bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sputtered Iridium Oxide Microsupercapacitors Operating in Physiological Electrolytes
Authors: Maeng Jimin , Geramifard Negar , Chakraborty Bitan , Cogan Stuart F. 
Published: February 2020

Implantable devices (e.g. biosensors, neural prosthetics) are increasingly an option for the prevention, diagnosis, and treatment of human diseases and disorders, leading to patient rehabilitation and health improvement. Such devices are typically powered by an external source through wires or an internal battery. Unfortunately, these conventional power sources pose challenges and concerns; while wires are primary sources of infection and patient discomfort, implanted batteries pose safety concerns and suffer from the need for periodic replacements that involve a surgery which is an additional risk. Therefore, there is a need for an alternative power source that safely operates in human body with sustained durability.
Supercapacitors are a class of electrochemical energy storage devices that may complement or even replace the implanted batteries. Besides the favorable traits of supercapacitors, including high power density, rapid charging and discharging, and long cycle life, the major advantage of supercapacitors particularly towards implantable applications lies in the possibility for directly utilizing physiological fluid as a source of electrolyte. This makes it unnecessary to house additional electrolyte in a package and thus precludes toxic electrochemical reactions associated with battery electrolytes. Such a package-free configuration also enables significant miniaturization of supercapacitors and may open up a possibility for implantation into previously unexplored body organs such as blood vessel, eyeball, or bladder.
Here, we present sputtered iridium oxide microsupercapacitors operating in physiological electrolytes as progress toward human-body implantable energy storage devices. Supercapacitors having micropatterned interdigital electrodes coated with sputtered iridium oxide films are fabricated and characterized in two types of physiological electrolytes: a phosphate-buffered saline (PBS) solution and an inorganic model of interstitial fluid (model-ISF) that mimics the body fluid more closely. These devices exhibit a maximum volumetric capacitance density of 342 F cm-3, an energy density of 47.5 mWh cm-3, and a power density of 40.5 W cm-3 in PBS. It is observed that 55-74% of these values are still available in model-ISF. The energy and power density values obtained here are higher than those for other reported microsupercapacitors characterized in conventional aqueous or solid-state electrolytes. The devices maintain a proportional increase in current density from a scan rate of 20 to 200 mV s-1 and retain 40% of the initial voltage against a self-discharging for 6 hours. They also exhibit a capacitance retention of 100% under 10000 charge-discharge cycles at a scan rate of 200 mV s-1. The demonstrated energy storage performance and the durability in the physiological electrolytes warrant investigation of the proposed microsupercapacitors in biological fluids toward human-body energy storage applications.
Redox-Mediated Bromate Based Electrochemical Energy System
Authors: Cho Kyu Taek , Razaulla Talha 
Published: February 2020

A promising redox-mediated bromate-ion (BrO3
-) based system was investigated through research combined with mathematical modeling and full-cell test to understand the characteristic effect of electrochemical reaction coupled with chemical reaction on the cell behaviors. This system has a unique feature of the reaction mechanism in which the reactant (Br2) is not provided externally, but is kept regenerated by a coupled chemical reaction of bromate in the cell, which may lead to “no limiting current” condition (i.e. non-zero concentration of the reactant species at the electrode surface for any current conditions) by eliminating mass transfer (i.e. concentration) over-potential, and thus this system is estimated to achieve the ultra-high performance [1-4].
From the full-cell based test, a unique behavior induced by this auto-catalytic reaction was found for the first time, and to understand the underlying physics and nature of the system, theoretical study was conducted through mathematical modeling and analytic analysis.
Three reaction mechanisms (E, EC, and EC’) were compared in their characteristic reaction behaviors to understand the nature of each reaction mechanism, and the results were analyzed with respect to reaction time and species concentration at the electrode surface. Furthermore, the effect of actual condition of bromate system (i.e. non-unity stoichiometry and limited amount of bromate) was analyzed at unsteady condition for the first time to understand its characteristic behavior in the actual battery condition.
As a final step, the effect of catalytic reaction was analyzed analytically to define the parameters to control the catalytic reaction, and especially, the effect of relative rate of electrochemical reaction and coupled chemical reaction on the autocatalytic reaction was compared through a zone diagram where conditions for pure diffusion controlled and pure kinetic controlled cases were defined.

References

[1] Y. Tolmachev, A. Piatkivskyi, V. Ryzhov, D. Konev, M. Vorotyntsev , J Solid State Electrochem, 19 (2015) 2711-2722.
[2] M.A. Vorotyntsev, A.E. Antipov, Y.V. Tolmachev, Electrochimica Acta, 222 (2016) 1555-1561.
[3] M.A. Vorotyntsev, A.E. Antipov, Journal of Electroanalytical Chemistry, 779 (2016) 146-155.
[4] M.A. Vorotyntsev, A.E. Antipov, Electrochimica Acta, 258 (2017) 544-553.
(Invited) Metal Halide Perovskites at the Nanoscale: High Quality Optoelectronic Materials with Unique Phase Properties
Authors: Luther Joseph M. 
Published: February 2020

The newly rediscovered perovskite semiconductor system has the potential to be extremely transformative for all optoelectronic devices, especially photovoltaics (PVs). Perovskite semiconductors of the form APbI3 where A is a large +1 charged cation, typically Cs, methylammonium, or formamidinium have had a huge resurgence among materials scientists for outstanding PV properties despite being overlooked for decades. Semiconductors containing the latter two A-site cations listed are hybrid organic-inorganic materials, and as such, are far less understood compared to conventional all inorganic or even organic material systems. Regardless of this spotty formal understanding, lead-halide perovskites have very rapidly been optimized to power conversion efficiency levels on par with all other materials even with extensive history of research. Perovskites show a unique tolerance to crystalline defects that cause trouble in most other semiconductors. Therefore the potential offered is that very high efficiency PVs can be fabricated in extremely fast and inexpensive ways, thus offering a revolution for the solar industry and a direct route toward producing the world’s energy with a simple and clean technology. Long-term durability of the devices is the critical remaining challenge to be solved.1 Two examples of major instabilities in device performance are the volatility of the organic cation and the specific crystal habit in which the material embodies.
Nanoscale versions (often termed quantum dots (QDs)) of the all-inorganic metal halide perovskite (CsPbI3) tend to retain the desired perovskite phase due to strain effects at the surface of the QDs whereas conventional films of the same material “relax” to an orthorhombic non-perovskite structure at room temperature. Therefore these QDs potentially solve both of the instability issues. The cubic CsPbI3 QD cells operate with a rather remarkable open-circuit voltage of >1.2 volts and have produced power conversion efficiencies over 13%.2,3 This customizable new nanomaterial system has incredible potential for many applications in optoelectronics, including photovoltaics, LEDs, displays and lasers. We describe the formation of perovskite phase-CsPbI3 QD films with long range electronic transport that retain the high temperature phase in ambient conditions making up the active layer in optoelectronic devices. Perspectives on how this technology can become transformative will be discussed.

References

A. Christians, P. Schulz, J.S. Tinkham, T.H. Schloemer, S.P. Harvey, B.J .Tremolet de Villers, A. Sellinger, J.J. Berry, J.M. Luther, Nature Energy, 2018, 3 (1), 68.

Swarnkar, A.R. Marshall, E.M. Sanehira, B.D. Chernomordik, D.T. Moore, J.A. Christians, T. Chakrabarti, J.M. Luther, Science, 2016, 354 (6308), 92-95.

M. Sanehira, A.R. Marshall, J.A. Christians, S.P. Harvey, P.N. Ciesielski, L.M. Wheeler, P. Schulz, L.Y. Lin, M.C. Beard, J.M. Luther, Science Advances, 2017, 3 (10), eaao4204.
Simple but Highly-Efficient Polysulfide Trapping Strategy for Lithium-Sulfur Batteries
Authors: Yuan Yan , Zheng Dongdong , Fang Zhao , Lu Hai 
Published: February 2020

Lithium-sulfur (Li-S) battery, as an attractive alternative to the state-of-the-art Li-ion battery by the merits of high energy density and abundant material sources, is expected to meet the urgent demand of next-generation electric vehicles. However, several challenges severely hinder its application process, including low conductivity of elemental sulfur and lithium sulfide, large volume expansion upon discharge, and unfavorable redox shuttle due to the soluble polysulfides (PSs). In order to increase sulfur utilization and cycle stability of the Li-S batteries, a variety of strategies on modifying sulfur cathode have been attempted, e.g. development of sulfur-carbon composite, introduction of extra surface coating and novel electrode component, etc.
It is worthy to note that many studies involving PS’ trapping material/structure always brought about significant improvement of cell performance. This is because that the active species loss and shuttle side effect were reduced. Recently our research group has reported the good chemical affinity of polyacrylamide (PAM) to PSs, coming from the strong binding of the amide group in the PAM with Li-S• species. Therefore, the polymer was successfully used in the surface coating on either sulfur cathode or porous separator [1, 2]. Poly(acrylic acid) (PAA), another water-soluble polymer, also can act as a favorable PS blocking layer because the COOH groups in the long chain can form strong hydrogen bonds with the PS anions [3].
This research demonstrates a simple but highly-efficient PS trapping strategy that employs PAA and PAM as a functional binder and additive for sulfur cathode, respectively. The synergistic action of these two distinctive agents contributes to higher reversible capacity and longer cycle life of Li-S batteries compared to conventional electrode. The mechanism of trapping PSs in the artificially-designed cathode framework was discussed, and the enhancement of hydrophilic nature of the cathode to the liquid electrolyte was also considered. It needs to be emphasized that the novel cathode can be easily fabricated on a large-scale without any additional procedures.
Fig. 1 Comparison of cycle performance of PAM/PAA-contained cathode and conventional sulfur cathode

Reference:

[1] T. Li, Y. Yuan, B. Hong, et al, Electrochim. Acta, 2017, 244, 192-198
[2] H. Lu, J. Wang, T. Li, et al, J Solid State Electrochem., 2018, 22, 953-958
[3] S. Zhang, D. Tran, Z Zhang, J. Mater. Chem. A, 2014, 2, 18288-18292

Acknowledgment:

This work was financially supported by National Natural Science Foundation of China (No.51704222, 51604221 and 51574191), Natural Science Basic Research Plan in Shaanxi Province of China (No.2016JQ5040), and Special Scientific Research Program of Education Department of Shaanxi in China (No.17JK0427).

Figure 1
Mxenes As Sulfur Host Material for Magnesium-Sulfur Batteries
Authors: Kaland Henning , Fagerli Frode Håskjold , Hadler-Jacobsen Jacob , Boge Lars-Arne , Schnell Sondre Kvalvaag , Vullum-Bruer Fride 
Published: February 2020

Magnesium-sulfur batteries offer the possibility of combining highly abundant and cheap elements with high energy density. Despite recent significant improvements, critical aspects still in need of optimization include electrolyte and cathode design [1]. The latter involves finding a cathode composition that prevents the polysulfide shuttle mechanism, which deteriorates the capacity retention, while at the same time providing high electrical conductivity to the insulating sulfur. Since its invention in 2011 [2], the MXene family of materials has attracted much attention for a range of applications, mostly due to its high electrical conductivity combined with hydrophilicity and good mechanical strength [3]. Recently, MXene-based sulfur composite cathodes have demonstrated promising performance for lithium-sulfur batteries [4].
Here, titanium- and vanadium-based MXenes have been investigated as sulfur host material for magnesium-sulfur batteries. MXenes were obtained by leaching out the aluminum from the corresponding MAX phase, which was confirmed by XRD and EDS. After sulfur loading, the MXene-sulfur composite was tested as cathode with a Mg anode, glass fiber separator and different Mg electrolytes, showing promising electrochemical performance. Optimization of the MXene surface termination, the sulfur infiltration method and the electrolyte is currently being investigated, with an aim of lowering the overpotential, improving capacity retention and increasing the sulfur utilization.

Reference
s
:

[1] Z. Zhao-Karger, M. Fichtner, MRS Communications (2017), 7, 770–784.
[2] Naguib et al., Adv. Mater. 23 (2011) 4248-4253.
[3] B. Anasori, M. R. Lukatskaya, Y. Gogotsi, Nature Reviews Materials 2 (2017) 16098, 1-17.
[4] Gao et al., Small (2018), 14, 1802443.
Understanding of Failure Mechanism of High Energy Lithium-Sulfur Pouch Cells
Authors: Shi Lili , Lu Dongping , Niu Chaojiang , Ren Xiaodi , Xiao Jie , Liu Jun 
Published: February 2020

Lithium sulfur (Li-S) battery is a promising next generation energy storage technology for vehicle electrification or large scale energy storage due to the high theoretical energy, low cost, and environmental friendliness of sulfur. 1 However, deployment of Li-S batteries in practical applications has been hindered by the low practical energy and limited cycle life. Extensive researches in Li-S batteries have been performed, and significant advances have been demonstrated in material development and fundamental understandings of the reaction mechanism. 2, 3 However, most of the previous studies are based on thin film sulfur electrodes, excess amount of electrolyte, or small size coin cell configuration. It has been reported that sulfur utilization and cycle life are both affected if using electrodes with elevated sulfur loading and under conditions of lean amount of electrolyte. 4 This indicates scientific gaps existing between the high loading electrodes and the reported thin film counterparts. The new understandings and knowledge linking the “theoretical” and “practical” are essential for the further maturing of the Li-S battery technology. In an attempt to fill such scientific gaps, high energy Li-S pouch cells were designed and fabricated in our research by using high loading electrodes and lean electrolyte. Practically high energy of 372 Wh kg-1 has been demonstrated in the Li-S pouch cells although cycle life is still limited. Systematic understanding of cell failure mechanism under practical conditions was carried out by using advanced characterization techniques. Electrolyte depletion and non-uniformity of electrochemical reactions of both cathode and anode were identified as dominant factors of cell capacity decay and internal short-circuit. Detailed postmortem analysis of the cycled Li-S pouch cell and failure mechanism understanding will be presented and discussed at the meeting.
References

A. Manthiram, Y. Z. Fu, S. H. Chung, C. X. Zu and Y. S. Su, Chem. Rev., 2014, 114, 11751-11787.

D. Aurbach, E. Pollak, R. Elazari, G. Salitra, C. S. Kelley and J. Affinito, J. Electrochem. Soc., 2009, 156, A694-A702.

X. L. Ji, K. T. Lee and L. F. Nazar, Nat. Mater., 2009, 8, 500-506.

D. P. Lv, J. M. Zheng, Q. Y. Li, X. Xie, S. Ferrara, Z. M. Nie, L. B. Mehdi, N. D. Browning, J. G. Zhang, G. L. Graff, J. Liu and J. Xiao, Adv. Energy Mater., 2015, 5, 8.
Electrolyte Effects on the Intercalation of PF6
- into Graphite Positive Electrode for Dual-Ion Batteries
Authors: Yu Denis , Wang Yao 
Published: February 2020

Different from traditional lithium-ion batteries (LIBs) which rely on Li+ as the only charge carriers, dual-ion batteries (DIBs) which use both cations and anions as electroactive species have received increasing attention due to their high power- density and low cost. So far, graphite has been shown to accommodate anions such as PF6
- and BF4
- with a capacity of close to 100 mAh g-1 and a potential of above 4.5V vs. Li/Li+ on the positive electrode [1-3]. Since the anions originate from the electrolyte, the electrochemical performances of the graphite electrode depend highly on the type of solvent used.
Figure 1a shows the cyclic voltammograms of graphite (KS6, Timcal) electrodes in 3M LiPF6 dissolved in linear carbonate solvents of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC) and diethyl carbonate (DEC). We can see that by changing the solvent, the reaction peaks are completely changed. In particular, the lower onset potential at around 4.39 V vs. Li/Li+ suggests that it is easier for PF6
- anions to intercalate into graphite with EMC than DMC and DEC. Rate performances of graphite electrodes in the three different solvents are shown in Figure 1b. Interestingly, electrolyte with EMC solvent also gives much better rate capability than those with DMC and DEC. This is attributed to the difference in chemical interaction between the PF6
- anions and the solvent molecules. Further works on understanding how solvents’ properties, solvation structure and charge transfer impedances etc. affect the observed performances are underway and will be presented at the meeting.

References

[1] J. A. Seel, J. R. Dahn, Electrochemical intercalation of PF6 into graphite, J. Electrochem. Soc. 147 (2000) 892-898.
[2] T. Ishihara, M. Koga, H. Matsumoto, M. Yoshio, Electrochemical intercalation of hexafluorophosphate anion into various carbons for cathode of dual-carbon rechargeable battery, Electrochem. Solid State Lett. 10 (2007) A74-76.
[3] G. Wang, M. Yu, J. Wang, D. Li, D.Tan, M. Loffler, X. Zhuang, K. Mullen, X. Feng, Self-Activating, Capacitive Anion Intercalation Enables High-Power Graphite Cathodes, Adv. Mater. 30 (2018) 1800533.

Figure 1
Fluorination of Mxene by Elemental F2 as Electrode for Lithium-Ion Batteries
Authors: Jafta Charl J , Thapaliya Bishnu , Lyu Hailong , Xia Jiexiang , Meyer Harry M , Paranthaman Mariappan Parans , Sun Xiao-Guang , Bridges Craig A. , Dai Sheng 
Published: February 2020

Extensive research efforts have been devoted to the development of alternative materials as electrode materials, in particular, exfoliated transition metal carbides, called MXene due to their 2D layered structure. We have thus investigated how modifying the anion sublattice of MXene can be used to address this challenge.
In this presentation we will show the transformation of MXene sheets into TiOF2 2D sheets with superior electrochemical performance. MXene synthesized from Ti3AlC2 has been fluorinated for 3 - (FMX3), 6 - (FMX6), and 24 hours (FMX24), respectively by means of a direct fluorination process. Exposure of MXene powder to elemental fluorine for 3 hours induces the formation of CF2 groups and TiF3 on the surface, which have beneficial effects on the electrochemical performance. X-ray photoelectron spectroscopy suggests that after fluorinating the MXene sample for 6 hours, that 2+ and 3+ Ti oxidation states are not present on the surface, with only Ti4+ present indicating TiOF2. X-ray diffraction indicates that there is TiOF2 present after fluorinating for 3 hours and after 24 hours the MXene has transformed to TiOF2 with minor impurities remaining, while maintaining the 2D layer morphology. All the fluorinated materials have cycling stabilities superior to MXene with capacities of > 200 mAh/g, which already has a good cycling stability with a stable capacity of ~ 100 mAh/g over 120 cycles. The electrochemical performance of FMX3 and FMX24 are superior as compared to MXene and FMX6, with the latter fluorinated MXene having a comparatively inferior performance. FMX24 with its TiOF2 phase has good capacity that increases with cycle number. FMX24 has a better rate capability as compared to a non 2D layered TiOF2, indicating the advantage of the 2D layered morphology derived from the parent MXene phase. These transformed MXene materials, in addition to being utilized as anode material for lithium ion batteries, can also be used beneficially in other battery chemistries such as lithium sulfur batteries.
Regulating Ca2+ Electrolyte Transport and Stability for Calcium Metal Deposition
Authors: Hahn Nathan T , Zavadil Kevin R , Self Julian , Seguin Trevor , Persson Kristin A 
Published: February 2020

Beyond Li-ion electrochemical energy storage systems based on divalent metal cations occupy a new frontier of research and development efforts related to materials chemistry and design. High energy density batteries based on the promise of high capacity Mg or Ca metal anodes are yet to be realized due to problems associated with the stability and ion transport properties of organic electrolytes and insertion cathodes. Controlling the stability of Ca2+ electrolytes at calcium metal anodes has been a particularly challenging task, although a recent demonstration suggests a possible path forward for reversible calcium electrodeposition in ethereal electrolytes.1 The calcium system, then, represents an intriguing exemplar for understanding divalent metal electrodeposition under conditions that push the boundaries of organic electrolyte stability. In this presentation we will discuss how interactions among species within Ca2+ electrolytes such as Ca(BH4)2/THF and other recently developed systems facilitate transport and delivery of the working cation to the interface for deposition and how surface interactions influence the stability of supporting electrolyte species and direct the system toward inefficiency and byproduct formation as a function of species susceptibility. These studies utilize a combination of experimental spectroscopy, microscopy and electrochemistry along with computational simulation of Ca2+ coordination cluster structures and stabilities. We will discuss the impact of these factors on calcium metal morphology and composition providing new insight into the rules connecting Ca2+ electrolyte properties to interfaces for Ca metal deposition. These design principles will serve as a guide to the development of advanced electrolyte concepts capable of pushing the boundaries of reductive stability in divalent metal electrolytes toward higher voltage beyond Li-ion batteries.
Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
References

Wang, D.; Gao, X.; Chen, Y.; Jin, L.; Kuss, C.; Bruce, P. G., Plating and stripping calcium in an organic electrolyte. Nature Materials
2017,
17, 16.