bluuebunny/crossref_metadata_2025_split huggingface dataset:
Si/Mnooh Composite with Superior Lithium Storage Property
Authors: Zhan Hui , Zhong Hai , Yang Yanbo , Zhou Yunhong 
Published: February 2020

High energy/power density Li-ion batteries have been pursued since the commercialization of Graphite/LiCoO2 LiBs, among all the cathode/anode combinations, LiBs with Si anode attracts more attention due to its potential high energy density. Nowadays, silicon have triggered much efforts due to the largest theoretical capacity (Li22Si5, ~4200 mAh g-1), and relatively lower electrochemical alloy/de-alloy reaction voltage (~0.4 V vs. Li/Li+). However, the repeated large volume changes during Li insertion and extraction can lead to electrode failure. The failure mechanism is believed to involve the particle pulverization, the electric contact deterioration which will finally cause the electrode disintegration and the rapid capacity fading. Recent research also prove that the solid-electrolyte interphase (SEI) degradation is another reason for the Si anode failure. A number of strategies have been implemented to suppress the volume change and enhance or maintain the electric contact between silicon and the conductive agent. Examples typically are the Si or Si/C composite with specially designed architecture, such as silicon nanowires, silicon nanorods, porous silicon and York-shell silicon/C composite, and they present the expected capacity performance and cycling stability. However, the relatively complicated multi-step synthesis and very fluffy, insufficiently compressible product powder brings the concerns on the cost and electrode fabrication. Except the material or architecture design, binder optimization or SEI additive has also been proposed to enhance the property of Si anode, and Carboxymethylcellulose (CMC) or Alginate binder and Fluoro-ethylene carbonate (FEC) additive are now been widely used in the researches on Si anode.
Though many composites have been successfully synthesized and with good property, most of them use carbon or conductive polymer as the component with the consideration of enhancing the electrical contact or buffering the volume expansion. Here we report a new Si/MnOOH composite which shows an improved Li-ion storage performance. Hydrothermally prepared g-MnOOH was ball milled with silicon to form Si/MnOOH composite. The obtained Si/MnOOH composite exhibits an initial charge capacity of 3058 mAh g-1 with a coulombic efficiency of 78.2% at a rate of 0.1 A g-1 between 1.5 and 0.01 V. An excellent rate capability has been obtained on the composite, which shows a capacity of 1200 mAh g-1 at 12 A g-1 and 700 mAh g-1
at 20 A g-1. In addition, the Si/MnOOH composite presents a very stable cycling with more than 1000 mAh g-1 after 1500 cycles. The superior electro-activity toward lithium of the Si/MnOOH electrode should be attributed to the positive effect of γ-MnOOH on the alloying/de-alloying reaction between lithium and silicon. The results supplies a new strategy to enhance the electrochemical performance of Si anode, and the facile preparation offers a new way to obtain mass-producible Si anode material with perfect Li+ storage property.

Figure 1
About Microwave Solvothermal Synthesis of Solid Solutions LiFexMn1-xPO4/C and Their Electrochemical Properties
Authors: Handel Patricia , Stangl Christoph , God Colin , Filzwieser Monika , Uhlig Frank , Schroettner Hartmuth , Koller Stefan 
Published: February 2020

In 1997, Goodenough and coworkers (1) discovered phospho-olivines LiMPO4 (M = Fe, Mn, Ni, Co) as promising positive electrode material for rechargeable lithium-ion batteries. Due to their flat voltage profile, high theoretical capacity (170 mAh*g-1 for LiFePO4), excellent thermal stability and environmental friendliness they attracted attention for both portable devices and automotive applications. Most research activities focused on the improvement of the electrochemical performance of LiFePO4, since LiMnPO4suffers from worse lithium-ion diffusion kinetics and Jahn-Teller distortion of its crystal lattice (2).
It is believed that the formation of solid solutions (3) between LiFePO4 and LiMnPO4 (LiFexMn1-xPO4) remarkably improves the electronic conductivity. This strategy seems auspicious, since the higher potential of LiMnPO4 (4.1V vs. Li/Li+) compared to LiFePO4 (3.5V vs. Li/Li+) leads to a superior energy density of the resulting lithium-ion battery.
Therefore, we report a microwave solvothermal synthesis of phospho-olivines LiMPO4(M= Fe, Mn, Co, Ni) and mixtures thereof within 10 minutes of reaction time. It is common for increasing the electronic conductivity of phospho-olivines to use one of the following problem-solving approaches: Coating with a conducting phase (4), minimizing of the particles in size (5) and doping with positive divalent\trivalent metal ions and\or fluorine (6).
Morphology of the samples is analyzed by scanning electron microscopy (SEM) as shown in figure 1. Additionally all powders are analyzed by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDX), cyclic voltammetry (CV) and galvanostatic cycling (CC) experiments.
The occurrence of Fe and Mn in the phospho-olivine and their influence on the cell performance will be discussed (cf. figure 2). Furthermore, Mg is incorporated into the lattice and its influence on electrochemical behavior will be shown as well (cf. figure 3).

Acknowledgement

Herbert Quandt Foundation is gratefully acknowledged for funding.

References

1. A.K. Padhi, K.S. Nanjundaswamy, J.B. Goodenough, J. Electrochem. Soc., 144, 1188 (1997).
2. J. Hong, F. Wang, X. Wang, J. Graetz, J. Power Sources, 196, 3659 (2011).
3. C.-K. Back, R.-Z. Yin, Y.-S. Kim, J. Electrochem. Soc., 160, A1551 (2013).
4. H.C. Shin, W.I. Cho, H. Jang, Electrochim.
Acta, 52, 1472 (2006).
5. I. Bilecka, A. Hintennach, M. D. Rossell, D. Vie, P. Novák, M. Niederberger, J. Mater. Chem., 21, 5881 (2011).
6. Y. Huang, Y. Xu, X. Yang, Electrochim. Acta, 113, 156 (2013).

Figure 1
Effect of Liquid Phase Sintering of Composite Electrode Containing 0.44LiBO2·0.56LiF Solid Electrolyte for All-Solid-State Batteries
Authors: Lee Seokhee , Woo Sungpil , Yoon Youngsoo , Kim Dong-Joo 
Published: February 2020

All-solid-state batteries have received significant attention around the world because of high safety, reliability and energy density [1]. Over the past 20 years, all-solid-state batteries fabricated by using thin film techniques have been thoroughly investigated [2, 3]. These batteries are developed as micro-batteries because typically their total thickness is approximately 15 μm, including the protective packaging. Their specific capacities are only between 5 and 100 μAh cm-2, depending on the thickness of electrodes [4]. The main challenge facing all-solid-state batteries is to enhance the surface capacity influenced by the thickness of cathode electrode. However, many attempts to increase the electrode thickness have not been successful because micro-cracks between the components are formed due to the stress generated at the solid electrode-electrolyte interface. Strong kinetic limitations due to the low mobility of the ions and electrons in the increased electrode is also another problem. To overcome these problems, a composite electrode made of multifunctional materials can be used as cathode electrode. The composite electrode should contain the electrochemically active material and should be able to transport electrons and ions in the electrode. In this study, a 0.44LiBO2∙0.56LiF solid electrolyte was used for Li+ conduction pathway in the composite electrode because it has a low melting point (> 700 °C) [5] and is expected to act as a bonding material at the interface resulted from liquid phase sintering. The composite electrode with a strong mechanically framework was fabricated by a simple one-step spark plasma sintering (SPS) technique. The composite formulation as well as sintering parameters were determined by the electrical properties and sintering behaviors of electrode materials. The composite electrode was very dense with very few voids visible in the TEM images (Fig. 1.). The 0.44LiBO2∙0.56LiF solid electrolyte was in close contact with the active materials due to liquid phase sintering. A Li-ion conduction path was formed along the electrode particles. In order to analyze the effects of liquid phase sintering systematically, the electrochemical performance of composite electrode is discussed in detail.
References
[1] C.W. Ahn, J.J. Choi, J.H. Ryu, B.D. Hahn, J.W. Kim, W.H. Yoon, J.H. Choi, J.S. Lee, D.S. Park, J. Power Sources 272 (2014) 554-558.
[2] N.J. Dudney, Y. I. Jang, J. Power Sources, 119-121 (2003) 300-304.
[3] Y.N. Zhou, M.Z. Xue, Z.W. Fu, J. Power Sources 234 (2013) 310-332.
[4] A. Patil, V. Patil, D. W. Shin, J. W. Choi, D. S. Paik, S. J. Yoon, Mater. Res. Bull., 43 (2008) 1913-1916.
[5] K. Chen, Y. Shen, Y. Zhang, Y. Lin, C. Nan, J. Power Sources 249 (2014) 306-310.

Figure 1
Phase Field Modeling of the Li2O2 Growth in a Porous Cathode in Li-Air Batteries with Organic Electrolytes
Authors: Liang Linyun , Stan Marius , Anitescu Mihai 
Published: February 2020

The electrochemistry of the Li-air batteries is based on a reversible reaction of 2Li++2e- +O2 = Li2O2 with forward direction describing the discharge of the cell. As the discharge proceeds, the pores of air cathodes become increasingly filled with Li2O2 precipitates, which eventually blocks oxygen from diffusing to the reaction sites. Therefore, the materials and architecture of air electrode influence its performance significantly. The optimization of the cathode microstructure by changing its specific surface area, thickness, and pore size distribution is an important aspect for developing efficient batteries. Beside, different ratios of carbon and electrolyte, wettablility of electrolytes, the effective electrochemical interface, result in variable electrochemical performance. To this end, a phase field model was developed to simulate and predict the Li2O2 crystalline growth in a three-dimensional electrolyte-filled porous carbon cathode in Li-air batteries. The model is able to capture the three-phase (carbon, electrolyte, and Li2O2) morphologies and their microstructural evolutions during the cell operation. The nucleation and growth of Li2O2 on the carbon surface is observed. The effects of oxygen pressure, interfacial energies, carbon substrate properties such as pore size and its distribution, thickness and volume fraction on the cathode performance will be discussed. The model provides useful information to optimize the electrode microstructure to enhance the battery performance.

Figure 1
The Porous Carbon Matrix for High Rate Performance Lithium-Sulfur Battery
Authors: Kang Hyo-Seok , Shin Hwang Dong , Lee Dong-Ju , Sun Yang-Kook 
Published: February 2020

As the demand for sustainable, clean energy technologies increases, rechargeable lithium-ion batteries remain one of the most feasible alternatives for the future.1 However, the ability to deliver safe and high-energy density components at low cost is a major obstacles for Li-ion batteries for use in electric vehicles (EVs) and energy storage systems (ESS).2 Lithium-Sulfur batteries, one of the alternatives, has a large theoretical specific capacity of 1675 mAh g-1 and an energy density of 2600 Wh kg-1.3 Sulfur is also abundant in nature, inexpensive and eco-friendly. In spite of these benefits, Li-S cells have reached their limits due to their intrinsic characteristics. Firstly, sulfur has an insulating nature. Secondly, the resulting product, lithium polysulfide, is easily dissolved in the electrolyte, which causes active material loss. Lastly, slow kinetics occur at a lower plateau during charging-discharging processes. There are several approaches to overcome the slow kinetics and dissolution of lithium polysulfide, such as employing mesoporous carbon or a graphene oxide coating on sulfur. However, the utilization of sulfur is still a challenge due to the slow kinetics. One approach to address this issue is to limit the voltage range to reduce the formation of Li2S2 and Li2S. The lower plateau region (Li2S4 ↔ Li2S) has slow kinetics due to the phase transformation from a liquid to solid state by the Li2S growth mechanism.4 Moreover, the Li2S species that accumulate on the electrode surface may reduce the cycle life due to poor conductivity. We previously limited the voltage range of the upper plateau region (~2.1V vs Li+/Li); known as the fast kinetics region (S8 ↔ Li2S4) with a theoretical capacity of 419 mAh g-1,5 so as to hinder the formation of insoluble species (Li2S2, Li2S). Herein, we simply upgrade the structure with a porous cathode material ( activated carbon, AC) with a gas diffusion layer (GDL); this porous carbon GDL (PCG) was compared with the conventional Al foil current collector (porous carbon Al foil, PCA) through an electrochemical performance test. This unique porous structure enhanced the facile transportation of the Li-ion in the liquid state Li-S cells so that the rate capability of the Li-S cells was increased.

References

1. J. B. Goodenough, Y. Kim, Chem. Mater., 22, 587 (2010).
2. J. M, Tarascon, M. Armand, Nature, 414, 359 (2001).
3. P.G. Bruce, S. A. Freunbergeg. L. J. Hardwich, J. M. Tarascon, Nat. Mater., 11, 19 (2012)
4. X. L. Ji, K. T. Lee L. F. Nazar, Nat. Mater., 8, 500 (2009)
5. C. Barchasz, F. Molton, C. Duboc, J. -C. Leprêtre, S. Patoux, F. Alloin, Anal. Chem., 84, 3973 (2012)
Synergistic Effect of Dual-Doping of Graphene Nanosheets on the Electrochemical Performance of Lithium-Air Cells
Authors: G Kannan Aravindaraj , Kim Jae-Hong , Kim Dong-Won 
Published: February 2020

Rechargeable lithium-air battery is considered as one of the promising next-generation energy storage systems for application in electric vehicles due to its high theoretical energy density. In general, the performance of lithium-air cells in non-aqueous electrolyte is significantly affected by the large polarization in air cathode due to the deposition of discharge products as well as the ineffective electrocatalytic activity of electrode materials during oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). To address these issues, noble metals are being used as catalysts, which may increase the cost of lithium-air cells. Recently, graphene nanosheets with a two-dimensional sp2-hybridized carbon structure have been actively explored as metal-free air cathode due to their superior electronic conductivity, mechanical strength, chemical stability, high surface-to-volume ratio and structural flexibility. The edge sites and other defect sites present in the basal plane of graphene prepared by chemical method have been demonstrated as catalytic sites for ORR.1 Furthermore, doping of graphene with heteroatoms such as nitrogen, boron, sulfur and phosphorus breaks the charge neutrality of carbon atoms and acts as catalytic centers.2 In this study, we demonstrate the synergistic effect of dual-doping of graphene nanosheets on the performance of lithium-air cells. Chemical and morphological characterization of the dual-doped graphene nanosheets along with their enhanced electrochemical performance over the single-heteroatom doped graphene as metal-free air-cathode will be presented.
References
1. E. Yoo and H. Zhou, ACS Nano, 5, 3020 (2011).
2. L. Lai, J. R. Potts, D. Zhan, L. Wang, C. K. Poh, C. Tang, H. Gong, Z. Shen, J. Lin and R. S. Ruoff, Energy Environ. Sci., 5, 7936 (2012).
Conducting Polymer-Coated Carbon Nanotubes As High Rate Anode Material for Rechargeable Aqueous Electrolyte Battery
Authors: Lim Hana , Lee Min Hyung , Lee Ho-Nyun , Kim Hyun-Jong 
Published: February 2020

Among various energy storage systems, the rechargeable battery has been proposed as one of the most promising strategy for grid-scale energy storage because of flexible power and energy characteristics, high energy conversion efficiency, and low maintenance. And, their compact size makes them well suited for use at distributed location to control the output fluctuations in local power generation.
Lithium-ion batteries are being considered as one of the most promising power sources for smart grids because of their high energy density and long cycling life. However, safety and fast charging performance are still two challenging issues to be solved for their use as large-scale systems. An attractive approach to circumvent this problem is to use an aqueous electrolyte for lithium-ion batteries, which adopt a ‘rocking-chair’ concept similar to the organic lithium-ion battery. In the mid 1990s, an aqueous lithium-ion battery was proposed that uses VO2 as the anode and LiMn2O4 as the cathode. By this combination, the safety problem of the organic electrolyte is fundamentally resolved. Furthermore, since the rigorous assembly conditions are avoided, the cost is reduced greatly, compared with the non-aqueous lithium-ion battery.
In this study, polypyrrole-coated carbon nanotube(CNT) was prepared by chemical oxidation polymerization of pyrrole on the surface-functionalized carbon nanotube in the presence of FeCl3. As increasing the concentration of pyrrole, the thickness of polypyrrole layer on the surface of CNT was gradually increased.
Polypyrrole was very stable during the lithium and sodium doping/dedoping processes in the aqueous solution without evolution of hydrogen. When the polymers were dispersed on the surface of carbon, the discharge capacity was highly improved due to the enhanced surface area and decreased diffusion length. In the charging-discharging experiments, the decay of capacity was greatly decreased although the charging/discharging rate was increased to 10C. The conducting polymer-coated CNT showed very promising charge-discharge characteristics at high-rate region in the aqueous sodium electrolyte.
Synthesis, Tailoring and Characterization of V2O5-Cathodes for High Performance Li+-, Na+- and Mg2+-Ion Batteries
Authors: Seidl Lukas , Ma Jiwei , Martens Sladjana , Mostafa Ehab , Schneider Oliver , Stimming Ulrich , Si Huinan , Qiu Xinping 
Published: February 2020

Battery technology based electric energy storage devices are inevitable on the way to electromobility and the widespread application of renewable energies like wind- or solar-power.1 Until now, Li+-ion batteries represent the state of art technology meeting best the demands of high energy- and power-densities. However issues related to high costs and safety still require improvement. 2,3 One strategy to tackle those issues is to replace the costly Li-metal by other, more abundant metals, such as Na or Mg.4 Due to the different ionic, electronic and chemical properties of Li+-, Na+- and Mg2+-ions, not every Li+-ion host material is suitable for the other ions. One exception is V2O5, which recently was successfully used as high voltage cathode for Na+- and Mg2+-ion intercalation.5,6

Similar to the research on Li-ion battery electrode materials, where people pursue the strategy of electrode nanostructuring in order to increase the rate capability and hence the power density, a wide variety of synthesis techniques was applied to obtain nano-V2O5, including top-down and bottom-up techniques.7 In this work, V2O5-nanofibres were synthesized by ultrasonication and electrochemical deposition. Anodization of vanadium metal yielded V2O5-nanotubes, while hydrothermal synthesis results in hollow V2O5-nanospheres. In order to characterize and specify the different electrode morphologies and performances, electrochemical, spectroscopic and microscopic techniques were applied (see Figure 1). In addition, fundamental studies on V2O5 and its interaction with Li+-, Na+- and Mg2+-ions were conducted making use of Scanning Tunneling Microscopy (STM) and the Electrochemical Quartz Crystal Microbalance technique (EQCM).

Figure 1. SEM images of (a) hollow V2O5-nanospheres, (b) electrodeposited V2O5 and (c) ultrasonicated V2O5

1B. Dunn, H. Kamath, J.-M. Tarascon, Science, 334 (2011) 928

2M. Armand, J.-M. Tarascon, Nature, 451 (2008) 652

3J. B. Goodenough, J. Solid State Electrochem., 16 (2012) 2019

4J. O. Besenhard, M. Winter, ChemPhysChem, 3 (2002) 155

5G. Gershinsky, H. D. Yoo, Y. Gofer, D. Aurbach, Langmuir, 29 (2013) 10964

6D. W. Su, S. X. Dou, G. X. Wang, J. Mater. Chem., 2 (2014) 11185

7A. S. Arico, P.Bruce, B. Scrosati, J.-M. Tarascon, W. van Schalkwijk, Nature, 4 (2005) 366

Figure 1
Comparative Study on Active Material in Solid and Liquid Form for Li-S Battery
Authors: Sawas Abdulrazzag , Ganguli Babu , Arava Leela mohana reddy , Bentley Jaron 
Published: February 2020

Li-ion battery materials use intercalation chemistry that imposes limitations on the energy density that can be stored. Alternatively, chemistries labelled beyond lithium ion batteries such as lithium/sulfur (Li/S) and Li-air batteries have gained paramount importance. In particular, Li-S systems have attracted widely due to their high theoretical capacity of 1675 mAh/g of sulfur cathode, and low cost. However, Li-S batteries have complications such as (i) the low active material utilization due to the insulating nature of sulfur and its intermediate byproducts, (ii) dissolution of intermediate lithium polysulfides (LiPS) in the electrolyte and thereby deposition on to the Li anode, and (iii) large volume changes between S and Li2S (end product) upon complete discharge. Current research efforts to address these issues can be broadly classified into two types; one being loading maximum amount of active solid sulfur into conducting carbon matrix and other being liquid cathode known as catholyte (such as Li2S8) as a starting material. It is believed that both Li-S battery configurations eventually morph itself into a liquid electrochemical cell due to the formation of intermediate polysulfides at the very beginning of the discharge step. However, the systematic comparison of electrochemical performance of these two configurations for a fixed electrode morphology is missing. In order to understand the effect of nature of cathode material (solid vs liquid) on electrochemical properties, we have carried out systematic study on solid sulfur and dissolved lithium polysulfide in electrolyte (0.6 M Li2S8) as an active component for a Li-S cell containing carbon paper as cathode/current collector in an electrolyte containing 1M solution of LiTFSI in tetraethylene glycol dimethyle ether (TEGDME). Coin cells were fabricated and tested for cyclic voltammograms (CV) in the potential range 1.5 ~3.0 V with different scan rates from 0.2 to 1.0 mV s-1 and impedance (EIS) studies from 100 KHz to 200 mHz. Charge- discharge studies at different current rates (0.2 and 0.5 C rate) were carried out in the potential range of 1.5 ~ 3.0 V. Cyclic stability and discharge capacity values for both configurations were compared by keeping all other parameters content.