Aqueous rechargeable battery technologies: from univalent to multivalent systems

Título: Aqueous rechargeable battery technologies: from univalent to multivalent systems
Subtítulo: Li-ion and Na-ion aqueous batteries are rather mature despite issues related to negative electrodes while Zn based technologies still suffer from side reaction bottlenecks.

Rechargeable aqueous electrolyte batteries: from univalent to multivalent cation chemistry
Rezan Demir-Cakan, M. Rosa Palacin, Laurence Croguennec.
J. Mat. Chem. A 7, 20519-20539, 2019
DOI: 10.1039/C9TA04735B

Figure: Scheme depicting the main challenges in multivalent aqueous battery chemistries.

Water is considered the universal solvent and can dissolve large concentrations of diverse ionic compounds.  Its high dielectric constant and low viscosity enable very high ionic conductivity for aqueous electrolytes (~1 S/cm), which is two orders of magnitude higher than those achieved with conventional organic electrolytes and particularly attractive for high power density batteries, since the cation transference numbers are also higher.  Additional advantages of water based electrolytes are lower cost and non-flammability. Their main bottleneck is the limited thermodynamic electrochemical window of water (1.23V), currently being challenged, through the use of highly concentrated electrolytes (“water in salt concept”).  Time is needed to assess whether the concept is efficient using high electrode loadings and if the stability of the Solid Electrolyte Interphase (SEI) formed is enough to grant operation at slow rates without significant corrosion.

Strong research efforts are currently focused on rechargeable aqueous M-ion batteries (M = Li, Na) mimicking the organic electrolyte Li-ion or Na-ion concepts, the main challenge being the development of new negative electrodes able to operate within the water redox stability window. The use of sodium and inexpensive abundant metal based electrode materials (based on Ti or Mn for instance) would add the sustainability perspective. Given the good power rate of the current aqueous M-ion technologies, they may be competitive versus asymmetric supercapacitors in terms of performances, especially if similar cost can be achieved. A more challenging topic is divalent ion concepts (M = Zn) using a Zn metal anode which could, in principle, deliver higher energy density, but for which issues still remain related to developing appropriate positive electrode materials for reversible Zn ion insertion and side reactions involving mostly H+ or OH species, which are not yet mastered.

Bacteria grown thermoelectrics for heat and solar energy harvesting

Título: Bacteria grown thermoelectrics for heat and solar energy harvesting
Subtítulo: This two studies represent our baby-step contributions towards engineering advanced functional materials based on circular economy approaches

Farming thermoelectric paper
Deyaa Abol-Fotouh,  Bernhard Dörling,  Osnat Zapata-Arteaga,  Xabier Rodríguez-Martínez, Andrés Gómez,  J. Sebastian Reparaz,  Anna Laromaine,  Anna Roig, Mariano Campoy-Quiles
Energy & Environmental Science 12, 716-719, 2019
DOI: 10.1039/C8EE03112F

Solar Harvesting: a Unique Opportunity for Organic Thermoelectrics?
José P. Jurado, Bernhard Dörling, Osnat Zapata-Arteaga, Anna Roig, Agustín Mihi, Mariano Campoy-Quiles
Advanced Energy Materials 9, 1902385, 2019
DOI: 10.1002/aenm.201902385

Figure: Bacterials enable the concept of farming thermoelectric materials by growing free standing films of carbon nanotubes embedded within a bacterial cellulose matrix.

Thermoelectric materials allow to directly convert waste heat into electricity without requiring any moving parts. Abundant and non-toxic organic materials present an opportunity towards cheaper renewable energy generation because they can be solution-processed at low temperatures.

Chemical engineering of ferroelectric BiFe1-xCoxO3 thin films with enhanced photo response

Título: Chemical engineering of ferroelectric BiFe1-xCoxO3 thin films with enhanced photo response

Band Gap Tuning of Solution-Processed Ferroelectric Perovskite BiFe1–xCoxO3 Thin Films
Pamela Machado, Mateusz Scigaj, Jaume Gazquez, Estel Rueda, Antonio Sánchez-Díaz, Ignasi Fina, Martí Gibert-Roca, Teresa Puig, Xavier Obradors, Mariano Campoy-Quiles, Mariona Coll
Chem. Mater. 31, 3, 947–954, 2019
DOI: 10.1021/acs.chemmater.8b04380

Figure: Solution processed BiFe1-xCoxO3 ferroelectric perovskite thin films are developed as promising photoactive layer. Band gap tuning is achieved by performing compositional tuning while enhancing ferroelectricity and photo response.

The use of ferroelectric oxide perovskites as a stable photoactive layer has opened up a ground-breaking new arena of research in the field of energy. They can be cheaply produced and present an unconventional photovoltaic mechanism that may surpass the power conversion efficiencies dictated in traditional semiconductors. In this work we demonstrate that the band gap of solution processed BiFeO3 can be tuned towards the visible by exploring the novel substitution of Fe by Co, while enhancing ferroelectricity. Non-optimized vertical devices prove enhanced photo response.

Ferroelectrics for photovoltaics is a young field and composition and interface engineering offer immense potential to further improve device performances. Also, it is envisioned many new opportunities arising from better understanding of the cross-coupling mechanism between light absorption, polarization and electronic properties.

Compositional variability in aerinite changes it from blue to brown

Título: Compositional variability in aerinite changes it from blue to brown

First identification and compositional study of brown aerinite directly on polished thin-sections by synchrotron through-the-substrate microdiffraction 
Anna Crespi, Oriol Vallcorba, Igors Šics, Jordi Rius
European Journal of Mineralogy 31 (5-6): 999–1005, 2019
DOI: 10.1127/ejm/2019/0031-2891

Figure: Photomicrograph under transmitted light of a region of the polished thin section containing a broad stripe of pale-blue aerinite and, in the middle, the brown aerinite zone (size is around 100 μm).

Aerinite is the characteristic blue pigment of Pyrenean Romanesque mural paintings. Although structurally solved by X-ray powder diffraction in 2004, the question if aerinite can display other colors is still open. Application of the through-the-substrate microdiffraction technique (jointly developed by ICMAB and ALBA Synchrotron) to a polished thin-section from Tartareu (Lleida) has confirmed that an Fe-Mn-rich zone observed in this thin-section effectively corresponds to brown aerinite with Fe and Mn partially replacing Al and Ca. This unprecedented result also indicates the tolerance of the aerinite structure type to compositional variability.

Correlation of the crystal structure, transport properties and silver mobility in a mixed silver-copper oxide

Título: Correlation of the crystal structure, transport properties and silver mobility in a mixed silver-copper oxide

Charge Delocalization, Oxidation States, and Silver Mobility in the Mixed Silver−Copper Oxide AgCuO2
Abel Carreras, Sergio Conejeros,  Agustín Camón, Alberto García, Nieves Casañ-Pastor, Pere Alemany, Enric Canadell
Inorganic Chemistry 58, 7026−7035, 2019
DOI: 10.1021/acs.inorgchem.9b00662

Figure: The crystal structure of AgCuO2 is built from the condensation of CuO2 chains and AgO2 units (top left). As a result of an electron transfer between formally Ag+ and Cu3+ d levels a Fermi surface (top right) with Ag and Cu contribution is created leading to a metallic behavior. Such transfer stabilizes oxidized silver and oxidized copper, and the structure may be described as Ag-O planes with intercalated Cu-O chains in between (center down).

The puzzling structural details of the mixed oxide AgCuO2 are shown to be related to a charge transfer between the AgO2 extended units and the CuO2 chains. As a result the system behaves as a metal and the silver atoms form quite stable chains that can easily slide among the CuO2 chains.

Halide perovskites are not ferroelectric

Título: Halide perovskites are not ferroelectric
Subtítulo: Lead halide perovskites are ferroelectricity-free, whereas domains observed in PFM measurements are likely due to twinning driven by strain compensation

Ferroelectricity-free lead halide perovskites
Andrés Gómez, Qiong Wang, Alejandro R. Goñi, Mariano Campoy-Quiles, Antonio Abate
Energy and Environment Science 12, 2537−2547, 2019
DOI: 10.1039/c9ee00884e

Figure: (a) Scheme of the DPFM measurement on a ferroelectric sample with antiparallel domain configuration. The current signal recorded in DPFM should reverse its sign when the tip crosses different domains, depending upon scan direction. (b) DPFM images obtained for periodically poled lithium niobate (PPLN), for which the current sign is reversed as the scan direction changes, exactly as expected for conventional ferroelectric materials. (c) DPFM images of the CsFAMA tri-cation perovskite scanned under similar conditions to those of PPLN. The CsFAMA perovskite does not show any sign reversal, resembling typical current-sensing AFM mappings.  

Ferroelectric materials are characterized by a switchable macroscopic polarization. A wide number of perovskite oxides have ferroelectric behavior. In contrast, the existence of ferroelectricity in organic-inorganic perovskite thin films has been matter of intense debate over the past few years.

Is manganese really inert in Manganese-rich Lithium batteries?

Título: Is manganese really inert in Manganese-rich Lithium batteries?
Subtítulo: Synchrotron light provides an insight on the supposedly inert manganese in the durability of lithium and manganese-rich high energy battery materials

Role of Manganese in Lithium- and Manganese-Rich Layered Oxides Cathodes
Laura Simonelli, Andrea Sorrentino, Carlo Marini, Ramanan, Nitya; Heinis, Dominique; Olszewski, Wojciech; Mullaliu, Angelo; Birrozzi, Agnese; Laszczynski, Nina; Giorgetti, Marco; Passerini, Stefano; Tonti, Dino
Journal of Physical Chemistry Letters 10, (12), 3359–3368, 2019
DOI: 10.1021/acs.jpclett.9b01174

Figure: Semiquantitative molar fractions for different oxidation states obtained from intensities of O and Mn K-edge absorption spectra from bare and coated samples at different charge states along charge (yellow background) and discharge (green) cycles: Ni4+ (a), Mn4+ (b) and Mn4+ vs. Ni 4+.

The environmental challenges issued by the current development of our societies urge a redesign of the whole energy cycle. The intermittence of renewable energies requires storage, and their use in most transport needs a vector with high energy density.

Laser-based synthesis of hybrid supercapacitors with high storage capacity

Título: Laser-based synthesis of hybrid supercapacitors with high storage capacity

Fabrication of graphene-based electrochemical capacitors through reactive inverse matrix assisted pulsed laser evaporation
Ángel Pérez del Pino, Mohamed Ahmed Ramadan, Pablo Garcia Lebière, Raluca Ivan, Constantin Logofatu, Ibraheem Yousef, Enikö György
Applied Surface Science 484, 245-256, 2019
DOI: 10.1016/j.apsusc.2019.04.127

Figure: (a) Assembled device. (b) Galvanostatic charge-discharge curves of symmetric GO-NiO-imidazole device at different current densities. (c) Areal capacitance at different current densities, from galvanostatic charge-discharge data. (d) Areal capacitance at different sweep rates calculated from cyclic voltammetry (CV) data. Inset: CV loop obtained at 100 mV s-1 from asymmetric GO-imi/GO-NiO-imi (-/+) device. (e) Ragone plot of the assembled devices. (f) Capacitance retention and coulombic efficiency (inset) of the devices.


Precursor molecules as citric acid, ascorbic acid and imidazole were added to aqueous dispersions consisting of graphene oxide (GO) platelets and NiO nanoparticles, submitted to UV laser irradiation. The precursor molecules determine the reduction degrees and nitrogen doping of GO platelets transferred to the substrates surface. The nitrogen doped, highly reduced GO/NiO electrodes exhibit enhanced storage capacity and high cycling stability.

Nano-imprinted organic layers for colloidal quantum-dot solar cells

Título: Nano-imprinted organic layers for colloidal quantum-dot solar cells

Nanostructured Back Reflectors for Efficient Colloidal Quantum-Dot Infrared Optoelectronics
Se-Woong Baek, Pau Molet, Min-Jae Choi, Margherita Biondi, Olivier Ouellette, James Fan, Sjoerd Hoogland, F. Pelayo García de Arquer, Agustín Mihi, Edward H. Sargent
Advanced Materials, 31 (33), 1901745, 2019
DOI: 10.1002/adma.201901745

Figure: a) Schematics of the PDMS imprinting process in CQD devices. b) Surface images and line profile of organic layer scanned by AFM after imprinting. Scale bar: 2 μm c) SEM images of organic hole transporting template after imprinting (left) and d) final metal structure deposited onto the organic template. e) Photograph of the pre-patterned PDMS mold (left) and the final IR CQD device after nano-imprinting (right).

In this work, we introduce a patterned organic layer in colloidal quantum-dot (CDQ) solar cells between the CQD solid and back metal electrode. This organic layer has preferred band alignment and suitable hole mobility, enabling it to act as an efficient hole-transport layer (HTL) instead of conventional 1,2-ethanedithiol (EDT)-treated CQD HTL.  In addition, this soft organic layer can be readily molded with soft nano-imprinting lithography and form high quality inverse 2D-photonic structure. The metal coated 2D photonic electrode generates such an efficient light scattering that we achieved a record External Quantum Efficiency (EQE) value of 86 % at 1220 nm.  This value is 20 % higher than previous best reports on IR PCE in CQD solar cells.

On the track for the fabrication of high performance energy storage devices based on 2D graphene, hexagonal boron nitride and molybdenum disulphide materials.

Título: On the track for the fabrication of high performance energy storage devices based on 2D graphene, hexagonal boron nitride and molybdenum disulphide materials
Subtítulo: Intense research is being done for the development of high performance energy storage devices based on 2D layered graphene, hexagonal boron nitride and molybdenum disulphide materials.

A review on synthesis of graphene, h-BN and MoS2 for energy storage applications:  recent progress and perspectives
Rajesh Kumar, Sumanta Sahoo, Ednan Joanni, Rajesh Kumar Singh, Ram Manohar Yadav, Rajiv Kumar Verma, Dinesh Pratap Singh, Wai Kian Tan, Angel Pérez del Pino, Stanislav A. Moshkalev, Atsunori Matsuda
Nano Research 12(11): 2655–2694, 2019
DOI: 10.1007/s12274-019-2467-8

Figure: (a) Scheme of graphene, MoS2 and h-BN for clean energy related applications, particularly, supercapacitors and batteries. (b) SEM image of carbon nanosheets obtained by CVD. (c) HRTEM images of hydrothermally synthesized MoS2 nanosheets. (d) Atomic-scale image of an h-BN film (scale bar = 2 nm).

Currently, graphene and its 2D layered analogue materials, particularly hexagonal boron nitride (h-BN) and molybdenum disulphide (MoS2), are attracting high research interest due to their exceptional functional properties for energy storage applications. Graphene reveals high electric conductivity and surface area, besides excellent mechanical, chemical and electrochemical stability. These properties are key for the development of advanced supercapacitor and battery devices. On the other hand, despite its low electric conductivity, h-BN exhibits outstanding chemical stability and charge storage capacity, showing high potential for secondary batteries. As well, semiconducting MoS2 displays remarkable capabilities for energy storage when combined with conducting polymers and graphene.

Several fabrication routes as chemical vapour deposition, hydro/solvothermal synthesis, wet chemical methods, liquid exfoliation, soft colloidal template approaches, mechanical exfoliation, epitaxial growth, sputtering, or laser-based techniques, are being employed to synthesize high quality materials and integrate them in efficient devices with special attention to scalability. Of significant importance is also the exploration of innovative growth approaches for fine tuning of the materials properties, with the aim of optimizing their functional properties. Thereby, different strategies as chemical doping, intercalation of different types of atoms and molecules, or combination with other nanostructures forming hybrid composites, are being constantly developed.

Regardless of the great advancements reached so far, the commercial exploitation of graphene, h-BN and MoS2 materials in real-world energy storage devices requires the previous resolution of challenges related to morphological optimization of the porous materials, electrochemical interferences, low internal conductivity, and low working potential. These issues, which are being addressed, hamper the great potential of these materials in terms of energy storage capacity and charge-discharge cycling life. This review describes the research strategies deployed for overcoming such drawbacks.

Perovskite gaps ruled by thermal expansion and electron-phonon interaction

Título: Perovskite gaps ruled by thermal expansion and electron-phonon interaction
Subtítulo: In lead halide perovskites, the variation of the fundamental gap with temperature is equally determined by thermal expansion and electron-phonon interaction effects

Equal Footing of Thermal Expansion and Electron-Phonon Interaction in the Temperature Dependence of Lead Halide Perovskite Band Gaps
Adrián Francisco-López, Bethan Charles, M. Isabel Alonso, Miquel Garriga, Mariano Campoy-Quiles, Mark T. Weller, Alejandro Goñi
J. Phys. Chem. Lett. 10, 2971−2977, 2019
DOI: 10.1021/acs.jpclett.9b00876

Figure: Sketch illustrating the contribution from thermal expansion (TE) and electron-phonon interaction (EP) to the temperature-induced renormalization of the perovskite band gap with temperature (data points).  

For all the spectacular developments in lead-halide perovskite-based photovoltaics, there are still several fundamental physical questions that remain a matter of debate. In particular, this is the case of the atypical temperature dependence of the fundamental optical gap of most halide perovskites, for which the gap increases with increasing temperature.

Small pores in the surface of feldspar minerals are responsible of ice formation in the atmosphere

Título: Small pores in the surface of feldspar minerals are responsible of ice formation in the atmosphere
Subtítulo: Environmental scanning electron microscopy images of ice-nucleation on feldspar surfaces, known to be the most efficient ice-nucleation agents present in the atmosphere, showed that nucleation is triggered at pores of the surface

Pores Dominate Ice Nucleation on Feldspars
Elzbieta Pach, Albert Verdaguer
Journal of Physical Chemistry C 123, 34, 20998–21004, 2019
DOI: 10.1021/acs.jpcc.9b05845

Figure: Sequence of enviromental SEM images showing ice nucleation occuring in a surface pore of a k-Feldspar mineral.

The formation of ice, when and how water freezes, is still poorly understood, even though this is essential for understanding Earth’s climate. Knowing more about the molecular mechanisms underlying these processes can help to build atmospheric and climate models with higher confidence.

State-of-the art and challenges in the development of Calcium batteries

Título: State-of-the art and challenges in the development of Calcium batteries
Subtítulo: The realization of calcium rechargeable batteries requires identification of suitable electrodes and electrolytes coupled to compatibility assessment and design of reliable experimental set-ups and protocols.

Achievements, Challenges, and Prospects of Calcium Batteries
M.Elena Arroyo-de Dompablo, Alexandre Ponrouch, Patrik Johansson, M.Rosa Palacín
Chem. Rev. 2019
DOI: 10.1021/acs.chemrev.9b00339

Figure: Artisitic impression of a rechargeable battery consisting of a calcium metal anode, a liquid electrolyte and an intercalation material

A comprehensive examination of the requirements and current state-of-the-art of electrolytes and electrodes for calcium batteries is presented, flowing from past attempts to develop (rechargeable) technologies via crucial breakthroughs to arrive at a comprehensive discussion of the current challenges at hand. Advantages being sustainability (calcium is the fifth most abundant element in the earth crust) and the potential to deliver high energy density, the realization of a rechargeable Ca battery technology primarily requires identification and development of suitable electrodes and electrolytes.  The progress starting from the fundamental electrode/electrolyte requirements, concepts, materials, and compositions employed is discussed and a critical analysis of the state-of-the-art allows to conclude with the particular roadblocks still exist. As for crucial breakthroughs reversible plating and stripping of calcium at the metal anode interface was achieved only recently and for very specific electrolyte formulations. Therefore, while much of current research aims at finding suitable cathodes to achieve proof-of-concept for a full Ca battery, the spectrum of electrolytes researched is also being gradually expanded. Assessing compatibility of cell components is essential.  To that end, proper characterization is needed, which requires design of a multitude of reliable experimental set-ups and sometimes methodology development beyond that of other next generation battery technologies, as know how gained in the field of Li-ion cannot be blindly adopted.

Strategies to make best use of the current advances in materials science combined with computational design, electrochemistry and battery engineering should serve to propel the Ca battery technology to reality and ultimately reach its full potential for energy storage.

Thermal conductivity à la carte for phononic applications

Título: Thermal conductivity à la carte for phononic applications
Subtítulo: We propose strategies to engineer materials with thermal properties on demand, which pave the way to the design of thermal devices and signal processing with phonons
Authors: Phonon Engineering in Twinning Superlattice Nanowires
Marta De Luca, Claudia Fasolato, Marcel A. Verheijen, Yizhen Ren, Milo Y. Swinkels, Sebastian Kölling, Erik P. A. M. Bakkers, Riccardo Rurali, Xavier Cartoixà, Ilaria Zardo
Nano Letters 19 (7), 4702, 2019
DOI: 10.1021/acs.nanolett.9b01775
Giant Electrophononic Response in PbTiO3 by Strain Engineering
Pol Torres, Jorge Íñiguez, Riccardo Rurali
Rev. Lett. 123, 185901, 2019
DOI: 10.1103/PhysRevLett.123.185901

Figure: TEM image of the atomic arrangement of a twin superlattice. The change in the stacking of the different layers can be appreciated and is also in the cartoon that displays the atomic arrangement around the twin inversion plane. The right-hand side panel displays the Raman signature of the twin superlattice.

In electronics, information is transferred with charge carriers, whose motion can be easily controlled with external fields. This is not the case of phononics, where the manipulation of phonons is intrinsically more challenging: this is why we live in a world of electronic devices and heat is normally regarded as a source of loss.

Unconventional cooperative interactions analyzed by DFT and electrostatic potential surface analysis

Título: Unconventional cooperative interactions analyzed by DFT and electrostatic potential surface analysis

Synthesis, X-ray Characterization and Density Functional Theory Studies of N6-benzyl-N6-methyladenine-M(II) Complexes (M=Zn, Cd): The Prominent Role of π-π, C-H···π and Anion-π Interactions
Roser Pons, Cristina Ibánez, Ana B. Buades, Antonio Franconetti, Àngel García-Raso, Juan J. Fiol, Angel Terrón, Elies Molins, Antonio Frontera
Applied Organometallic Chemistry 33, e4906, 2019
DOI: 10.1002/aoc.4906.

Figure: (a) Molecular Electrostatic Potential (MEP) surface (0.002 a.u.) of the zwiterionic complex [Zn(HL)Cl3]·H2O  being L= N6-benzyl-N6-methyladenine. MEP values at selected points of the surface are indicated. (b) Lp–π and anion–π assembly. (c) Lp–π complex where only water is considered.

Unconventional cooperative lone pair–π, anion–π and π+–π+ interactions appear in the studied complexes. The energies associated with these assemblies have been computed using density functional theory (DFT) calculations and rationalized by molecular electrostatic potential surface analysis. The protonated adenine ring presents an extended π‐acidic surface adequate for the interaction with electron–rich atoms (O/Cl) or moieties (phenyl ring). However, in another complex, establishes unexpected π+–π+ interactions with an adjacent diprotonated adenine ring promoted by the [Cd3(μ–L)2(μ–Cl)4Cl6]4 anions.

Why the interface matters in perovskites solar cell performances

Título: Why the interface matters in perovskites solar cell performances
Subtítulo: The reported data for diverse hole-transporting-material (HTM) deposited on a perovskite layer help understanding the limitations when designing new organic semiconductor molecules to improve the perovskite solar cell efficiency.

Energy Alignment and Recombination in Perovskite Solar Cells: Weighted Influence on the Open Circuit Voltage
Ilario Gelmettia, Núria F. Montcada, Ana Pérez-Rodríguez, Esther Barrena, Carmen Ocal, Inés García-Benito, Agustín Molina-Ontoria, Nazario Martín, Anton Vidal-Ferrana, Emilio Palomares
Energy and Environment Science 12, 1309-1316, 2019
DOI: 10.1039/C9EE00528E

Figure: (Top) Kelvin Probe Force Microscopy measurements for surfaces of pristine CsFAMAPbIBr and the different HTM devices (spiro-OMeTAD, TAE-1, TAE-3 and TAE-4). The vacuum level shifts are obtained by extracting the diverse work function from the parabolic data. (Bottom) Molecular representation of the HTM devices.


Organic-inorganic lead halide perovskites have become the focus of intense research due to their outstanding performance in hybrid photovoltaic devices.  One essential component for attaining stable and high efficient solar cell is the employed hole transporting material (HTM).

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