bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Influence of Carbon Cathode in Rechargeable Li-O2 Batteries Based on a LiNO3-Litfsi/DMSO Electrolytes
Authors: Yoo Eunjoo , Zhou Haoshen 
Published: February 2020

Rechargeable Li-O2 batteries have been considered one of the most promising candidates as the power source for electric vehicles due to their extremely high energy density [1,2]. In spite of this great prospect, there are still many obstacles such as the degradation of the electrode, huge polarization, low energy efficiency and poor reversibility [3]. Thus, developing stable and effective cathode catalysts is important as they can be utilized to decrease the polarization and increase the reversibility. Carbon materials are known to advantageous air electrodes for Li-O2 batteries with nonaqueous electrolyte due to their good conductivity and site of reversible electrode reaction. However, the influence of carbon materials on electrochemical performance in Li-O2 batteries is not clear. Furthermore, recent research focused on selecting a combination of lithium salt and electrolytes by challenge in improving the electrochemical performance of Li-O2 batteries. In this study, we select four different kinds of carbon materials such as multi-walled carbon nanotubes (MWCNTs), CMK-3, Graphene nanosheets (GNSs), and KB as air electrodes and further examine their electrochemical performance in Li-O2 batteries with 0.7 M LiNO3-0.3 M LiTFSI/DMSO electrolytes.
We find that the Li-O2 cell with a MWCNTs electrode in a 0.7 M LiNO3-0.3 M LiTFSI/ DMSO electrolyte demonstrates good rate performance and cycle stability comparison with other carbon electrodes. The result shows that the Li-O2 cell based on MWCNTs electrodes with a cut-off capacity of 1000 mAg-1 at 500 mAg-1 can undergo around 90 cycles without obvious capacity loss. Even when the discharge depth is increased to 2000 mAhg-1, stable cycling is maintained for 45 cycles with a charge potential below 4.0 V vs. Li/Li+. Moreover, when the rate performance of Li-O2 cell with MWCNTs electrodes is examined at different current densities from 200, 400, 500, and 1000 mAg-1 with a cut-off capacity of 2000 mAhg-1, interestingly, the discharge voltage is not drastically increased even the current density is 1000 mAg-1. And then, the chare voltage remains at around 3.85 V, which is similar to the current density of 200 mAg-1 (about 3.82 V). Therefore, these results demonstrate that the MWCNTs maintain excellent activity and stability of catalysts toward the reversible formation-decomposition of Li2O2.
Reference
[1] P. G. Bruce, S. A. Freunberger, L. J. Hardwick, J. M. Tarascon, Nat. Mater. 2012, 11, 172– 172
[2] J. Lu, L. Li, J.-B. Park, Y.-K. Sun, F. Wu, K. Amine, Chem. Rev. 2014, 114, 5611 –
5640.
[3] L. Grande, E. Paillard, J. Hassoun, J.-B. Park, Y.-J. Lee, Y.-K. Sun, S. Passerini,
On the Ambiguous Nature of the Discharge Products in Sodium-Oxygen Batteries: From Theoretical Considerations to Operando XRD Analyses
Authors: Pinedo Ricardo , Bender Conrad L. , Schröder Daniel , Bergner Benjamin J. , Weber Dominik , Adelhelm Philipp , Janek Jürgen 
Published: February 2020

Rechargeable lithium-oxygen and sodium-oxygen cells are considered as promising systems for next-generation batteries, both scientifically and technologically [1,2]. While the desired cell reaction is clear in the case of non-aqueous Li/O2 batteries (Li2O2 formation), the situation is much less clear in the case of non-aqueous Na/O2 cells. Two discharge products, with almost equal free enthalpy of formation but different number of transferred electrons and completely different kinetics, appear to compete, i.e. sodium superoxide (NaO2, one-electron-transfer) and sodium peroxide (Na2O2, two-electron-transfer) [3]. In spite of the several fundamental studies published until now, the experimental control parameters for the exclusive formation of one or the other phase during discharge are still unknown.
Moreover, under certain conditions, dihydrated sodium peroxide has also been found. The formation of this product has been ascribed to undesired reactions, such as electrolyte degradation [4], which could provide the required water source. However, this hypothesis is not consistent with the results of the group of Nazar, who reported that Na-O2 cells cannot be discharged in absence of water, which acts as a proton source [5]. Consequently, if the proton source could be supplied by the electrolyte, Na-O2 cells with 0 ppm water could be also discharged.
This work tries to summarize and answer the major questions that propel research on Na/O2 cells at the moment. For this purpose, theoretical and thermodynamic considerations, together with operando XRD analyses are presented. In addition, the implications on the electrochemical performance of the different discharged products are also evaluated, shedding some light on the chemistry of these promising systems. Nevertheless, many questions remain open, and their precise answer will help to improve the understanding of further non-aqueous metal-oxygen systems and to propel the research efforts on their cell chemistry.

References

[1]. P. Hartmann et al., Nat. Mat.
2013, 12, 228-232.
[2]. B. Bergner et al. J. Am. Chem. Soc.
2014, 136, 15054-15064.
[3]. C.L Bender et al., Angew. Chem. Int. Ed.
2016, (accepted).
[4]. J. Kim et al. Phys. Chem. Chem. Phys.
2013, 15, 3623-3629.
[5]. C. Xia et al. Nat. Chem.
2015, 7, 496-501.
High Electrochemical Performance of Hirechically Porous MnCo2O4 Microsphere As an Anode Material for Li-Ion Batteries
Authors: Thorat Gaurav M. , Jadhav Harsharaj S. , Seo Jeong Gil 
Published: February 2020

Alternative active anode materials for graphite and its electrode designs for lithium ion batteries (LIBs) are under extensive investigation to meet the increasing energy storage demands. The rational design of three-dimensional (3D) hierarchical pore architectures of metal oxides and related hybrids possessing are advantageous to improved electrical conductivity and reduced volume change during charge–discharge processes. Manganese cobaltate (MnCo2O4) is considered as one of the most prospective anode material in LIBs due to its high reversible capacity and structural stability. In this work, hierarchically porous MnCo2O4 microspheres are synthesized via facile hydrothermal and chemical bath deposition methods followed by post –annealing treatment. FE-SEM and TEM analysis reveal that resulting microspheres consists of a smaller secondary nano-particles. Benefited from such mesoporous structure with much higher specific surface area, the LIBs assembled with MnCo2O4 microspheres as anodes material showed high specific capacity and excellent rate capability with superior cycle life. Such excellent electrochemical performance may originate from the reduced particle size and more active interfacial sites in the hierarchical structure. Also, the large volume variation of the anode material by the redox reactions occurs during Li+ insertion- extraction process can be effectively buffered due to the appropriate pore size of MnCo2O4 microspheres and as consequences the microsphere structure has become structurally robust which is important for enhanced electrochemical stability of anode material. As obtained results indicate that MnCo2O4 is a finer material for Li storage and with the simplicity in synthesis route its mass-production can be easily achievable which makes MnCo2O4 as competent anode material for LIBs. The overall synthesis strategy in this work is simple, cost effective and inspires for the rational design of hierarchical porous structures with enhanced properties for other spinel transition metal oxide on the nanoscale, where these spinel structures may present potential applications in the field of energy storage. This work was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education (Grant number: NRF-2013R1A1A2060638 and No. 2009-0093816).
The Synthesis of Micrometer-Sized Spherical Li4Ti5O12/Reduced Graphene Oxide for High-Performance Lithium Ion Batteries
Authors: Kim Myeong-Seong , Lee Geon-Woo , Kim Kwang-Bum 
Published: February 2020

With the expanding the market of lithium-ion battery (LIBs) from portable electronic devices to electric vehicles and energy storage system (EES), the improvement on their energy density, power density, safety, and cost should be highly necessary. Among the promising anoode materials for LIB, Li4Ti5O12 has various advantages, such as high theoretical capacity (175 mAh g-1), good Li-ion intercalation reversibility, and extremely small structural changes during charge–discharge cycling.
Despite these advantages, Li4Ti5O12 is limited for use of LIBs due to its low electronic conductivity (10-13 S cm-1), which leads to poor rate capabiltiy.1 Several effective ways to improve the rate capability of Li4Ti5O12 have been reported, including reduction of the particle size to the nanoscale, doping Li, Ti, or O sites with small amounts of metal or nonmetal ions, surface modification or carbon coating, and its incorporation into composites with carbonaceous materials.2

Among the various carbonaceous materials, reduced graphene oxide (RGO) or graphene nanosheets has attracted considerable interest as electrode materials for electrochemical energy storage because of their unique properties such as high electronic conductivity, large surface area, and good mechanical properties. Some recent studies have demonstrated the excellent rate capability and cycle stability of Li4Ti5O12/RGO nanocomposites.3 However, previously reported Li4Ti5O12/RGO nanocomposites mostly have 2-dimension morphologies with low tap density.3 The 2-dimentional Li4Ti5O12/RGO nanocomposites are not suitable for commercial use because their low tap density limits the volumetric energy density. Therefore, a simple and facile synthesis of micrometer-sized spherical Li4Ti5O12/RGO composites with a high tap density and superior rate capability is highly desirable.
In this study, we report one-pot synthesis of micrometer-sized spherical Li4Ti5O12/RGO with high tap density, wherein the initial Li-Ti-O/RGO precursor is fabricated by the spray drying method in the presence of all precursors in a solution. Upon subsequent heat treatment, phase-pure micrometer-sized spherical Li4Ti5O12/RGO with high tap density was successfully synthesized. More detailed on the synthetic procedure, morpology, electrochemical and structural properties of micrometer-sized spherical Li4Ti5O12/RGO will be presented at the meeting.

References

[1] S. G. Doo et al, J. Am. Chem. Soc., 2008, 130, 14930
[2] N. Ohta et al, Adv. Mater., 2006, 18, 2226
[3] H. K. Kim et al, Electrochem. Commun., 2010, 12, 1768
Thermodynamics and Kinetics of Li Extraction from Li-Rich Layered Manganese Oxide Cathodes
Authors: Chen Hungru , Islam M. Saiful 
Published: February 2020

Li-rich layered oxides Li1+xM1-xO2 (0<x<0.33), where M=Co, Mn, Ni, have emerged as promising cathode materials, because they can deliver much higher capacities (> 250 mAh/g) than the conventional LiCoO2 cathode. Important issues relate to what is the origin of the electrochemical activity and high capacity? In this work, possible charge compensation mechanisms upon lithium extraction from Li2MnO3 are studied by ab-initio density functional theory calculations: (a) Reversible oxidation of bulk O2- to other anion species such as superoxide or peroxide; (b) Loss of lattice oxygen (oxygen evolution). Both thermodynamic (reaction enthalpies and electrochemical potentials) and kinetic (ion migration) aspects are investigated.
Evolution of Nano-Crystalline Silicon Anode upon Cycling Probed By E
x Situ Raman Spectroscopy and Operando Synchrotron X-Ray Diffraction
Authors: Pavlenko Ekaterina , Quazuguel Lucille , Boniface Maxime , Tardif Samuel , Rieutord François , Marechal Manuel , Micha Jean-Sébastien , Mareau Vincent , Gonon Laurent , Lyonnard Sandrine 
Published: February 2020

Silicon is being considered as one of the most promising anode materials for next generation lithium-ion batteries due to its high theoretical capacity (3580 mA h g-1 at room temperature) (1). Upon charging, Si and Li react via an alloying process with a sharp interphase separating the growing LixSi amorphous phase from the pristine crystalline Si. In case of spherical particles this leads to a core-shell structure captured in Figure1a. The alloying process leads to an enormous volume expansion of Si resulting in cracking of the electrode material and rapid fading of its performance that impedes the commercialization of Si-based anodes. Nevertheless below a critical particle diameter of 150nm volume expansion does not lead to cracking (2). In order to profit from silicon unique properties, the structural evolution along charging/discharging must be understood.
Using ex situ Raman spectroscopy we observed the gradual transformation of initially crystalline silicon into amorphous one upon cycling. The resulting stresses generated in the crystalline cores of the core-shell structures were probed as well as their evolution along lithiation/delithiation. The changes of the crystalline lattice during the initial cycles were also monitored using operando synchrotron X-ray diffraction (XRD). In addition we were able to further quantify the constrained/unconstrained state of the silicon core. We show that combined ex situ Raman spectroscopy and in situ XRD provide in-depth understanding of the nanoparticles evolution.

Figure
1
. Schematic representation of silicon electrodes: a) Formation of a core-shell structure upon cycling, b) Influence of the laser power on the Raman signal and c) Gradual amorphization of the electrode along cycling
(All spectra were normalized to the maximum of the c-Si peak)

1. Obrovac, M. N., and Leif Christensen. "Structural changes in silicon anodes during lithium insertion/extraction." Electrochemical and Solid-State Letters 7.5 (2004): A93-A96.
2. Liu, Xiao Hua, et al. "Size-dependent fracture of silicon nanoparticles during lithiation." Acs Nano 6.2 (2012): 1522-1531.

Figure 1
Study on Phase Transitions of Lithium-Nickel-Manganese Oxide Li1+XNi0.5Mn1.5O4.0 (0 < x < 1) As High-Voltage and High-Capacity Cathode Materials
Authors: Mancini Marilena , Axmann Peter , Gabrielli Giulio , Kinyanjui Michael Kiarie , Golla-Schindler Ute , Kaiser Ute , Wohlfahrt-Mehrens Margret 
Published: February 2020

Rising demands for high-energy density Li-ion batteries require the development of new cathode active materials with enhanced specific capacity and energy, increased safety and reduced cost. Currently used high-cost metals, such as cobalt and nickel, need to be replaced with more abundant and less toxic elements.
A Co-free cathode material with high-voltage and high-capacity has been developed in our labs. The lithium‐nickel‐manganese oxide with composition Li1+xNi0.5Mn1.5O4.0 (0<x<0.5) was tailored with respect to morphology, particle size and shape distribution. The particles consist of densely packed nano‐sized primary crystallites and the free‐flowing powder shows a tap‐density of 2.4 g cm-3.
The cathode material shows a specific capacity of about 210 mA h g-1 in the potential window 2.4-4.9 V. The working mechanism involves two distinct voltage plateaus at 4.7 and 2.9 V vs. Li/Li+. Very good cycling stability is obtained for more than 200 cycles in half-cell.
Compared to other high-capacity materials, such as lithium-manganese-rich layered oxides, their spinel integrated variants and the cation disordered materials [1-3], this material does not need an activation cycle; it shows good rate capability and low voltage hysteresis.
In full-cell vs. graphite anode, a stable capacity of 160 mA h g-1 is reached.
For full-cell application no electrochemical pre-treatment or structural activation has to be applied in order to achieve the full capacity; therefore, the material can be directly assembled vs. graphite anode.
Cathode material features will be described, electrochemical performances in half- and full-cell will be presented and the influence of the operating voltage window will be shown. The effects of particle shape, grain architecture and structural features on the electrochemical behavior will be discussed.
Phase transitions in the low-potential region have been studied by HRTEM, EELS and XRD and the involved mechanism will be discussed.
Acknowledgements
This work was supported by the German Federal Ministry of Education and Research (BMBF) in the project Li-EcoSafe (03X4636A).
References
[1] Thackeray, M.M.; Kang, S.-H.; Johnson, C.S.; Vaughey, J.T.; Benedek, R. and Hackney, S.A., J. Mater. Chem., 17 (2007) 3112
[2] Park, S.-H.; Kang, S.-H., Johnson, C.S., Amine, K.; Thackeray, M.M., Electrochem. Comm., 9 (2007) 262
[3] Yabuuchi, N.; Takeuchi, M.; Nakayama, M.; Shiiba, H.; Ogawa, M.; Nakayama, K.; Toshiaki Ohta, T.; Endo, D.; Ozaki, T.; Inamasu, T.; Sato, K.; Komaba, S., PNAS 12 (2015) 7650
Organosilane Cathode Coatings for High-Voltage Lithium Ion Batteries
Authors: Peebles Cameron , He Meinan , Dogan Fulya , Hubaud Aude A. , Vaughey John T. , Liao Chen 
Published: February 2020

One of the more promising cathode materials for high-energy high-voltage lithium ion batteries (LIBs) are Ni-rich layered cathode materials such as LiNixMnyCozO2 (where x + y + z = 1). Although these cathode materials are attractive from a high capacity standpoint, they commonly suffer from poor structural stability at highly delithiated (charged) states leading to poor electrochemical performance.1-3 To help aid these issues, surface coatings are becoming a widely adopted method to improve the cycling performance of high-voltage cathode materials. More widely investigated coating materials include oxide coatings (Al2O3, TiO2, etc.)4 while comparatively fewer studies have investigated organic monomer or polymer coatings (PEDOT, polyimide, etc.).5

In this work, the surface of LiNi0.5Mn0.3Co0.2O2 cathode materials were coated with organosilane reagents to investigate their effect on cell electrochemical performance. The impact of the weight percentage of organosilane used and the functionality of the organosilane used will be presented. Characterization of the organosilane coating using XRD, XPS and FTIR confirm the presence of a Si-containing coating. Cycling performance for half cells (Li/ LiNi0.5Mn0.3Co0.2O2) using the organosilane coated cathodes will be shown. In conclusion, a new type of organic coating was utilized on Ni-rich cathode materials and this research explores a new type of coating for high voltage cathodes.
1) Son, I. H.; Park, J. H.; Kwon, S.; Mun, J. and Choi, J. W. Chem. Mat.
2015, 27, 7370-7379.
2) Bak, S.-M.; Hu, E.; Zhou, Y.; Yu, X.; Senanayake, S. D.; Cho, S.-J.; Kim, K.-B.; Chung, K. Y.; Yang, X.-Q. and Nam, K.-W. ACS Appl. Mater. Interfaces
2014, 6, 22594-22601.
3) Lin, F.; Markus, I. M.; Doeff, M. M.; Xin, H. L. Sci. Rep., 2014, 4, 5694.
4) Xu, S.; Jacobs, R. M.; Nguyen, H. M.; Hao, S.; Mahanthappa, M.; Wolverton, C.; Morgan, D. J. Mater. Chem. A, 2015, 3, 17248.
5) Zhang, J.; Lu, Q.; Fang, J.; Wang, J.; Yang, J. and NuLi, Y. ACS Appl. Mater. Interfaces
2014, 6, 17965-17973.
Self-Healing Lithium-Based Batteries
Authors: Roumi Farshid 
Published: February 2020

We are proposing a novel approach to enable rechargeable lithium metal anode batteries. The scientific merit of our approach is based on the effect of electric field manipulation in the vicinity of the lithium metal on the electrodeposition of lithium metal. We demonstrate how the spatial gradient of the electric field in the cell can be controlled and its effect on the electrodeposition of lithium metal during charging is studied. More than 200 cycles at C-rate in Li-metal- LTO cells with commercial electrolyte is achieved.
For the first time we show that it is possible to control the electric field inside the battery cell with addition of a porous metallic layer in the middle of the cell. The metallic layer significantly reduces the spatial gradient of the electric field, if any shorts reaches this layer. We will discuss how different metallic materials affect the dendrite destiny. Specifically, we show how an aluminum based layer can react with a lithium dendrite, consumes the available energy, and eventually burns out the lithium dendrite, such that the cell can keep functioning as a fresh cell with no indications of a short in its past cycling. Numerical and theoretical studies accompany our experiments to shed life on this interesting physical observation. The approach may give us an understanding of unprecedented methods to enable safe rechargeable lithium metal batteries.

Figure 1
Tailoring Nickel-Rich LiNi0.8Co0.1Mn0.1O2 Cathode Material with LiNi0.
4Co0.
2Mn0.
4O2 Surface Composition
Authors: Shin Youngho , Kahvecioglu Feridun Ozgenur , Krumdick Gregory 
Published: February 2020

Nickel-rich cathode material, LiNi0.8Co0.1Mn0.1O2, exhibits high specific capacity of approximately 200 mAh/g-oxide and potential for use in plug-in hybrid electric vehicles. However, significant challenges remain to improve the cycle life and thermal-abuse tolerance of this material. To improve the stability of this material, several researchers have investigated a core-shell approach resulted in a nickel-rich LiNi0.8Co0.1Mn0.1O2 core and a manganese-rich LiNi0.5Mn0.5O2shell for surface stabilization [1]. However, the structural mismatch between the core and shell compositions leads to large void formation at the core-shell interface which triggers a sudden drop in capacity after long-term cycling. To overcome the volume change between the core and shell compositions, concentration gradient shell was investigated [2] and full concentration gradient material was suggested which shows the gradual decrease of nickel concentration and increase of manganese concentration from the centre towards the outer layer of the particle [3].
Even though many researchers showed the promising high energy, long calendar life and excellent abuse tolerance of core-shell, core-concentration gradient shell and full concentration gradient materials by their synthesis optimization, the compared nominal composition of LiNi0.8Co0.1Mn0.1O2 was not well-optimized. Here, we report the optimized synthesis condition of a nominal composition of LiNi0.8Co0.1Mn0.1O2, core-shell and core-concentration gradient shell materials with LiNi0.4Co0.2Mn0.4O2 surface composition. The detailed comparison of the physical and electrochemical properties of the prepared materials will be discussed.

References

Y.-K. Sun, S.-T. Myung, M.H. Kim, J. Prakash and K. Amine, J. Am. Chem. Soc. 127(38), 13411 (2005).

Y.-K. Sun, S.-T. Myung, B.-C. Park, J. Prakash, I. Belharouak and K. Amine, Nature Mater. 8, 320 (2009).

Y.-K. Sun, Z. Chen, H.-J. Noh, D.-J. Lee, H.-G. Jung, Y. Ren, S. Wang, C.S. Yoon, S.-T. Myung and K. Amine, Nature Mater. 11, 942 (2012).
Doped TiNb2O7 with Enhanced Lithium-Ion Storage Performance
Authors: Li Shuang 
Published: February 2020

Pure and doped TiNb2O7 nanoparticles were synthesized from niobium ethoxide (Nb(OC2H5)5) and titanium isopropoxide ( C12H28O4Ti). The resulting material has been subjected to systemic structural and property characterization such as X-ray diffracttometry (XRD), scanning and transmission electron microscopies (SEM/TEM), nitrogen sorption isotherms, electrochemical impedance spectrum (EIS), and capacitance measurements. Different ratio materials including TiNb2O7, TiNb1.9O7, Ti09Nb2O7, and Ti0.95Nb2O7 with defects and oxygen vacancy were obtained in this study. Ti0.95Nb2O7 and TiNb1.9O7 have demonstrated specific capacity much greater than both pure TiNb2O7 and Ti09Nb2O7 counterparties. The relationship between processing condition, micro- and porous structure, electrochemical properties of pure and defective TiNb2O7 electrodes will be discussed.