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The lithium–sulfur battery has long been seen as a potential next generation battery chemistry for electric vehicles owing to the high theoretical specific energy and low cost of sulfur. However, even state-of-the-art lithium–sulfur batteries suffer from short lifetimes due to the migration of highly soluble polysulfide intermediates and exhibit less than desired energy density due to the required excess electrolyte. The use of sparingly solvating electrolytes in lithium–sulfur batteries is a promising approach to decouple electrolyte quantity from reaction mechanism, thus creating a pathway toward high energy density that deviates from the current catholyte approach. Herein, we demonstrate that sparingly solvating electrolytes based on compact, polar molecules with a 2:1 ratio of a functional group to lithium salt can fundamentally redirect the lithium–sulfur reaction pathway by inhibiting the traditional mechanism that is based on fully solvated intermediates. In contrast to the standard catholyte sulfur electrochemistry, sparingly solvating electrolytes promote intermediate- and short-chain polysulfide formation during the first third of discharge, before disproportionation results in crystalline lithium sulfide and a restricted fraction of soluble polysulfides which are further reduced during the remaining discharge. Moreover, operation at intermediate temperatures ca. 50 °C allows for minimal overpotentials and high utilization of sulfur at practical rates. This discovery opens the door to a new wave of scientific inquiry based on modifying the electrolyte local structure to tune and control the reaction pathway of many precipitation–dissolution chemistries, lithium–sulfur and beyond., Achieving sparing solubility of polysulfides in electrolytes for Li−S cells induces fundamental changes in the reaction pathway that give rise to low polarization.

Increasing the areal capacity or electrode thickness in lithium ion batteries is one possible means to increase pack level energy density while simultaneously lowering cost. The physics that limit use of high areal capacity as a function of battery power to energy ratio are poorly understood and thus most currently produced automotive lithium ion cells utilize modest loadings to ensure long life over the vehicle battery operation. Here we show electrolyte transport limits the utilization of the positive electrode at critical C-rates during discharge; whereas, a combination of electrolyte transport and polarization lead to lithium plating in the graphite electrode during charge. Experimental measurements are compared with theoretical predictions based on concentrated solution and porous electrode theories. An analytical expression is derived to provide design criteria for long lived operation based on the physical properties of the electrode and electrolyte. Finally, a guideline is proposed that graphite cells should avoid charge current densities near or above 4 mA/cm2 unless additional precautions have been made to avoid deleterious side reaction.

Low-cost energy storage systems are required to support extensive deployment of intermittent renewable energy on the electricity grid. Redox flow batteries have potential advantages to meet the stringent cost target for grid applications as compared to more traditional batteries based on an enclosed architecture. However, the manufacturing process and therefore potential high-volume production price of redox flow batteries is largely unquantified. We present a comprehensive assessment of a prospective production process for aqueous all vanadium flow battery and nonaqueous lithium polysulfide flow battery. The estimated investment and variable costs are translated to fixed expenses, profit, and warranty as a function of production volume. When compared to lithium-ion batteries, redox flow batteries are estimated to exhibit lower costs of manufacture, here calculated as the unit price less materials costs, owing to their simpler reactor (cell) design, lower required area, and thus simpler manufacturing process. Redox flow batteries are also projected to achieve the majority of manufacturing scale benefits at lower production volumes as compared to lithium-ion. However, this advantage is offset due to the dramatically lower present production volume of flow batteries compared to competitive technologies such as lithium-ion.

Gadolinium-doped ceria (GDC) deposited by radio frequency magnetron sputtering is utilized as the anode interlayer for low-temperature solid oxide fuel cells (LT-SOFCs) with a nanothin yttria-stabilized zirconia (YSZ) electrolyte and Ni/Pt electrodes. When the thickness ratio of YSZ electrolyte versus 100 nm GDC anode interlayer is at or below 1.5, the electrochemical performance of the LT-SOFC is severely poor due to the microstructural instability of the GDC anode interlayer under high-temperature reducing atmospheric conditions. At 500 °C, the peak power density of the LT-SOFC with a Ni anode and a 20 nm GDC anode interlayer is ~ 30% higher than that without the GDC anode interlayer due to faster reaction kinetics on the anode side.

Although an onboard fuel cell system is able to provide sufficient electricity to power a vehicle, a secondary energy storage system such as an electrical battery is desirable because the fuel cell system is generally not capable of braking energy recuperation, and the efficiency of the fuel cell system can be improved by using the secondary energy system. In this paper, sufficient conditions are obtained for an optimal control idea for fuel cell hybrid electric vehicles when the fuel cell system is combined with a rechargeable battery. The optimal control is based on Pontryagin’s minimum principle, and this study demonstrates that it results in total hydrogen consumptions if the properties of the fuel cell hybrid system satisfy two assumptions: first, the hydrogen consumption rate of the fuel cell system is convex and, second, the time derivative of the state of charge is concave. In order to validate optimality of the control concept, a vehicle simulation model is developed for a fuel cell hybrid electric vehicle, and control based on Pontryagin’s minimum principle is applied in a backward-looking simulator. In the simulation results, control based on Pontryagin’s minimum principle produces an optimal solution, which is very close to the global optimal solution obtained by dynamic programming. In addition, control based on Pontryagin’s minimum principle simplifies the control organization; the control concept should be considered as a promising solution for fuel cell hybrid electric vehicles because it really achieves results which are near the global optimal results.

In valuing new active materials chemistries for advanced batteries, the theoretical specific energy is commonly used to motivate research and development. A packaging factor is then used to relate the theoretical specific energy to the pack-level specific energy. As this factor is typically assumed constant, higher theoretical specific energies are judged to result in higher pack-level specific energies. To test this implicit assumption, we calculated the fraction of the theoretical specific energy achieved on the pack level for hypothetical cell chemistries with various open-circuit voltages and theoretical specific energies using a peer-review bottom-up battery design model. The pack-level specific energy shows significant dependence on the open-circuit voltage and electrochemical impedance due to changes in the quantity of inactive materials required. At low-valued average open-circuit voltages, systems with dramatically different theoretical specific energies may result in battery packs similar in mass and volume. The fraction of the theoretical specific energy achieved on the pack level is higher for the lower theoretical specific energy systems mainly because the active materials mass dominates the pack mass. Finally, low-valued area-specific impedance is shown to be critical for chemistries of high theoretical specific energy and low open-circuit voltage to achieve higher pack-level specific energies.

This paper presents the architecture of a nano thin-film yttrium-doped barium zirconate (BYZ) solid-oxide fuel cell that uses nanoporous anodic aluminum oxide (AAO) as a supporting and gas-permeable substrate. The anode was fabricated by sputtering 300 nm platinum thin film that partially covered the AAO surface pores, followed by an additional conformal platinum coating to tune the pore size by atomic layer deposition. Two different nano-porous anode structures with a pore size of 10 nm or 50 nm were deposited. Proton-conducting BYZ ceramic electrolyte with increasing thicknesses of 300, 600, and 900 nm was deposited on top of the platinum anode by pulsed laser deposition, followed by a 200 nm layer of porous Pt sputtered on BYZ electrolyte as a cathode. The open circuit voltage (OCV) of the fuel cells was characterized at 250 °C with 1:1 volumetric stoichiometry of a methanol/water vapor mixture as the fuel. The OCVs were 0.17 V with a 900 nm-thick BYZ electrolyte on 50 nm pores and 0.3 V with a 600 nm-thick BYZ electrolyte on 10 nm pores, respectively, but it increased to 0.8 V for a 900 nm-thick BYZ electrolyte on 10 nm pores, indicating that increasing the film thickness and decreasing a surface pore size help to reduce the number of electrolyte pinholes and the gas leakage through the electrolyte. A maximum power density of 5.6 mW/cm 2 at 250 °C was obtained from the fuel cell with 900 nm of BYZ electrolyte using methanol vapor as a fuel.

This paper investigates the analysis and design of optimal operational conditions for vapor-fed direct methanol fuel cells (DMFCs). Methanol vapor at a temperature of 35 °C is carried with nitrogen gas together with water vapor at 75 °C. In this experimental condition, stoichiometry of 10 is maintained for each fuel gas. The results show that the optimal operational concentration was 25–30 wt.% under methanol vapor feeding at the anode. The peak power was 14 mW cm 2 in polarization curves. To analyze major losses, the activation losses of the anode and cathode were measured by an in situ reference electrode and a working electrode. The activation loss of the anode is proportional to the water content and the high methanol concentration caused the activation loss of the cathode to increase due to methanol crossover. In the vapor-fed DMFC, the activation loss of the anode is higher than that of the cathode. Also, depending on the variation of the methanol concentration, the IR loss and Faradaic impedance is measured via impedance analysis. The methanol concentration significantly affects the IR loss and kinetics. Although the IR loss was more than the desired value at the optimal condition (25–30 wt.%), it did not significantly affect the cell’s performance. The cell operated at room temperature and ambient pressure that is a typical operation environment of air-breathing fuel cells.

This work examines the effect of fuel delivery configuration on the performance of a passive air-breathing direct methanol fuel cell (DMFC). The performance of a single cell is evaluated while the methanol vapour is supplied through a flow channel from a methanol reservoir connected to the anode. The oxygen is supplied from the ambient air to the cathode via natural convection. The fuel cell employs parallel channel configurations or open chamber configurations for methanol vapour feeding. The opening ratio of the flow channel and the flow channel configuration is changed. The opening ratio is defined as that between the area of the inlet port and the area of the outlet port. The chamber configuration is preferred for optimum fuel feeding. The best performance of the fuel cell is obtained when the opening ratio is 0.8 in the chamber configuration. Under these conditions, the peak power is 10.2 mW cm−2 at room temperature and ambient pressure. Consequently, passive DMFCs using methanol vapour require sufficient methanol vapour feeding through the flow channel at the anode for best performance. The mediocre performance of a passive DMFC with a channel configuration is attributed to the low differential pressure and insufficient supply of methanol vapour.

Achieving reversible electrochemistry under lean electrolyte operation is key to moving LiS chemistry to potentially transformational performance.1 The use of electrolytes that are sparingly solvating to Li polysulfide intermediates is a promising approach to decouple electrolyte volume from reaction mechanism, thus creating a pathway towards high energy density LiS batteries that deviates from the current catholyte approach.2In this work, we discuss the design rules for sparingly solvating electrolytes and the unique electrochemistry that arises through the use of this class of electrolytes. 1D. Eroglu, K. R. Zavadil and K. G. Gallagher, J. Electrochem. Soc., 2015, 162, A982. 2L. Cheng, L. A. Curtiss, K. R. Zavadil, A. A. Gewirth, Y. Shao and K. G. Gallagher, ACS Energy Lett., 2016, 1, 503.

A novel processing sequence for the formation of gated diamond field emitter array (triode system) is proposed and the feasibility is tested by investigating the field emission property. The processing scheme is based on the selective deposition of diamond by using the well established nucleation enhanced process on substrate, so callled bias enhanced nucleation (BEN). The structure of substrate was patterned [SiO 2 /Mo(gate)SiO 2 (insulator)Si(100). Our preliminary results show that the diamond field emitter is turned on at around 87 V/μm with the current level of about several μA.

Lithium ion batteries are now deployed to various portable electric devices and electric vehicles. However, the energy density, especially the volumetric energy density of the battery does not reach ideal target from a consumer perspective. The multivalent metal batteries are one of the promising candidates as a beyond lithium ion battery with 2–3 times the energy density of what lithium ion can offer. Among multivalent metals, magnesium provides double the volumetric capacity of lithium. However, the standard reduction potential of magnesium is 700 mV less negative than that of lithium. Therefore, the approach to increasing its operating voltage is very important to increase energy density of battery. Due to the demand for high voltage operation, comprehensive efforts have been demonstrated for high voltage electrolyte. The oxidative stability of many magnesium electrolytes is reported to be over 3 V vs Mg when tested by cyclic voltammetry on a Pt working electrode. However, their window of operation when assembled in coin cells and operated at constant current using typical stainless steel current collector and case is rarely above 2.0 V. We demonstrated assembly of pouch cells for multivalent metal batteries and performed electrochemical testing. Initial work to identify high-performing materials, composition, fabrication variables and cycling conditions is conducted in cyclic voltammetry and coin cell test. The resulting information is then used for the pouch cell demonstration.

Energy storage is increasingly seen as a valuable asset for electricity grids composed of high fractions of intermittent sources, such as wind power or, in developing economies, unreliable generation and transmission services. However, the potential of batteries to meet the stringent cost and durability requirements for grid applications is largely unquantified. We investigate electrochemical systems capable of economically storing energy for hours and present an analysis of the relationships among technological performance characteristics, component cost factors, and system price for established and conceptual aqueous and nonaqueous batteries. We identified potential advantages of nonaqueous flow batteries over those based on aqueous electrolytes; however, new challenging constraints burden the nonaqueous approach, including the solubility of the active material in the electrolyte. Requirements in harmony with economically effective energy storage are derived for aqueous and nonaqueous systems. The attributes of flow batteries are compared to those of aqueous and nonaqueous enclosed and hybrid (semi-flow) batteries. Flow batteries are a promising technology for reaching these challenging energy storage targets owing to their independent power and energy scaling, reliance on facile and reversible reactants, and potentially simpler manufacture as compared to established enclosed batteries such as lead–acid or lithium-ion.

Energy storage systems are increasingly seen as a critical component of the electricity grid to support extensive deployment of intermittent renewable energy such as solar and wind systems. The flow batteries with low cost and high energy density are promising for reaching these challenging energy storage target owing to their power and energy separation characteristics. Lithium-polysulfide (Li-PS) flow batteries are of particular interest due to their high theoretical energy density, and relatively inexpensive raw materials for grid storage applications. Unfortunately, present state-of-the-art technologies are too expensive for broad deployment. One possible pathway to reduced system costs is increasing manufacturing volume and engineering advancements. System cost reductions in manufacturing costs and associated overheads are identified as the single largest cost-savings opportunity for today's battery-based storage options. The simpler assembly process for a flow battery is projected to be a key distinguishing factor compared to enclosed cells. In addition, increasing production volume and market competition will lead to lower material costs. Here in, we examine in detail the manufacturing cost and additional mark-up of Li-PS flow battery by using techno-economic model, and it is compared to enclosed system(Li-ion) and aqueous flow battery(Vanadium redox flow battery). Here we show the consequences on system price breakdown to assess the cost benefits of simple assembly process and mass manufacturing, Figure 1. Figure 1

In response to the development effort of battery powered electric vehicles, the search for new battery chemistries with sufficiently high specific energy and energy density has been accelerated. The lithium-sulfur battery is one of the candidate chemistries that has gained significant attention over the several decades due to its much higher theoretical specific energy and energy density compared to today's Li-ion battery [1, 2]. Theoretical specific energy and energy density, which are calculated considering only the active material mass and volume, are frequently used for the comparison of candidate chemistries; however the conclusions can be significantly different when one considers the system-level properties. In this study, the dependence of the system-level properties on the open-circuit voltage, theoretical specific energy, and area-specific impedance of the cell couple are discussed. The system-level specific energy and energy density are estimated for hypothetical cell chemistries with various open-circuit cell voltages and theoretical specific energies using the publically available Battery Performance and Cost (BatPaC) model [3, 4] for a 50 kWh, 100 kW and 360 V battery. The system-level energy density predictions can be seen in Figure 1 for various open-circuit voltage and theoretical specific energy couples. The dependence of the system-level specific energy on OCV is critical; at low OCVs systems with significantly higher specific energies show similar system-level properties. High theoretical specific energy systems continue to get lighter and smaller with increasing OCV whereas low theoretical specific energy systems do not because of the maximum electrode thickness limitation. System-level specific energy and fraction of the theoretical specific energy and energy density achieved on the pack level are also discussed as a function of OCV, theoretical specific energy and area-specific impedance. Finally, the Li-S battery, which has high theoretical specific energy but low OCV, is investigated. Figure 1. The effect of open-circuit voltage on the system-level energy density for different theoretical specific energies. Theoretical energy density is not constant on constant theoretical specific energy curves. Acknowledgments This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. References 1. Bruce, P.G., S.A. Freunberger, L.J. Hardwick, and J.-M. Tarascon, Nature Materials, 11, 19 (2012). 2. Ji, X.L. and L.F. Nazar, Journal of Materials Chemistry, 209821 (2010). 3. Nelson, P., K. Gallagher, I. Bloom, and D. Dees, Modeling the Performance and Cost of Lithium-Ion Batteries for Electric Vehicles, Chemical Sciences and Engineering Division, Argonne National Laboratory, ANL-11/32, Argonne, IL USA, (2011). 4. Nelson, P.A., K.G. Gallagher, and I. Bloom, BatPaC (Battery Performance and Cost) Software, (2012).

Energy storage systems are crucial for extensive deployment of renewable energy such as solar and wind systems and huge demand on the electrical grid to recharge electric vehicles. Scalable energy storage with low cost and high energy density will be a key to meet these challenges [1]. Lithium-polysulfide (Li-PS) flow batteries are of particular interest due to their scalability, high potential chemistries, and potentially low cost for grid storage applications [2]. Here we present a materials-to-system analysis of the Li-PS flow battery by using techno-economic model which combines electrochemical performance and cost calculation model to examine feasibility for grid storage application. In the system, lithium polysulfide in ether-based solvent and metallic lithium are used as the catholyte and anolyte, respectively [3]. The model examines the correlation between performance and cost as considering the physical property limitations of the system components, Figure 1. Additionally, the consequences on cost and energy density from change in system properties such as redox material concentration, potential, and specific capacity are assessed to probe design phase space for the requirements of an application. Figure 1. Summary flow of the techno-economic model Acknowledgments This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences. The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. References [1] G. Crabtree, J. Misewich, R. Ambrosio, K. Clay, P. DeMartini, R. James, M. Lauby, V. Mohta, J. Moura, P. Sauer, F. Slakey, J. Lieberman, H. Tai, Integrating Renewable Electricity on the Grid – A Report by the APS Panel on Public Affairs American Physical Society, Washington DC 2010. [2] Yuan Yang, Guangyuan Zheng and Yi Cui, Energy Environ. Sci., 2013, 6, 1552-1558. [3] Kevin G. Gallagher, Paul A. Nelson, Denis W. Dees, Journal of Power Sources 196 (2011) 2289–2297

This paper presents a combinatorial deposition of a nano-thin film yttria-stabilized zirconia (YSZ) electrolyte deposited on a nanoporous anodic aluminum oxide (AAO) membrane, which serves as a supporting and gas-permeable substrate. The dense YSZ electrolyte was deposited by combining atomic layer deposition (ALD) and sputtering in an attempt to realize a pinhole-free electrolyte on a porous structure with a minimum electrolyte thickness. The YSZ electrolyte with an overall thickness of about 390 nm was successfully fabricated on porous AAO with this combined deposition method, and the open circuit voltage (OCV) of the cell with this electrolyte was verified to reach a high value of 1.14 V at 350 °C under an atmosphere of pure hydrogen and ambient air. The fuel cell performance reached power densities of 88, 129, and 180 mW cm−2 at 350, 400, and 450 °C, respectively, and has been so far the highest attainable for a nanoscale thin film electrolyte on a porous substrate at such low temperatures. The addition of the pre-ALD YSZ layer also serves to confine the anode morphology and thus enhance the thermal stability of the metal electrodes.

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