Nanomaterials for renewable energy storage: synthesis, characterization, and applications

1Department of Chemical and Materials Engineering, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia 2Gas Processing Center, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar 3Electrochemical Power Systems Division, CSIR-Central Electrochemical Research Institute, Karaikudi 630006, India 4SABIC Chair in Catalysis, King Abdulaziz University, P.O. Box 80204, Jeddah 21589, Saudi Arabia 5Game Lab, Chenergy Group, Department of Applied Science and Technology (DISAT), Politecnico Di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Ital

Siloxane Diacrylate-based All-Solid Polymer Electrolytes for Lithium Batteries

Fully solid polymer electrolyte (SPE) membranes were prepared by UV induced free radical polymerisation (UV-curing) of acrylated siloxane polyalkyleneoxide copolymers in the presence of different lithium salts. The main chain contains locally mobile segments of ethoxy groups as part of the copolymer, and these moieties can provide coordination sites for the mobility of Li+ ions. The materials are produced through a solvent free procedure, and used as ion-conducting media as well as a separator in high temperature lithium-based batteries. The preparation process is easy, simple and versatile. The final product obtained demonstrates good mechanical integrity due to the highly cross-linked nature of the polymer network, and wide thermal stability. The membranes are also soft, easy to manage and transparent. They also exhibit acceptable ionic conductivity and wide electrochemical stability window

A bilayer polymer electrolyte encompassing pyrrolidinium-based RTIL for binder-free silicon few-layer graphene nanocomposite anodes for Li-ion battery

A binder-free electrode made of polycrystalline carbon-coated silicon nanoparticles encapsulated in few-layer graphene flakes is coupled with a PEO-based crosslinked bilayer polymer electrolyte (BLPE). A soft polymer electrolyte layer enriched with a pyrrolidium-based ionic liquid (Pyr14TFSI) is deposited on top of the electrode and UV cured by an in situ process to achieve optimal interfacial contact. A hard layer consisting of a crosslinked PEO-based polymer electrolyte film with a lower amount of Pyr14TFSI is integrated with the electrode/electrolyte assembly to improve the self-standing and shape-retention abilities. Proof-of-concept lab-scale Si-C||Li-metal polymer cells demonstrate a reversible specific discharge capacity up to 1044 mAh gSi–1 at 80 °C, largely outperforming the one with Pyr14TFSI/LiTFSI liquid electrolyte under the same experimental condition. Our results highlight the beneficial effect of the crosslinked PEO-based polymer matrix on the cycling performance, despite the absence of any SEI-forming agent

Temperature Dependence of Electric Transport in Few-layer Graphene under Large Charge Doping Induced by Electrochemical Gating

The temperature dependence of electric transport properties of single-layer and few-layer graphene at large charge doping is of great interest both for the study of the scattering processes dominating the conductivity at different temperatures and in view of the theoretically predicted possibility to reach the superconducting state in such extreme conditions. Here we present the results obtained in 3-, 4- and 5-layer graphene devices down to 3.5 K, where a large surface charge density up to about 6.8x10^14 cm^(-2) has been reached by employing a novel polymer electrolyte solution for the electrochemical gating. In contrast with recent results obtained in single-layer graphene, the temperature dependence of the sheet resistance between 20 K and 280 K shows a low-temperature dominance of a T^2 component - that can be associated with electron-electron scattering - and, at about 100 K, a crossover to the classic electron-phonon regime. Unexpectedly this crossover does not show any dependence on the induced charge density, i.e. on the large tuning of the Fermi energy.Comment: 13 pages, 6 color figure

Large conductance modulation of gold thin films by huge charge injection via electrochemical gating

By using an electrochemical gating technique with a new combination of polymer and electrolyte, we were able to inject surface charge densities n_2D as high as 3.5 \times 10^15 e/cm^2 in gold films and to observe large relative variations in the film resistance, DeltaR/R', up to 10% at low temperature. DeltaR/R' is a linear function of n_2D - as expected within a free-electron model - if the film is thick enough (> 25 nm), otherwise a tendency to saturation due to size effects is observed. The application of this technique to 2D materials will allow extending the field-effect experiments to a range of charge doping where giant conductance modulations and, in some cases, even the occurrence of superconductivity are expected.Comment: 5 pages, 5 figures, RevTe

UV-Induced Radical Photo-Polymerization: A Smart Tool for Preparing Polymer Electrolyte Membranes for Energy Storage Devices

In the present work, the preparation and characterization of quasi-solid polymer electrolyte membranes based on methacrylic monomers and oligomers, with the addition of organic plasticizers and lithium salt, are described. Noticeable improvements in the mechanical properties by reinforcement with natural cellulose hand-sheets or nanoscale microfibrillated cellulose fibers are also demonstrated. The ionic conductivity of the various prepared membranes is very high, with average values approaching 10-3 S cm-1 at ambient temperature. The electrochemical stability window is wide (anodic breakdown voltages > 4.5 V vs. Li in all the cases) along with good cyclability in lithium cells at ambient temperature. The galvanostatic cycling tests are conducted by constructing laboratory-scale lithium cells using LiFePO4 as cathode and lithium metal as anode with the selected polymer electrolyte membrane as the electrolyte separator. The results obtained demonstrate that UV induced radical photo-polymerization is a well suited method for an easy and rapid preparation of easy tunable quasi-solid polymer electrolyte membranes for energy storage devices

Innovative high performing metal organic framework (MOF)-laden nanocomposite polymer electrolytes for all-solid-state lithium batteries

An enhancement of two orders of magnitude in the ambient temperature ionic conductivity of poly(ethylene oxide)-based nanocomposite polymer electrolyte (NCPE) membranes is here fundamentally achieved by the incorporation of specific amounts of aluminium-based metal organic framework (MOF) as the filler. Thorough characterization, particularly solid-state NMR and FT-IR studies, shed light on the specific role of the defective MOF frameworks in greatly enhancing the Li+ ion mobility inside the polymeric matrix. The prepared NCPEs are highly stable towards lithium metal even after prolonged storage time, and an excellent cycling profile is evidenced even at moderate temperatures, which has never been reported so far for an all-solid-state lithium polymer cell composed of Li/NCPE/LiFePO

New electrolyte membranes for Li-based cells: Methacrylic polymers encompassing pyrrolidinium-based ionic liquid by single step photo-polymerisation

We demonstrate herein the application of an in situ single-step free radical photo-polymerisation process to incorporate room temperature ionic liquids (RTILs) into polymer membranes to be used as quasi-solid electrolytes in lithium-based batteries. The membranes are prepared by UV irradiating a mixture of photo-curable dimethacrylic oligomers and a proper radical photo-initiator along with a large quantity (i.e., 60 wt %) of ether-functionalized pyrrolidinium-imide ionic liquid (PYRA1201-TFSI) and LiTFSI lithium salt. Stable and flexible polymer films with homogeneous nature are easily produced: they combine the advantages of polymer electrolytes swollen by conventional organic liquid electrolytes with the non-flammability, high thermal and electrochemical stability typical of RTILs. Appreciable ionic conductivity values (0.1-1 mS/cm) and good overall electrochemical performances are obtained in a wide temperature range. The polymer electrolyte membranes are tested in lab-scale cells using LiFePO4 as the cathode and Li metal as the anode. Good charge/discharge capacities, Coulombic efficiency close to unity, and low capacity loss at medium C-rates during preliminary cycling are obtained. These interesting properties high light that such green and safe electrolyte systems could become a strong contender in the field of thin and flexible Li-based power source