From its earliest days, BINA researchers have played a vital role in the development of renewable energy applications. Focusing on photovoltaics, energy storage, solar thermal energy, energy conservation – as well as basic research – BINA’s nano-energy experts are world leaders in the techniques that are forging a path toward practical and green solutions for a sustainable future.
- Advanced materials for rechargeable battery systems and super capacitors
- Dye-sensitized solar cells
- Nano-based optics for photovoltaics
- Low cost, multi-band-gap photovoltaic systems
- Carbon engineering and electrochemistry for EDL capacitors
- Electrical and optical properties of carbon nanotube structures
- Carbon nanotube-based electrodes for batteries and super capacitors
- Solid-liquid interfaces of ionic liquids
In-silico studies of oxide materials for all-oxide photovoltaics
Metal oxides are cheap, stable, non toxic, ubiquitous materials, and are therefore attractive for the use in a variety of devices, including photovoltaic cells. However, the short excited state lifetime of these materials, and the low speed at which electronic charge travels through them, makes them unsuitable for solar energy production. In an attempt to optimize the properties of metal oxides for solar energy conversion, BINA researchers have adopted a computational strategy. Specifically, they studied the complex electronic and photonic properties of iron oxide (a-Fe2O3) and cobalt oxide (Co3O4). We used density functional theory to predict the electronic structure (e.g. band gap) and the results were found to be in good agreement with experiment. Importantly, they have generated in-silico doped materials (e.g. Mg, Na, K) which were found to have enhanced electronic properties potentially making them suitable for photovoltaic use.
Advances in cathode materials for Li-ion battery
The heart of an electric vehicle is its battery pack. The performance of a Li-ion battery depends greatly on the chemistry of the cathode and anode, and their reactivity with the electrolyte. The development of cathode materials with superior electrochemical properties – which can substitute conventional cathode materials like layered LiCoO2 – is a key to producing the next generation of lithium-ion batteries. The studies on Li-rich layered materials of the general formulae of Li[Li-Mn-Ni-Co]O2 have become appealing, because they exhibit much higher capacities (~250 mAh/g) in the potential range from 2.0 V to 4.6 V. BIU is working in collaboration with BASF in developing this novel cathode material, which exhibits both the high energy density and safety which are critical for electric vehicle applications. In order to reach this goal, the scientists studied the electrochemistry of Li[Li-Mn-Ni-Co]O2 electrodes at various temperatures in relationship with the structural changes of the active material due to the lithium extraction at high anodic potentials.
Photo-Induced Dipoles: A New Method to Convert Photons into Photovoltage in Quantum Dot Sensitized Solar Cells
High photovoltage is an essential ingredient for the construction of a high efficiency quantum dot sensitized solar cell (QDSSC). In a recent study, BINA researchers presented a novel configuration of QDSSC which incorporates the photo-induced dipole (PID) phenomenon for improved open circuit voltage (Voc). This configuration is based on a dipole moment which is created only under illumination. The generation of photo-dipoles was achieved by the creation of long-lived trapped holes inside a core of type-II ZnSe/CdS colloidal core/shell QDs, which are placed on top of the standard CdS QD sensitizer layer. Upon photo-excitation, the created photo-dipole negatively shifts the TiO2 energy bands, resulting in a photovoltage which is higher by ~100 mV compared to the standard cell, without type-II QDs. This work provides new understanding regarding the operation mechanisms of photoelectrochemical cells, while presenting a new strategy for constructing high voltage QDSSCs. In addition, the PID effect has the potential to be implemented in other promising PV technologies.
Feasibility Studies of Rechargeable Lithium Air Batteries
Discharge of lithium oxygen battery systems forms Li oxides. Their mechanism of formation is complex, and the stability of most relevant polar aprotic solvents towards these Li oxides is questionable. In a BINA study, several spectroscopic tools and in situ measurements using electrochemical quartz crystal microbalance (EQCM) were employed to explore the discharge-charge processes and related side reactions in Li-O2 battery systems containing polar aprotic electrolyte solutions. The systematic mechanism of lithium oxides formation was monitored. A combination of FTIR, NMR, and matrix-assisted laser desorption/ionization (MALDI) measurements in conjunction with electrochemical studies demonstrated intrinsic instability and incompatibility of these solvents for Li-air batteries. The figure below reflects the EQCM response of oxygen reduction and evolution vs. Li anodes in poly-ether based solutions. In these studies the researchers simultaneously measure charge transfer and mass accumulation/depletion onto/from the electrodes, from which they can follow the chemistry of these systems. Reaction products are identified by comparison of mass per electron transfer to possible equivalent weights of relevant moieties that can be formed by oxygen reduction in the presence of Li ions.
Synthesis of large mats of carbon nanofibers from in-situ delaminating of catalyst layer
Functionalized carbon nanostructures are a promising electrode material for future batteries and super-capacitors. Using a self-delaminating stack of thin catalytic films on a substrate, BIU researchers synthesized very large mats of carbon nanofibers (CNFs) using chemical vapor deposition (CVD). The yield obtained was over two orders of magnitude greater than that of substrate-bound CNF growth. This result outlined a new growth mechanism for catalysts not mechanically constrained by a substrate. Interestingly, the team obtained different morphologies when changing the substrate from which the catalyst stack delaminated. They plan to functionalize these structures and to test them as electrodes for batteries and super-capacitors.