bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tuning the Polysulfides Chemistry in Li-S Batteries Via Electrolyte Salt Selection
Authors: Chen Junzheng , Han Keesung , Henderson Wesley A , Vijayakumar Murugesan , Lau Kah Chun , Dzwiniel Trevor L , Pan Huilin , Curtiss Larry A , Xiao Jie , Mueller Karl T , Shao Yuyan , Liu Jun 
Published: February 2020

Fast capacity fading due to polysulfide dissolution is a significant challenge for Li-S batteries. Porous carbon is widely studied for physically trapping polysulfide species. Here, we report a different chemical approach through suppressing polysulide dissolution using lithium 2-trifluoromethyl-4,5-dicyanoimidazole (LiTDI) as a supporting salt in electrolytes. The electrolyte to sulfur ratio(E/S) is carefully controlled and the results show that under the optimized E/S ratio the cycling stability of the lithium sulfur cell is improved in the LiTDI supported electrolyte. The Combined experimental and simulation results reveal the dissolution mechanism of lithium polysulfides and suggest that the dominating disproportionation product of Li2S8 is Li2S4 in the LiTDI electrolyte due to a coordination between Li+ and TDI anion, rather than separated Li2S3 and Li2S5 as in the LiTFSI electrolyte. The Li2S4 would continuously form a Li4S8 dimer and precipitate out. Detailed DFT calculation and Li NMR results suggest lithium ion cation has a higher solvation level in the TDI based electrolyte. Furthermore, the Li-S cells with LiTDI based electrolyte with optimized sulfur to electrolyte ratio was firstly applied into a high loading cathode and achieve a stable cycling. The use of the electrolyte with the LiTDI salt (with polysulfide and LiNO3 additives) enables a cell with a high sulfur loading (3 mg-S cm-2) to deliver a 1.67 mAh cm-2 areal capacity after 300 stable cycles at a high current (2.4 mA cm-2) density. The fading of Li metal anode is also suppressed.

Figure 1 Capacity retention of cells with (a) 1M LiTFSI and (b) 1M LiTDI in DOL/DME electrolytes (no additives) with different sulfur to electrolyte (S/E) ratios at a C/5 rate. 1C = 1675 mA g-1 of S and the cathode was prepared with 64 wt% S (i.e., S8), 16 wt% MWCNTs, 10 wt% Super P carbon additive and 10 wt% PVDF binder.

Figure 1
Effects of Cell Construction Parameters on the Performance of Lithium-Air (Li-O2) Batteries
Authors: Lee Jung-In , Song Min-Kyu 
Published: February 2020

Lithium ion batteries (LIB) are widely used in small portable devices and still represent one of the best options available for large-scale power sources such as electric vehicles (EVs) and renewable energy storage systems (ESS). The low theoretical specific energy (~400 Wh Kg-1) of current LIB is insufficient for emerging technologies, thus many researchers have investigated novel battery systems with high specific energy to replace current LIB. Among various candidates, lithium-air (Li-O2) batteries have received much attention due to the very high theoretical specific energy (~3500 Wh kg-1, Li2O2), abundant oxygen source and simple reaction chemistry (2Li+ O2 + 2e- à Li2O2, Eo = 2.96V vs. Li/Li+). Although the advantages of Li-O2 batteries are attractive, the practical adoption of Li-O2 batteries has been restricted by a large irreversible capacity, poor cycle retention characteristics, and low energy efficiency due to the large hysteresis of charge/discharge and side reactions between battery components.
Here, we report our recent findings in exploration of new electrolytes and oxygen cathodes in order to develop Li-Air batteries with sustainable, high-energy density. We investigated the performance of Li-O2 batteries using various porous carbon materials, electrolytes based on both organic and ionic liquids, and additives such as redox mediators. Various carbon substrates (such as Super-P, CNT, graphene and Ketjen black, Figure 1) were used to construct a porous cathode structure. It appears that their electrochemical properties (relevant to Li-Air batteries) are different due to their dissimilar morphology and surface area. We also conducted experiments with various electrolytes including some additives (LiNO3, LiI, etc.) as shown in Figure 2. Ionic liquids are promising electrolytes owing to relatively high electrochemical and chemical stabilities, along with safety benefits and environmental friendliness. Recently, the use of redox mediators has been identified as a promising route for reducing the overpotentials of the charge process. Based on these studies, we also investigated the effects (nature and concentration) of solvents (ionic liquids, ethers, and their mixtures) and redox mediators in electrolytes on the charging potential and reversibility of oxygen cathodes. Furthermore, we have used different porous carbon fiber papers as both a current collector and gas diffusion media. It appears that the physical oxygen diffusion property is closely linked to the capacity and cycling performance of Li-Air batteries due to the different sizes and connectivity of pores in different gas diffusion media. Electrochemical characterization techniques were combined with microanalysis (SEM, XRD) to optimize the electrode structures and performance. It is hoped that this study will provide some useful insights to the design criteria for high-performance Li-Air batteries.

Figure 1
Flexible Fibrous Substrates for Li-S Battery Cathodes
Authors: Musameh Mustafa , Chew Narelle , Truong Yen , Barghamadi Marzi , Ruether Thomas , Bhatt Anand , Hollenkamp Anthony F. , Best Adam Samuel , Kyratzis Illias Louis 
Published: February 2020

Electrically and non-electrically conductive fibrous substrates have been investigated for the preparation of S cathodes. For nonconductive substrates such as wool and glass membranes, cathodes were prepared by spraying a mixture containing sulfur, carbon black and a polymer such as polyacrylic acid or PVDF. The preparation process is fast and well suited for large scale production of large cathodes with uniform coating and good adhesion. High sulfur loading of 55% or higher was possible by using this process. Cathodes prepared by spraying were assembled into 2032 coin cells with a Li anode, Solupor separator and an ionic liquid based electrolyte. Cycling of cells at the C/10 rate showed high initial discharge capacities, close to 1500 mAh g-1, with good stability.
Sulfur cathodes were also prepared by electropolymerisation with electrically conductive substrates such as carbon fibre cloth and fine stainless steel mesh. For electropolymerisation, a solution containing sulfur, carbon black, Nafion, pyrrole monomer and a dopant like sulfate is prepared. Cathodes were readily prepared by applying a potential for a certain period of time while mixing the solution. The loading of sulfur can reach up to 30% based on the amount of sulfur in the starting solution. The prepared cathodes showed high initial discharge capacities of 1500 mAh/g along with a coulombic efficiency of 97%.
The use of such fibrous substrates adds another dimension to sulfur cathode technology by providing more control over the content and nature of active functional groups, surface porosity, and morphology. Each of these factors can be employed to counter the problem of polysulfide shuttling by enhancing the retention of sulfur reduction products within the cathode. In addition substrates which are electrically non-conductive can act both as a cathode and separator at the same time, without the need for an additional physical separator, by simple re-arrangement of the cell’s active components.
Research on Cell Chemistry of Sodium-Oxygen Battery for Improved Electrochemical Performance
Authors: Zhao Ning , Guo Xiangxin 
Published: February 2020

Developing sodium-oxygen (Na-O2) batteries with high energy efficiency depends on identifying stable solvents resistant to decomposition. Here, we focus on the solvent stability against Hydrogen-abstraction by superoxide radicals during discharge. Using a detailed quantitative analysis, we show that the solvent’s resistance to H-abstraction is determined by its acid dissociation constant, pKa. The ether (TEGDME)-based electrolyte with a larger pK
a value (i.e. 46-52) leads to form a much larger percentage of NaO2 among the discharge products than the carbonate (EC/PC with pK
a of 20.9) and the ionic liquid (PP13TFSI with pK
a of 30.0)-based ones. It is indicated that the larger value of pK
a corresponds to the better electrolyte stability, beneficial to high round-trip efficiency of the Na-O2 battery.
Based on these results, the cyclability and rate-capability of Na-O2 batteries with TEGDME-based electrolyte have been optimized under various operation conditions. Under static O2/Ar atmosphere, they exhibit high energy storage (i.e. capacity of 4200 mAh g-1 at 0.1 mA cm-2), excellent cyclability (i.e. the batteries cycle 130 times with 750 mAh g-1 depth of discharge at 0.1 mA cm-2) and good rate performance (i.e. ~1500 mAh g-1 at 1.0 mA cm-2 with pre-deposition of a NaO2 nucleus layer). Such high performance indicates the importance of stable electrolyte and operating condition for high performance Na-O2 batteries. Further, the fundamental issues associated with the phase transformation from NaO2 to Na2O2·2H2O will be discussed in this presentation.
Improved Electrochemical Performance By Templating Carbon-Sulfur Composite Electrodes for Lithium-Sulfur Batteries
Authors: Robledo Carla Belen , Cámara Osvaldo Raúl , Thomas Jorge , Leiva Ezequiel Pedro Marcos , Harks Peter-Paul , Mulder Fokko M. , Visintin Arnaldo 
Published: February 2020

Replacing fossil energy sources by renewable and clean energies is of large importance for decades to come. The mainly electric and intermittent renewables energies require proper electricity storage systems that must be: clean, economical, efficient, long life, safe and have high specific capacities (mass and volume). For Argentina, with its significant reserves of lithium in the north west of the country, developments on lithium-ion battery technology are of paramount importance. Current research in Argentina is carried out to improve future lithium battery prospects. Focus is on development and characterization of new active materials for Li-ion battery electrodes, and on systems beyond Li-ion. Li-S batteries are promising candidates to replace current Li-ion technology. In the case of C-S composite cathodes, there are several factors regarding the composition and structure that affect the performance of the battery. Nonetheless, little is known on how the architecture of the composite electrode influences the electrochemical performance of the battery. The present work consists of a systematic investigation of the influence of two very important factors regarding composite electrode fabrication and cell assembly. The factors that are considered are the electrode architecture, modified by templating, and the electrolyte to sulfur ratio. A full factorial two-by-three experimental design is employed, considering five response variables: the initial and final specific capacity of the sulfur cathode, the specific capacity loss per cycle, as well as the initial and final cell energy density. All battery cells are tested for 100 cycles galvanostatically with a C/10 current. Statistically significant factors and their interactions are identified.
New Procedures to Improve Tap Density of Li-Rich Layered Cathode Materials for Li-Ion Batteries
Authors: Zhang Lianqi 
Published: February 2020

A significant drawback for Li-rich layered materials is the low tap and compaction density in contrast to layered LiMO2[1]. Thus, improving tap density is an important issue for Li-rich layered materials. In our work, some efforts are contributed to addressing the issue. On one hand, a new pre-heat treatment procedure of carbonate precursors firstly using N2 and then O2 is adopted to separate processes of CO2 emission and O2 absorption, which presumably can reduce porosity of materials and then result in an improved tap density. The remarkably improved tap density of metal oxide (2.20 g cm–1) and cathode material (2.20 g cm–1) is observed with the procedure. However, it is at a cost of capacity. On the other hand, the dual chelating agents, ammonia and oxalate, which have a synergistic action on chelating transition-metal ion, are successfully introduced to prepare high tap density hydroxide precursors (1.67 g cm–3) and Li-rich cathode (2.28 g cm–3) with atomic level uniformity of elemental distribution.
From Fig.1 (b) and (c), it is obviously found that the two-steps procedure is indeed beneficial for obtaining the dense morphology with less pores, resulting in a higher tap density. From Fig.2, with the function of the dual chelating agents, the spherical secondary particles with dense morphology, which are closely aggregated from nano-sized primary particles, are demonstrated to be obtained.

References

[1] P.Oh, S. Myeong, W. Cho, M.-J. Lee, M. Ko, H.Y. Jeong, J. Cho, Nano Lett. 14 (2014) 5965−5972.

Figure 1
Development of New Synthesis Process of LiFePO4/C Composite
Authors: Aziam Hasna , Larzek Mohamed , Bilal Essaid , Solhy Abderrahim , Saadoune Ismael 
Published: February 2020

Abstract:

At the present time, our way of life has become completely dependent on energy. In order to solve the depletion of fossil fuels, an energy transition towards renewable energies such as solar energy, wind power, hydropower, geothermal power, bio energy, heat pump became inevitable. The development of such renewable but intermittent energy requires the development of energy storage solutions.
Lithium ion (Li-ion) batteries had gained a lot of attention for powering portable electronic devices owing to its combination of high power and energy density, long cycle and stability.
Current Li-ion battery technology consists of LiCoO2 and graphite as the cathode and anode materials, respectively. Nevertheless, LiCoO2 has a limited abundance in nature, toxic and very expensive. Its main drawback indeed is thermal instability leading to many safety issues. For this reason, LiFePO4 was presented as a potential candidate to replace LiCoO2, especially in the stationary applications
LiFePO4 was first reported as positive electrode material for rechargeable Lithium batteries by Goodenough et al. in 1997. It shows a high theoretical capacity (170 mAh g-1), a high discharge potential (3.45 V Vs Li+/ Li), an excellent thermal stability, a low cost and it is environmentally friendly. Nevertheless, it has a poor ion diffusion coefficient (10-14 cm2 s-1) and low electrical conductivity (10-9 S cm-1). Carbon coating, reducing the particle sizes and doping with the conductive elements were the solutions suggested to overcome these drawbacks.
This study aims to develop a scalable synthesis process of LiFePO4/ C composite starting from H3PO4 produced by OCP group. The electrochemical performances of various samples prepared by varying many synthesis parameters will be presented in this conference.

Keywords: Li-ion batteries, LiFePO4, H3PO4, carbon coating.

Acknowledgement:

The financial assistance of the office Chérifien des Phosphates in the Moroccan Kingdom (OCP group): The authors are hereby acknowledged. Ms H. Aziam is grateful to Mohammed VI Polytechnic University for the scholarship.

References:

Tarascon, J.M., Armand, M., (2001) Issues and challenges facing rechargeable lithium batteries, Nature, 414 (6861), 359.
Goodenough, J. B, kim, Y., (2009) Challenges for Rechargeable Li Batteries, chem. Mate. 22 (3) 587.
Ohzuku, T., Brodd, R. J., (2007) An overview of positive-electrode materials for advanced lithium-ion batteries, Journal of power sources, 174, 449-456.
Padhi, A.K., Nanjundaswamy, K.S., and Goodenough, J.B., (1997) Phospho‐olivines as Positive Electrode Materials for Rechargeable Lithium Batteries, J. Electrochem. Soc. , Vol. 144, No. 4.
Fergus, J. W., (2010) Recent developments in cathode materials for lithium ion batteries, Journal of power sources, 195, 944-945.
Application of Atomic Layer Deposition to Lithium-Oxygen Batteries
Authors: Park Da-Hee , Choi Yoo-Jin , Seo Ki-Won , Lee Jon-Won , Park Min-Sik , Kim Ki Jae , Hwang Jinha 
Published: February 2020

Rechargeable lithium-oxygen (or lithium-air) batteries have been recognized as next-generation batteries which can replace the prevailing lithium-ion batteries. The non-aqueous Li-O2 batteries involve carbon materials as cathode materials due to their natural abundance and high surface areas per weight. However, the exposure of carbon to air and Li2O2 deteriorates the stability of cathodes, in association with the subsequent electrolyte decomposition, leading to the low round-trip efficiency and poor cycle performance. The atomic layer deposition (ALD) of oxide materials possesses several unique features: self-limiting surface reactions and atomic-scale deposition, and conformal deposition. Such features can be applied to control artificially the deposition morphology on the underlying carbon cathodes, which affects the performance of Li-O2 batteries. In order to improve the well-known issue present in the Li-O2 (Li-air) batteries, the ALD of oxide materials was combined with the carbon materials with the aim to controlling the cathode degradation issues. The current work reports zinc oxide and aluminum oxide as coating materials deposited onto carbon cathode materials, i.e. carbon nanotubes (CNTs): zinc oxide (ZnO) shows a semiconducting property, while aluminum oxide (Al2O3) exhibits an insulating property. The ALD-coated ZnO and Al2O3 onto the carbon electrodes are characterized using analytical electron microscopy. The implications of ALD-based ZnO and Al2O3 are discussed in terms of the performance of Li-O2 secondary batteries in connection with the underlying microstructure and chemistry.
Ni-Sn-Si/C Based Composite As Negative Electrode for Li-Ion Batteries
Authors: Bibent Nicolas , Lippens Pierre-Emmanuel , Olivier-Fourcade Josette , Jumas Jean-Claude , Azib Tahar , Cuevas Fermin , Latroche Michel 
Published: February 2020

New electrode materials and battery design are required to improve the electrochemical performances of Li-ion batteries. Some metals like Al, Si or Sn can form alloys with Li by reversible electrochemical reactions and can be used as negative electrodes of high specific capacities (600 - 4000 Ah/kg) for high density Li-ion batteries. However, alloying reactions cause large volume variations resulting in the loss of electronic percolation and SEI instability at the origin of the usually observed poor cycle life of such materials. Different approaches were considered to overcome these problems based, for example, on the nanostructuration of the active material, the dispersion of the particles and the use of intermetallics or composites [1]. Recently, we have proposed a family of new composite materials formed by Si nanoparticles dispersed within a tin based intermetallic matrix Ni3Sn4 that exhibits high specific capacity and coulombic efficiency [2]. In order to improve the performances and reduce the cost of such composites, we propose now a new material with a lower tin content with the overall composition Ni0.15Sn0.14Si0.26Al0.04C0.41.
In this communication, the synthesis method, the material characterization and the electrochemical performances are presented. We show that the composite is formed by Si nanoparticles embedded in a matrix composed of Ni3Sn2 and Ni3Sn4 particles (Figure 1). The specific capacity after 200 cycles is of about 500 Ah/kg (Figure 2), which is surprisingly close to that obtained by the Ni3Sn4 based composite. To understand this results, X-ray diffraction and 119Sn Mössbauer spectroscopy were combined to explore in situthe reaction mechanisms that reveal the electrochemical activities of the different components of the composite.

Figure 1 SEM image of Si/Ni3Sn2-Ni3Sn4/Al/C composite as negative electrode for Li-ion batteries.

Figure 2 Specific capacity and coulombic efficiency vs. cycle number for the Si/Ni3Sn2-Ni3Sn4/Al/C composite at C/10 galvanostatic regime

References

(1) D. Larcher, S. Beattie, M. Morcrette, K. Edström, J.C. Jumas, J.M. Tarascon, J. Mater. Chem
. 17 (2007) 3759.
(2) Z. Edfouf, F. Cuevas, M. Latroche, C. Georges, C. Jordy, T. Hézèque, G. Caillon, J. C. Jumas, M.T.Sougrati, J. Power Sources, 196 (2011) 4762.

Acknowledgments

The authors would like to thank the French National Research Agency for the funding of the project NEWMASTE under the grant N°ANR-13-PRGE-0010.

Figure 1
Structural Influence of Magnetron-Sputtered Silicon-Carbon Thin Films on the Anode Performance in Lithium-Ion Batteries
Authors: Reyes Jiménez Antonia , Winter Martin , Placke Tobias 
Published: February 2020

The next generation of lithium-ion batteries (LIBs) for the application in miniaturized electronic devices and traction batteries need further development of new active materials with higher specific capacities to increase the resulting energy and power of the battery cells. In particular, new anode materials with high specific capacities and improved cycling performance are of great interest.[1]
Since silicon provides a very high gravimetric and volumetric capacity, a low operation potential and low costs, it is widely regarded as the most promising anode material in LIBs for the future.[1] However, major issues arise from its poor capacity retention due to mechanical degradation caused by the large volume expansion during lithium insertion/extraction. In recent years, several attempts have been undertaken to overcome this problem.[2] Compared to bulk silicon anodes, which contain at least 10 wt.% of inactive binders and conductive additives, silicon thin film anodes contain no inactive materials, giving an increased specific capacity.[3]
In this work, silicon-carbon thin films have been prepared by magnetron sputtering. The silicon-carbon thin films have been prepared by alternatively sputtering layers of silicon and carbon (layered structure of silicon and carbon) or by co-sputtering silicon and carbon (mixed silicon-carbon layers). The characterization of the electrodes was performed by focused ion beam-scanning electron microscopy (FIB-SEM), Raman spectroscopy and electrochemical impedance spectroscopy. Furthermore, the influence of the carbon content and layered/non-layered silicon-carbon structure was thoroughly investigated in cycling experiments compared to the bare thin film silicon electrodes.
Literature:
[1] R. Wagner, N. Preschitschek, S. Passerini, J. Leker, M. Winter, J Appl Electrochem. 43 (2013) 481-496.
[2] M.N. Obrovac, L.J. Krause, J Electrochem Soc. 154 (2007) A103-A108.
[3] U. Kasavajjula, C. Wang, A.J. Appleby, J Power Sources, 163 (2007) 1003-1039.
Hierarchical Porous Anatase TiO2 Derived from a Titanium Metal-Organic Framework As Superior Anode Materials for Lithium Ion Batteries
Authors: Xiu Zhiliang , Kim Dongyun , Alfaruqi Muhammad Hilmy , Song Jinju , Kim Sungjin , Kim Jaekook 
Published: February 2020

Hierarchical meso-/macroporous anatase TiO2 (HPT) was synthesized from the hydrolysis of a titanium metal-organic framework precursor followed by calcination in air. The HPT possesses bimodal and hierarchical porosity: mesopores with pore diameters of 12, 16 and 28 nm along with macropores with pore diameters of up to 185 nm.This unique porous feature enables the superior rate capability and excellent cycling stability of anatase TiO2 as an anode for rechargeable lithium-ion batteries(LIBs). At a rate of 5 C, the specific discharge capacity of the HPT electrode is about 155 mA h g-1. After 200 cycles at 5 C charging/discharging rates, the capacity loss was only ~6.5 %. The superior rate capability and excellent cycling stability make HPT a promising anode material for fast rechargeable LIBs.

Figure 1