bluuebunny/crossref_metadata_2025 huggingface dataset:
Improved Solid Electrolyte Interface on Lithium Metal Using High-Sulfur-Content Polymers
Authors: Regula Michael John , Wang Donghai
Published: February 2020

Recent studies in lithium-sulfur batteries have demonstrated the need to balance suppressing the lithium polysulfide effect with protecting lithium metal anodes. On one hand, polysulfides - intermediates of lithium’s reaction with sulfur that are soluble in compatible electrolytes - react with and shuttle between the cathode and the anode, contributing to undesired self-discharge and capacity fading. On the other hand, those same polysulfides, working in conjunction with lithium nitrate (LiNO3, a common electrolyte additive), help form a stable SEI and suppress lithium dendrite formation by limiting unfavorable electrolyte decomposition reactions.

The objective, then, is to find electrolyte additives that can protect lithium metal like polysulfides do, but without the self-discharge and capacity fading issues. We explore high-sulfur content polymers to accomplish this task. In this study, we specifically experiment with high-sulfur-content polymers based on trichloropropane (TCP).

TCP-based sulfur polymers are synthesized via a facile emulsion method, with CTAB serving a phase transfer catalyst between TCP and lithium/sodium polysulfides. The sulfur content in the polymers can be highly controlled and can be as high as 90 wt%. Upon reacting with lithium, these polymers form both inorganic polysulfides and organic Li-S-C species, which improves the mechanical stability of the SEI. A lithium deposition efficiency of >99% can be achieved for 400 cycles using these high-sulfur-content polymers.

Sulfur cathodes and lithium metal anodes could potentially move battery technology into the 21st century, but challenges still remain to realize their full potential. High-sulfur content polymers mimic the positive effects that lithium polysulfides have on the SEI of lithium metal, while also mitigating self-discharge and capacity fading.
Three-Dimensional Copper Nanowire Sponges As Novel Current Collector for Dendrite-Free Lithium Deposition
Authors: Xie Keyu
Published: February 2020

Lithium (Li) metal, with the ultra-high theoretical capacity and the low electrochemical potential, is the ultimate anode for next-generation Li metal batteries. However, the undesirable Li dendrite growth usually results in severe safety hazards and low Coulombic efficiency. In this work, a three-dimensional (3D) conductive submicron wire sponge,fabricated using a facile one-step synthetic strategy, has been proposed to homogenize the electric field distribution on the top of Li anode, so as to inhibit the growth of Li dendrite from the root. Our experimental and simulation results show that the 3D porous structure of the Cu submicron wire sponge enables the electric field to distribute homogeneously on the top of the whole anode, and accommodates the Li deposits within its 3D porous spaces. A LiFePO4 full cell, coupled with the 3D porous Cu submicron wire sponge, shows good cycle stability as well as excellent rate capability without the Li dendrite formation after cycling. Our results obtained here provide valuable guidance and deeply understanding on the design of novel nanomaterials or structures to address the cause of the Li dendrite growth and also point out a new direction for further development of the next-generation metal-based batteries.
The Sodium Storage Mechanism in a Metal-Organic Compound with 3D Framework Structure
Authors: Liu Yao Jun , Zhao Xiao Lin , Fang Chun , Liu Jian Jun , Huang Yun Hui
Published: February 2020

In this paper, a metal-organic compound Zn-PTCDA with 3D framework structure is investigated as an anode material for sodium-ion batteries. Zn-PTCDA delivers a high reversible specific capacity of 357.1 mAh g-1 at a current density of 50mA g-1 within the potential window of 0.01-2 V vervus Na/Na+, corresponding to an eight-electron transfer process. The Na ions storage mechanisms are studied by both experimental and theoretical methods. A combination of ex-situ X-ray photoelectron spectroscopy, Fourier transform infrared, X-ray diffraction and calculation studies reveal that both the carboxylate groups and the perylene rings involved in the sodium insertion process. Unraveling the Na insertion mechanism will open up new perspectives for designing novel metal-organic electrode materials.

Figure 1
Electrochemical Studies of Tin-Based Anode Materials for Rechargeable Magnesium Batteries
Authors: Nguyen Thi Huong Giang , Nguyen Dan Thien , Song Seung-Wan
Published: February 2020

Lithium-ion batteries have been the premier technology in modern portable devices and electric vehicles but they exhibit certain limitations such as mineral resources and cost. Recently, the search for alternative battery systems particularly based on earth-abundant elements has thus attracted remarkable attention. Of the possible substitute to lithium-ion, rechargeable magnesium (Mg) batteries are a potential candidate due to the abundance of Mg in the earth’s crust, as well as the high specific volumetric capacity (3833 mAh/cm-3), and good safety features of Mg metal.1 However, critical issues impeding commercialize Mg battery prototypes is the formation of surface blocking layer in conventional electrolytes which passivate and inactivate Mg metal anode, and limited selections of cathode material and electrolyte materials against Mg metal anode. To mitigate those issues, insertion-type anode materials have been developed as alternatives to Mg metal.2-4
Our recent works have shown that tin-based anode materials are capable of providing superior operating voltage and capacity for rechargeable Mg batteries.4 In this presentation, we report synthesis and characterization tin-based anode materials, and electrochemical studies with Mg-cells.

 

Acknowledgements

This work was supported by National Research Foundation of Korea (2015062107) and Creative Human Resource Development Consortium for Fusion Technology of Functional Chemical/Bio Materials of BK Plus program by Ministry of Education of Korea.

 

References

1. D. Aurbach, Z. Lu, A. Schechter, Y. Gofer, H. Gizbar, R. Turgeman, Y. Cohen, M. Moshkovich and E. Levi, Nature, 407, 724 (2000).

2. N. Singh, T. S. Arthur, C. Ling, and M. Matsui, Chem. Commun, 49, 149 (2013).

3. F. Murgia, L. Stievano, L. Monconduit, and R. Berthelot, J.
Mater. Chem. A, 3, 16478 (2015).

4. D.T. Nguyen, X.M. Tran, J. Kang, and S.-W. Song, ChemElectroChem, 3, 1813 (2016).
Layered P2-NaxCoO2 and P2-NaxFeO2 As Cathode Materials for Potassium-Ion Batteries
Authors: Baskar Senthilkumar , Sada Krishnakanth , Barpanda Prabeer
Published: February 2020

Potassium ion battery seize the attention of the scientific community due to high negative potential (-2.93V Vs SHE) of the cathode materials next to Li-ion and almost having equal abundance like the Na-ion. Very recently, interesting result based on K-ion intercalating behaviour of graphite and P2-and P3-KxCoO2 was demonstrated by Komaba et al. [1-2]. Remarkable electrochemical properties of NaxCoO2 motivated us to study the K-ion intercalation behaviour. In our work, we have investigated potassium-ion intercalation behaviour of NaxCoO2 for the first time. Hexagonal P2-type NaxCoO2 platelets were synthesized by solution-combustion synthesis (SCS) method using urea as fuel and nitrate salts as reactants. Formation of hexagonal P2-type structure with the space group of P63/mmc was confirmed from X-ray Diffraction and refined the structure using GSAS software. Atomic ratio of Na:Co was analysed using inductively coupled plasma optical emission spectroscopy (ICP-OES) which is 0.84:1.0. The systematic studies carried out by assembling a K-ion half-cell with K-metal as anode and Na0.84CoO2 as active material in 0.8 M KPF6 non-aqueous electrolyte. The K-ion intercalated structure Na0.34K0.5CoO2 was delivered a reversible capacity of 82 mAh g-1 and good rate performance with columbic efficiency of 93 %. The K-ion cell with Na0.34K0.5CoO2 was cycled up to 50 cycles at C/10 rate showed excellent cycling stability [3]. The Ex-situ XRD measurements confirmed the phase transition and K-ion intercalation/de-intercalation. P2-type NaxFeO2 was prepared by SCS method and tested as cathode material for K-ion battery. The charge storage mechanism and phase transitions in P2-type NaxCoO2 and NaxFeO2 structure will be discussed.

Acknowledgement

Author B.S. gratefully acknowledges the DST (SERB), New Delhi, India (PDF/2015/00217) for providing Fellowship.

References:

1) S. Komaba et. al., Electrochem. Commun., 2015, 60, 172

2) Y. Hironaka et. al., Chem. Commun., 2017, 53, 3693

3) K. Sada et al., Chem. Commun., Submitted

Figure 1
High Energy Density Cathode Frameworks for Potassium-Ion Battery
Authors: Masese Titus , Sano Hikaru , Senoh Hiroshi , Shikano Masahiro
Published: February 2020

Potassium-ion battery (PIB) has recently attracted great attention not only as a low-cost alternative to lithium, but also as a high-voltage contender considering the significantly negative potential of the K+/K redox couple, which is close to or even lower than that of Li+/Li depending on the solvent [1-3]. However, the large ionic radius of potassium limits the number of potassium-based compounds that can practically be utilized as high capacity materials. As shown in Fig. 1, a vast number of polyanion-based frameworks exhibit high voltages, prime among them being vanadium-based compounds (viz., KVPO4F, KCoSO4F, KNiSO4F and KVOPO4 [4]) that show voltages exceeding 4 V vs. K. Equally important as the high voltage is high capacity, that is difficult to achieve considering the high molecular weight of most of the K-containing polyanion frameworks. This has motivated an impetus to develop high capacity oxide-based cathode materials for PIB. We will highlight potential potassium-rich manganese- and iron-based oxides, while underpinning promising polymorphs of phosphate-and sulphate-based polyanion cathode frameworks.

Reference
s
:

[1] Y. Marcus, Pure Appl. Chem., 57 (1985) 1129-1132.

[2] S. Komaba, T. Hasegawa, M. Dahbi and K. Kubota, J
.
Power Sources,
60 (2015) 172-175.

[3] A. Eftekhari, J. Power Sources,
126 (2004) 221-228.

[4] T. Masese, M. Shikano, H. Sakaebe, H. Senoh and H. Sano, PCT /JP2017/000301.

Figure 1
Solution Combustion Synthesis and Electrochemical Characterization of Mixed-Anion Phosphates As Electrode Material for Na-Ion Batteries
Authors: Ryu Soojy , Jung Young Hwa , Wang Ji Eun , Kim Joo-Hyung , Kim Do Kyung
Published: February 2020

Low cost with wide availability of sodium resources makes Na-ion battery (NIB) a promising alternative to energy storage system (ESS) for Li-ion technology. For grid applications, ESS requires large storage capacity, high power density and long lifetime of batteries. In this regard, polyanion-type based materials with the 3-D framework structure have attracted much attention due to high operating voltage and structural stability. Among the various polyanion-type materials, a mixed-anion phosphate is known to have a high power, small volume change and high thermal stability properties. However, these phosphates synthesized by solid state process have limitations such as poor electronic conductivity and sluggish kinetics of the electrochemical reaction.

In this study, solution combustion synthesis (SCS) of nano-sized Na4Mn3(PO4)2(P2O7) and its electrochemical properties are reported. The structure and the phase stability was confirmed by powder X-ray diffraction (XRD). The morphological changes were further characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical performance of nano-sized Na4Mn3(PO4)2(P2O7) was evaluated using cyclic voltammetry and galvanostatic charge-discharge cycling. Nano-sized Na4Mn3(PO4)2(P2O7) electrodes exhibit better electrochemical performance than that of micro-sized particles obtained by solid state method. A complete physico-chemcial and electrochemical characterization of nano-sized Na4Mn3(PO4)2(P2O7) will be discussed in detail.
A Nitrogen-Rich Carbon Welded Multi-Dimensional Architecture for High Mass Loading Sulfur Cathode
Authors: Zhang Yuegang
Published: February 2020

Lithium/sulfur (Li/S) batteries hold promising potential for next-generation energy storage because of their high theoretical energy density, but their practical application is hindered by low utilization of sulfur and fast capacity fading. Herein, we propose a novel cathode structure with sulfur infused into a 3D nanocarbon architecture which is constructed by welding nitrogen-doped graphene (NG) and carbon nanotubes (NCNT) together with nitrogen-doped carbon shells (NCS). The rationally designed structure provides a robust and efficient network for electron conduction and lithium ion transporting as well as strong physical and chemical confinements to sulfur and polysulfides, which is confirmed by the electrochemical and in-situ Raman analysis. The NG-NCNT@NCS@S cathode exhibits a high initial discharge capacity of 1421 mA h g-1, corresponding to ~82% sulfur utilization at 0.05C, excellent rate capacities of 750 mA h g-1 at 2C and 465 mA h g-1 at 5C, and a capacity fading rate as low as 0.037% per cycle at 2C for up to 1400 cycles. Most importantly, cathodes with areal sulfur loading up to 10.2 mg cm-2 can be readily prepared and deliver an outstanding areal capacity of 5.43 mA h cm-2 after 150 cycles at a high current rate (1C), suggesting its bright prospect in advanced Li/S batteries.
Lithium Sulfide – Carbon Composite Cathode Materials Via Aerosol Spray Pyrolysis
Authors: Hart Noam , Guo Juchen
Published: February 2020

We report the synthesis of several carbon encapsulated lithium sulfide (Li2S@C) composites via aerosol spray pyrolysis (ASP), followed by an investigation of the electrochmical properties as cathodes in lithium-sulfur batteries. In this work we show that the challenges of the sulfur cathode, electrical insulation as well as polysulfide dissolution can be addressed by the arrangement of the active cathode material inside amorphous carbon confinement, accomplished with the simple, scalable manufacturing technique of ASP. In this method, ASP is first used to generate composite particles of dispersed lithium carbonate within amorphous carbon (Li2CO3@C). We show that ASP method can generate the Li2CO3@C composite from various water-soluble precursors including lithium acetate (CH3COOLi), lithium nitrate (LiNO3) or lithium carbonate, respectively, all of which yield Li2CO3 under identical reaction conditions. Sucrose is used as the carbon precursor. The obtained Li2CO3@C composites are post-treated to yield a Li2S@C composite using mixed hydrogen sulfide/argon gas (H2S/Ar at 5/95 vol.%) at evaluated temperature. The selection of precursors has an impact on particle morphology, and as such on electrochmical performance.
High Concentrated Electrolytes for Li Metal Anodes
Authors: Alvarado Judith , Schroeder Marshall , Wang Xuefeng , Xu Kang , Meng Ying Shirley
Published: February 2020

Li metal is seen as the ultimate anode for LIBs due to its extremely high theoretical energy density (3860 mAh g-1) and low negative redox potential (-3.04 V vs. standard hydrogen electrode). Making Li metal a ubiquitous anode is the key in propelling energy storage and conversion systems. It is one of the key components that will further the development of next-generation batteries, such as Li-S, Li-O2, and high energy density batteries (500Wh/kg) for the automotive industry. One way to address the dendritic growth and low coloumbic efficiency of the Li metal, is to focus on the electrolyte to form a robust and stable solid electrolyte interphase (SEI). There are several types of electrolytes that one can use for Li metal, each serving its purpose to fulfill a need in high voltage and low voltage applications.

Herein, the focus on electrolytes for both high and low voltage applications. Simple electrolyte formulations containing LiFSI, yield a robust and stable SEI that is primarily composed of inorganic functionalities due to salt reduction. A bisalt formulations yield high plating and stripping efficiencies (98.5 at 0.5mA/cm2), even higher efficiencies at elevated temperatures. We further demonstrate the use of a high concentrated carbonate based electrolyte in a high voltage anode free and half cell that out performs the conventional carbonate electrolyte.
Mechanical Properties of Li7La2.75Ca0.25Zr1.75Nb0.25O12 Garnet Electrolyte—a Preliminary Study of a Porous Layer Support All-Solid State Battery
Authors: Fu Zhezhen , Gong Yunhui , Zhang Lei , Gritton Evans , Godbey Griffin L. , Ren Yaoyu , McOwen Dennis W. , Wachsman Eric D.
Published: February 2020

In order to study the feasibility of porous layer supported all-solid state battery, mechanical properties including flexural strength, Young’s modulus, and hardness of Li7La2.75Ca0.25Zr1.75Nb0.25O12 (LLCZN) were studied. The flexural strength of LLCZN with varies porosity and grain size was determined based on ASTM C1161. Young’s modulus and hardness was obtained through nanoindentation technique. The flexural strength of LLCZN with full density is ~150 MPa. The refinement of the grain size can further increase the flexural strength. The dense LLCZN garnet has a Young’s modulus of ~147.2±6.6 GPa and a hardness of ~13.9±1.4 GPa. Above results indicate that the LLCZN garnet has sufficient strength, stiffness, and hardness as the dense layer in a porous layer supported all-solid state battery.
Mechanics of Amorphous Lithium Dendrites
Authors: Aryanfar Asghar , Cheng Tao , Goddard William A
Published: February 2020

The formation of dendrites is a critical drawback for the utilization of Li and other metals in secondary batteries. These emorphous crystals can pierce into the polymer electrolyte and short the cell. Therefore the design/selection criterion requires the dendrite-polymer mechanical compatibility. Hereby we characterize the dendrites morphological evolution based on the intrinsic material property (surface energy). Consequently, we perform force field calculations on the created microstructures to extract the effective mechanical properties such as elastic modulus and poission ratio. In particular, our study is also useful for understanding the mechanics of amorphous structures.
Design of Porous Anolytes for Rechargeable Metal Batteries
Authors: Thomas-Alyea Karen E.
Published: February 2020

Recently there has been great interest in porous lithium metal electrodes for rechargeable batteries, which have demonstrated remarkable improvements in cycle life and charge-rate capability compared to planar lithium metal [1]. In this type of cell design, the porous electrode consists of a porous solid electrolyte with void space in the discharged state. During charge, the metal plates onto the surface of the solid electrolyte, filling the pores. During discharge, the pores empty as lithium reacts at the surface of the electrolyte to produce lithium ions which travel through the porous electrolyte. The electrolyte is rigid, so its shape remains fixed over the life of the cell. This design is advantageous because the solid-electrolyte interphase (SEI) is stationary on the surface of the electrolyte, and therefore there is little capacity fade over cycling, because there is no volume change to cause cracks in the SEI. The design also allows space for the metal to deposit into, thereby reducing the cyclic stress of depositing metal pushing against the separator. By reducing the stress of the lithium pushing against the separator, the risk of a dendrite growing through a defect in the separator is reduced.

Here we present an electrochemical model for a cell with a porous anolyte based on porous-electrode theory [2], and apply the model to optimize the design of the porous anolyte to maximize cycle life and safety. For example, we find that, because the electronic conductivity of lithium metal is over 7 orders of magnitude higher than the ionic conductivity of present state-of-the-art solid electrolytes, electronically conductive additives provide no benefit for the porous electrode. As the lithium plates onto the electrolyte surface (initially at the interface with the current collector), the plated lithium itself provides a sufficiently electronically conductive network. Furthermore, if the area-specific resistance of the porous electrode is too low, the current distribution can be highly nonuniform, which can have deleterious consequences for cycle life and safety. Finally, we discuss the implications of the model for the necessary mechanical properties of the solid electrolyte to prevent dendrites even in the presence of manufacturing tolerances.

References

[1] C. Wang, Y. Gong, B. Liu, K. Fu, Y. Yao, E. Hitz, Y. Li, J. Dai, S. Xu, W. Luo, E. D. Wachsman, and L. Hu, NanoLetters 2017, 17(1) p. 565.

[2] J. Newman and K. E. Thomas-Alyea, Electrochemical Systems, 3rd edition, Hoboken: John Wiley & Sons, Inc., 2004.
A Tetrasubstituted Hydroquinone Ether Catholyte for Non-Aqueous Redox Flow Batteries: Bicyclic Substitution Enabling High Stability
Authors: Zhang Jingjing , Yang Zheng , Shkrob Ilya A , Assary Rajeev , Tung Siu on , Silcox Benjamin , Duan Wentao , Hu Bin , Thompson Levi T , Wei Xiaoliang , Liao Chen , Zhang Zhengcheng , Zhang Lu
Published: February 2020

The practical application of non-aqueous redox flow batteries (NRFBs) sets stringent requirements on the electrochemical stability of the redox active materials. In the redox pair for NRFBs, the high-potential species is referred to as the catholyte, which is oxidized into the radical cation state in the charging process. Hydroquinone ethers are a key class of catholyte materials, but the intermolecular reaction between the radical cations is a dominating decomposition pathway of the catholyte during functioning. In order to increase the electrochemical stability of the catholyte materials, the introduction of bulky alkyl spacers at 2,5- positions of the arene ring is commonly used as a strategy in the molecular design to suppress this type of undesirable side reaction. However, the unsubstituted 3,6- positions that are favored for the electrochemical reversibility are responsible for the radical cation reaction in the long-time cycling. Tetrasubstitution of the arene core with either primary or secondary alkyl groups often leads to a compromised redox reversibility. This talk will describe a tetrasubstituted hydroquinone ether-based catholyte molecule that retains excellent redox reversibility and illustrates exceptional stability. Unique bicyclic alkyl groups are incorporated to the molecular scaffold, eliminating the bimolecular reaction between the radical cations. A hybrid NRFB using such catholyte has been operated for over 150 charge-discharge cycles with minimal loss of capacity.
(Invited) Design and Commercialization Challenges of Garment-Based Textile Electronics
Authors: Jur Jesse S , Bowles Allison , Bhakta Raj , Myers Amanda , Shahariar Hasan , Twiddy Jack
Published: February 2020

Textile electronics is a rapidly evolving industry, particularly in sectors of wellness, medical, and athletics. The advantage of a textile electronic, over current wrist worn wearables products, is the ability to form a non-noticeable integrated system of multiple sensors across the large contact area that the garment has in intimate contact with the body. Key challenges exist in the commercialization of these technologies, as it relates to identifying the consumer needs for justifying the use of the technology and cost factors for fabrication that are limited by the low-cost principles of the textiles industry. This talk explores new technology developments and trends in garment fabrication that provide the opportunity for resolving these challenges. Of particular interest is the ability to leverage techniques founded in the printed electronics industry and elements of the rapid developing 3D whole garment manufacturing to fabricate customized electronics and garments, a key to optimizing the data quality of integrated sensors to that of the consumer expectations.
A Fuel Cell Sensing Platform for Selective Detection of Acetone in Hyperglycemic Patients
Authors: Jalal Ahmed Hasnain , Umasankar Yogeswaran , Chowdhury Mustahsin , Bhansali Shekhar
Published: February 2020

In this work, a three-electrode fuel cell sensor is integrated with a miniaturized potentiostat (LMP91000) and a microcontroller (nRF51822) for selective detection of acetone. Elevated level of acetone in breath or sweat is an indication of systemic ketosis, hyperglycemia or type-I diabetes [1]. Rise of ketone concentrations leads to an increase in acid levels in the blood, called ‘Ketoacidosis’. Ketoacidosis is a serious hyperglycemic condition in patients with type-I diabetes. Among the conventional sensing methods (e.g. breathalyzer for lung ketone analysis, chemical strips, laboratory blood test and urine test), continuous monitoring is a challenge [2]. Also, though real time detection of acetone from different biofluids is promising, interference from other biomarkers remains an issue [3]. To address the above in non-invasive detection, we have developed a statistical model and algorithm which enable separation of signals and eliminate interference from other associated biomarkers. In the developed sensing platform, our fabricated sensor comprises an electrolyte membrane, nafion and monel mesh, as electrodes. Catalytic oxidation of acetone occurs on the working electrode in presence of moisture while oxygen is reduced on the counter electrode. Applying a constant potential across the working and reference electrodes, current is measured between the working and counter electrodes. With the change of concentrations of acetone, the current varies linearly. From this study, it is observed that the sensor is capable to detect as low as 1 ppm of acetone with the sensitivity of 60 nA ppm-1 cm-2. The developed platform has been based on the pre-calibrated data to interpret precise measurement of acetone.

Reference:

Matzeu, G.; Florea, L.; Diamond, D. 2015. Advances in wearable chemical sensor design for monitoring biological fluids, Sensors and Actuators B, 211:403–418.

Tricoli, A.; Nasiri, N.; De, S. 2017. Wearable and Miniaturized Sensor Technologies for Personalized and Preventive Medicine, Advanced Functional Materials, 27(15): 1-19.

Jalal, A. H.; Umasankar, Y.; Gonzalez, P. J.; Alfonso, A.; Bhansali, S. 2017. Multimodal technique to eliminate humidity interference for specific detection of ethanol, Biosensors and Bioelectronics, 87(15): 522–530.
Nanoporous Electrospun Li7La3Zr2O12 As Filler in PEO/Litfsi Hybrid Electrolyte
Authors: Letfullina Alla R , Uddin Md-Jamal , Cho Jong-Soo , Alaboina Pankaj Kumar , Cho Sung-Jin
Published: February 2020

Solid polymer electrolytes (SPE) have gained a lot of attention recently due to their lower interfacial resistance with electrodes and high processability. However, these electrolytes still suffer from low ionic conductivity at room temperature. The lithium ion transfer within the polymer electrolyte is heavily dependent on polymer chain mobility, and one of the most efficient ways to enhance its ionic conductivity is by an addition of a filler that would prevent the polymer from crystallizing. In this work, we utilize nanoporous electrospun Li7La3Zr2O12 (LLZO) as fillers in polyethylene oxide(PEO)/bis(trifluoromethane)sulfonimide lithium (LiTFSI) polymer electrolyte. Nanoporous LLZO was synthesized by electrospinning LLZO precursor fibers followed by calcination. LLZO is one of the most popular inorganic solid electrolytes (ISE) due to its great electrochemical stability and high ionic conductivity. LLZO serves a multifunctional role of inhibiting polymer crystallinity as well as of providing an additional lithium ion transfer mechanism. The ultra-fine nanoporous particle morphology enhances the polymer chain mobility which has the potential to significantly improve the ionic conductivity of hybrid polymer electrolyte (HPE).
Uniform Distribution of Sn Nanoparticles in Carbon Matrix As Anodes for High-Performance Lithium-Ion Batteries
Authors: Han Weiqiang , Ying Hangjun , Xin Fengxia
Published: February 2020

Abstract

Presently, nanocrystallization and carbon composite modification are two main strategies to mitigate the volume change of Sn and prolong the cycle life. Nanoscale Sn can reduce the absolute volume change and suppress the volume mismatch in a single granule and the particle breakage is significantly inhibited. Moreover, the small size can shorten the ions diffusion distance in the material and improve dynamic performance. Carbon is the ideal material to modify Sn anodes. On one hand, the soft and flexible carbon works as “buffer zone” to hold the volume change and inhibit the particles aggregation. On the other hand, it serves as the conductive network to accelerate the ions transport and electrons transfer, as a result, improving the rate capability of Sn based materials.

Taking the advantages of nanoscale Sn and carbon modification, we recently designed nano-Sn/reduced graphene oxide (Sn/RGO) composites with extra small Sn particles uniformly dispersing in the carbon matrix. The 3D few-layer stacked Sn/RGO composite shows a structural evolution phenomenon from a stratified structure to a curly Sn@Carbon nanocage-like structure after cycling. The nanocage-like Sn@C structure is stable and guarantees the ultralong cycle life of Sn/RGO. It can steadily cycle up to 1000 times without obvious attenuation at 0.2 C, the specific capacities remain stable above 550 mAh g-1.

Figure 1. Schematic illustration of structural evolution of Sn/RGO during cycling

 

Acknowledgments

This work is supported by the National Natural Science Foundation of China (Grant No. 51371186), the “Strategic Priority Research Program” of the Chinese Project Academy of Science (Grant No.XDA09010201), Ningbo 3315 International Team of Advanced Energy Storage Materials, Zhejiang Province Key Science and Technology Innovation Team (2013TD16).

Figure 1
Synthesis of Water-Resistant thin TiOx Layer-Coated High-Capacity LiNi
a
Co
b
Al1-a-B
O2 (a > 0.85) Cathode and Its Stable Charge/Discharge Cycle Cathode Performance to Apply a Water-Based Hybrid Polymer Binder to Li-Ion Batteries
Authors: Liu Yubin , Tanabe Toyokazu , Miyamoto Koki , Irii Yuta , Maki Fumihiko , Gunji Takao , Kaneko Shingo , Ugawa Shinsaku , Lee Hojin -J , Ohsaka Takeo , Matsumoto Futoshi
Published: February 2020

Titanium oxide (TiOx) coating was treated on a surface of A LiNi
a
Co
b
Al1-a-b
O2 (a > 0.85) cathode material, which exhibited high capacity of 200 mAhg-1 and however, the charge/discharge capacity with pristine LiNi
a
Co
b
Al1-a-b
O2 degraded seriously after contacting with water. The formation of TiOx layer on the cathode material surface was characterized with field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The TiOx-coated LiNi
a
Co
b
Al1-a-b
O2 cathode material did not form bubbles in the coating process when a water-based slurry was prepared with TiOx-coated LiNi
a
Co
b
Al1-a-b
O2 particles and a water-based hybrid polymer binder, and then the slurry was coated on a aluminum current collector. Therefore, the cathode electrode fabricated with TiOx-coated LiNi
a
Co
b
Al1-a-b
O2 exhibited comparable cycle and rate performance with the cathode which was composed of pristine LiNi
a
Co
b
Al1-a-b
O2 particle and organic solvent-based PVdF binder even after it was exposed in the water-based slurry for 7 days.
Metal-Assisted Chemical Etching of GaAs Using Au Nanodots
Authors: Imai Ryota , Hashimoto Hideki , Asoh Hidetaka
Published: February 2020

III-V compound semiconductors have attracted attention as next-generation materials and potential alternatives to silicon-based semiconductors because of their excellent properties including superior carrier mobility and direct band gap. In a previous study, we fabricated microbump arrays of InP [1] and line patterns and pillar arrays of GaAs using metal-assisted chemical etching [2]. However, the dimensions of the resultant patterns ranged from several micrometers to several tens of micrometers. To the best of our knowledge, no study has reported the formation of ordered GaAs nanostructures with submicron-scale or smaller periodicity using metal-assisted chemical etching. Thus, we attempted to clarify the etching mechanism of GaAs on the nanometer scale. In this study, we investigated the effects of etchant composition and temperature on the morphology of the etched GaAs during metal-assisted chemical etching using Au nanodot arrays as a catalyst. A through-hole porous alumina mask with an ordered array of openings was set on an n-type GaAs. Subsequently, a 20-30 nm thick Au layer was evaporated through the alumina mask using a mixed vacuum deposition system. The periodicity of Au nanodot arrays, which were formed on GaAs substrate, was 100 nm and the diameter of Au dot was 50-60 nm corresponding to the dimensions of anodic alumina mask. After the formation of Au dot arrays on GaAs substrates, the specimens were immersed in a mixed solution of HF and KMnO4. When the specimen was etched in a HF containing relatively low concentration of KMnO4 at high temperature, Au dots sank into the GaAs substrate. The positive holes (h+), which were generated by reduction of oxidant (i.e., KMnO4) at Au surface, are thought to be consumed immediately at the Au/GaAs interface. As a result, Au dot arrays sank into the substrate, resulting in the formation of pore arrays. On the other hand, in the case of high concentration of KMnO4, h+ diffused into the surrounding Au-coated GaAs; thus, site-selective etching occurred on the exposed GaAs surface. Attempts to clarify the effects of the concentration of oxidizing agent on the generation of h+ and morphology of etched are currently underway.

[1] H. Asoh, T. Yokoyama and S. Ono, Jpn. J. Appl. Phys., 49, 046505 (2010).

[2] H. Asoh, Y. Suzuki and S. Ono, Electrochim. Acta, 183, 8-14 (2015).
The Electrochemical Activity of Nitrogen Doped Graphene Towards Oxygen Reduction Reaction in Ionic Liquid at Intermediate Temperature
Authors: Puthen Peediyakkal Hasna , Kikuchi Syojiro , Yu Jie , Munakata Hirokazu , Kanamura Kiyoshi
Published: February 2020

Among the various types of fuel cells, polymer electrolyte membrane fuel cells (PEFCs) have attracted much attention as future electrical energy production system due to its high power density and wide range of applications in portable and stationary devices. The properties of commonly used perfluorosulfonate polymer membranes like Nafion®limit the operating temperature of PEFCs upto 80 ⁰C resulting the difficulty in heat and water management, CO poisioning of catalyst and its low electrochemical activity.

Recently proton conducting ionic liquids, particularly N,N-diethymethylammoniumtetraflurosulfonate (dema-TfO) have attracted much attention as electrolytes enabling the fuel cell operation at intermediate temperature above 100 ⁰C. In fact, prototypes of intermediate temperature fuel cells using dema-TfO have been developed by some research groups including us1,2. As increasing the operating temperature, the electrochemical activity of catalyst increases which can expand the selection of electrode catalysts.

Carbon-based nanostructures have been confirmed to be excellent materials for enhancing oxygen reduction reaction (ORR) for conventional PEFCs with perfluorosulfonate polymers3. In this study, we have synthesized nitrogen-doped graphene (NG) by simple pyrolysis of graphene oxide (GO) and urea mixture at 900 ºC under Ar atmosphere as an ORR catalyst for intermediate temperature fuel cells using ionic liquids. The oxygen reduction activity of NG has been studied using a rotating disc electrode in dema-TfO under N2 and O2atmosphere at different temperatures. The ORR onset potential and current density shifted to positive and increased with increasing temperature. The comparison with pristine graphene at 120 ⁰C (Fig. 1) clearly indicated the positive effect of nitrogen doping on the improvement of ORR activity. Although the ORR activity of NG was still lower than that of commercially available Pt/C (37.5%), it has excellent electrochemical stability. The durability test was measured based on the protocol of the Fuel Cell Commercialization Conference of Japan (FCCJ). Even after 2000 cycles in the potential range of 1.0 to 1.5 V vs. RHE, NG retained almost the same onset potential, which is much higher durable than those of Pt/C (~ 15.6 % loss).

Reference

1. S.-Y. Lee, A. Ogawa, M. Kanno, H. Nakamoto, T. Yasuda and M. Watanabe, J. Am. Chem. Soc., 132, 9764 (2010).

2. M. Haibara, S. Hashizume, H. Munakata and K. Kanamura, Electrochim. Acta, 132, 208 (2014).

3. Z. Lin, G. Waller, Y. Liu, M. Liu and C.-P. Wong, Advanced Energy Materials, 2, 884 (2012).

Figure 1
Self-Assembly- and Preshaping-Assisted Synthesis of Ultrathin Nitrogen-Doped Graphitic Carbon Lamellas Supported Molybdenum Carbide for Hydrogen Evolution Reaction
Authors: Peng Lishan , Zhang Ling , Shen Jingjun , Wei Zidong
Published: February 2020

The sustainable generation of hydrogen through water electrolysis by using electricity has attracted great attention but remains an elusive goal in catalysis. Metallic carbide have been ardently expected to be the most promising alternatives to replace or reduce Pt employment in electro-catalyze HER.[1,2] Herein, we report a “self-assembly and preshaping” strategy for the controllable synthesis of porous graphitic carbon lamellas supported highly dispersed Mo2C nanoparticles (Fig. 1a-c). The self-assembly and preshaping not only efficiently promoted the distribution of Mo2C on the highly conductive carbon nanolamellas, but it also impeded the aggregation and excessive growth of ultrafine Mo2C nanoparticles at high temperatures. These features enabled the full exposure and utilization of the Mo2C active sites for H+ adsorption and reduced the electrical resistance between neighboring surface-Mo2C, endowing the constructed Mo2C/C-lamellas with a superior HER activity and long-term stability compared with traditional bulk Mo2C/C. As a matter of course (Fig. 1d-g), relative to traditional Mo2C/C-bulks, the as-constructed Mo2C/C-lamellas exhibits higher activity for the HER with a lower onset overpotential (145 mV), a smaller Tafel slope (60.5 mV dec-1), better electroconductivity, and improved stability over 20 h during operation in 0.5m H2SO4. This self-assembly and preshaping assisted carburization method represents a rational strategy for the preparation of robust carbon composite materials with hierarchically ordered structures, especially high melting point and easily-aggregation compound.

Figure 1. (a) Schematic illustration of the synthetic procedure of Mo2C/C lamellas; (b,c) TEM images of Mo2C/C lamellas; (d,e) Linear Sweep Voltammetry curves and Tafel plots during HER over 20 wt% Pt/C, SA-C, Mo2C/C bulks and Mo2C/C lamellas; (f) Current density vs. time (I–t) curve of HER over Mo2C/C lamellas at I=10 mA over 20 h-long electrocatalytic reaction; (g) Polarization curves of Mo2C/C lamellas before and after ageing.

Reference:

[1] M. S. Dresselhaus, I. L. Thomas, Nature
2001, 414, 332-337.

[2] W.-F. Chen, J. T. Muckerman, E. Fujita, Chemical communications
2013, 49, 8896.

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Controlled Synthesis of Hollow Micro/Meso-Pore Nitrogen-Doped Carbon with Tunable Wall Thickness and Specific Surface Area As Efficient Electrocatalysts for Oxygen Reduction Reaction
Authors: Wu Rui , Chen Siguo , Wei Zidong
Published: February 2020

Here, we demonstrate a rational design and preparation of hollow micro/meso-pore nitrogen-doped carbon (HMNC) catalysts with micro-, meso-, and macroporosity integrated into one structure through high temperature pyrolysis of the precursor containing polydopamine (PDA) coated silica spheres and FeCl3. The TEM and BET analysis results show that the wall thickness and specific surface area of HMNC can be simply controlled by adjusting the Fe content absorbed on PDA. The ORR activities have a strong correlation with the specific surface area and the wall thickness of the HMNC electrocatalysts. The optimized HMNC catalyst with ~5 nm wall thickness and 1703.5 m2 g-1 specific surface areas showed highest ORR performance, which was comparable with Pt/C in both the reaction current and the initial potential in alkaline media. The remarkable ORR activity is ascribed to its unique hollow micro/meso-pore structure, which can provide shortest diffusion channels for oxygen and electrolyte as well as a high specific area and sufficient exposure of inner-pore catalytic sites. This work provides an important guidance to other researcher in designing and fabricating high performance N-doped carbon electrocatalysts for industrial purposes that range from catalysis and sensors to supercapacitors and lithium-ion batteries.

Figure 1
Synthetic Melanin Films As Potential Interfaces for Peroxynitrite Detection and Quantification
Authors: Kalil Haitham , Kay Clara , Al-Mahmoud Ousama , Bayachou Mekki
Published: February 2020

Peroxynitrite (PON) is a highly reactive oxygen-nitrogen species that facilitates both oxidation and nitration reactions. PON is the primary product of the reaction of superoxide anion-radical with nitric oxide radical. It has been well established that PON is a major noxious molecule, which is implicated in a host of pathophysiological conditions. Recently, PON has emerged as a new member of the nitroxidative array of reactive metabolites. Early clinical reports have emphasized the deleterious physiological reactivity of PON with many cellular targets including DNA, proteins, and lipids at cell/tissue levels.

Melanin is a natural pigment that has many physiologic functions including the neutralization of highly reactive oxidative species. Tyrosine and its derivative 5,6-dihydroxyindole (DHI) are precursors of eumelanin, a brown or black forms of melanin that is also photo-stable. Recent studies have suggested that melanin can act as antioxidative therapy to scavenge reactive oxygen and nitrogen species including PON.

In this project, we examine the chemical interaction between synthesized PON and polymerized films of DHI as a model of synthetic melanin. First, we studied the electrochemical characteristics of polymerized 5,6-dihydroxyindole on graphite electrodes, and then monitored the changes after adding aliquots of PON. This part of the work reports primarily on chemical changes within the electro-polymerized films of melanin on the electrode. We also studied the rates of chemical decay of PON in the presence of the transparent Indium Tin Oxide (ITO) electrodes coated with melanin films using absorbance spectroscopy. Ultraviolet-visible spectroscopy showed a significant difference between the decomposition rates of PON alone and in the presence of DHI films. The melanin films were characterized with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) to image and determine the surface chemical composition of the synthetic film. X-ray Photoelectron Spectroscopy (XPS) has been used to detect and analyze the change on the synthetic melanin films coated ITO slides before and after exposure to PON. Finally, we report on the possibility of using DHI films as a platform for the quantitative detection of PON in solutions using amperometry and impedance.
Redox-Dependent Binding to an Electroactive Urea: Comparison of Ferrocene and Phenylenediamine Redox Couples with Two Different Guests
Authors: Logan Kyle , Smith Diane K.
Published: February 2020

In previous work in our lab, the redox-dependent binding behavior of a phenylenediamine urea, UHH, was investigated in the presence of different guests in CH2Cl2. The urea functionality contains two good H-donors in the two urea NH bonds (a DD motif) that are capable of H-bonding with two appropriately spaced H-acceptors (AA motif). Examples are the cyclic diamide PZD (see Figure) and 1,8-naphthyridine, naph. 1H NMR studies indicated a modest Kbinding of 100 M-1 with PZD and 30 M-1 with naph in CH2Cl2. The expectation was that oxidation of the phenylenediamine couple in UHH to the radical cation would increase the acidity of one of the NH’s leading to stronger H-bonding with the guests and a negative shift in the observed redox potential upon addition of these guests. A small negative shift was observed with PZD, but further research indicated that the actual overall reaction occurring upon oxidation of UHH was not the simple 1 electron oxidation to the radical cation expected, but rather 2 electron oxidation of one UHH accompanied by proton transfer to a reduced UHH to give UH+ and HUHH+ as shown in the Figure. Addition of PZD does not change this overall reaction. An alternative explanation of the potential shift is that PZD is actually H-bonding to the protonated HUHH+, which would also be a stronger H-donor. Interestingly, similar magnitude shifts are observed upon oxidation of the ferrocene-containing urea, FcUHH. Since Fc is only capable of being oxidized by 1 electron, oxidation of the Fc also makes a +1 charge, which appears to have a similar effect on the H-bonding ability of the urea as does protonation.

In contrast to the PZD, addition of naph causes the current for the oxidation of UHH to increase with little change in peak potential. This can be explained by proton transfer from the UHH radical cation to the naphthyridine. The resulting neutral radical will be immediately oxidized by a second electron leading to the increase in current. The proton transfer will change the H-bonding motif from AA-DD to AD-DA, which is inherently weaker because of unfavorable secondary interactions. In addition, because of the two electron oxidation, both binding partners in the resulting complex, (naphH+)(UH+), will be positively charged. Therefore it is not surprising that the H-bonding does not strengthen upon oxidation. It will be of interest to compare this behavior to that of FcUHH and naph. Cyclic voltammetry experiments will be run with FcUHH and naphthyridine to see if eliminating the possibility of the second electron transfer prevents proton transfer and results in the expected stronger H-bonding to the oxidized form.

Figure 1