Lia Kouchachvili

Bio: Lia Kouchachvili is an academic researcher from Natural Resources Canada. The author has contributed to research in topics: Battery (electricity) & Supercapacitor. The author has an hindex of 8, co-authored 13 publications receiving 527 citations.

Improving the efficiency of pyroelectric conversion

Abstract: Pyroelectric conversion utilizes low-grade waste heat as a heat source, and thus produces clean energy. Low-grade heat is abundant in the various industries and it is practically free. It can be converted to high-voltage electricity by pyroelectric conversion. Our pyroelectric converter uses copolymer of poly-vinylidene fluoride with trifluoroethylene [60/40% P(VDF-TrFE)]. Previously, we encountered a substantial power loss due to internal leakage at high temperature and voltage. In order to increase the power output, we examined the effect of polymer purification using solvent extraction. We compared the electrical properties of purified copolymer with those of 'as-received' copolymer. Although we removed only 0.4wt% of the copolymer by solvent extraction, the electrical resistivity of purified copolymer was 35% higher than that of the 'as-received' copolymer. We also observed that thin films produced using purified copolymer were able to withstand 50% higher electric field before they were ruined by the electrical short circuit. Subsequently, we conducted pyroelectric conversion using 25 μm thick 60-40% P(VF 2 -TrFE) copolymer films. Copolymer purification resulted in a three-fold increase in net power output. Net power output per unit volume of the 'as-received' copolymer was 95 J L -1 but it increased to 279 J L -1 for purified copolymer. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2007.

Ultracapacitors: Why, How, and Where is the Technology

Abstract: The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Mutual Insight on Ferroelectrics and Hybrid Halide Perovskites: A Platform for Future Multifunctional Energy Conversion.

Abstract: An insight into the analogies, state-of-the-art technologies, concepts, and prospects under the umbrella of perovskite materials (both inorganic-organic hybrid halide perovskites and ferroelectric perovskites) for future multifunctional energy conversion and storage devices is provided. Often, these are considered entirely different branches of research; however, considering them simultaneously and holistically can provide several new opportunities. Recent advancements have highlighted the potential of hybrid perovskites for high-efficiency solar cells. The intrinsic polar properties of these materials, including the potential for ferroelectricity, provide additional possibilities for simultaneously exploiting several energy conversion mechanisms such as the piezoelectric, pyroelectric, and thermoelectric effect and electrical energy storage. The presence of these phenomena can support the performance of perovskite solar cells. The energy conversion using these effects (piezo-, pyro-, and thermoelectric effect) can also be enhanced by a change in the light intensity. Thus, there lies a range of possibilities for tuning the structural, electronic, optical, and magnetic properties of perovskites to simultaneously harvest energy using more than one mechanism to realize an improved efficiency. This requires a basic understanding of concepts, mechanisms, corresponding material properties, and the underlying physics involved with these effects.

Pyroelectric materials and devices for energy harvesting applications

Abstract: This review covers energy harvesting technologies associated with pyroelectric materials and systems. Such materials have the potential to generate electrical power from thermal fluctuations and is a less well explored form of thermal energy harvesting than thermoelectric systems. The pyroelectric effect and potential thermal and electric field cycles for energy harvesting are explored. Materials of interest are discussed and pyroelectric architectures and systems that can be employed to improve device performance, such as frequency and power level, are described. In addition to the solid materials employed, the appropriate pyroelectric harvesting circuits to condition and store the electrical power are discussed.

Hybrid energy storage system for microgrids applications: A review

Abstract: Energy storages introduce many advantages such as balancing generation and demand, power quality improvement, smoothing the renewable resource’s intermittency, and enabling ancillary services like frequency and voltage regulation in microgrid (MG) operation. Hybrid energy storage systems (HESSs) characterized by coupling of two or more energy storage technologies are emerged as a solution to achieve the desired performance by combining the appropriate features of different technologies. A single ESS technology cannot fulfill the desired operation due to its limited capability and potency in terms of lifespan, cost, energy and power density, and dynamic response. Hence, different configurations of HESSs considering storage type, interface, control method, and the provided service have been proposed in the literature. This paper comprehensively reviews the state of the art of HESSs system for MG applications and presents a general outlook of developing HESS industry. Important aspects of HESS utilization in MGs including capacity sizing methods, power converter topologies for HESS interface, architecture, controlling, and energy management of HESS in MGs are reviewed and classified. An economic analysis along with design methodology is also included to point out the HESS from investor and distribution systems engineers view. Regarding literature review and available shortcomings, future trends of HESS in MGs are proposed.