Lightweight Current Collector Research Articles

Lightweight current collector based on printed-circuit-board technology and its structural effects on the passive air-breathing direct methanol fuel cell

To realize lightweight design of the fuel cell system is a critical issue before it is put into practical use. The printed-circuit-board (PCB) technology can be potentially used for production of current collectors or flow distributors. This study develops prototypes of a single passive air-breathing direct methanol fuel cell (DMFC) and also an 8-cell mono-polar DMFC stack based on PCB current collectors. The effects of diverse structural and operational factors on the cell performance are explored. Results show that the methanol concentration of 6 M promotes a higher cell performance with a peak power density of 18.3 mW cm−2. The combination of current collectors using a relatively higher anode open ratio and inversely a lower cathode open ratio helps enhance the cell performance. Dynamic tests are also conducted to reveal transient behaviors and its dependence on the operating conditions. To validate the real working status of the DMFC stack, it is coupled with an LED lightening system. The performance of this hybrid system is also reported in this study.

Development of a Direct Methanol Fuel Cell with Lightweight Disc Type Current Collectors

The direct methanol fuel cell (DMFC) adopts methanol solution as a fuel suitable for low power portable applications. A miniature, lightweight, passive air-breathing design is therefore desired. This paper presents a novel planar disc-type DMFC with multiple cells containing a novel developed lightweight current collector at both the anode and cathode sides. The present lightweight current collector adopts FR4 Glass/Epoxy as the substrate with the current collecting areas located at the corresponding membrane electrolyte assembly (MEA) areas. The current collecting areas are fabricated by sequentially coating a corrosion resistant layer and electrical conduction layer via the thermal evaporation technique. The anode current collector has carved flow channels for fuel transport and production. The cathode current collector has drilled holes for passive air breathing. In order to ensure feasibility in the present concept a 3-cell prototype DMFC module with lightweight disc type current collectors is designed and constructed. Experiments were conducted to measure the cell performance. The results show that the highest cell power output is 54.88 mW·cm−2 and successfully demonstrate the feasibility of this novel design.

Applications of carbon nanotubes in high performance lithium ion batteries

The development of lithium ion batteries (LIBs) relies on the improvement in the performance of electrode materials with higher capacity, higher rate capability, and longer cycle life. In this review article, the recent advances in Carbon nanotube (CNT) anodes, CNT-based composite electrodes, and CNT current collectors for high performance LIBs are concerned. CNT has received considerable attentions as a candidate material for the LIB applications. In addition to a possible choice for anode, CNT has been recognized as a solution in improving the performance of the state-of-the-art electrode materials. The CNT-based composite electrodes can be fabricated by mechanical or chemical approaches. Owing to the large aspect ratio and the high electrical conductivity, CNTs at very low loading can lead to an efficient conductive network. The excellent mechanical strength suggests the great potential in forming a structure scaffold to accommodate nano-sized electrode materials. Accordingly, the incorporation of CNTs will enhance the conductivity of the composite electrodes, mitigate the agglomeration problem, decrease the dependence on inactive binders, and improve the electrochemical properties of both anode and cathode materials remarkably. Freestanding CNT network can be used as lightweight current collectors to increase the overall energy density of LIBs. Finally, research perspectives for exploiting CNTs in high-performance LIBs are discussed.

Design and Development of a Sheet Metal Plastic Backed Proton Exchange Membrane Fuel Cell

The high costs associated with fuel cell manufacturing have precluded its production on a large scale. The major emphasis of the present wok is to bring down the overall cost of an independent fuel cell unit. The manufacturing cost can be reduced using commonly available and corrosion resistant materials into the fuel cell assembly. Bipolar plates usually employed in proton exchange membrane fuel cells are fabricated from conducting graphite. Graphite owing to its conductivity, corrosion resistance and easy machinability, is the preferred material in static systems. However, due to its brittle characteristics and failure under bending loads, graphite is inferior in its mechanical properties as compared to metals and their alloys. Dimensional stability is also compromised due to wear and friction. In the present work, an attempt is made to assemble a fuel cell stack which would have durability and sustainability in dynamic conditions, where the setup would be able to withstand periodic shocks, vibrations, and fatigue loads. Instead of employing graphite as the bipolar plate which serves the dual purpose of a current collector and area for flow fields, graphite foil protected aluminum as the current collector and machined plastic slabs on which the flow fields are carved, have been employed. Both the substitutes are easily available owing to mass production and have a small processing cost associated with them. Further, the technique employed for processing of Nafion and hot pressing of the catalyst loaded gas diffusion layer onto the proton exchange membrane have been elaborated in the present paper along with the systematic approach followed by the research group eliminating various current collector candidates for fuel cell applications. The various stages attained towards the final fabrication of the foil protected lightweight current collector, has also been highlighted in the present work.

Design and fabrication of light weight current collectors for direct methanol fuel cells using the micro-electro mechanical system technique

The direct methanol fuel cell (DMFC) is suitable for portable applications. Therefore, a light weight and small size is desirable. The main objective of this paper is to design and fabricate a light weight current collector for DMFC usage. The light weight current collector mainly consists of a substrate with two thin film metal layers. The substrate of the current collector is an FR4 epoxy plate. The thin film metal layers are accomplished by the thermo coater technique to coat metal powders onto the substrate surfaces. The developed light weight current collectors are further assembled to a single cell DMFC test fixture to measure the cell performance. The results show that the proposed current collectors could even be applied to DMFCs because they are light, thin and low cost and have potential for mass production.

Highly conductive paper for energy-storage devices

Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (Omega/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30-47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices.