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Nafion membranes were shown to be suitable substrates for atomic layer deposition (ALD) process. ALD utilising trimethyl aluminum as a precursor leads to well reproducible formation of smooth single-sided Al2O3 coating on the membranes. Physicochemical and mechanical properties of the coated membranes were compared to those of the unmodified ones. The coating reduced water uptake and thus also conductivity. Moreover, the Al2O3 coating decreased the oxygen permeability of the membrane by 10 % and the methanol permeability 30-50 %. The mechanical properties of the Nafion® membrane were improved. The resulting membranes were successfully applied in hydrogen fuel cells, direct methanol fuel cells and microbial fuel cells. In the microbial fuel cell, the Al2O3 coated membrane showed stable performance during long-term measurements of more than 100 d and doubled power densities in comparison to a cell equipped with a pristine membrane. The membrane modification strategy has potential for improving the performance of various types of membrane fuel cells and could be used for several types of functional membranes containing active groups for ALD growth.

By using sp group metals as modifiers, the catalytic properties of Pt can be improved toward alcohols oxidation. In this work we report the performance increase of direct alcohol fuel cells (DAFC) fuelled with ethanol or 2-propanol with platinum based anode electrodes modified with Bi and Sb adatoms. For example, by simply adding Sb to the Pt/C based anode ink during membrane electrode assembly fabrication of a direct ethanol fuel cell (DEFC) its performance is improved three-fold, with more than 100 mV increase in the open circuit potential. For the fuel cell fuelled with 2-propanol high power densities are obtained at very high potentials with these catalyst materials suggesting a great improvement for practical applications. Particularly in the case of Pt/C-Bi, the improvement is such that within 0.6 V (from 0.7 to 0.1 V) the power densities are between 7 and 9 mW/cm2. The results obtained with these catalysts are in the same range as those obtained with other bimetallic catalysts comprising of PtRu and PtSn, which are currently considered to be the best for these type of fuel cells and that are obtained by more complicated (and consequently more expensive) methods.

Silicon is being increasingly studied as the next-generation anode material for Li-ion batteries because of its ten times higher gravimetric capacity compared with the widely-used graphite. While nanoparticles and other nanostructured silicon materials often exhibit good cyclability, their volumetric capacity tends to be worse or similar than that of graphite. Furthermore, these materials are commonly complicated and expensive to produce. An effortless way to produce nanostructured silicon is electrochemical anodization. However, there is no systematic study how various material properties affect its performance in LIBs. In the present study, the effects of particle size, surface passivation and boron doping degree were evaluated for the mesoporous silicon with relatively low porosity of 50%. This porosity value was estimated to be the lowest value for the silicon material that still can accommodate the substantial volume change during the charge/discharge cycling. The optimal particle size was between 10–20 µm, the carbide layer enhanced the rate capability by improving the lithiation kinetics, and higher levels of boron doping were beneficial for obtaining higher specific capacity at lower rates. Comparison of pristine and cycled electrodes revealed the loss of electrical contact and electrolyte decay to be the major contributors to the capacity decay., published version, peerReviewed

The performance of a direct methanol alkaline anion-exchange membrane (Fumatech FAA3) fuel cell with Pt-free nitrogen-doped few-walled carbon nanotubes (N-FWCNT) as the cathode catalyst is compared with a commercial supported Pt catalyst. The ionomer content of the N-FWCNT cathode catalyst layer is therefore optimized and it is shown to be 40wt% of FAA3. Scanning electron microscopy images of the catalyst layer show that the ionomer forms aggregates with N-FWCNTs probably due to their charged nature and that the catalyst layer structure is remarkably open even with high ionomer contents facilitating the mass transfer of reactants and products to the active sites. With oxygen as the oxidant, the maximum power density obtained with our Pt-free N-FWCNTs (0.78mWcm-2) is slightly higher than with the Pt catalyst (0.72mWcm-2). However, when more practical air is used as the oxidant, the N-FWCNTs (0.73mWcm-2) show clearly superior performance compared to the Pt catalyst (0.18mWcm-2). The lower performance with the Pt catalyst is attributed to the denser electrode layer structure resulting in higher mass transport resistance and to the presence of methanol in the cathode, which poisons the Pt but not the N-FWCNTs.

The Langmuir-Schaefer (LS) technique was applied to prepare two-dimensional films of tridodecylamine (TDA)-stabilized Co nanoparticles. Ethylene glycol was used as the subphase because the Co nanoparticles spread better on it than on water. Surface pressure-area isotherms provided very little information on the floating films, and Brewster angle microscopy (BAM) was needed to characterize the film formation in situ. In addition to the subphase, various other experimental factors were tested in the LS film preparation, including solvent and presence of free TDA ligands and poly(styrene-b-ethylene oxide) (PS-b-PEO) in the nanoparticle dispersion. LS films deposited from dispersions from which the excess TDA ligands had been removed by washing the Co nanoparticles with 2-propanol consisted of hexagonally organized particles in rafts that were organized in necklace structures. The addition of PS-b-PEO to the deposition dispersion resulted in small nanoparticle rafts evenly distributed over the substrate surface. The best Co-nanoparticle-PS-b-PEO films were obtained with a mass ratio of 20:1 between Co (9 nm) and block copolymer (38 200 g/mol, PEO content 22 mass %). These films were successfully transferred onto Formvar-coated TEM grids and characterized by transmission electron microscopy (TEM) and a superconducting quantum interference device (SQUID) magnetometer. At room temperature the films showed superparamagnetic behavior with a saturation magnetization M(s) of 100 emu/g (Co). Our work indicates that it is possible to obtain thin superparamagnetic LS films of TDA-stabilized Co nanoparticles. This is an important result as the TDA-stabilized Co nanoparticles show a very good resistance to corrosion.

Traditionally electrodes for lithium ion batteries are manufactured using carbon additives to increase the conductivity. However, in case of lithium titanate, Li4Ti5O12 (LTO), carbon free electrodes have gathered some interest lately. Therefore two LTO materials synthesized using the same synthesis but different end milling process resulting in materials with different particle size and surface area are compared here using electrodes manufactured with and without carbon additives. Both LTO samples (LTO-SP with small primary particle size and high surface area, and LTO-LP with larger primary particle size and small surface area) produce similar capacities and voltages with or without carbon additives at low C-rates at the room temperature. However, at high C-rates and/or sub-zero temperatures electrodes with carbon additives produce higher capacities and smaller ohmic losses and this behavior is more pronounced for the LTO electrodes with smaller primary particle size and larger surface area. These results show that the feasibility of carbon free LTO electrodes depends on the properties of LTO affecting the morphology of the electrode and consequently, the transport properties. This is most pronounced under conditions where electron and Liþ ion transfer become limiting (high C-rates and low temperature).

Two different Li4Ti5O12 materials were investigated: smaller primary particle size forming large secondary particle aggregates (LTO-SP, surface area 22 m2/g) and larger primary particle size with less secondary particle aggregates (LTO-LP, surface area 7 m2/g). Both samples were synthesized using the same high temperature solid state synthesis but different end processing, resulting in same crystalline structure but different particle morphology. At 0.1C measured discharge capacities were close to the theoretical capacity of Li4Ti5O12 (175 mAh/g) and similar capacities were obtained at low C-rates and room temperature for both LTO-SP and LTO-LP. However, higher capacities were obtained with LTO-SP at high C-rates and -20 °C indicating beneficial effect of small particle size and large surface area. Shapes of the charge/discharge curves were different for LTO-SP and LTO-LP and this is attributed to the large surface area of LTO-SP which affects the electrochemical performance because of different reaction potentials at surface sites vs. bulk.

We introduce an ultra-low-energy system comprised of a prototype 1.55V Li-ion battery, fully integrated switched-capacitor (SC) DC-DC 3:1 converter, and a 32-bit RISC CPU with timing-error prevention (TEP). The DC-DC converter and CPU are manufactured in 28nm UTBB FD-SOI. The DC-DC converter uses the battery's flat discharge curve and low nominal voltage to achieve a peak efficiency of 85%. The CPU operates from 0.3V-0.5V and with energy as low as 4.9pJ/cyc. The battery, DC-DC converter, and CPU system is able to operate with an average energy of 8pJ/cyc over 95% of the battery's discharge curve in the temperature range of −20oC to 70oC.

Ultra-low voltage is the key to ultra-low power consumption. Hence, there is a drive to lower the operating voltage of wireless sensor System-on-Chips as much as possible. State-of-the-art components already operate below 1V and some below 0.5V. However, commercial rechargeable lithium-ion batteries show a high nominal voltage in the range of 3.4–4.1V. Were such batteries paired with ultra-low-voltage systems, cost effective power-conversion design (without off-chip components) becomes difficult and energy will in all likelihood be lost in the conversion. While sub-2V lithium-ion batteries exist, sub-1V water-based electrolyte batteries with high energy density should also be developed. Shown here is experimental low voltage lithium battery with an ultra-low-voltage DC-DC converter / processor test system. Simulations on the DC-DC show from 12% to 74% efficiency improvement depending on the configuration. Measurements on the processor show 83% energy-delay product and 39% energy / operation improvement.

This research aims at improving the performance of lithium iron phosphate (LiFePO4) positive electrode material by using carbon nanotubes (CNT) to increase the conductivity and nonionic surfactant to achieve better dispersion of CNTs in the composite material. LiFePO4-CNT composites were synthesized by the wet chemical method and functionalized multi-walled carbon nanotubes MWCNT-COOH were added in-situ. The nonionic surfactant polyoxyethylene-oleyl ether (E-230) was used to enhance the dispersion of MWCNT in the LiFePO4nanopowder and removed during the last step of the synthesis to avoid possible unwanted side reactions of the surfactants in the battery. During this last step, the composite materials were heated at 500-700°C in an Ar-H2 atmosphere for several hours. XRD, DTA/TG, FESEM and EFTEM were used for characterization of the crystallization and microstructure of the obtained composites. Electrochemical performance was characterized by charging and discharging experiments with various C-rates using standard lithium ion battery half cells. Results showed that the addition of MWCNT-COOH and the surfactant E-230 remarkably increased the obtained capacities of LiFePO4. Acting as a dispersant and interfacial coupling agent, the nonionic surfactant enhanced the dispersion of carboxylic MWCNT into the LiFePO4 during the in-situ synthesis and enhanced the specific capacity of the tested composites.

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Fluorinated polymers are used in a variety of applications providing benefits to the society, but at the same time also causing risks of irreversible pollution and impacts on the environment and human health in different stages of the lifecycle. The main aim of the study was to provide information on impacts of fluorinated polymers along their lifecycles in a low carbon, circular and toxic-free economy, which could be relevant to consider in future assessments. An important part of the work was also to discuss options for risk governance and to identify knowledge gaps. The work was based on a literature survey of recently published reports and selected peer-reviewed articles on the topic. The report presents the results of the work carried out by the ETC/WMGE and ETC/CME.

This ETC/WMGE report provides an analysis of environmental risks and impacts related to the critical raw materials (CRMs) in the following applications: magnets, batteries, alloys, mineral fertilizers and electronics. The report also presents an overview of CRMs and their potential substitution solutions in these applications. In addition, it examines the economic importance and future aspects related to the use of CRMs in these applications.