Time filter

Source Type

Pawcatuck, CT, United States

Aravindan V.,Nanyang Technological University | Gnanaraj J.,Yardney Technical Products, Inc. | Lee Y.-S.,Chonnam National University | Madhavi S.,Nanyang Technological University
Chemical Reviews | Year: 2014

Apart from the mentioned applications, wind power generation, uninterruptible power sources, voltage sag compensation, photovoltaic power generation, CT and MRI scanners, and energy recovery systems in industrial machineries are worth mentioning. Carbonaceous materials are favored as EDLC components due to their high specific surface area, relatively low cost, chemical stability in solutions irrespective of the pH value, ease of synthesis protocols with tailored pore size distribution and its amphoteric nature that allows rich electrochemical properties from donor to acceptor state, and a wide range of operating temperatures. The combination reactions enable one to achieve higher energy density and specific capacitance than the EDLC counterpart. Conducting polymers and transition metal oxides are the perfect examples for pseudocapacitive materials. Source

Aravindan V.,Nanyang Technological University | Gnanaraj J.,Yardney Technical Products, Inc. | Lee Y.-S.,Chonnam National University | Madhavi S.,Nanyang Technological University
Journal of Materials Chemistry A | Year: 2013

Development of an eco-friendly, low cost and high energy density (∼700 W h kg-1) LiMnPO4 cathode material became attractive due to its high operating voltage ∼4.1 V vs. Li falling within the electrochemical stability window of conventional electrolyte solutions and offers more safety features due to the presence of a strong P-O covalent bond. The vacancy formation energy for LiMnPO4 was 0.19 eV higher than that for LiFePO4, resulting in a 10-3 times-diluted complex concentration, which represents the main difference between the kinetics in the initial stage of charging of two olivine materials. This review highlights the overview of current research activities on LiMnPO4 cathodes in both native and substituted forms along with carbon coating synthesized by various synthetic techniques. Further, carbon coated LiMnPO4 was also prepared by a solid-state approach and the obtained results are compared with previous literature values. The challenges and the need for further research to realize the full performance of LiMnPO4 cathodes are described in detail. © 2013 The Royal Society of Chemistry. Source

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 749.11K | Year: 2011

Li-ion batteries are attractive candidates for use as power sources in military, aerospace, commercial, and vehicular applications. Outstanding properties of Li-ion include longer battery life, reduced weight and size, lower maintenance costs, higher power capacity and higher energy densities. However, there are issues with making a truly safe Li-ion battery. For this project, Yardney has approached making a safer battery by incorporating modeling and testing, and based on that moving forward towards larger cells for Navy applications. Though a goal is to make a Li-ion cell incapable of failing, reality has us accepting a cell failure, but preventing that occurrence from propagating. Improvements include materials internal to the cell to decrease the risk of an event and its magnitude upon such an occurrence, and then considering cell geometry and inter-cell separators to 1) remove that heat as rapidly to a"safe zone"as possible, and 2) to block a majority of the heat from causing a neighboring cell to also reach it"s activation energy for thermal runaway. In addition, electronics play a major role in monitoring, and in this project Yardney is incorporating some of their latest electronics to provide a hearty monitoring system, and a safer Li-ion battery.

Agency: Department of Defense | Branch: Navy | Program: STTR | Phase: Phase I | Award Amount: 79.75K | Year: 2014

Yardney will design and develop a lightweight, safe, reliable, and cost-effective aircraft battery with improved thermal design and the use of active cooling techniques. As a novel part of the battery design, Yardney will investigate and implement high performance electrodes using three dimensional (3D) micro-porous current collectors, safer thin metal case cell design, a micro-channel heat pipe thermal control system to collect heat generated inside the battery and then conduct the heat to the outer shell, thus providing direct cooling for the overheated region. The novel design will also prevent heat propagation between the cells with a lightweight aerogel that has low thermal conductivity. Tests of the enhanced cell design will be compared with Yardney"s existing battery, which meets current full aircraft electrical performance requirements. Yardney will work with the University of Arizona, experts in thermal modeling and heat-generation studies in battery electrodes and the battery cells and investigate the most effective thermal design for the 3D electrodes and the battery pack using high performance computing systems.

Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 730.46K | Year: 2012

The goal of this project is to take silver-zinc battery technology to a new level for programs important to the Navy. Silver-Zinc batteries provide high energy and power density cells, and since the electrolyte is a water-based alkaline fluid, provide a comparatively safe battery. A disadvantage to this technology is large format cells, which are required to provide high power, do not provide comparable cycle life performance to competing systems. There are two main issues. One is the negative electrode, having redox products being zinc and zinc oxide, experiences non-uniform re-plating of the zinc upon charging. The mass tends toward the bottom of the current collector as the cell accumulates cycles. The other issue is the separator, commonly used cellophane, experiences degradation due to the strongly oxidative positive silver oxide electrode. The primary work will be to advance from the Phase I to the Phase II the further refinements of circumventing the shortcomings of silver/zinc. This includes incorporating binders with the negative electrodes to limit dissolution of the electrode while cycling and developing a non-cellulosic cellophane replacement. Also included will be advances in thermal pathway to remove heat from cells during discharge and providing an advanced silver/zinc battery management system.

Discover hidden collaborations