bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of Convective Drying Parameters on Electrode Performance and Physical Electrode Properties
Authors: Westphal Bastian , Bockholt Henrike , Kwade Arno
Published: February 2020

As the need for nonpolluting individual mobility is rising, the production processes of lithium-ion batteries are gaining more and more attention. Although a lot of research for new battery materials or even for alternative battery technologies is done, the state of the art production process for large scale automotive lithium-ion batteries is still not completely understood. To get as close as possible to the theoretical performances of the used materials, an optimized process which includes a deep understanding of its influences on electrode structure and in the end on cell performance is essential. For this reason the drying process as one of the key-process-steps in the electrode production process is examined.

Since drying fixes the coating structure by evaporation of the solvent, the sedimentation of active material particles and the formation of the binder and carbon black matrix is influenced in a crucial way. In the present work some of the various drying parameters such as air temperature, outlet speed, air flow rate and residence time are varied and their influence on electrode structure is examined. A pilot-plant continuous convective dryer with three individual adjustable segments and a total length of six meters is basis of these investigations.

In order to analyze the resulting electrode structure measurements like mercury porosimetry (to determine the porediameter distribution of the coating), electrode conductivity (to describe the network of the conductive additives) and adhesion force measurements (to characterize the binder distribution) were carried out. As an example, a strong impact on the coating’s adhesion force to the current collector with increasing drying intensity (or faster solvent evaporation, respectively) and coating thickness could be found and explained by changes in electrode’s structure. Deeper insights in the processes affecting electrode structure can be obtained by determination of the electrochemical cell performance, thus allowing the establishment of process-structure-property relations.

Besides offline measurements to determine the electrode structure the drying process itself is monitored online by detecting the shift from constant rate drying period to falling rate period via infrared temperature sensors which measure the surface temperature of the coating. If the coating speed is kept constant the point of drying period change can be detected within a shorter distance from the dryer inlet when the air temperature is increased (see Fig. 1). The period change is identified for different drying parameters and electrode thicknesses as thicker electrodes tend to show a more distinct influence by the drying process.

In summary recent investigations show that electrode properties (e.g. adhesion force) resulting from solvent evaporation and structure fixation are clearly dependent on drying parameters and thus enabling a way for enhancing the battery’s performance.
Performances and Ageing Mechanisms of LiMn1-XFexPO4 // Graphite Prototype Cells
Authors: Dumont Erwan , Castaing Frédéric , Tessier Cécile
Published: February 2020

Olivine C-LiFePO4 has been intensively studied since 1997
[1
] due to its high thermal stability and the expected material cost reduction compared to usual cobalt based oxides. However, the energy density loss induced by the low operating voltage of LiFePO4, 3.45V, leads to consider LiMnPO4, 4.0V, as a promising candidate. But without dopants this material is kinetically limited: iron substitution seems to be a solution to make its utilization possible.

Several publications[2
]
,
[3
]
,
[4
]
present promising results on this type of material with good rate capabilities, good cycle life, but these results are mainly obtained in half cells vs Li° with low loaded electrodes.

Our work is focused on C-LiMn2/3Fe1/3PO4which has shown an excellent cyclability in half cells vs Li°.

Prototype cells vs graphite have been assembled using high loaded electrodes, with a design close to industrial cells. Results obtained show:

- excellent rate capability: >90% of capacity is recovered at 5C

- excellent cycle life: 80% of capacity is still remaining after 900 cycles

The study of ageing mechanisms by post-mortem analyses will be discussed.

Acknowledgment: All results presented here have been obtained on a material supplied by Clariant

[1] A. K. Padhi, K. S. Nanjundaswamy and J. B. Goodenough, Journal of The Electrochemical Society 1997, 144, 1188-1194.

[2] S.-M. Oh, H.-G. Jung, C. S. Yoon, S.-T. Myung, Z. Chen, K. Amine and Y.-K. Sun, Journal of Power Sources 2011, 196, 6924-6928.

[3] B. Z. Li, Y. Wang, L. Xue, X. P. Li and W. S. Li, Journal of Power Sources 2013.

[4] L. Hu, B. Qiu, Y. Xia, Z. Qin, L. Qin, X. Zhou and Z. Liu, Journal of Power Sources 2014, 248, 246-252.
Effects of Heat Treatment Temperature on the Electrochemical Performance of LiV3O8 Obtained By Solid-State Method
Authors: Bae Ki Yoon , Yoon Woo Young
Published: February 2020

The LiV3O8 compounds were synthesized by Solid-state method and calcination at different temperature (with heat treatment temperature ranging from 300 °C ∼ 600 °C) in order to find the relationship between heating temperature and electrochemical properties of LiV3O8.

The effects of precursor and heat treatment conditions on the structure, morphology, and electrochemical properties of the LiV3O8 were investigated by the implementation of X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), and energy dispersive spectroscopy (EDS). In order to find proper heat treatment temperature, TGA/DSC was performed too. All cells were cycled 50 times at a C-rate of 0.2 with the cut-off voltage ranging from 1.8 to 4.0V (versus Li/Li+). The result was analyzed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).

As the heat treatment temperature is increased, LiV3O8 has better crystalline phase but its primary particle size is grown bigger. For the sake of better electrochemical performances, especially high capacity retention, LiV3O8should have a proper size and size distribution.

[1] J. Feng, X. Liu, X. X. Zhang, J.Jiang, Z. Zhao, and M. Wang, J. Electrochem. Soc,
156, A768 (2009)

[2] H. Yang, J. Li, X.G. Zhang, Y.L. Jin, J. Mat. pro. tec, 207, 265 (2008)

[3] D. Wang, L. Cao, J. Huang, J. Wu, Ceram. Int, 38, 2647, (2012)

[4] Y.Q. Qiao, J.P. Tu, X.L. Wang, J. Zhang, Y.X. Yu, and C.D. Gu, J. Phys. Chem, 115, 25508 (2011)
Electrochemical Properties of LiMn2O4-Li7La3Zr2O12 Composite Film Electrode Fabricated By Aerosol Deposition Method
Authors: Inada Ryoji , Nakanishi Yuta , Masada Chiaki , Tojo Masaru , Tojo Tomohiro , Sakurai Yoji
Published: February 2020

LiMn2O4 (LMO)-Li7La3Zr2O12(LLZO) composite film electrode was successfully fabricated without any heat treatments by using aerosol deposition (AD) method. Mixture of 75wt%-LMO and 25wt%-LLZO powders with the averaged particle sizes around 1 μm was directly used as raw material. The mixed LMO and LLZO powders were sprayed onto a stainless steel substrate in deposition chamber evacuated to a low vacuum state below 10 Pa with N2 carrier gas for several 10 minutes. Mass flow of N2 carrier gas was set to be 20 L min-1 to form LMO-LLZ composite film via room temperature impact consolidation (RTIC). From both SEM observation and XRD measurement, it was found that as-deposited film has very dense structure without pores and is consisted from fractured LMO and LLZO crystalline particles with the sizes of several 10-100 nm. The thickness of composite film is 4 μm and LLZO content in the film was estimated to be around 21wt%. LMO-LLZO composite film electrode showed good electrochemical property in liquid electrolyte and higher discharge capacity than LMO film without including LLZO. The discharge capacities reduced by the weight of LMO-LLZO composite film electrode was 70 mAh g-1, 62 mAh g-1 and 55 mAh g-1 at different discharge current rates of 0.07C, 0.7C and 3C (1C = 0.11 mA cm-2). They are corresponding to the specific capacity per LMO in the film of 90 mAh g-1, 80 mAh g-1 and 71 mAh g-1, respectively. In addition, the LMO-LLZO composite film electrode showed good capacity retention during cycle testing, which is attributed to strong adhesion between the composite film and substrate by AD. The present results suggest that AD method can potentially be used for electrode layer composed of active material and solid electrolyte for all-solid state lithium-ion battery.
Potential and Current Distributions in Planar Electrodes of Lithium-Ion Batteries
Authors: Taheri Peyman , Mansouri Abraham , Yazdanpour Maryam , Bahrami Majid
Published: February 2020

Two-dimensional distribution of potential and current density in planar electrodes of pouch-type lithium-ion batteries are investigated numerically and analytically. A concentration-independent polarization expression, obtained experimentally, is used to mimic the electrochemical performance of the battery. By numerically solving the charge balance equation on each electrode in conjugation with the polarization expression, the battery behavior during constant-current discharge processes is simulated. The numerical analysis shows that reaction current density between the electrodes remains approximately uniform during most of the discharge process, i.e., when depth-of-discharge varies from 5% to 85%. This observation suggested simplifying the electrochemical performance of the battery such that the charge balance equation on each electrode can be solved analytically to obtain closed-form solutions for potential and current density distributions. The analytical model shows fair agreement with experimental and numerical data at modest computational cost. The model is applicable for both charge and discharge processes, and its application is demonstrated for 20 Ah and 75 Ah prismatic lithium-ion batteries. The analytical model is used to describe electrical conduction in the electrodes, and to investigate the effects of tab design on voltage drop. It is demonstrated that constriction/spreading resistance in current collectors of the considered battery is fairly small; about 10% of the total cell resistance but it is larger than the contribution of bulk resistance which is about 3%. The model confirms that constriction/spreading increase with: decrease in the aspect ratio of the current collector, decrease in the tab width, and increase in the tab eccentricity.
A Direct Route to Prepare Graphene/Tin Oxide Nanocomposites with Superior Electrochemical Properties As a Lithium-Ion Battery Anode
Authors: Shin Dong Ok , Park Hun , Kang Kun-Young , Lee Young-Gi , Kim Kwang Man , Han Tae Hee
Published: February 2020

A facile direct hybridization route to prepare SnO2/graphene nanocomposites for electrode application is demonstrated. Uniformly distribution of SnO2 nanoparticles on the graphene layers is enabled by one-step, hydrothermal reaction. While XRS result clearly indicates the crystalline nature of SnO2, TGA, TEM, SEM and galvanostatic analysis are perforemed to determine the optimized SnO2 content in nanocomposite. The nanocomposite anode with SnO2 content of 70.3 wt% retained the reversible capacity of 643.6 mAh/g after 50 cycles and high discharge capacity of 347.8 mAh/g at current density of 3000 mA/g. Taking advantage of nano-sized SnO2 and electron conductive and mechanically flexible graphene layer, the SnO2/graphene nanocomposites with the optimized SnO2 content exhibit excellent electrochemical properties as lithium-ion battery anode.
Single Step Aerosol Route Synthesis of Mixed Oxide Nanostructures for Useas Additive Free Lithium Ion Battery Electrodes
Authors: Chadha Tandeep Singh , Fang Jiaxi , Biswas Pratim
Published: February 2020

Lithium titanate has been successfully used as anode for lithium ion batteries due to its high rate capability, enhanced structural stability and safety, making it suitable for application in electric vehicles (EV) and hybrid electric vehicles (HEV). Current synthesis methods involve multiple steps including the production a nanoparticle powder, followed by coating the powder onto a conductive substrate along with conductive additives and binding agents and finally annealing. These processes do not offer sufficient control over the morphology, crystallinity and orientation of the active material. A single step process for the synthesis of nanostructured thin films directly on the current collector would facilitate the fabrication of nanostructured anodes without the use of any binding agent.

The aerosol chemical vapor deposition (ACVD) process is a single step, low cost method for the synthesis of nanostructured thin films. ACVD has been successfully demonstrated for the synthesis of metal oxides such as TiO2 and NiO and for mixed oxides of Al2TiO5. The process involves decomposition of a metal organic precursor in the reactor to yield metal oxide molecules which grow by homogenous nucleation to yield particles. These particles deposit onto a heated substrate where they sinter to form thin films of different morphologies. The synthesis of mixed oxide thin films involves heterogeneous nucleation of multi-component metal oxides to yield mixed oxide particles. The process allows for the synthesis of different nanostructures with varying morphologies, which include dense, single crystal columnar, granular and branched morphologies, through control over various process parameters.

This work focuses on controlling the composition and morphology of lithium titanate thin films synthesized by the ACVD process. Control over the characteristic times and the reaction rates was used to control the morphology and the stoichiometry of the synthesized thin films. The surface morphology of the films was characterized by scanning electron microscopy and the crystal structure was examined by x-ray diffraction analysis. X-ray photoelectron spectroscopy was used to probe the chemical composition of the films. Electrochemical characterization of the synthesized nanostructured anodes was performed in half cell configurations vs Li/Li+. The effect of stoichiometry and composition of the film on the electrochemical performance will be presented.
Development of Novel Fe2O3-Al2O3 Solid Solution Electrode by Using Mechanochemical Synthesis
Authors: Sawada Eisuke , Takemoto Masahi , Harada Jumpei , Takai Shigeomi , Yao Takeshi
Published: February 2020

Introduction

α-Fe2O3 is expected to perform as a favorable electrode material for lithium ion battery due to low cost and low toxicity. The cathode reaction is Fe2O3+6Li++6e-→2Fe+3Li2O. It is considered that Fe site in crystal structure of α-Fe2O3 is lost during cathode reaction, and then the specific capacity declines drastically.

When crystal structure of α-Fe2O3 is held, cyclic performance will be enhanced. In this study, we synthesized Fe2O3-Al2O3 solid solution in various molar ratios by mechanochemical synthesis. We investigated cyclic performance of the solid solution for the electrode of lithium ion battery.

Experiment

γ-Fe2O3 and γ-Al2O3 were mixed in molar ratios of Fe:Al=(1-x):x (x=0.05, 0.33, 0.40, 0.45, 0.50, 0.60, 0.65, 0.67, 0.95) by theta composer (Tokuju corp.), then synthesized Fe2O3-Al2O3 solid solution by mechanochemical synthesis with ball mill (Premium line, Fritsch GmbH). X-ray diffraction analysis of the obtained sample was conducted using Ultima IV (Rigaku co.) (CuKα, 40kV, 40mA).

The electrode was fabricated by mixing powder of the solid solution as the active material, acetylene black as a conducting additive and PTFE as a binder at the ratio of 60:40:3 by weight. C。opper mesh was used as current collector. Metal lithium was used as counter electrode and reference. The electrolyte was an 1M LiPF6 EC:EMC (3:7 v/v%).

We discharged the electrode material to the cutoff voltage of 0.1V (vs.Li/Li+) at 0.1A/g and charged to the cutoff voltage of 3.5V (vs.Li/Li+) at 0.1A/g. We measured cyclic performance of the solid solution.

Result and Discussion

We measured X-ray diffraction (XRD) of the samples synthesized with ball mill in various molar ratios from 20 degrees to 80 degrees in 2θ. We obtained lattice constants precisely by fitting the XRD peaks with Lorentz function. Unit cell volume is calculated from the lattice constants. For every molar ratio, the lattice constants and the unit cell volume are almost equal to those calculated from the lattice constants of α-Al2O3 and α-Fe2O3 (JCPDS database) by using Vegard’s law. It is confirmed that the all samples obtained by this mechanochemical synthesis were solid solutions. It is considered that this is the first report of the synthesis of complete solid solutions of α-Fe2O3 and α-Al2O3.

Fig.1 shows an example of charge-discharge curves of the solid solution (Fe0.6Al0.4)2O3. It shows that 1.4V plateau of the discharge curve is getting to ambiguous as number of cycles increases. Fig.2 shows cyclic performance of the solid solution (Fe0.6Al0.4)2O3. It shows that the specific capacity did not decline even after 300 cycles. It is indicated that the obtained solid solution (Fe0.6Al0.4)2O3 has excellent cyclic performance. It seems that α-Al2O3 solved in α-Fe2O3 keeps crystal structure of the active material.

References

T. Yao, S. Esaki, M. Nishijima, T. Yoshie, S. Park, M. Oda and J. Harada, PCT/JP2012/ 83694
Fabrication of Li4Ti5O12 Spinel Thin Films for Li Mirobattery Applications
Authors: Fung Kuan-Zong , Tsai Shu-Yi , Ni Chung-Ta , Orliukas Antanas F. , Bajars Gunars , Chen Mei-Han
Published: February 2020

Lithium titanium oxide spinel Li4Ti5O12 has been reported to be a zero-strain lithium insertion host material because it exhibits extremely small variations of the lattice parameters during the charge and discharge processes. In general, Poor adhesion between thin-film electrode and substrates is the common cause for performance degradation of thin-film electrode during repeated charge/discharge tests. Thus, Li4Ti5O12 spinel may be the ideal candidate for the anode of thin-film Li ion battery for long cycle applications.

However, different electrochemical behaviors will be expected when Li4Ti5O12 spinel is prepared in thin-film compared to that in power forms. Therefore, the objective of this work is (1) to fabricate thin film of Li4Ti5O12 spinel by using RF-sputtering technique, (2) to investigate the effect of annealing temperature/atmospheres on the electrical/electrochemical properties of thin film Li4Ti5O12, (3) to evaluate the feasibility of using thin film of Li4Ti5O12 as anode for Li microbattery applications.

In this study, the Li4Ti5O12 thin film was deposited on either the Si substrate or glass substrate by sputtering technique. The crystallization of deposited Li4Ti5O12 thin film will be enhanced by annealing at various atmospheres and temperatures. The single phase Li4Ti5O12 was finally obtained after co-sputtering of Li-containg and Ti-containing targets. The crystal structure and crystallization will be examined by glancing XRD. The resistivity of Li4Ti5O12 thin film will be evaluated by four probe technique and our novel micromeaurement system. The capacity of Li4Ti5O12 thin film will be evaluated from charge/discharge tests.
Improving Electrochemical Performance of Cusi Thin Film By Depositing Cu Thin Film Via Magnetron Sputtering
Authors: Polat Deniz Billur , Eryilmaz Levent , Keleş Özgül
Published: February 2020

Huge volumetric change occurs in Si anode material during lithiation process results in pulverization or delamination of the thin film from the current collectors, which eventually brings a short cycle life. Previously the use of CuSi as anode material to overcome this problem has been proposed. The results seem promising, even though more improvement has still been required for commercial applications. In this study, we present a strategy to improve the cycle performance of CuSi thin film: depositing a very thin Cu layer on top of the CuSi film. It is believed that Cu presence would improve the electrochemical performance of the anode due to its ductile and electrical conductive behavior.

In this sense, we produced two CuSi films by a magnetron sputtering method. To compare the effect of compliant layer presence on the anode performance, 10nm of Cu film was deposited on the top of the one CuSi film. The electrochemical performance proves that the coulombic efficiency as well as the cycle life of the CuSi film was increased due to the compliant layer existence.
Influence of Doping, Surface Area, and Porosity of Nanostructure Electrodes in Lithium-Ion Batteries
Authors: Stuve Eric M. , Cao Guozhong
Published: February 2020

Lithium-ion batteries store electrical energy in the form of chemical potential, the same as that in primary batteries; however, the charge-discharge process in lithium-ion batteries is more complex as it involves not only Faradaic reactions at the interface between electrode and electrolyte, but also mass and charge transport and volume change of electrodes that commonly possess low electrical conductivity. One strategy for improving battery performance is the use electrodes away from thermodynamic equilibrium. These include nanostructures with high surface energy, poor-crystalline materials, and materials with significant surface or bulk defects. Such materials are in a higher energy state and more readily undergo phase transformation and nucleation. Their less closely packed structures enhance mass transport, lithium-ion accommodation, and tolerance to volume change.

As an example, Figure 1 shows cycling performance of V2O5 electrodes in pure form (a), after Sn doping (b), and in the nano-belt configuration (c) [1,2]. Both the pure and Sn-doped electrodes exhibit an initial drop in specific capacity followed by an activation period that is somewhat longer for the Sn-doped electrode than for the pure electrode. The specific capacity of the pure electrode decays to about 180 mAh g–1 within 50 cycles. Notably, the Sn-doped electrode retains nearly its maximum capacity of 320 mAh g–1 throughout 50 cycles. Given the similar morphologies of these two electrodes, shown in Fig. 2(a) and (b), the change in capacity is most likely due to a chemical or electronic structure effect brought about by Sn-doping.

In contrast, the Na400 nano-belt electrode, prepared by reaction of V2O5 with H2C2O4 and NaNO3 and subsequent calcining to 400 °C, exhibits a steady yet slightly increasing capacity with cycling. The capacities of the pure V2O5 electrode (a) and the nano-belt electrode (c) become similar at about 40 cycles. This similarity may reflect changes in surface area of the pure electrode. Initially, the nano-belt electrode has, due to its well-formed belt structure [Fig. 2(c)], lower surface area than does the pure electrode. With cycling time the pure electrode eventually loses surface area, reaching a point similar to that of the nano-belt.

The extent of other factors, such as surface and bulk defects and volume change, are currently under investigation. This presentation will consider V2O5 electrodes and a new lithium titanate electrode as two model materials to illustrate the influences of doping, surface defects and carbon coating, and nanostructures on the lithium-ion intercalation properties.

1. Y. Li, J. Yao, E. Uchaker, M. Zhang, J. Tian, X. Liu, and G. Cao, J. Phys. Chem. C, 117, 23507 (2013).

2. S. Liang, T. Chen, A. Pan, D. Liu, Q. Zhu, and G. Cao, ACS Appl. Mater. Interfaces, 5, 11913 (2013).
Carbon-Rich Silicon Oxycarbide - a Promising Anode Material: Recent Findings Related to Microstructural, Electrochemical and Electroanalytical Characterization
Authors: Kaspar Jan , Graczyk-Zajac Magdalena , Riedel Ralf
Published: February 2020

The electrochemical properties of silicon oxycarbide ceramics (SiOC), in view of application as anode material for Li-ion batteries, were first studied in the middle of the 1990’s by Dahn et al. [1,2]. Since that time SiOC compounds with various chemical compositions have been examined and stoichiometries with an exceptionally high content of free carbon were identified as perspective anode materials, with respect to gravimetric capacity, rate capability and cycling behavior [3-6].

Within this work, the comprehensive characterization of carbon-rich SiOC derived from commercially available polyorganosiloxane RD-684a (Starfire Systems Inc., USA) is presented. The overview includes the correlation of electrochemical properties with microstructural features in dependence of the ceramization temperature of the Si-based polymer [6]. The dependency of the Li-ion diffusion coefficient on the potential is determined by electroanalytical methods PITT, GITT and EIS and analyzed with respect to the microstructural features of the ceramic [7]. In addition, the benefits of chemical modification of the precursor with Sn(ac)2, in order to enhance the lithium storage properties of SiOC by in-situ precipitation of metallic Sn as additional electrochemically active phase, is highlighted [8]. Finally, our newest results from ex-situ and in-situ Raman-spectroscopy measurements are presented, which directly trace and verify the Li-ion uptake within the free carbon phase in the SiOC microstructure.

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Quantitative Modeling of Microbial Fuel Cells for Water Purification
Authors: Calabrese Barton Scott
Published: February 2020

Although the 2015 Millennium Development Goal (MDG) for access to safe drinking water has largely been achieved, over 700 million people cannot access safe drinking water [1]. More importantly, the MDG for water sanitation is is far from achieved: 2.5 million people, primarily in sub-saharan Africa, lack access to water sanitization.

One solution for these populations is low-cost, mobile water purification based on microbial fuel cells (MFCs). MFCs are capable of producing energy from organic water contamination by oxidizing the contaminants, thereby producing electricity and reducing the chemical oxygen demand (COD) a key measure of water contamination, by more than 90% [2]. However, such a system would need to meet stringent cost and durability requirements; a self-powered purification system would require an approximately 10-fold increase in typical MFC power density and lifetime. Moreover, bench scale MFCs of 0.1 L size would would need to be scaled up to over 10 L for practical applications. These requirements can only be met by through careful engineering design and optimization.

Here we describe a numerical model of the the steady-state and transient operation of a microbial fuel cell for water purification. The model is based on laboratory-scale experiments conducted on MFCs using the Dissimilatory metal reducing bacteria Shewanella oneidensis MR-1 [3]. The model accounts for growth of bacterial biofilms, transport of reactants and products within the films, and related consumption of organic contaminants to electricity production.

Particular attention is paid to biofilm composition, and electron transport mechanisms with the biofilm, including electron transport via dissolved mediators, pili and nano filaments, and surface exchange. These considerations allow the the model to applied to a variety of metal-reducing species. After calibration with laboratory-scale MFC data, the model is used to predict performance of 10L-scale MFCs, including the relationship between decontamination rate, water flow rate, and power generation. Sensitivity studies may be directly compared with principal component analysis of experimental results, indicating the degree to which the model can be used for design and optimization of real-world devices.

"Millennium Development Goal drinking water target met”, http://www.who.int/mediacentre/news/releases/2012/drinking_water_20120306/en/

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E. Baranitharan, M. R. Khan, D. M. R. Prasad and J. Bin Salihon, Water, Air, Soil Pollut., 224, 1533 (2013). doi:10.1007/s11270-013-1533-1

S. Babanova, O. Bretschger, J. Roy, A. Cheung, K. Artyushkova and P. Atanassov, Phys. Chem. Chem. Phys., 16, 8956 (2014). doi:10.1039/c4cp00566j
Application Driven Fundamental Research on Microbial Electrochemical Technologies: From Components to System
Authors: Schroder Uwe , Harnisch Falk
Published: February 2020

Microbial electrochemistry is the study and application of interactions between microbial cells and electron conductors (electrodes). For a long time this field of bioelectrochemistry has been the interest of only fundamental researchers. This has significantly changed during the last decade, in which microbial electrochemistry gained increasing interest from applied researchers and engineers. Among other types of potential application, these researchers developed microbial fuel cells (MFCs), microbial electrolysis cells (MECs) and microbial desalination cells (MDCs) – electrochemical systems that utilize the organic load in wastewater to produce electric power, to produce chemical compounds or to desalinate salt water, respectively. However, the great majority of research on full systems is still being performed at laboratory scale (less than 1 L reactor volume) and technical or even pilot scale studies are rare. Rationally the majority of current studies do not focus on the system scale, but on the advancement of components, e.g. electrodes and membranes, and the investigation of fundamental processes of these components, e.g. interactions in microbiomes formed at electrodes, aiming at their subsequent engineering. However, system scale studies have clearly revealed a substantially higher degree of complexity and thus achievements on the component scale often cannot be simply transferred.

Therefore, we advocate that the most important issue is wisely merging fundamental research at the component scale with full system development. In this presentation we will illustrate on selected, recent examples the rationale of our appeal, spanning from very fundamental aspects like the development of high-performance electrode materials via the removal of micropollutants from wastewater at laboratory scale to a recent technical scale demonstrator and its performance in cleaning municipal wastewater and nitrogen recovery.
Engineering of Microbial Fuel Cells: The Things We Need to Know to Move Forward
Authors: Babanova Sofia , Bretschger Orianna , Artyushkova Kateryna , Atanassov Plamen
Published: February 2020

Microbial fuel cells (MFCs) provide a unique opportunity to combine the advantages of two worlds, wastewater purification and electricity production, that can be successfully explored for the development of self-sustainable portable wastewater plants. Unfortunately the level of development of this technology is just heading into the list of the practical devices. A significant part of the efforts in this area has been associated with fundamental understanding of the operational laws behind MFCs. Now, when the pile of knowledge regarding biofilm formation, electrode respiration by bacteria, biological interfacial reactions, etc. reached significant level, the next step in the scale-up process should involve material and design optimization. By looking back at what has been developed so far using innovative statistical interpretation of data, a numerous conclusions regarding bacteria features, metabolic pathways, electrode characteristics and MFC design can be withdrawn. Based on these conclusions, and mainly based on the observed correlation between parameters, a model describing MFC operation was created. This model included sub-modules describing the bacterial community, bacteria-electrode interactions, material properties as well as MFC overall design parameters[
1
].

The major factors influencing MFCs was recognized through Principal component analysis and their ascendency over MFC operational characteristics was statistically evaluated. The outputs of this analysis were further used as inputs for the development of a mathematical model, combining those factors. Path analysis was the main analytical tool for the model establishment. The model was first developed for pure culture of Shewanella oneidensis and expanded to include mixed communities naturally occurring in wastewater, which makes this study unique.

Successful engineering of MFCs, or other bioenergy systems, requires understanding of the underlying physical and biological processes, materials and abiotic structures, and the technical limits of their implementation in practical devices. This presentation will chart our strategies in bioenergy device design at all these four technology levels.

[1] a) S. Babanova, O. Bretschger, J. N. Roy, A. Cheung, K. Artyushkova and P. Atanassov, Phis.Chem.Chem.Phys.
2014, doi: 10.1039/C4CP00566J; b) C. Santoro, M. Guilizzoni, J.P. Correa Baena, U. Pasaogullari, A. Casalegno, B. Li, S. Babanova, K. Artyushkova, P. Atanassov, Carbon
2014, 67, 128–139.
Membrane Design for Water Separation Technologies
Authors: Nunes Suzana Pereira
Published: February 2020

Membranes are the core of efficient technologies for water desalination (reverse osmosis) and reuse (ultrafiltration and membrane bioreactor), biomedical processes (hemodialysis) and energy conversion (fuel cell and pressure retarded osmosis). We have been designing multifunctional polymers and copolymers and manufacturing membranes with tailored morphologies for different membrane applications. We have been synthesizing polyazoles with controlled hydrophilicity and porosity and testing for different applications. We explored dense films of polyoxadiazoles and polytriazoles with ionic charge for fuel cell. Hydrophobic fluorinated polyazoles were tested for membrane distillation. The exceptionally high oxidative and temperature resistance as well as the possibility of preparing membranes insoluble in organic solvents have extended the applications to harsh conditions, usually addressed only by ceramic membranes. The biocide function of triazole has been also investigated to reduce biofilm formation under operation for wastewater treatment. Triazole modified polysulfone membranes were synthesized for manufacture of ultrafiltration membranes with low fouling susceptibility. Porous asymmetric polyazole membranes have been prepared as flat-sheet and hollow fiber membranes. Random, graft and block coopolymers based on triazole are currently being explored for membrane manufacture in our group.
Electrochemical Disinfection of Liquid Human Waste for Developing World Application
Authors: Rogers Tate , Jackson Kathryn , Flynn Michael , Stoner Brian R. , Rowe Brfent R
Published: February 2020

This research reports the continued development of an electrochemical disinfection (ED) system for the treatment of liquid human waste. The system is a portion of a modular toilet designed for developing countries that will not require piped-in water, a sewer connection or outside electricity. Raut et al. (1) demonstrated the ability of the ED system to completely disinfect synthetic urine spiked with E. coli. This study reports the disinfection and total chlorine production capabilities of the system using field simulated conditions. The ED system is designed to treat liquid waste that has been separated from the solid waste deposited into the toilet. The effluent will contain urine, a small amount of fecal matter (~ 0.5% w/w), flush water, and cleansing water. This liquid waste will be treated to standards suitable for discharge to soil or for reuse as rinse or flush water.

The ED system was tested with the expected daily output of urine and flush water from one person and the solids/liquids interaction with feces was simulated to obtain the desired fecal contamination. E. coli was chosen as the disinfection indicator with starting concentrations ranging from 2.5 x 104 – 1.4 x 107 MPN/mL. As shown in Figure 1, disinfection was achieved by 110 minutes of processing time at 12 V.

Effective treatment of pathogens is expected to be a function of the production of chlorine containing species and other reactive oxygen species. However, to maintain disinfection in the system after ED treatment, a residual chlorine concentration is desired. Figure 2 shows the total and free chlorine produced over long electrochemical cell run times. Large amounts of chlorine were shown to be produced, however; most is consumed within 24 hours after the cell is turned off.

The ED system has demonstrated effective disinfection of fecal-contaminated liquid waste in simulated field conditions. Continued research will include pilot testing and demonstration of the ED’s effectiveness at killing chlorine resistant pathogens.

Acknowledgements

Financial support for this work was provided by the Bill & Melinda Gates Foundation.

References

1. A. Raut, G.B. Cunningham, C.B. Parker, B.R. Stoner and J.T. Glass, in 223rd ECS Meeting (May 12-17, 2013).
Water Quality and Water Toxicity Sensing
Authors: Minteer Shelley D.
Published: February 2020

Water quality sensing varies from specific chemical and biological sensing to toxicity sensing, depending on the application. This paper will give an overview of quantitative electrochemical sensors for the presence of heavy metals and bacteria in water supplies for use for commercial and municipal water analysis, but then goes on to detail new water toxicity biosensors utilizing thylakoid membrane modified electrodes and mitochondrial modified electrodes to provide threshold sensing of water toxicity. These type of sensors do not determine the contaminate present in the water and do not provide quantification of amount of contaminate present, but instead provide a sensor that determines if water is safe or toxic via the effect of plant (thylakoid) photosynthesis rates and mammalian (mitochondrial) metabolism. These new sensors are being designed for individual, point of use analysis.
(High Temperature Materials Division Outstanding Achievement Award) Semiconducting Properties and Defect Disorder of Indium-Doped Titanium Dioxide
Authors: Nowotny Janusz , Bak Tadeusz
Published: February 2020

Rutile is the promising inexpensive raw material for processing photocatalysts for solar water disinfection and photoelectrodes for solar hydrogen fuel (1). This work studied the effect of indium on surface vs. bulk electrical properties and the related defect disorder of TiO2 (rutile). It is shown that the effect of oxygen activity on both thermoelectric power and electrical conductivity of In-doped TiO2, determined at 1023 K – 1273 K in the gas phase of controlled oxygen activity [10-16 Pa<p(O2)<105 Pa], is consistent with a dual mechanism of indium incorporation, involving acceptor energy levels in the bulk and donor levels at the interface. The latter process leads to the formation of a quasi-isolated thin interface layer that differs from the bulk phase in the semiconducting properties and the related defect disorder as a result of segregation. This conclusion is supported by surface analysis of secondary ion mass spectrometry (SIMS) showing strong indium segregation towards negatively charged surface layer enriched by titanium vacancies (2). It is shown that the semiconducting properties may be modified in a controlled manner by defect engineering. It is also shown that segregation may be used as the technology in processing TiO2 with desired surface vs. bulk semiconducting properties that are required to form high-performance photoelectrodes for production of solar hydrogen fuel using photoelectrochemical cells and photocatalysts for water purification from toxic contaminants, such as bacteria, using solar energy as the only driving force of the process. The related studies are being conducted by parallel projects within the UWS R&D program on solar water decontamination and the generation of solar fuel.

Acknowledgements

The support was provided by the University of Western Sydney through the FIR program.

References

A Fujishima, K Honda, Nature 238 (1972) 37

A. Atanacio, T. Bak, J. Nowotny, ACS Appl Mater. & Interf., 4 (2012) 6626
Two Peas in a Pod: Sustainable Electrochemical Solutions for Waste and Water Reuse
Authors: Reguera Gemma
Published: February 2020

Satisfying the energy demands of the world population will require the development of technologies for waste and water reuse. Glycerol-containing wastewater is, for example, the major waste product of the biodiesel producers and bioethanol refineries, and it has become an economical and environmental liability to the industry. Purifying, concentrating, and selling the glycerol is no longer a profitable option and producers must pay to dispose of the wastewater as a hazardous waste. Electrochemical platforms show promise for the processing of wastewater and, if driven by customized consortia, they could be used to simultaneously generate added-value products from the organic waste. Hence, we developed an electrochemical reactor for the treatment of glycerin wastewater and the generation of ethanol, which can be used as alcohol feedstock for the transesterification reaction of oils to make the biodiesel industry fully petroleum independent. The electrochemical reactor was driven by the synergistic metabolisms of the exoelectrogen Geobacter sulfurreducens and the bacterium Clostridium cellobioparum, which fermented glycerol into ethanol at high yields (90%) and produced fermentative byproducts that served as electron donors for Geobacter. The synergistic interactions of the microbial catalysts stimulated glycerol consumption and ethanol production. At the same time, the fermentation byproducts were converted into cathodic H2, which facilitated the stripping of ethanol and resulted in clean waste streams that could be reused in upstream reactions. The platform was further improved to process glycerol loadings typical of biodiesel wastewater and to improve ethanol productivity. Furthermore, other alcohols could be produced to improve the economics of the electrochemical platform and address the needs of the producers in a fluctuating market. The results highlight the potential of electrochemically systems to simultaneously treat wastewater and harness the energy in the waste to generate bio-based feedstocks, fuels, and/or specialty or commodity chemicals.
Electrochemical Lithiation of Two Dimensional Materials By Nano Battery---an in Situ Study
Authors: Wan Jiayu , Hu Liangbing , Bao Wenzhong , Fuhrer Michael , Liu Yang
Published: February 2020

Layer-structured materials with van der Waals gaps have long been utilized as active electrode materials in rechargeable Li ion batteries. However, the intrinsic electrical, optical, and structural properties are not well understood at a single flake scale. We developed a planar nano battery for in situ measurement of large-area, uniform, two-dimensional (2D) flakes during lithiation process. A huge, simultaneous increase of optical transmittance and conductivity was observed with Lithium insertion in graphene and MoS2 flakes. The excellent performance (up to 200% transmittance increase and two orders magnitude of resistance decrease) is studied and explained by the unique band structure of the 2D materials and in situ TEM measurements. The proposed methodology can be applied to study a broad range of nanomaterials electrodes by electrochemical intercalation, and the excellent property of lithiated 2D materials will inspire a variety of applications such as electrochromic devices and transparent electrodes.
Coaxial Nanotube Battery inside Single Nanopore
Authors: Liu Chanyuan , Gillette Eleanor , Chen Xinyi , Pearse Alexander J , Kozen Alexander C , Schroeder Marshall A , Gregorczyk Keith , Lee Sang Bok , Rubloff Gary W
Published: February 2020

We report here a nanobattery comprised of nanotubular electrodes and electrolyte confined within an anodic aluminum oxide (AAO) nanopore. To construct confined electrically insulating electrolyte space in batteries with aligned nanoelectrodes, we have used atomic layer deposition (ALD) to synthesize nanotubular, heterogeneous coaxial electrodes at both ends of AAO nanopores. The nanoelectrodes include Ru nanotube current collectors with V2O5storage material on top of the Ru to form a symmetric full storage cell, with anode and cathode separated by an electrolyte region.

The V2O5 is prelithiated at one end to serve as anode while pristine V2O5 at the other end serves as cathode, so that the battery can be asymmetrically cycling between 0.2V and 1.8V. Capacity retention at high power (relative to 1C values 178mAh/g) is 95% at 5C and 46% at 150C. At 5C rate (12 min charge-discharge cycle), 81.3% capacity remains after 1000 cycles. The importance of incorporating integrated current collectors is demonstrated by the rate performance of V2O5 cathode with Ru nanotube current collector as compared to a Au planar current collector. While both show similar capacity at low rate (1C), at high rates (150C) that demand fast electron transport the V2O5/Ru nanotube (78mAh/g) exhibits almost twice the capacity of the V2O5/planar Au (42mAh/g).

This nanopore battery poses an extreme case of highly confined organic electrolyte environments in ultrasmall batteries. These promising results demonstrate the importance of integrating current collectors with storage nanoelectrodes, the benefit of electrolyte-accessible surface area of the nanotubular electrodes, and the cycling robustness of the nanostructures. At the same time, they provide a valuable data source for fundamental modeling to understand and quantify a science of “nanoionics” – a mesoscale phenomenon resulting from dense packing of ion storage nanostructures.
Modulating Effect of Core Composition in AuxCuy@Pt/C Core-Shell Nanoparticles for the Methanol Oxidation Reaction
Authors: Vázquez-Huerta Gerardo , Aldana-González Jorge , Montes de Oca Maria Guadalupe , Garfias-García Elizabeth , Romero-Romo Mario Alberto , Palomar-Pardavé Manuel
Published: February 2020

In the past decades, direct methanol fuel cell (DMFC) has attracted much interest for their significant advantages in portable and automobile applications, for this technology the anode electrocatalyst is the most important part. The Pt catalyst is widely recognized as the best catalyst for DMFC and one of the key objectives in fuel cell technology is to improve the electrochemical activity and reduce Pt loading of the electrocatalyst. One way to reduce the Pt content in the electrocatlyst is by synthetizing core–shell structural catalysts, in which only surface atoms are active in the catalytic reaction (i.e. Pt as shell). In this work, the modulating effect given by the composition of the core in AuxCuy@Pt/C for the methanol oxidation reaction (MOR) is analyzed. For this purpose, AuxCuy@Pt/C catalysts were prepared varying the Au:Cu percentage (i.e. 100:0%, 75:25%, 50:50%, 25:75%, 0:100%), the catalysts were prepared by a two-step method.