCoO2 via In Situ Electrochemical Raman Microscopy
2020|Journal article|BATTERIES & SUPERCAPSelectrode-solid electrolyte interface, electrochemistry, in situ Raman microscopy, interfaces, solid-state batteries -
Increasing the electrochemical activity of basal plane sites in porous 3D edge rich MoS2 thin films for the hydrogen evolution reaction
2019|Journal article|Materials Today Energy© 2019 Elsevier Ltd Molybdenum disulfide (MoS2)has been extensively utilized as an electrocatalyst for the hydrogen evolution reaction (HER)with edges as the primary active catalytic sites. Previous work on edge-rich MoS2 nanoplatelet 3D porous films (3D-ER-MoS2)shows they are promising catalysts, yet have basal planes that are inactive. Here we demonstrate how hydrogen annealing and oxygen plasma etching of 3D-ER-MoS2 generates defects and increases active site density within the basal plane, leading to dramatic improvements in HER catalytic activity. We also explore the critical processing parameters for electrocatalytic enhancement. Significantly enriched edge density was revealed for both routes. O2 plasma treatment was more effective in increasing the number of edges by creating micro-cracks and local surface damage on the basal planes as well as structuring saw-toothed edges; H2 etching mainly introduced irregular shaped basal surface nanopores and strips. By controlling processing parameters, optimum surface area/active sites density enhancement can be achieved, together with the robust 3D porous architecture and superaerophobic surface. The defect-rich MoS2 catalysts exhibit excellent HER activity: 700 °C – H2 – MoS2 shows Tafel slope of 94 mV/dec and low onset overpotential of 193 mV; 15 min – O2 – MoS2 performs amongst the best with excellent exchange current density of 57 μA/cmgeo−2. Our defect engineered 3D-ER MoS2 exhibits jgeo (η = 0.5 mV)of 6-fold and 38-fold compared to monolayer MoS2 subject to similar process, for O2 plasma and H2 etching approaches respectively. Our study demonstrates an effective way to realize high performance Pt-free electrocatalysts for hydrogen generation by dual enhancement via edge enrichment and basal surface activation. -
Charge-Free Mixing Entropy Battery Enabled by Low-Cost Electrode Materials.
2019|Journal article|ACS omegaSalinity gradients are a vast and untapped energy resource. For every cubic meter of freshwater that mixes with seawater, approximately 0.65 kW h of theoretically recoverable energy is lost. For coastal wastewater treatment plants that discharge to the ocean, this energy, if recovered, could power the plant. The mixing entropy battery (MEB) uses battery electrodes to convert salinity gradient energy into electricity in a four-step process: (1) freshwater exchange; (2) charging in freshwater; (3) seawater exchange; and (4) discharging in seawater. Previously, we demonstrated a proof of concept, but with electrode materials that required an energy investment during the charging step. Here, we introduce a charge-free MEB with low-cost electrodes: Prussian Blue (PB) and polypyrrole (PPy). Importantly, this MEB requires no energy investment, and the electrode materials are stable with repeated cycling. The MEB equipped with PB and PPy achieved high voltage ratios (actual voltages obtained divided by the theoretical voltages) of 89.5% in wastewater effluent and 97.6% in seawater, with over 93% capacity retention after 50 cycles of operation and 97-99% over 150 cycles with a polyvinyl alcohol/sulfosuccinic acid (PVA/SSA) coating on the PB electrode. -
Effect of the Particle-Size Distribution on the Electrochemical Performance of a Red Phosphorus-Carbon Composite Anode for Sodium-Ion Batteries
2019|Journal article|Energy and Fuels© 2019 American Chemical Society. Red phosphorus (RP) is a promising candidate as an anode for sodium-ion batteries because of its low potential and high specific capacity. It has two main disadvantages. First, it experiences 490% volumetric expansion during sodiation, which leads to particle pulverization and substantial reduction of the cycle life. Second, it has an extremely low electronic conductivity of 10-14 S cm-1. Both issues can be addressed by ball milling RP with a carbon matrix to form a composite of electronically conductive carbon and small RP particles, less susceptible to pulverization. Through this procedure, however, the resulting particle-size distribution of the RP particles is difficult to determine because of the presence of the carbon particles. Here, we quantify the relationship between the RP particle-size distribution and its cycle life for the first time by separating the ball-milling process into two steps. The RP is first wet-milled to reduce the particle size, and then the particle-size distribution is measured via dynamic light scattering. This is followed by a dry-milling step to produce RP-graphite composites. We found that wet milling breaks apart the largest RP particles in the range of 2-10 μm, decreases the Dv90 from 1.85 to 1.26 μm, and significantly increases the cycle life of the RP. Photoelectron spectroscopy and transmission electron microscopy confirm the successful formation of a carbon coating, with longer milling times leading to more uniform carbon coatings. The RP with a Dv90 of 0.79 μm mixed with graphite for 48 h delivered 1354 mA h g-1 with high coulombic efficiency (>99%) and cyclability (88% capacity retention after 100 cycles). These results are an important step in the development of cyclable, high-capacity anodes for sodium-ion batteries.
