bluuebunny/crossref_metadata_2025 huggingface dataset:
Highly Efficient Rechargeable Sodium-Oxygen Battery Using Carbon Paper As Binder and Catalyst Free Air Cathode
Authors: Kretschmer Katja , Sun Bing , Wang Guoxiu
Published: February 2020

Metal-air batteries, which utilize conversion chemistry rather than intercalation mechanisms, have attracted large research interest due to their high theoretical energy density. Much work has been devoted to investigate and optimize Li-O2 cell, which suffer from large overpotential and poor energy efficiency due to complex cell chemistry and undesired side reactions. Recently, Janek et al. have reported the approach of substituting lithium with sodium in an air battery system and surprised the research community with outstanding performance. Their Na-O2 was reversibly charged/discharged at very low overpotentials using a pure carbon cathode without the addition of a catalyst [1]. They further more claimed that low surface area can provide a more efficient cycling performance as well as high absolute capacity [2]. To further understand the impact of the carbon material used as air cathode inside the Na-O2 system, we investigated a range of carbonized fiber based materials. We found that commercially available and heat-treated filter paper provides outstanding oxygen reduction reaction and oxygen evolution reaction activities without any additional catalyst. An initial absolute capacity of 1.26 mAh cm-2 and low overpotential <400 mV could be achieved when cycled between 1.8 and 3.0 V at 100 µA cm-2 without any capacity restriction.

References:

[1] P. Hartmann, C.L. Bender, J. Janek et al., N
at. mater.
2013, 12, 228-232.

[2] C.L. Bender, P. Hartmann, J. Janek et al. Adv. Energy Mater.
2014, 4, 1301863
Structure and Properties of the Amorphous Lipon Electrolyte By First-Principles Simulations
Authors: Sicolo Sabrina , Albe Karsten
Published: February 2020

Amorphous materials belonging to the family of Lithium Phosphorus Oxynitrides (LiPON) are increasingly popular solid electrolytes for thin-film Li-ion batteries. RF-sputtering of a lithium orthophosphate target in a nitrogen plasma leads to the deposition of amorphous glasses. Rationalization of the transport properties rests on a valid structural model for these glassy structures, whose simulation represents a main challenge from a computational point of view also because of their non-trivial compositions. In close cooperation with experimental partners, we assessed the structural, electronic and transport properties of an amorphous member of the LiPON family with non-trivial composition and cross-linking. 

The issue of structure prediction for a given composition is a longstanding problem even for the simplest crystalline solids. The problem is further complicated in the case of an amorphous material, as the potential energy landscape that describes the glassy region exhibits a large number of minima of varying depths. We circumvented the problem by using an evolutionary algorithm to find a stable structure for a realistic, composition provided by experiments and subjecting it to ab-initio simulated annealing to create disorder. 

In this work we present the results of Density Functional Theory calculations. After characterizing the structural and electronic properties of our material, we addressed the issue of ionic conductivity by calculating the defect formation energies of neutral and charged point defects with respect to two different Li reservoirs: a typical anode, metallic lithium, and a typical cathode, lithium cobalt oxide (LCO). 

We found that charged defects dominate over neutral ones, as expected of an ionic conductor. Li+ interstitials dominate by far over vacancies, both when the lithium reservoir is metallic lithium and LCO. The formation of charged interstitials when LiPON is brought into contact with LCO has already been observed by our experimental partners. Furthermore, at the interface with metallic lithium the formation of neutral interstitials is a competitive process that results in the chemical reduction of LiPON and the disruption of the network. The occurrence of side reactions at the interface between LiPON and lithium has been observed and quantified by means of X-ray photoemission spectroscopy by our experimental partners. Following up on this result, we proceeded to investigate the structural and electronic properties of the interface between LiPON and metallic lithium with a special focus on the occurrence of side reactions. We conclude by showing preliminary studies of the interface between LiPON and selected LCO terminations suggested by available experimental results.
Dual Carbon-Coated Si Porous-C Composite for Li-Ion Battery Anode
Authors: Chung Eun Hyuk , Lee Sun-Young , Hong Tae Eun , Jong Pil Kim , Jong-Seong Bae , Lee Jung Kyoo , Kim Jeom-Soo , Jeong Euh Duck
Published: February 2020

Recently Li-ion battery has been used extensively as a portable power source for small electronic devices, a power source for electric vehicles and an attractive option for energy storage.

Artificial graphite, natural graphite, hard carbon, such as carbon-based materials as anode active material have been applied, According to the requirements of high capacity, high theoretical capacity such Si (ca. 4200mAh/g) which is 5 times higher than carbon-based mateirlas has been actively studied in recent years.

There are several problems to overcome despite the advantages of the theoretical capacity values of the Si.

First low electrical conductivity, second due to the significant change in volume of the active material of the Si particle during Li insertion/extraction, it causes pulverization of the active material particels.

In order to overcome these problems, the mixture of high carbon Si/carbon composite was synthesized, but showed a limitation in the number of times the cycle test because of the lack of sufficient change in volume of the internal volume of Si.

Our study was performed to study the synthesis of a nanoparticle dual carbon-coated Si porous-C composite using glucose and PVDF to form an inner space. Also, GO was added to improve the cyclability.

Characterization of Si porous-C was explored by Scaning transmission electron microscopy (STEM), X-ray photoelectron scpectroscopy (XPS) and the electrochemical performace was carried out as shown in figure. 

Two different current density (100, 500mA/g) was applied. 100mA/g was applied upto 5th cycles and the rest of cycels was obtained at 500mA/g.

Figure 1
Multi-Scale Modeling of Multi-Physics Processes in Lithium Ion Battery Cells
Authors: Salvadori Alberto , Magri Marco
Published: February 2020

Lithium-ion (Li-ion henceforth) batteries application to high power and high capacity demanding systems still encounters limitations. This technology is based on the classical intercalation reaction, during which Li is inserted into or extracted from electrodes. During this process the hosting material experiences large volume changes, leading to mechanical degradation, loss of integrity and of electric contact with current collectors. Nano-structured and composite material electrodes may reduce such damaging phenomena.

Computational modeling and simulations may be helpful in designing new combinations of materials and geometries. To simulate a whole battery cell at the scale at which Lithium ions intercalate would be computationally unfeasible. A multi-scale approach is desirable and the Computational Homogenization (CH) technique is here adopted. This allows to track micro structural events that initiate damage and lead to macroscopic failure from macroscopic boundary conditions, while limiting the computational cost.

This contribution extends to large strains the framework of the CH developed in [1,2]. Temperature dependence is also included, towards modeling batteries under extreme conditions. The adopted approach originates from the fundamental balance laws (of mass, force, charge) and the weak formulation derived has a clear energy interpretation. Electroneutrality assumption has been taken into account. Maxwell's equations are considered in a quasi-static sense in a rigorous setting.

All the materials forming the multi-component porous electrode are clearly identified. Migration, diffusion, and intercalation of Lithium in the active particles are modeled. Constitutive assumptions, that emanate from a rigorous thermodynamic setting, complete the formulation.

After spatial discretization, a Backward Euler time-advancing algorithm has been implemented in FEM codes. Different finite elements have been designed to deal with the electrolyte, the electrodes and the reaction layer between them. Several case studies have been simulated to validate the implemented formulation.

References

[1] A. Salvadori, E. Bosco, and D. Grazioli. A computational homogenization approach for Li-ion battery

cells. Part 1 - Formulation. Journal of the Mechanics and Physics of Solids, 65:114-137, 2014.

[2] A. Salvadori, D. Grazioli, and M.G.D. Geers. Governing equations for a two-scale analysis of Li-ion

battery cells. International Journal of Solids and Structures, 59:90-109, 2015.
Comparative Study on Experiment and Simulation of Power Prediction of Lithium-Ion Batteries
Authors: Park Joonam , Appiah Williams Agyei , Byun Seoungwoo , Yeon Daeyong , Kim Hee Joong , Kim Tae Shin , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

As the size of lithium-ion batteries (LIBs) becomes larger, it is also time consuming and expensive to get lots of electrochemical properties experimentally. In particular, it needs more resources to optimize all cases for designing and developing the right large format cell for a given application. Hence, we adopt a previously designed pseudo two dimensional (P2D) model to simulate the electrochemical performance of a 20 Ah pouch cell consisting of LiFePO4cathode and a graphite anode. The model was used to analyse the adequacy of two pulse based power measurement methods; hybrid pulse power characteristics (HPPC) and J-pulse (JEVS D 713, Japan Electric Vehicle Association Standards), in predicting the direct resistance (DC-IR) and power as a function of state of charge by comparing the simulation results to those of experiments.

There was a good agreement between the simulation results and those of the experiment. DC-IR as a function of SOC was obtained from P2D model, and converted to power. Both two methods showed that DC-IR of charge and discharge increase from about 10% to about 20% at the SOC below 20%. DC-IR of the cell during charge in HPPC was predicted to be higher than discharge and vice versa for J-Pulse. Hence, a different current density should be used for the two methods for effective power predictions.

References

1. J. Park et al., KEPCO Journal on Electric Power and Energy,
33, 2465-8111 (2015).

2. M. Doyle and J. Newman et al., Journal of the Electrochemical Society, 143, 1890-1903 (1996).

3. H. Lee and Y. M. Lee,  Journal of The Korean Electrochemical Society, 10(3), 115-123 (2012).

Acknowledgements

This work was supported by the Human Resource Training Program for Regional Innovation and Creativity through the Ministry of Education and National Research Foundation of Korea (NRF-2014H1C1A1066977) and by the Sebang Global Battery.

Figure 1
Aligned Helix Si Nanostructures As High Performance Anode Material in Secondary Lithium Ion Battery
Authors: Wang Hsiao-Chien , Yen Wen-Chun , Huang Jian-Shiou , Medina Henry , Chueh Yu-Lun
Published: February 2020

The increasing demand for advanced electronic devices and energy storage have stimulated significant interest in the development of batteries of high capacity. Li ion based battery is the most promising system which is light-weight and energy-delivering efficient. Compared to the existing graphite-anode system, Si is known to have highest theoretical specific capacitance which makes Si be the most promising candidate for the next-generation anode material for lithium battery systems. However, the large volume expansion and the serious material pulverization of Si after cycling result in a poor life time, and become a stumbling block for being commercialized. In this research, glancing angle deposition (GLAD) technique is utilized to deposit uniform and aligned intrinsic Si-spiral nanostructure. By varying different rotation angles during GLAD, various spiral Si nanostructure with various porosities are deposited. With increasing rotation number , the porosity also increases giving as a result less Si volume occupation. The silicon content in the porous film can be precisely controlled from 77.5% to 74.69% by tuning the formation of the nanostructure. As a result the porous silicon film offers an enhanced battery cycle life for intrinsic silicon based anode material. TEM and XPS analysis were carried out to analyze the composition and bonding information for de-/lithiation mechanism. After the optimization, our porous Si anode shows an electrochemical performance with volumetric specific capacity of 2019.2 mAh/cm3. After 100 cycle test, the volumetric specific capacity retention still remains at 359.4 mAh/cm3. Furthermore, we believe that the adequate porosity helps to retard the enormous stress among the film by providing enough space for volume expansion to gain longer life time and better electrochemical performance.
Atomic Layer Deposition of Lithium Titanate on 3D-Structured 300 Mm Silicon Substrates
Authors: Bönhardt Sascha , Zybell Sabine , Liske Romy
Published: February 2020

Thin film battery technology delivers high added value for autonomous microsystems in e.g. wireless sensor networks, Internet of Things (IoT) applications and medical implants. The transition to solid state electrolytes means significant improvement of the battery safety and even opens possibilities for integration into silicon technology.

The 3D micro battery concept, including deposition of functional layers on structured surfaces with high aspect ratio, has been shown to improve both, capacity and rate performance of all-solid-state batteries [1]. Our aim is the development and characterization of functional stacks allowing direct integration into microsystems. For CMOS compatible design and production, we manufacture functional electrode and electrolyte layers on 300 mm wafer using standard industrial thin film deposition equipment.

Atomic layer deposition (ALD) is a vapor-phase technique based on sequential, self-limiting surface reactions enabling conformal deposition of thin films. In this work, alternate atomic layer deposition of titanium oxide and lithium carbonate is demonstrated. The formation of the desired spinel lithium titanate (LTO) is investigated by subsequent high temperature anneals. Although its comparatively low capacity LTO is a promising electrode material for 3D integration. It stands out due to its zero-strain characteristics and the three dimensionality of ion transport [2].

[1] Y. Wang, B. Liu, Q. Li, S. Cartmell. S. Ferrara, Z. Deng, and J. Xiao, Journal of Power Sources 286 (2015) 330-345.

[2] V. Miikkulainen, O. Nilsen, M. Laitinen, and T. Sajavaara, RSC Advances 3 (2013) 7537.
Tunable Carbon Scaffolds As Materials Platforms for a Silicon-Based Anode Used in Lithium Ion Batteries
Authors: Estevez Luis , Jeong Sookyung , Cao Ruiguo , Li Xiaolin , Xu Wu , Bhattacharya Priyanka , Zhang Ji-Guang
Published: February 2020

Carbon and carbon-based composite materials are an important component in electrodes utilized for energy storage applications. Their widespread use can be attributed to carbon’s combination of good electrical conductivity, relative chemical inertness and low bulk material density (~2 g/cm3). For lithium ion battery (LIB) anodes, graphite is typically employed, but silicon has been heralded an excellent replacement candidate due to its very high theoretical capacity (~ 4200 mAh/g—a capacity over ten times greater than that of graphite). A principal obstacle for the practical application of a Si anode is the extreme volume changes (> 300%) during the lithiation process which eventually leads to a pulverization of the Si material. This is particularly true for larger Si particles (> 200 nm), which severely compromises the commercialization of Si based LIB anodes. Herein, we present our recent work utilizing hierarchical porous carbon as a host for silicon to be used as an anode for LIB anodes. We will show that by using a porous carbon scaffold with tailorable textural properties such as pore size, surface area and pore volume, we are able to provide silicon nanoparticles with an excellent scaffold for attachment. Furthermore, we will reveal how this tailorable carbon structure can be further modified via functionalization pathways for both the carbon and silicon materials. We will demonstrate how these strategies improved various performance parameters for these LIB anodes; specifically in terms of cyclic performance—a characteristic weak point for silicon-based LIB anodes.
Novel Binary Binder PAA-SBR Towards Silicon Anodes in Li-Ion Batteries
Authors: Huang Qianye , Loveridge Melanie , Wan Chaoying , Bhagat Rohit
Published: February 2020

Silicon remains a promising anode material for next generation lithium-ion batteries, despite the well-documented issues associated with it, due to its abundance and high capacity (3579mAh/g: almost 10 times higher than the capacity of graphite).  The problems still facing Si-based battery commercialization are volume expansion, which results in rapid capacity fade, and continued Li loss through SEI formation from electrolyte decomposition.  To address this problem, effective binders are considered to be one solution, and could help to maintain good contact between the active material and current collector but also to generate effective, stable networks between silicon particles and conductive carbon additives.

This work will introduce a new binder system: Polyacrylic Acid-Styrene Butadiene Rubber (PAA-SBR). PAA is an aqueous-based polymer and possesses a high concentration of carboxyl group, which effectively bonds with the surface of silicon but also can H-bond with other polar species contributing to a good cohesive composite. SBR (Styrene Butadiene Rubber) is well known for its good flexibility, which can improve the tensile property of the electrode towards volume expansion. Therefore, it is hypothesized that the binary binder PAA-SBR can help Si anode achieve an improved, more stable performance because it can preserve good adhesion and flexibility simultaneously under the stress of the Si expansion.

A preliminary study was conducted on Si vs.Li/Li+ half cells with different binder systems: PAA, PAA-SBR (2:1 mass ratio) and PAA-SBR (5:1 mass ratio), where PAA-only is used as the control binder. Cells are tested under the maximum lithiation capacity of 1200mAh/g at a C rate of C/5. Electrochemical cycling data indicates that for first 100 charge-discharge cycles, the PAA-SBR (2:1) showed a similar level of performance compared with PAA in terms of specific capacity (~1194mAh/g) and columbic efficiency (~99.5%), while the PAA-SBR (5:1) displayed capacity fade after 80 cycles, as shown in Fig.1. We anticipate that an optimized PAA-SBR ratio will generate superior composite durability during longer-term electrochemical testing. To further approve the hypothesis, a comprehensive study based on PAA-SBR (2:1) will be followed including polymer stability in electrolyte solvents, tensile properties, adhesion and impedance testing.

Figure 1
Ionic Liquid Based Polymer Gel Electrolyte Membranes for Lithium Ion Rechargeable Batteries
Authors: Kataria Shalu - , Balo Liton , Gupta Himani , Singh Varun Kumar , Singh Shishir Kumar , Tripathi Alok Kumar , Verma Yogendra Lal , Singh Rajendra Kumar
Published: February 2020

Li-ion conducting polymer gel electrolyte membranes (PGEMs) based on polymer poly(vinylidene fluoride-co-hexafluoropropylene) PVdF-HFP, ionic liquid, 1-butyl-3-methylimidazolium tetrafluroborate BMIMBF4 and Lithium bis(trifluoromethanesulfonyl)imide) LiTFSI salt (having different anion i.e. BF4
- and TFSI-)  have been synthesized and  characterized  by  scanning  electron microscopy  (SEM),  X-ray diffraction  (XRD), Differential  scanning  calorimetry  (DSC), Thermogravimetric  analysis  (TGA),  Fourier  transform infrared  (FTIR),  complex impedance spectroscopy and  cyclic voltammetry.  After incorporation of IL in polymer electrolyte, (i.e. PVdF-HFP+20wt.% LiTFSI) different physicochemical properties such as melting temperature (Tm), glass transition temperature (Tg), thermal stability, degree of crystallinity (Xc), and ionic transport behaviour of these materials are found to change. The pristine PVdF-HFP possessed a semi-crystalline structure and its amorphicity increased with the addition of LiTFSI salt and BMIMBF4 ionic liquid. An impedance measurement indicated that the room-temperature ionic conductivity of the membranes increased with increasing IL content and attains a maximum value of 3.2 *10-3 S/cm at 30 °C and ~ 8.7*10-3 S/cm at 130 °C. An schematic representation exhibiting increase  in ionic conductivity with increasing     amount of dopant ionic liquid has been shown in the given figure. In addition, temperature dependent ionic conductivity seems to obey Arrhenius type thermally activated behaviour. A high total ionic transference number > 0.99 and the cationic transference number (tLi
+) ~0.33 with a wider electrochemical window (ECW) ~4.0–5.0 V for the PGEMs containing higher loading of IL have been obtained.

Fig. Schematic representation exhibiting increase  in ionic conductivity with increasing     amount of dopant Ionic Liquid.

Figure 1
Supercapacitors Based on Iron Decorated Carbon Nanofibers with Excellent Cyclability
Authors: Pai Rahul , Singh Arvinder , Simotwo Silas , Hart James , Suri Pranav , Taheri Mitra , Kalra Vibha
Published: February 2020

Supercapacitors are attractive energy storage devices due to their high specific power and excellent cyclability. The supercapacitor field is currently dominated by porous carbon-based electric double layer capacitors (EDLC) that lack energy density. The energy density of porous carbon materials can be effectively improved by fabricating composites of carbon (for EDLC) with metal oxides/hydroxides (for pseudocapacitance). Among the metal oxides, iron oxide shows great promise owing to its high theoretical capacitance, negligible environmental impact and natural abundance. In this work, a facile methodology for obtaining freestanding, binder-free, iron decorated porous carbon nanofibers (Fe-CNF) for supercapacitor application is outlined. Briefly, blend of iron precursor and polyacrylonitrile (PAN) was electrospun into non-woven, freestanding nanofiber mats and subsequently subjected to heat treatment at 1000 degree Celsius in an inert atmosphere. Besides this thermal treatment, no additional chemical or physical activation process was conducted. The morphology of the nanofiber mat was characterized using scanning electron microscopy. The fibers exhibit diameters in the range of 150-200 nm. Electrochemical activity of the electrode was studied using cyclic voltammetry and galvanostatic charge-discharge techniques. Electrochemical measurements showed a large specific gravimetric capacitance of ~260 F/g at 20 mV/s in 6 M KOH aqueous electrolyte between 0 to -1.3 V range. The resulted synergistic effect between iron nanoparticles (pseudocapacitance) and carbon nanofibers (EDLC and conductivity) leads to such high capacitance value. The electrodes retain ~82% capacitance after 6500 cycles indicating excellent cyclic stability of these electrodes. Further, Fe-CNF’s electrodes were extensively characterized at various stages of charge-discharge using X-ray diffraction, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy to understand the redox reactions of the fabricated electrode material.

Figure 1
Flexible Probe for Measuring Local Conductivity Variations in Li-Ion Electrode Films
Authors: Hardy Emilee E , Vogel John E , Clement Derek V , Wheeler Dean R , Mazzeo Brian A
Published: February 2020

Electrical conductivity is a fundamental characteristic determining the performance of lithium-ion batteries. However, methods to measure the conductivity nondestructively have proven difficult. This is due to the presence of a metallic conductive current collector as well as dominating effect of the contact resistance between the film and the probe. In previous research we developed a micro-four-line probe [1] that can measure thin-film electrodes without removing the current collector. We found that the conductivity of even high-quality electrodes is not homogenous, and has variation on length scales much larger than the size of the active material particles.

Even though the micro-four-line probe worked well, we continue to improve the design. The previous design was fabricated in a clean room on a rigid glass substrate. This limited the geometry of the sample and made adaptation to industrial use difficult. To address this problem, we switched to a flexible polymer substrate, as shown in the figure, which allows for increased sample size and potential low-cost manufacturing. In addition, changes were made to the computer-controlled probe holder and stage, again with an aim toward lowering cost and increasing usability. The stage is used to move the probe over the surface of the sample in order to produce a conductivity map.

We will report conductivity results using the new probe for both anodes and cathodes, including the effect of cycling. Results will also be compared to related work on ionic conductivity of the same electrodes. The hope is that this probe technology can be adapted to manufacturing use as well as to assist other researchers in understanding limiting mechanisms in battery performance.

[1] Lanterman et al., J. Electrochem. Soc. 162, A2145 (2015).

Figure 1
(Invited) P2-Nax(Mn,Fe,Co,Ni) Layered Oxides in Na-Batteries
Authors: Delmas Claude , Yoshida Jun , Mortemard de Boisse Benoit , Guerin Elodie , Carlier Dany , Guignard Marie , Duttine Mathieu , Duttine Mathieu , Wattiaux Alain
Published: February 2020

In the perspective of the development of electrical vehicles and also of very large scale renewable energy systems the prevailing parameters are the lifetime, the price and the material availability. From these points of view, sodium based batteries have to be investigated. Our research group studied layered oxides as positive electrode for 30 years. Recently, a general investigation was undertaken with a focus on P2-type layered phases.

One of the main interests of this structure is the existence of an ion conduction plane made of face sharing trigonal prims which exhibits a high ionic diffusivity thanks to the existence of a large bottleneck (oxygen rectangle) for sodium diffusion. This structure is able to accommodate a lot of transition metal cations, allowing the optimization of the properties by cationic substitution.

The study will be focused on the P2-Nax(Mn,Fe)O2, P2-Nax(Mn,Co)O2 Nax(Mn,Fe,Co)O2 and Nax(Mn,Fe,Ni)O2 systems with various amounts of transition metal ions. All materials crystallize in the hexagonal system (P63/mmc space group). The structure is made of MO2 slabs built of corner sharing MO6 octahedra. The sodium ions are in trigonal prismatic sites. Half of them share edges (Nae) with the MO6 octahedra while the other one share faces (Naf). As the two types of prisms share a common faces, they cannot be occupied simultaneously. The sodium distribution depends of the cationic charge distribution and of the sodium amount is order to minimize the Na+-Na+ and Na+-Mn+ electrostatic repulsions.

In all systems, the P2 type packing is preserved in the 0.3 < x < 1 range. The fully intercalated phase is difficult to be obtained due to the very low ionic conductivity when the amount of vacancies is very small. For these compositions, only the Naf prisms are occupied. The specific capacity is in the 130-170 mAh.g-1 depending on the voltage range.

In the case of materials with a single transition metal ion like NaxCoO2 and NaxVO2 the shape of the electrochemical curves present a lot of plateau resulting from ordering Na+/Vacancies in the sodium layer. For multi-cations systems, the transition metal disordering is the MO2 slabs prevents from most of the ordering except for the Na.050MO2 composition.

A general overview of the electrochemical behavior of these materials will be presented with a special focus on the relation between the oxidation process and the shape of the electrochemical curve.
Reversible Aqueous Zinc Battery Using Molybdenum-Based Intercalation Cathode
Authors: Xu Wangwang , Cui Xiaodan , Xie Zhiqiang , Wang Ying
Published: February 2020

As an alternative for lithium ion batteries, aqueous energy storage system has recently attracted tremendous attentions due to the low cost, non-flammable and non-toxic materials.[1] Among various aqueous batteries, aqueous Zn ion batteries are particularly advantageous owing to a high-capacity Zn metal anode (819mAh/g).[2] However, limited cathode materials have been explored for reversible Zn2+-ion intercalation, and most of which exhibit poor rate capabilities and inadequate cycling performance, or limited specific capacity. α-MoO3, as a typical layered transition metal oxide, has been extensively studied as electrode material for lithium batteries due to the advantages of high capacity, low cost, abundant resources and non-toxic.[3] Based on our research, we have found α-MoO3 can be used as host material (cathode) for zinc ions as well owing to the large interlayer space. However, the capacity fading in the initial cycles is still significant and unavoidable. The reason for irreversible capacity fading of MoO3 in the initial cycles can be attributed to its unstable structural prosperity. Recently, pre-intercalation has been demonstrated as an effective way to improve the electrochemical performance for zinc-ion batteries. For example, Linda et.al has reported vanadium oxide bronze pillared by interlayer Zn2+ ions and water can supply the remarkable performance.[2] However, the related research of α-MoO3 as electrode for zinc-ion is still blank.

For the first time, we have studied the electrochemical performance of zinc pre-intercalation α-MoO3 as cathode material for zinc batteries and investigated the electrochemical mechanism during charging and discharging. The zinc pre-intercalation α-MoO3 can supply the initial specific capacity as high as 300 mAh/g, exhibiting great potential for application as high-performance cathode material for zinc-ion batteries.

Reference

1. Pan, H.; Shao, Y.; Yan, P. F.; Cheng, Y. W.; Han, K. S.; Nie, Z. M., Wang, C. M., Yang, J. H.; Li, X. L.; Bhattacharya, P.; Mueller, K. T.; Reversible Aqueous Zinc/Manganese Oxide Energy Storage From Conversion Reactions. Nature Energy, 2016, 1, 16039.

2. Kundu, D.; Adams, B. D.; Duffort, V.; Vajargah, S. H.; Nazar, L. F.; A High-Capacity and Long-life Aqueous Rechargeable Zinc Battery Using a Metal Oxide Intercalation Cathode. Nature Energy. 2016,1,16119.

3. Dong, Y. F.; Xu, X. M.; Li, S., Han, C. H.; Zhao, K. N.; Zhang, L.; Niu, C. J.; Huang, Z.; Mai, L. Q.; Inhibiting Effect of Na+ Pre-Intercalation in MoO3 Nanobelts with Enhanced Electrochemical Performance. Nano Energy. 2015, 15, 145.
Study of Bifunctional Catalysts Based on Perovskite Structures for Zinc-Air Batteries
Authors: Valencia Osorio Laura Margarita , González Ocampo Javier
Published: February 2020

In this paper the performance in alkaline medium of different catalysts based on perovskite structures are examined, in order to employ them in rechargeable zinc-air batteries. The combinations of compounds in the perovskite structure examined are Sm0.5Sr0.5CoO(3-δ), Sm0.5Sr0.5Co0.8Fe0.2O(3-δ), Ce0.05Sr0.95CoO(3-δ) and La0.6Sr0.4Co0.8Fe0.2O(3-δ). These combinations have not been well studied for this application, so in this study, it is found that these structures could be highly promising as bifunctional catalysts, because according to the electrochemical tests it is found that the compounds have a significant catalytic activity in both charge and discharge processes. The catalytic powders are synthesized by nitrate co-precipitation technique and they are characterized physically, chemically and electrochemically.
Impact of Electrolyte Composition on Seebeck Coefficient of Molten Carbonate Thermocell
Authors: Kandhasamy Sathiyaraj , Burheim Odne Stokke , Solheim Asbjørn , Kjelstrup Signe , Haarberg Geir Martin
Published: February 2020

A thermocell with molten carbonate electrolyte mixture with two identical gas (CO2|O2) electrodes may be a suitable alternative to the conventional semiconductor thermoelectric converters. Also, it shows the ability to harvest the waste heat at higher temperatures and utilize the available CO­­2 off-gases from metal producing industries for the thermoelectric conversion. Using symmetrical gas electrodes, high Seebeck coefficients in the range of 1 mV/K were measured, whereas the most conventional semiconductor thermoelectric cell shows only 0.2 mV/K.

The inclusion of solid oxide in the electrolyte mixture was found to influence the transported entropy of the carbonate ions and expand the appropriate conditions for thermoelectric conversion. Similarly, the change in the cationic composition of the molten carbonate melt in the electrolyte mixture leads to alter the entropy of the ionic species. Thus, the effect of a compositional change in the electrolyte mixture is studied in detail, towards its contribution to the Seebeck coefficient of the molten carbonate thermocell.
Lithium-Ion Capacitor Based on LiFePO4 and Nanostructured Carbon By Electrostatic Spray Deposition
Authors: Adelowo Ebenezer , Agrawal Richa , Wang Chunlei
Published: February 2020

Many efforts have demonstrated the practicability of power units based on electrical double-layer capacitors (EDLCs) to replace or complement batteries, generally because of their ability to deliver higher power density, faster charge and discharge rate as wells as longer operational life cycle. However, EDLCs exhibit relatively poor energy density. This limitation is revealed in portable electronic systems whose functions demand high energy and power density at the same time. In order to overcome the low energy density limitation of EDLCs, lithium-ion capacitors have gained much interest. Lithium-ion capacitors are hybrid electrochemical charge storage devices that combine the high energy density capability of lithium-ion batteries and the high power density in EDLCs. This is typically achieved by using electrodes based on battery-type lithium intercalating material as the high energy density source, and a capacitor-type material as the high power density source, in a lithium-containing electrolyte. In this work, we evaluated the electrochemical performance of lithium-ion capacitor comprising lithium iron phosphate (LiFePO4) battery-type cathode and reduced graphene oxide-carbon nanotube (RGO-CNT) composite as capacitor-type anode for half and full cells. The electrodes were prepared via electrostatic spray deposition (ESD) method, a thin-film deposition method capable of operating in ambient conditions. The choice of LiFePO4 is mainly because it is relatively inexpensive and exhibit attractive electrochemical properties such as good cycling stability, high intercalating potential of ~3.5 V versus Li+/Li as well as flat voltage plateaus. On the other hand, among a variety of nanostructured carbon materials, RGO-CNT composite has been shown as a good double-layer electrode material in EDLCs with high power density capability. Material characterization of the electrodes was carried out using scanning electron microscopy (SEM) and X-Ray diffractometry (XRD) respectively. Detailed results will be presented at the meeting.
Understanding and Optimizing Ionic Conductivity in Polyborane Solid Electrolytes from Ab Initio molecular Dynamics
Authors: Wood Brandon C. , Varley Joel , Kweon Kyoung , Shea Patrick , Stavila Vitalie , Udovic Terrence John
Published: February 2020

Polyborane salts based on B12H12
2-, B10H10
2-, CB11H12
- and CB9H10
- demonstrate extraordinary Li and Na superionic conductivity that make them attractive as potential electrolytes in solid-state batteries. The rich chemical and structural diversity of the various cation-anion combinations establishes a diverse design space offering a wide range of superionic transition temperatures and ionic conductivities. Recent synthesis and processing advances have improved ionic conductivity at modest temperatures; however, the origins of these successes are generally poorly understood. Likewise, key questions remain regarding the fundamental mechanisms that drive ionic conductivity, which has impeded the adoption of a more rational design approach.

We have performed extensive ab initio molecular dynamics simulations to broadly explore the dependence of ionic conductivity on cation/anion pair combinations for Li and Na polyborane salts. Additional simulations are used to probe the influence of local modifications to chemistry, stoichiometry, and composition. Carbon doping, anion alloying, and cation off-stoichiometry are found to be favorable because they introduce intrinsic disorder, which facilitates local deviations from the expected cation population. Anion reorientations are also discovered to be critical for conduction. In this case, benefits are traceable the specific chemistry of the cation-anion interaction, which acts to create intrinsic frustration that motivates cation mobility. Our computational studies offer new mechanistic understanding and guidance for future optimization of ionic conductivity in emerging polyborane-based solid electrolytes.

This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
(Invited) Site-Selective Covalent Patterning of Epitaxial Graphene with Periodicity at the Nanometer Scale
Authors: Miranda Rodolfo , Perez Emilio M , Calleja Fabian , Navarro Juan Jesus , Vazquez de Parga Amadeo L.
Published: February 2020

The covalent functionalization of graphene with long-range periodicity is highly desirable to provide control over its electronic, optical, or magnetic properties. We describe a method for the site-selective, covalent modification of graphene with strict spatial periodicity at the nanometer scale. The periodic landscape is provided by a single monolayer of graphene epitaxially grown on Ru(0001), that presents a moiré pattern with 3 nm periodicity due to the mismatch between the carbon and ruthenium hexagonal lattices. The moiré contains periodically arranged sites where the charge transfer from the metallic substrate is enhanced as a result of the local graphene-ruthenium interaction and, as a consequence, these sites show higher chemical reactivity. This is illustrated by imaging with STM under UHV conditions the attachment of cyanomethyl radicals (CH2CN) produced by homolytic breaking of acetonitrile (CH3CN), which present an almost ideal (98%) site selectivity to bind covalently to graphene on these areas. The subsequent specific reaction of the cyanomethyl radicals with TCNQ is observed in the real space by STM and STS, which reveals the specific character of the bond formed.
(Invited) Endohedral Metallofullerene-Based Lewis Acid-Base Pairs
Authors: Lu Xing
Published: February 2020

Carbon-based Lewis acids are limited merely to trityl cations and some electron-poor allenes.
[1]
 Recently, Bazan and coworkers reported that C60 and C70 can behave as all-carbon Lewis acids to form the corresponding Lewis acid–base pairs with a normal NHC structure.
[2]
 This work opens a new perspective on the research of carbon-based Lewis acids. Meanwhile, as a novel class of metal-carbon hybrid molecules, endohedral metallofullerenes (EMFs) feature electron transfer from the internal metallic species to the carbon cage, forming zwitterionic compounds.
[3]

 Accordingly, it is of special interest to study whether the highly charged carbon cages of EMFs are willing to accept additional electrons to act as Lewis acids or not.

In this representation, taking several kinds of EMFs as a representative, we show that EMFs also exhibit excellent Lewis acidity to form Lewis acid-base pairs with NHCs. Our unambiguous X-ray results reveal that the NHC moiety uses either its normal site or abnormal active center to react with the EMFs under study to form the corresponding adducts with different structures (Scheme 1). It is conformed theoretically the the inherent characteristic of the EMFs is responsible for the addition patterns.

R
eferences：

[1] F. E. Ahn and M. C. Jahnke, Angew. Chem., Int. Ed., 2008, 47, 3122.

[2] H. P. Li, C. Risko, J. H. Seo, C. Campbell, G. Wu, J. Bredas and G. C. Bazan, J. Am. Chem. Soc., 2011, 133, 12410.

[3] X. Lu, L. Echegoyen, A. L. Balch, S. Nagase and T. Akasaka, Endohedral Metallofullerenes: Basics and Applications, CRCPress, New York, 2015.

[4] M. Q. Chen, L. P. Bao, M. Ai, W. Q. Shen and X. Lu. Chem. Sci., 2016, 7, 2331-2334.
Formation and Characterization of Sub-Micron Inert Particle Embedded Nickel Composite Coatings
Authors: Yilmaz Olgun , Erdogan Metehan , Karakaya Ishak
Published: February 2020

Composite coatings have a wide range of application areas requiring improved mechanical and tribological properties[1,2]. These application areas include aerospace, automotive, chemical and electrical industries. High mechanical and tribological performances can be achieved by incorporation of hard ceramic particles into nickel matrix, which possess anti-corrosion properties. Due to its enhanced properties, Ni-Al2O3 electro-co-deposition rather than pure Ni electrodeposition was investigated. A typical sulfamate bath was used to evaluate the effects of current density, the amount of alumina in the electrolyte and the amount of surfactants. Ammonium lignosulfonate and sodium dodecyl sulfate were used as the surfactants in varying concentrations to arrange the floatation and wetting conditions of Al2O3particles (~300 nm) in the electrolyte. The influences of plating parameters on mechanical and tribological properties of the co-deposits like hardness, friction coefficient and wear were determined.

It was found that Increase in current density increases the hardness and deposited wt.% Al2O3 particles within the parameter ranges covered in this study. A representative cross-sectional view of Al2O3–Ni composite coating is shown in Figure 1.

References

[1] Vitry, V., Kanta, A. F., and Delaunois, F. (2012). Application of nitriding to electroless nickel–boron coatings: Chemical and structural effects; mechanical characterization; corrosion resistance. Materials & Design, 39, 269-278.

[2] Saraloğlu Güler, E., Karakaya, İ. and Konca, E. (2014) Effects of current density, coating thickness, temperature, pH and particle concentration on internal stress during Ni-MoS2 electrocodeposition, Surface Engineering, 30, 109-114.

Figure 1
(Invited) Chemical and Photochemical Transformations of Bismuth Vanadate and Catalyst Integration for Stable Photoanodes
Authors: Liu Guiji , Sharp Ian D. , Toma Francesca Maria
Published: February 2020

Artificial photosynthesis relies on the availability of stable semiconductors that efficiently harness the solar radiation and convert it into chemical energy for the sustainable production of solar fuels. Because of the thermodynamic and kinetic challenges associated with the oxygen production from water and of the harsh conditions in which this reaction is performed, much attention has been devoted to the study of stable n-type metal oxide semiconductors. Among available candidates for photoanodes, bismuth vanadate (BiVO4) is a promising, widely utilized metal oxide material for water splitting catalysis. In this work, we present a detailed study on the corrosion and photocorrosion of BiVO4 through analysis of changes in morphology, bulk and surface composition as a function of the photoelectrochemical perforomance and stability. We find that BiVO4 degradation is accelerated, in decreasing order, by light, increasing pH and applied bias. Electron microscopy and in-situ electrochemical atomic force microscopy indicate that degradation initiates at and propagates from surfaces and grain boundaries at solid/liquid interfaces. While from a thermodynamic perspective, it is expected that BiVO4 self-passivates via formation of a chemically stable and less catalytically active bismuth oxide at its surface, we observe the contemporary presence of Bi and V ion in the electrolyte solution, and conclude that self-passivation does not prevent corrosion. By using computational methods, we surmise that the degradation of this material cannot be only described by theromodynamic considerations, and that kinetic limitations must be taken into account in this process. In addition, our finding suggest that the accumulation of photogenerated holes at the surface accelerate degradation. Using this material as a model example, we have recently described high-throughput methodologies, which demonstrated that specific compositions and loadings of mixed-metal oxide catalyst coatings can significantly improve the performance of BiVO4-based photoanodes. In order to further understand the role of interface property in catalyst/BiVO4 assemblies, it is critical to employ a deposition method that is able to produce diverse compositions and interfacial structures of the catalysts. Photoanodic-electrochemical deposition (PED) is a straightforward method to achieve this goal since the growth of catalysts can be easily controlled by deposition variables such as potential, current and time. Here we will also show how PED of different catalyst compositions based on Ce-containing catalysts can be applied for the investigation of stabilities of new functional materials under operating conditions, where kinetic factors should be considered in the search for stable and visible-light-absorbing novel semiconductors for solar-to-fuel conversion.
(Invited) Concepts of the Solid-Electrolyte Phase Boundary: Experimental Evidence and Resulting Devices
Authors: Lewerenz Hans Joachim
Published: February 2020

The original fundamental concepts at solid-electrolyte interfaces are reviewed including the traditional microcapacitor model of the Helmholtz layer1. Theoretical approaches that expand beyond the classical dielectric model for water and solvation shells are accounted for and recent advanced experiments will be presented that enable a direct profiling of the energetics at this junction by tender x-ray synchrotron radiation photoelectron spectroscopy (TSRPES) 2,3. Combined (photo)electrochemical and surface analytical investigations are presented. For the rectifying semiconductor - solution junction, the space charge behavior of semiconductors in concentrated electrolytes is examined and in dilute solutions, the Galvani potential profiles at metal - electrolyte junctions are followed by TSRPES. The role of truncated profiles for thinner water layers and dilute electrolytes on charge equilibration and build-up of contact potential differences is analyzed. Fig.1 shows an example of the resulting photoelectron spectroscopy tomography.

Fig.1: (left): scheme for tomographic peak sampling; (right): influence of electrostaic potential on peak width

Implications regarding charge transfer and the development of efficient devices for light - induced fuel generation are outlined and optimized structures which show unassisted water splitting are presented, obtained upon modifying the surfaces of III-V tandem absorbers. Application of (photo)electrochemically induced surface transformations 4,5 and of re-directed (photo)corrosion reactions allows passivation of surface and interface states and increased robustness. Details of these procedures will be given. The achieved efficiencies are compared to theoretically achievable limits of solar hydrogen evolution for the respective material combinations6. The influence of the optical properties of the combined catalyst - electrode - solution composite structures is described and routes to more advanced multi-electron and proton transfer reactions are outlined.

 
References

1. D.C. Grahame, Chem. Rev. 41 (1947) 441-501

2. M.F. Lichtermann, M.H. Richter et al., Energy Environm. Sci. 8 (2015) 2409-2416

3. M.F. Lichtermann, M.H. Richter et al., J. Electrochem. Soc. 163 (2016) H 139-146

4. H.J. Lewerenz, C. Heine et al., Energy Environm. Sci. 3 (2010) 748-760

5. M.M. May, H.J. Lewerenz et al., Nature Comm. 6 (2015) 8286

6. K.T. Fountaine, H.J. Lewerenz, H.A. Atwater, Nature Comm. 7 (2016) 13706

Figure 1