Coin Type Research Articles

Two sides of the same coin: Improved ancient coin classification using Graph Transduction Games

In this work we tackle the problem of automatic recognition of ancient coin types using a semisupervised learning method, namely Graph Transduction Games. Such problem is complex, mainly due to the low inter-class and large intra-class variations and the task becomes even more complex due to lack of labeled large datasets from certain ancient ages. In this paper we propose a new dataset which is chiefly the extension of a previous one both in terms of quantity and diversity. Moreover, we propose a game-theoretic model that exploits both sides of a coin to achieve higher classification accuracy. We experimentally demonstrate that proposed approach brings performance improvement in this complex task even when few number of labelled images are available.

Ancient coin designs encoded increasing amounts of economic information over centuries

Coinage, the practice of minting small bits of metal with distinctive marks, appearing in the second half of the 7th century BCE, had a transformative impact upon ancient economies and societies. Controversies endure concerning the original function of ancient coinage, in particular the respective role of states and markets in its emergence. Applying information-theoretic measures to a corpus of 6859 distinct coin types from the Ancient Mediterranean world, dated between c. 625 and c. 31 BCE, we show that the symbols minted on coins (designs combining images of plants, deities, animals, etc.) became increasingly informative about a coin’s value. This trend was specific to value-relevant information, as distinct from information concerning issuing states. Coin designs also carried more information about higher denominations than about lower ones. Before numerical or written marks of value became widely used on coinage, these iconic symbols were carrying economic information.

PLC Based Multi-Product Vending Machine

The vending machine is a kind of cash driven machine that automatically distributes snacks, drinks and other consumer products automatically. Consumer pay coin into a slot, once a choice is made by pressing the push button, the machine dispenses the item purchased. Money, card or coin-based product vending machine by using embedded microcontrollers; Arduino and Raspberry Pi are currently used in systems. By using these microcontrollers, it is complicated when there was a technical error. In this project, we have created a multi-product coin type vending machine by using Mitsubishi PLC. The Programming Logic Controller (PLC) used automatically to monitor and control with high speed, efficiency, and reliability. Switch ON the power supply. Put the coin in the coin acceptor, and then select the product by pressing push button. The motor starts rotating along with the spring and moves the selected item until it released from the spring. The Hall Effect sensor used to count the rotation with the help of the magnet to sense. When the product released from the spring the motor stop rotating and the released product is ready to dispense. The drawback of the project is the vending machine cannot detect fake coins and the consumer cannot refund the money if they slot a coin when there is no product in the machine. [1],[ 3],[5]

Different Technology In Designing Vending Machine

The vending machine is a kind of cash driven machine that automatically distributes snacks, drinks and other consumer products automatically. Consumer pay coin into a slot, once a choice is made by pressing the push button, the machine dispenses the item purchased. Money, card or coin-based product vending machine by using embedded microcontrollers; Arduino and Raspberry Pi are currently used in systems. By using these microcontrollers, it is complicated when there was a technical error. In this review paper, we have created a multi-product coin type vending machine by using Mitsubishi PLC. The Programming Logic Controller (PLC) used automatically to monitor and control with high speed, efficiency, and reliability. Switch ON the power supply. Put the coin in the coin acceptor, and then select the product by pressing push button. The motor starts rotating along with the spring and moves the selected item until it released from the spring. The Hall Effect sensor used to count the rotation with the help of the magnet to sense. When the product released from the spring the motor stop rotating and the released product is ready to dispense. [1],[ 3],[5]

П.Я. Марпергер и его труд «Московитский купец…» («Moscowitischer Kauffmann…», 1723)

The scope of work carried out by the German scholar and entrepreneur P.J. Marperger is much broader than its title and represents a sort of a reference for foreign business people, who arrived in Russia, steering them through the country. The author, using authentic documents, oral sources and, possibly, his own observations, provided extensive information about the international commerce as such, trade laws and rules, features of the Russian customs, types of coins, common measures and weights. He also (mainly, referring to the available Western European literature in English, French and Latin) obtained in-depth insights into the internal and overseas political and military history of our country, depicted its geography with natural and climatic conditions, the largest cities, rivers, lakes and seas; described the living conditions, way of living and manners, customs and religious preferences of the peoples living in the country. P.J. Marperger introduces readers to the convenient ways of quick traveling of travelers and postal officers through the empire. A special chapter is the Russian-German dictionary and phrasebook.

Which coin is easier to pass esophagus spontaneously?

ObjectiveTo determine the factors associated with the spontaneous passage (SP) of coins lodged in the esophagus in children. Subjects and MethodsA total of 351 pediatric patients with coin ingestion admitted to our hospital from March 2016 to March 2019 were included in the study. The patients underwent a period of overnight watch with a repeated chest x-ray within 24 h after the commencement of hospitalization. The influencing factors (sex, age, types of coin, time in the esophagus, and location) were analyzed. ResultsThe repeated chest x-ray showed coins that had passed into the stomach or intestine in 68 patients. Sex, age, time in the esophagus, location in the esophagus or the types of coins were not associated with SP, but the distribution of the esophageal coins varied statistically significantly in the different ages. ConclusionCoins pass spontaneously through the esophagus (19.4%) within 24 h, unrelated to sex, age, time of esophagus lodging, coin location in the esophagus, or coin types. Children approximately two years old were more likely to ingest small coins (10 or 50 cents), whereas children approximately five years old were more likely to ingest a large coin (1 Yuan).

Increased Cycle Stability of Dual Carbon Batteries By Using LiPF6 – LiTFSI Mixed Salt Electrolyte

Rechargeable battery with large energy capacity as well as superior rate property is strongly required for electric vehicle and hybrid vehicle. Dual carbon battery which is expected as a post Li ion battery, is based on intercalation of anion and cation into graphitic carbon and advantages on cycle stability and high discharge potential (> 4 V). However, low coulomb efficiency by gas formation is the most serious issue for this battery. In this study, effects of mixing LiPF6-LiTFSI in dimethyl carbonate (DMC) for electrolyte of DCB were studied. For electrochemical measurements, graphitic carbon of KS6 (TIMCAL) and MAGD (Hitachi Kase) were used for the positive and negative electrode, respectively. For the charge/discharge investigations, a constant current rate of 0.5 mA cm−2 was applied for both charge and discharge steps, and the potential windows of 3.0 V to 5.2 V was used. LiPF6, LiTFSI and DMC of lithium battery grade (Kishida Chemical Co., Ltd., Japan) were used. The LiPF6-LiTFSI/DMC electrolyte was prepared by dissolving LiPF6, LiTFSI (battery grade) in DMC in a dry argon-filled glove box without further purification. Coin type cell was assembled in a glove box filled with a dry argon atmosphere. It was found that mixing LiPF6 and lithium bis(trifluoro methanesulfonyl)imide (LiTFSI) at 1:1 for a support salt was highly effective for increasing coulomb efficiency and cycle stability. When LiPF6-LiTFSI in DMC was used, the discharge capacity of 90 mAh/g-cathode was sustained over 300 cycles without almost no degradation. Coulomb efficiency higher than 98% was achieved after 10 cycles suggesting a decreased gas formation, and it was also found that corrosion of Al current corrector was prevented by using LiPF6-LiTFSI mixed salt. DFT calculation and NMR measurement suggests that the complex anion of (PF5-TFSI)- and F- was formed resulting in the increased stability of intercalated anion and preventing Al current collector corrosion. It was also suggested that PF5-TFSI anion shows fast diffusivity in graphitic carbon which is in good agreement with superior rate property.

Lithium –Manganese Rich Li1.2Mn0.55Ni0.15Co0.1O2 (LMR-NMC) Based Cathodes and Si-C Composite Anodes for High Energy Density Lithium-Ion Batteries

US Department of Energy predicts the next generation lithium ion batteries (LIBs) will have almost the double the energy density (235 Wh kg-1) of the currently available Li-ion batteries based on layered transition metal (TM) oxides or Phosphates, Mn based spinels as cathodes and graphitic carbon as the anode. Besides the batteries should have reduced cost (100-125 USD per kWh) and improved thermal safety. The nominal capacity of most of these cathodes are in the range between 140-180 mAhg-1 when cycled up to 4.2V. This is only half the specific capacity of graphite anode (372 mAhg-1). Thus, there has been an intense research activity in the last decade to develop high capacity or high energy cathodes and anodes for lithium-ion batteries. Lithium and manganese rich TM oxide composite cathodes such as, xLi2MnO3. (1-x)LiMO2 (M= Co, Mn and Ni, etc.) (LMR-NMC) that has almost double the capacity (280 mAh g-1) of layered TM oxides, but needs to be electrochemically cycled to a voltage > 4.5 V which causes electrochemical instability. When cycled above 4.5 V the Li2MnO3 component is activated and forms Li2O and MnO2. The decomposition contributes to the high irreversible capacities >25% for LMR-NMC electrodes and capacity fade due to significant reduction of electrolytes and electrode conductivity due to high voltage cycling [3]. The capacity fade also associated with Mn dissolution from the host structure upon repeated high voltage cycling. Beside, LMR-NMC cathodes undergo structural changes upon high voltage cycling causing energy loss. The energy density of LMR-NMC cathodes are reduced from 1000 Wh kg-1 during initial cycles to ~750 Wh kg-1 during 100th cycle which makes LMR-NMC practically impracticable. The structural transition to the spinel phase is an intrinsic phenomena associated with Ni ions migration to the lithium layer during high voltage cycling. In this work we present doped or blended composite electrodes to reduce energy loss in LMR-NMC during high voltage cycling [1-2]. LiF coating onto LMR-NMC is used to stabilize thes interface and mitigate voltage fade [1]. In this approach, some of the M-O bonds are replaced by M-F bonds on the surface. The M-F bond is stronger and stabilizes the interphase during cycling. Partially, O2- is replaced by F- on the surface of LMR NMC due to which the average oxidation state of the surface metal ions is slightly decreased which lead to decrease in charge potential, thus minimizing the electrolyte decomposition and delivering better electrochemical performance. Fluorine doped cathodes deliver high capacity of ~300 mAh g-1 at C/10 rate, have high discharge voltage plateau (> 0.25V) and low charge voltage plateau (0.2 to 0.4V) compared to pristine LMR NMC cathodes. Beside fluorine doping, improved interfacial stability and reduce voltage decay can be achieved through both cation and anion dopings. By cation doping of Ni with Mg, voltage fade has been significantly improved due to structural stabilization. By substituting Ni2+ with Mg2+ can minimize the cation migration as it blocks the tetrahedral void through which movement of cations takes place from transitional metal layer to Li-layer. The synergistic effect of both magnesium and fluorine substitution on electrochemical performance of LMR-NMC shows excellent discharge capacity of ~300 mAhg-1 at C/20 rate and cycles well. Besides, blending with LiMnPO4 has been found a classical strategy to improve interfacial stability and voltage drop in LMR-NMC [2]. Silicon is an attractive anode material for Li-ion batteries mainly because of its very high theoretical charge capacity of 4200 mAh g-1 (Li4.4Si) and natural abundance. But Si undergoes 310% volume change during lithium insertion, causing pulverization and subsequently rapid capacity fade. To enhance the performance of Si-C anodes, nanoengineering and 3D electrode architecture of Si-C electrodes developed shows >2000 mAh g-1 capacity for the Si-C electrodes with >250 cycles. Full cells developed using LMR-NMC cathodes and Si-anodes in Li-ion coin type cells shows high open-circuit voltage of >4V and energy density of >500 Wh kg−1 (Fig.1), more than the double energy of the currently available LIBs [3]. It is believed that the study opens a new realm of possibility for the development of high energy density Li-ion batteries that could be ideal for electric vehicles. Acknowledgements This work has been supported by IIT Hyderabad and DST-SERB under project code: SB/FT/CS-147/2014. References S. Krishna Kumar, S. Ghosh, P. Ghoshal, S. K. Martha, J. Power Sources , 356, 115-123 (2017). S. Krishna Kumar, S. K. Martha, J. Electrochem. Soc. 165 (3) A463-A468 (2018).S. Krishna Kumar, S. Ghosh, S. K. Malladi, J. Nanda, S. K. Martha, ACS Omega, 3, 9598−9606 (2018). Figure 1

Preparation and Application of Li4Ti5O12 anode Material in Lithium-Ion Battery

This research is focusing on preparing the Li4Ti5O12 anode material by a spray-drying method. Normally, we use graphite carbon as an anode material. The formation of dendrites on the graphite electrode surface may cause short circuits during high-rate charging or long-term cycling, and it possibly leads to thermal runaway of the battery. So, we use the Li4Ti5O12 anode material to solve its safety problem for lithium ion battery. However, the Li4Ti5O12 anode material cannot form a SEI film on the electrode surface; the electrolyte will decompose and even generate some gases (e.g., CO2, H2, CO, etc.). Therefore, the surface of the Li4Ti5O12 anode material is coated with aluminum phosphate (AlPO4); it can prevent that the Li4Ti5O12 anode material contact with the electrolyte directly. Moreover, LiAlPO4F solid ionic conductor might be formed on the surface to improve ionic conducting properties and reduce electrolyte decomposition. Systematical investigations including crystal structure analysis, micro-Raman spectroscopy, morphology characterization, and dynamic light scattering, were carried out. The electrochemical performance on half cells (2032 type coin cells) with Li/Li4Ti5O12 (LTO) electrode was tested. Electrochemical tests of the coin cells were conducted over the voltage range of 1.0–2.5V at a current density from 0.1C to 10C. The results of characterization properties demonstrated that LTO-P25-750oC sample possesses several notable results, such as: small particle size, spherical morphology, and better ionic conductivity, etc. The specific capacities of LTO-P25-750oC batteries at 0.1, 1, 5, and 10C were found to be 167, 160, 154, and 148 mAh g-1, respectively. In order to verify the performance in practical battery applications, LiNi0.5Mn1.5O4 (LNMO) material is chosen as the cathode material and assembled into LNMO/LTO full cell for performance study. It was found that the specific capacity was 136 mAh g-1 at a charge/discharge rate of 0.1 C/0.1 C. Moreover, the specific capacity at different rates (0.2/0.2C, 0.5C/0.5C, 1C/1C, 3C/3C, 5C/5C) were 123, 111, 96, 50, and 5 mAh g-1, respectively. It was found that the specific capacity still maintains around 122 mAh g-1 when the rate returned to the charge/discharge rate of 0.2C/0.2C. In conclusion, the our as-prepared LTO anode composite show excellent rate performance, good long-term cycling performance. It might be a potential anode material for Lithium-ion battery. Keywords: Lithium titanium oxide (Li4Ti5O12), Titanium dioxide (TiO2, type P25), Spray-drying method, Lithium-ion battery (LIB), Aluminum phosphate (AlPO4)

A combined experimental approach to the study of ancient coins and its application the Venetian “sesino”

The material study of ancient coins is very often rendered particularly challenging by several factors: the presence of surface alteration products; the occasional or deliberate, e.g., forgery, changes in the composition of the base alloy; the misleading information deriving from historical and literature sources.We present herewith a multi-analytical approach to the study of ancient coins. The selected test samples are coins widely used in the Venetian Republic over a time span ranging from the second half of the 16th until the early years of the 17th century: the so-called “sesino”. The rationale of the study was to establish a model, taking into account the layered structure of the surface region of the coins, that once validated could be used for a fully non-destructive characterization of similar items. The specific interest of the results obtained from this investigation is twofold. First, the actual composition of the copper based alloy used for these specific type of Venetian coin, has been measured for the first time with direct measurements on the coin cross-section. Second, the detailed characterization of the coins provides an essential background knowledge for a fully non-destructive characterization of the same kind of coins.

Real-time Automatic Calculation of Euro Coins and Banknotes in a Cash Drawer.

A very interesting and useful complement to classical cash-registers is presented in this paper, coming up with a real-time auto-counting solution for the money inside a cash drawer. The system allows knowing not only the total amount of money but also how many coins and banknotes there are of each value. The embedded solution developed has been intended to become a low-cost solution, allowing better control over the money and helping both owners and workers in the establishments. By using this system, new utilities including automatic final balancing, instant error handling when making operations, and the lack of certain types of banknotes or coins inside the drawer or the excess of some in a certain compartment, could be implemented. Coins-counting solution is based on their weight, and small individual scales made by load cells have been integrated in each coin compartment. With respect to the banknotes, an innovative alternative based on the electrical properties of capacitors is presented. Additionally, considering the relevance of interoperability in today’s systems, a Bluetooth module has been integrated into the system, allowing for data to be accessed remotely from any smartphone, tablet or computer within the range of the module. In this work, an Android application to both control and interact with the system has also been designed.

A Single Coin Monetary Mechanism for Distributed Cooperative Interference Management

We present an example, where a distributed coordinated protocol supported by a simple monetary mechanism leads to achieving optimal information theoretic degrees of freedom gains. The considered setting is that of a linear interference network, where cooperative transmission is allowed, but at no cost in terms of the overall backhaul load. We show that a simple monetary mechanism that consists only of one coin type can enable the achievability of the optimal centralized solution. The proposed greedy distributed algorithm relies on incentivizing the users to share their resources in one channel use, in return of credit they receive for maximizing their rate gains in future channel uses. This example is the first in its class and it opens the door for constructing a unified framework for monetary mechanisms for optimal interference management and spectrum sharing. This problem carries the promise of a significant impact as blockchain techniques open the door for implementing such mechanisms in practice.

An enhanced electrochemical properties of novel tin based layered Li(Ni–Sn–Mn)O2 cathode material for rechargeable Li-ion batteries

In this work, the synthesis of newly prepared cathode material, Li(NixSnyMnz)O2, which is used as a positive electrode material and is suitable for energy storage and conversion in lithium-ion rechargeable batteries, are taken into account. Indeed the main goal is to replace the conventional cathodes such as lithium cobalt oxide, lithium manganese oxide and lithium iron phosphate in view of achieving higher capacity, long cycle life, and better environmental compatible compounds. The stoichiometric ratio of the Li(Ni0.4Sn0.3Mn0.3)O2 material exhibits better performance, after evaluating with various other ratios and it is prepared via a hydrothermal process using Teflon lined autoclave reactor vessel and followed by calcination technique. Furthermore, the prepared material is subjected to XRD, FE-SEM with EDAX, TEM analysis, and also the electrochemical test has been assessed. It includes electrochemical impedance spectroscopy and electrochemical charge-discharge studies using Li/Li(Ni0.4Sn0.3Mn0.3)O2 coin type half-cell (2032 size) at the 0.1 C rate and the voltage range between 4.3–2.5 V. From the electrochemical studies, it has been found that the first charge-discharge capacity obtained of 192 mAh g−1 and 176 mAh g−1, respectively. Thus, the battery efficiency acquired is 97% and it has been maintained after the 1st cycle with a good cyclability also without huge fading. It may be a suitable positive electrode in the half cell Li-ion rechargeable batteries.

(Keynote) Developing High Voltage Li-Ion Batteries Based on Lithium Cobalt Phosphate (LCP)

Olivine structured lithium cobalt phosphate, LiCoPO4 (LCP), is an attractive cathode material that has a theoretical energy density of 802 Wh/kg based on LCP’s 4.8 V redox potential and 167 mAh/g theoretical capacity. The investigation of this material was first reported in 2000 by Amine et al. [1] realizing a capacity of only 70 mAh/g. The low capacity was attributed to both the poor electronic conductivity of LCP and the initiation of the electrolyte salt decomposition [1]. Considerable efforts worldwide since then made on improving the utilization of LCP through the reduction of particle size, carbon blending, carbon coating and morphology improvement have led to an increase of capacity utilization to 140 mAh/g [2]. Efforts have also been made in developing compatible high voltage electrolytes [3]. However, these efforts had not resulted in a rechargeable LCP without substantial loss of capacity in limited cycles. A breakthrough in improving the cycle life of LCP against Li up to 500 times with 80% capacity retention was made by substituting part of Co by Fe, which was first reported by Allen et al. in 2011 [4]. Further substitutions by Cr and Si in Fe substituted LCP (s-LCP) with improved electrolyte improve the discharge capacity to 140 mAh, coulombic efficiency to 99.7% and cycle up to 250 times with almost no capacity fade [5]. The success in realizing the potential of this material is attributed to the success in modifying the electronic structure and stabilizing the electrochemical stability of LCP through atomic level substitutions. Good cycle life has also been demonstrated in full cells made of graphite anode and s-LCP cathode in coin cells and 1.2 Ah pouch cells [6]. This talk will present a progression of the s-LCP based Li-ion cells development and the importance of the atomic level engineering in improving the performance of the high voltage cathodes. References K. Amine, H. Yasuda, M. Yamachi, Olivine LiCoPO4 as 4.8 V Electrode Material for Lithium Batteries, Electrochem. Solid-State Lett. 2000, 3(4) 178-179.S.-M. Oh, S.-T. Myung, Y.-K. Sun, Olivine LiCoPO4–carbon composite showing high rechargeable capacity, J. Mater. Chem., 2012, 22, 14932.R. Sharabi, E. Markevich, K. Fridman, G. Gershinsky, G. Salitra, D. Aurbach, G. Semrau, M. A. Schmidt, N. Schall, C. Bruenig, Electrolyte solution for the improved cycling performance of LiCoPO4/C composite cathodes. Electrochem. Commun. 2013, 28, 20-23.J. L. Allen, T. R. Jow, J. Wolfenstine, Improved cycle life of Fe-substituted LiCoPO4, J. Power Sources, 2011, 196(20), 8656-8661.J. L. Allen, J. L. Allen, T. Thompson, S. A. Delp, J. Wolfenstine, T. R. Jow, Cr and Si Substituted-LiCo0.9Fe0.1PO4: Structure, Full and Half Li-ion Cell Performance, J. Power Sources, 2016, 327, 229-234.D. Liu, W. Zhu, C. Kim, M. Cho, A. Guerfi, S. A. Delp, J. L. Allen, T. R. Jow and K. Zaghib, High-Energy Lithium-Ion Battery Using Substituted LiCoPO4: From Coin Type to 1Ah Cell, J. Power Sources, 2018, 388, 52-56.

CNF/S Cathodes for RT Na-S Batteries in Carbonate Electrolyte: Understanding the Role of Sulfur Phase and Solid Electrolyte Interphase

Over the last few years, there is growing interest towards safe and stable room temperature sodium-sulfur batteries owing to their high theoretical capacity and energy density of ~1672 mAh/g and 1230 Wh/kg respectively based on the final discharge product of Na2S. However, these Na-S batteries exhibit poor cycling properties mainly due to severe shuttle effect. Sulfur cathodes with various nanostructured carbon have been introduced to achieve long-term cycling. However, that these advances are partially due to the use of a non-carbonate solvent-based ethereal electrolytes, and the additive NaNO3 salt, in which the solubility of polysulfides is reduced or the polysulfide shuttle is passivated. Given the high flammability of ether-based electrolytes, such systems are not practically viable. Moreover, the conversion of sulfur to Na2S/Na2S2 in these reports is unclear. In this work, we have developed free-standing carbon nanofiber/S cathodes for achieving long-term cycling in RT Na-S batteries. The as-prepared CNF/S (~1.08 mg/cm2, 43.8 wt% S) cathodes were used directly as cathodes in 2032 type coin sized RT Na-S cells. The electrochemical tests were performed in EC/PC/FEC based electrolyte against Na/Na+ anode. The cyclic voltammetry and charge discharge results showed a single potential for conversion of sulfur to Na2S. The CNF/S cathodes delivered capacity of ~1229 mAh/g during the first cycle with ~51.1% coulombic efficiency. The capacity of RT Na-S cells was stabilized at ~350 mAh/g after Ist cycle and sustained up to 300 cycles with only ~.03% decay rate per cycle. The postmortem XRD results confirmed the conversion of sulfur to Na2S and vice versa. Further, we performed in situ electrochemical impedance spectroscopy, postmortem XPS and galvanostatic intermittent titration technique (GITT) to understand the underlaying conversion mechanism. The preliminary results showed that the observed single plateau and long term cycling of RT Na-S cells were the convoluted effect of deposited sulfur and stable SEI layer on the cathode side. #RP and AS have contributed equally

A Facile Way to Synthesize Carbon-Coated LiMn0.7Fe0.3PO4/Reduced Graphene Oxide Sandwich-Structured Composite for Lithium Ion Batteries

Introduction Olivine-type LiMnPO4 which is a cathode material for lithium ion batteries exhibits a higher operating potential (4.1 V vs. Li+/Li) than LiFePO4 thus has gathered more attention in recent years. However, due to the low electron conductivity of LiMnPO4 and the Jahn-Teller effect of Mn3+, it is difficult to achieve satisfied cycle performance. Fe doping of 10-30 mol% is promising as a solution to this problem [1]. Graphene is a single atomic monolayer of graphite and has been found a variety of applications in energy conversion and storage devices, due to the excellent properties such as high carrier mobility (~10,000 cm2 V−1 s−1 at room temperature), structural flexibility, chemical and thermal stability, mechanical strength and ultrahigh theoretical specific surface area (2630 m2g−1) [2]. Previous studies have reported the improved performance of LiMPO4 (M = Fe, Mn and Co by combining with graphene. In particular, it is attractive that the active material is supported on both sides of graphene to form a sandwich structure. One is that active material particles can be highly loaded and interconnected by the highly conductive matrix formed by graphene. The other one is that the sandwich structure can be beneficial for suppressing the graphene restacking and active material particles agglomeration. It is reported that such a graphene-metal oxide nanoparticle composite material can greatly improve the performances of the anode. However, there is still lack of a facial way to obtain ideally sandwich-structured composite material for cathode [3]. We will introduce a facial and high efficient way to synthesize carbon-coated LiMn0.7Fe0.3PO4 (LMFP)/reduced graphene oxide (rGO) sandwich-structured composite for high power lithium ion batteries [4]. Results and discussion The synthesis of sheet-like carbon-coated LMFP/rGO composite material is shown in Fig. 1. First, 0.3 g of LMFP powder (without carbon coating, average particle size 200 nm), 3 mL of oxidized graphite suspension and 0.04 g of sucrose are dispersed in 100 mL of water. Thereafter, by ultrasonic treatment for 2.5 hours, the oxidized graphite gradually peels off to form graphene oxide, and at the same time, the LMFP nanoparticles are supported on the surface of the GO by interaction with the GO functional group. The dissolved sucrose is coated with GO and LMFP particles to form a polymeric coating. After lyophilization, carbon coated LMFP/rGO composite material (LMFP/rGO@C) having a sandwich structure was obtained by heat treatment at 700 degrees under a reducing atmosphere. LMFP/rGO@C, acetylene black and binder were mixed at a mass ratio of 8:1:1 and coated onto Al foil to obtain a cathode electrode. Electrochemical characteristics were evaluated by preparing a 2032 type coin cell using Li foil as the counter electrode. The electrolyte was 1 mol dm-3 LiPF6/EC-DEC (1: 2). SEM image of the synthesized LMFP/rGO@C composite material is shown in Fig. 2. It is clearly observed that all the LMFP particles are uniformly dispersed on the rGO surface at high density (50 to 100 particles mm-2), forming a sandwich structure. The total content of rGO and carbon coating is estimated to be about 7 wt% from TG. Figure 3 shows the discharge rate performance of LMFP/rGO@C and carbon coated only LMFP (LMFP@C). It was confirmed that the discharge capacity of LMFP/rGO@C is greatly improved compared with LMFP@C. This should be due to the formation of a good three-dimensional conductive network by graphene. Acknowledgement We thank Taiheiyo Cement Co., Ltd for the providing of LiMn0.7Fe0.3PO4 powders and NIMS for the TEM measurement. Reference 1) Gong, et.al., Energy Environ. Sci. 4, 3223 (2011). 2) S. Han, et.al., Small. 9 1173–1187 (2013). 3) Z.-S. Wu, et.al. Nano Energy. 1 (2012). 4) D. Ding, et.al., submitted. Figure 1

Shutdown-Enabled Electrospun Polyimide Composite Film Prepared By Novel Spin-Coating Method with Polyethylene As Separator for Rechargeable Lithium-Ion Batteries

Global demand for lithium-ion secondary batteries have been increasing due to new market growth from electric vehicles and power storage systems. Lithium-ion batteries possess high power density, energy density and long cycle life without memory effect and little self-discharge, and have been primary energy storage system for commercial electronics. However, recent accidents regarding battery safety, such as Samsung Note 7 issue, has raised doubt among public about lithium-ion batteries as option for energy storage. Separator is one of the primary component for lithium-ion battery safety. Commercial separators like PE or PP not only possess outstanding mechanical and electrochemical performance, but also have thermal shutdown function that provide safety measure by pore—blocking with melted polyolefin materials. Nevertheless, polyolefin materials suffered serious shrinkage at elevated temperature, which cause internal short-circuited of batteries ; also, polyolefin materials have relatively low electrolyte uptake, and could be major obstacle for future lithium-ion battery application. Hence it’s necessary to design new type of separator that guarantee battery safety and demonstrate better electrochemical performance In this study, we proposed a brand-new method to design composite separator with high thermal stability, electrolyte uptake ability and thermal shutdown function. Polyimide(PI) nanofiber film was used as substrate and produced by electrospinning technique, and ultra-thin Low-Density-Polyethylene(LDPE) layer was laid upon PI by simple spin-coating method. Spin-coating method provided unique advantages such as ultra thin coating layer (less than 1 micron), uniform coating structure and simple process, and was yet been applied for construction of composite film as lithium-ion battery separator. Coating parameter was tuned to obtain the optimized composite separator. Field-emission scanning electron microscope (FE-SEM) was used to investigate morphologies of separators ; Contact angle measurement was conducted to verify electrolyte affinity of different separators ; A.C. impedance method was used to measure conductivities and verify thermal shutdown of separators, and electrolyte uptake of different separators were measured by electrolyte soaking method in an argon-filled glovebox. The composite film had sub-micron average pore size, and possessed excellent physical properties, for instance, high porosity(73%), electrolyte uptake(1300%), ion conductivity(4.3*10-4 S/cm), air permeability(gurley value=0), and thermal stability(no shrink up to 150。C). Thermal shutdown function of composite film was also confirmed by impedance measurement at elevated temperature. It was noticed that physical properties between pristine PI and composite film were similar owning to ultra-thin coating layer, which mitigate performance loss from LDPE coating. Afterward, full cell battery tests were conducted with CR2032 type coin cell (Cathode : LFP, anode : MCMB, electrolyte : 1 M LiPF6 in EC/EMC/DMC=1:1:1+1%VC, 1C=2.4mAh/g). The first cycle charge-discharge curves, rate capability and cyclic performance were conducted. The composite film showed flatter first cycle charge-discharge plateau, better capacity retention at higher C-rate (Composite film :102 mAh/g at 1C, 79% retention, Celgard 2500 : 73 mAh/g, 51% retention , w.r.t. 0.1C), and higher discharge capacity at 0.5C 50th cyclic test. The higher porosity and electrolyte uptake of composite film facilitated ion conduction and were the main cause for enhanced battery performance. With enhanced thermal stability and electrochemical performance, we expected this type of composite separator to be promising for future lithium-ion battery application. Figure 1

Counter anion effects on the energy density of Ni(II)-chelated tetradentate azamacrocyclic complex cation as single redox couple for non-aqueous flow batteries

Tailoring the energy density of Ni(II)-chelated complex cation is accomplished by substituting various counter anions. Larger-sized anions are favored for increasing both the solubility and working voltage. The former advantage with larger-sized anion can be readily assumed since the binding energy is smaller to allow a higher solubility in solvents. The latter comes from the fact that Ni(II)(cyclam) complex cation in square-planar geometry shows a higher working voltage. Furthermore, the solubility of redox couple is enhanced by increasing the dielectric constant of used solvent. Consequently, the largest anion (TFSI−) demonstrates the most promising physicochemical/electrochemical properties; the energy density of redox couple reaches 27.3 W h L−1 with the working voltage, 2.55 V. The Ni(cyclam)[TFSI]2 shows very reversible electrochemistry in 1.0 M TEABF4 in EC/PC (1:1 = v/v) electrolyte and presents stable cycleability at non-flowing coin type static cell.

A new type of bi-material coin

This article presents a new type of bi-material coin with a polymer centre and a metal ring. The polymer-metal coin is fabricated by combination of coin minting and joining by forming in a single die stroke. The design of the coin is based on an analytical model built upon plasticity theory and plastic instability of circular plates under uniform radial edge compression. The analytical model and the bi-material coin concept are supported and validated by means of finite element modelling and experimentation. Destructive tests for pushing the polymer centre out of the metal ring demonstrate the effectiveness of the mechanical joint resulting from the interface contact pressure between the polymer and the metal. The new bi-material coin was developed to obtain new aesthetic effects for the collection market, and its polymer core can additionally be used for other applications such as the incorporation of advanced security features in high-denomination coins.

Electrochemical characteristics of lithium-excess cathode material (Li1+xNi0.9Co0.05Ti0.05O2) for lithium-ion batteries

A Ni0.9Co0.05Ti0.05(OH)2 precursor was synthesized with the concentration gradient method. To overcome the Li-ion shortage the problem due to the formation of a solid electrolyte interphase (SEI) layer during the initial charge/discharge process in the cathode material, lithium-excess Li1+xNi0.9Co0.05Ti0.05O2 (0≤x≤T0.07) cathode materials were investigated by physical and electrochemical analyses. The physical properties of the lithium-excess cathode materials were analyzed using FE-SEM and XRD. A coin type half-cell was fabricated with the electrolyte of 1M LiPF6 dissolved in organic solvents (EC:EMC=1: 2 vol%). The electrochemical performances were analyzed by the initial charge/discharge efficiency, cycle stability, rate performance and electrochemical impedance spectroscopy (EIS). The initial charge capacity of the cathode material was excellent at about 199.8–201.7mAh/g when the Li/Metal ratio was 1.03–1.07. Additionally, the efficiency of the 6.0 C/0.1 C was 79.2–79.9%. When the Li/Metal ratio was 1.05, the capacity retention showed the highest stability of 97.8% after 50 cycles.