bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal Foam Electrodes Incorporated with Molten Active Materials for Thermal Batteries
Authors: Cheong Hae-Won , Lee Jungmin , Yu Hye-Ryeon , Choi Yu-Song , Kang Seung-Ho , Cho Sung-baek
Published: February 2020

A Li-Si/FeS2 electrochemical system, which is widely used for thermal batteries, has limited energy density and power capability due to the partial utilization of the active materials. A single cell with a molten lithium anode or a molten sulfur cathode has a high energy density with a high open circuit voltage compared to that with a Li-Si/FeS2 couple. The main challenges in the molten electrodes arise from the instability of liquid active materials which can directly react with the other electrode and results in catastrophic thermal runaways, such as vent, fire or even explosion. For the practical application to thermal batteries which operates at above the melting point of the active electrode materials, the immobilization of the molten electrode is inevitably required. The combination of the porous metal foams with liquid active materials is found to be quite effective solution to attain unconventionally high energy density as well as high power capability. In this study, highly conductive nickel foam electrodes are incorporated with pure lithium or sulfur. The electrochemical characteristics are investigated along with the single cell tests and the microstructural analysis.
Spherical/Porous Cox-Mny-O4 Spinel Compound for High Performance Lithium Rechargeable Battery Electrodes
Authors: Choi Sungho , Yun Young Jun , Park Jin-Seong , Jung Ha-Kyun
Published: February 2020

Transition metal oxides such as cobalt- or manganese-based oxides have been proved to be promising materials for applications in high voltage and high energy density Li-ion batteries (LIBs) [1-3]. Most of those ²conversion reaction² involved metal oxides, however, suffer from limited reversible capacity and fast capacity fade due to their poor electronic conductivity and large volume changes. Thus, fabrication of nanostructured materials and/or intrinsically enhanced electrically conductive materials have been demonstrated to be effective ways to alleviate these problems [4,5]. In this work, ternary Co-Mn-O spinel oxides have been investigated as electrode materials for Li-ion and Li-air rechargeable battery. Crystalline spinel structured CoMn2O4 and MnCo2O4 compounds with nano/submicrorods were synthesized by a using hydrothermal reaction. When evaluated as an anode material for LIBs, the as-synthesized spherical/porous spinels exhibited superior initial charge/discharge capacity including good rate capability. The developed hierarchical structure with high surface area, catalyst(CoMn2O4 and MnCo2O4)/activated carbon, can also be applied to the analogous hybrid cathodes used in Li-air batteries.
Separator-Free Hybrid Electrolytes Composed of Inorganic, Polymer and Liquid Electrolyte for Lithium-Ion Batteries with Enhanced Safety
Authors: Kim Seul-Ki , Jung Yun-Chae , Han Man-Seok , Shin Woo-Cheol , Ue Makoto , Kim Dong-Won
Published: February 2020

Lithium-ion batteries have rapidly become the dominant power sources for portable electronic devices and electric vehicles.  However, safety issues still prevent full utilization of these batteries owing to the use of flammable liquid electrolytes, and safety problems have become a significant concern especially in large capacity applications such as electric vehicles and energy storage systems.  In this respect, fabrication of solid-state lithium batteries by using inorganic solid electrolytes may give a fundamental solution for the safety issue of lithium batteries.  However, sheet manufacturing, especially using thin-film technologies for making large-scale batteries, is considered to be difficult because of hard and brittle ceramic materials.  In this work, flexible hybrid electrolytes composed of inorganic electrolyte with polymer binder and liquid electrolyte were prepared in the form of flexible film, and their electrochemical characteristics were investigated.  An addition of small amount of liquid electrolyte significantly improved ionic conductivity and interfacial properties between electrodes and electrolyte.  The optimized hybrid electrolyte was applied to the graphite/LiCoO2 pouch cells and their electrochemical performances were evaluated.  The enhancement of battery safety was confirmed at the cell level by various techniques such as Accelerating Rate Calorimetry (ARC).
Enhancement of Irreversible Capacity By Pre-Formed Lithium Silicates and Lithium Oxide in Sio Anode for Lithium Ion Battery
Authors: Yom JeeHo , Yoon Woo Young
Published: February 2020

This study focuses on effect of improved irreversible capacity in SiO anode. Irreversible phases such as Li4SiO4, Li2SiO3, Li2O were synthesized by a solid state reaction using a mixture composed of 70 wt% SiO powder and 10 wt% Li-powder. The mixture was mixed by homogenizer and was heated at 600 °C for 2 h in an argon atmosphere. The irreversible phases were observed by XRD, XPS and TEM. Irreversible phases-formed SiO/lithium metal coin cells (2032) were assembled in a dry room. The discharge-charge cycling was performed with cut-off voltage of 0-1.5V. The electrochemical characteristics of the irreversible phases-formed SiO anode were rationalized through impedance analysis, cycle data and voltage profile. The irreversible phases-formed SiO anode’s capacities were 1265.36 mAh g-1 (lithiation) and 1052.03 mAh g-1 (delithiation) after first cycle. The reversible capacity of irreversible phases-formed SiO /lithium metal cells was estimated 83.14% in 1st cycle. It’s larger than pristine SiO/lithium metal which has 60.08%.

Figure 1
Al2O3/C-Composite Coated LiV3O8 As a Cathode Material for Lithium Ion Battery
Authors: Kim Byung Hyuk , Yoon Woo Young
Published: February 2020

LVO(LiV3O8) cathode coated with alumina(Al2O3) and carbon composite is successfully synthesized via sol-gel method process. Al2O3/C composite was expected to enhance the electrical conductivity and mechanical strength of LVO. To analyze the effect of Al2O3/C, coating depths with different thickness were investigated controlling the concentration of precursor. The interfacial characteristics were examined by SEM, EDS, TEM, and XPS. The cell with the concentration of 2wt.% Al2O3/C showed the best electrochemical performance. And the initial discharge capacity of the cell with 2wt.% Al2O3/C-coated LVO cathode was 280 mAh g-1 at 0.2 C-rate. The capacity retention and structural stability of Al2O3/C coated LVO was higher than pristine LVO after 100th cycle. Additionally, the rate capability test was conducted also showing the enhanced stability on each cycles attributed by Al2O3/C composite coating. From the results above, it can be concluded that the Al2O3/C composite coating on LVO can improve the electrochemical performance of LVO.
Improved Lithium Sulfur Battery Performance through Attaching Nanosilica on the Backside of Nickel Foam
Authors: Cho Sung Ho , Yoon Woo Young
Published: February 2020

Lithium Sulfur (Li-S) battery has a theoretically high specific capacity of 1675 mAh g-1, which one of the most promising energy source for electric vehicles (EVs), hybrid electric vehicles (HEVs) and energy storage system (ESS). However, Li-S batteries have crucial problem resulting from the polysulfides dissolution which is called ‘Shuttle Effect’. This shuttle effect causes overpotential and lowers its Coulomb efficiency. Also, a loss of active material by dissolution makes capacity fading. So the prevention of the polysulfides dissolution is the main issue of sulfur batteries. To solve the polysulfides dissolution we use nanosilica material on the current collector of cathode. It is reported that nanosilica has a characteristics of absorbing polysulfides. Zhang. et. al reported that they could control the shuttle mechanism by using nanosilica on the separator. However, the polysulfides accumulated on the separator hinder Li ion transport, leading to low capacity values compared to pristine Li-S batteries. In our research, nickel foam based sulfur cathode with silica coated on backside is investigated. Silica on the backside absorbs polysulfides, eventually suppressing the shuttle effect and reducing the quantity of the polysulfides on the separator. As a result, the coulomb efficiency and the capacity of the Li-S battery has increased comparing the uncoated Li-S battery. The examination was conducted by comparing between the pristine and the silica coated sample. Cells were tested at the current densities of 0.1 C rate with limited voltage of 1.8 to 2.8V. The morphology of the samples was observed on a field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The structure of the samples was characterized by X-ray diffraction (XRD) spectroscopy. The result was analyzed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).
Evaluation of Flexible Li4Ti5O12 Anode Electrodes Using Water-Based Binder for Li-Ion Batteries
Authors: Lu Huiran , Behm Mårten , Cornell Ann , Leijonmarck Simon , Lindbergh Göran
Published: February 2020

Li-ion batteries are today essential for portable electronic devices as a main power source. Flexible Li-ion batteries have attracted great attention and could be very useful in the emerging fields of flexible, wearable, implantable and bendable electronic devices. Nano-fibrillated cellulose (NFC), with a high aspect ratio (length/diameter) of the nanofibrils, has shown to be a promising binder material for flexible Li-ion batteries [i] [ii]. As a reinforcement component, it gives flexible electrodes good mechanical properties. In addition, the process of making the flexible electrodes is water-based, eliminating the toxicity problem of using conventional poly(vinylidene fluoride) (PVDF) as binder. However, capacity fading limits the stability of the flexible electrodes during repeated cycling. Side reactions on the graphite negative electrodes could be the reason for the capacity loss. Li4Ti5O12(LTO), with a high potential of 1.55 V versus Li metal, could be an alternative to graphite for flexible negative electrodes, reducing the reactivity with the electrolyte. In this work, the electrochemical performance, such as specific capacity and columbic efficiency (CE), and mechanical properties of flexible LTO anode electrodes using NFC as binder are investigated. Fig 1 shows the photograph of LTO electrode, illustrating the flexibility. Fig. 1 Photograph of flexible Li4Ti5O12
negative electrode.

[i] S.Leijonmarck, et al. Flexible nano-paper-based positive electrodes for Li-ion batteries-Preparation process and properties, Nano Energy, 2013, 2, 794–800.

[ii] S.Leijonmarck, et al. Single-paper flexible Li-ion battery cells through a paper-making process based on nano-fibrillated cellulose, Journal of Materials Chemistry A, 2013, 1, 4671-4677.

Figure 1
Lithium Metal Polymer Battery: Towards Optimized Cathodes and Crosslinked Polymer Electrolytes
Authors: Jeong Jiseon , Hoogil Lee , Choi Jaecheol , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Although lithium metal polymer batteries (LMPBs) have lots of advantages such as high energy density, design flexibility and enhanced safety, they have not been widely used in the commercial market due to low ionic conductivity and poor interfacial stability towards electrodes comparing to liquid electrolytes. However, most of researches on LMPBs have been focused for electrolytes themselves without broad cell performance data such as cycle life and rate capability. Furthermore, as discovered in previous works on commercial LIBs, the electrode density and thickness are also very crucial parameters governing the electrochemical performance of batteries.

For the purpose of providing basic but essential electrochemical properties of LMPB, we have manufactured four different LiFePO4 cathodes with different densities and thicknesses. Their physical and electrochemical properties are investigated by using the unit cells consisting of LiFePO4/cross-linked polymer electrolyte/Li metal. In particular, with the optimized cathode and crosslinked polymer electrolyte, high capacity retention could be realized at even 5C and room temperature.

Acknowledgements

This research was financially supported by the Ministry of Education, Science and Technology (MEST) and National Research foundation (NRF) of Korea through the Human Resource Training Project for Regional Innovation (2014066977) and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2014046008).

Figure 1
Binder-Free Ceramic Coated Separators Prepared By Polydopamine Treatment and RF-Sputtering
Authors: Lee Taejoo , Lee Yunju , Yeon Daeyong , Ryou Myung-Hyun , Lee Yong Min
Published: February 2020

Most commercially available polyolefin separators are made of polyethylene (PE) and polypropylene (PP). Such separators have excellent mechanical strength, electrochemical stability and thermal shutdown properties, but their thermal properties are not sufficient to secure safety of large-format LIBs. As a result, most of separator manufacturers prefer to coat ceramic layer on at least one-side of the conventional polyolefin separators. However, this comes at an additional cost with the battery. Radio frequency (RF)-sputter process has been considered as an economically viable process to prepare ceramic separator coatings [1]. The major disadvantage associated with it is high operating temperature, which can give some thermal damage on polyolefin separator.

In this study, polydopamine is coated on a polyethylene separator which can improve the heat resistance of the polyethylene separators. Then using RF sputtering and Al2O3 targets, ceramic coatings are made on this separator. With a submicron polydopamine and ceramic coating layer, the coated polydopamine and Al2O3 (PDA) separator has sufficient thermal properties comparable to conventional ceramic coated separators. In addition, PDA separator is electrochemically evaluated by ion conductivity and uptake amount for wettability, impedance analysis, rate capability, and cycle life.

Acknowledgements

This research was financially supported by the Ministry of Education, Science and Technology (MEST) and National Research foundation (NRF) of Korea through the Human Resource Training Project for Regional Innovation (2014066977) and IT R&D program of MOTIE/KEIT (10046314).

References

[1] T. Lee, W. Kim, Y. Lee, M. Ryou, Y. Lee, Macromolecular Research, 22 (2014) 1190-1195
Simulation Model of a Prismatic Lithium-Ion-Battery for Temperature Propagation in the Cell after a Short Term Thermal Stress
Authors: Bohn Pamina , Liebig Gerd , Vasic Stanislav , Komsiyska Lidiya , Wittstock Gunther
Published: February 2020

For several years lithium-ion batteries have been commercially used in portable devices such as camcorders, laptop computers and cell phones. Battery lifetime plays only a minor role in such applications due to rapid product innovation and strong competition. However, the increasing demand for lithium-ion batteries for automotive traction applications requires drastic increase in battery life-time and safety.[1] The majority of the existing life-time and performance prognoses are based on accelerated aging tests at elevated temperatures such as 40 °C, since the temperature plays a crucial role on the battery performance, safety and life-time.

However automotive lithium-ion cells must endure multiple production processes during the fabrication of a high-end traction battery system, such as contact welding, where the cells are exposed to elevated temperatures for a short period of time.[2] Up to date there is little information on the temperature propagation within the cell during the short-term thermal stress and also the influence of such short period thermal stress on the cell performance and cyclic ability.

For a better understanding of the temperature propagation in the cell, a simulation model based on the thermal material characteristics of a prismatic Li-NiMnCoO2 cell was created in COMSOL Multiphysics®. The thermal characteristics of the battery components are experimentally determined using Laser Flash Analysis (LFA) and Differential Scanning Calorimetry (DSC). In order to validate the modeling approach in this work, we built an experimental setup to measure the temperature propagation within a dummy cell. This dummy cell includes a carbonate solution as electrolyte, yet without a lithium salt.

After validating the model is used to describe the temperature propagation after a short-term temperature stress on automotive lithium-ion cells. Furthermore, it’s possible to predict the temperature propagation in the cell with this simulation model, after the short-term stress on different positions on the cell casing surface and at different SOC’s.

[1] J. Vetter, P. Novák, M.R. Wagner, C. Veit, K.-C. Möller, J.O. Besenhard,M. Winter, M. Wohlfahrt-Mehrens, C. Vogler, A. Hammouche; Ageing mechanisms in lithium-ion batteries. J. Power Sources 147 (2005) 269–281

[2] M. Yoshio, R.J. Brodd, A. Kozawa; Lithium-Ion Batteries, Science and Technologies; Springer (2009)
Model Based Dynamic Optimization Strategies for Lithium-Ion Batteries
Authors: Sonawane Dayaram , Suthar Bharatkumar , Pathak Manan , Santhanagopalan Shriram , Subramanian Venkat
Published: February 2020

Accurate estimation of battery internal states i.e. state of charge (SOC), state of health (SOH) and battery power is of great significance for safe and optimal performance of proactive Battery Management Systems (BMS) (1).

Mathematical models for lithium-ion batteries (2, 3) vary with complexity, computational costs and reliability of predictions. Incorporating more physicochemical phenomena in a model can improve its prediction accuracy but they cannot be directly employed for online control due to their high computational requirements. So, it is important to have reformulated battery models for online control and accurate predictions of internal states. Efforts have been made in past (4), to reformulate battery models to significantly reduce its computational expenses, allowing for real time control and simulation. 

In this work, we explored the use of an experimentally validated reformulated pseudo two dimensional model to derive the optimal charging profiles at different temperatures. The two distinct dynamic optimization strategies i.e. simultaneous optimization (5) and control vector parameterization (CVP) (6, 7, 8) to estimate optimal charging current profile for effective use of lithium-ion batteries are evaluated.   

 Acknowledgements

The work presented herein was funded in part by the Advanced Research Projects Agency – Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000275.

References

V. Pop, H. J. Bergveld, D. Danilov, P. P. L. Regtien and P. H. L. Notten, Battery management systems: accurate state-of-charge indication for battery powered applications, Springer Verlag (2008).

M. Doyle, T. F. Fuller and J. Newman, J. Electrochem. Soc.,140, 1526 (1993).

T. F. Fuller, M. Doyle and J. Newman, J. Electrochem. Soc., 141, 1 (1994).

P. W. C. Northrop, V. Ramadesigan, S. De and V. R. Subramanian, J. Electrochem. Soc., 158, A1461 (2011).

Biegler, L.T. Cervantes, A. M. Wachter, A., Advances in simultaneous strategies for dynamic process optimization, Chemical Engineering Science, 57(4):575-593, (2002).

J. R. Banga, E. Balsa-Canto, E. G. Moles, and A. A. Alonso, Dynamic optimization of bioprocesses: Efficient and robust numerical strategies. Journal of Biotechnology, 117:407–419, (2005). 

R. N. Methekar, V. Ramadesigan, R. D. Braatz, and V. R. Subramanian, Optimal charging profile for lithium-ion batteries to maximize energy storage and utilization, ECS Trans, vol. 25, no. 35, pp. 139-146, (2010).

Fathy, Hosam K., Reyer, Julie A., Papalambros Panos Y., and Ulsoy, A. Galip, On the Coupling between the Plant and Controller Optimization Problems, in Proceedings of the ACS, (2001).
Lifetime Prediction Based on the Load Profile of Lithium Ion Batteries
Authors: Kleiner Karin , Jakes Peter
Published: February 2020

Different operation conditions of lithium ion batteries like the temperature, the applied current and the state of charge of the electrodes determine the kinetics of the elementary reaction steps and therefore determine which reaction (reversible or irreversible) take place. The different reaction kinetics lead to different fatigue processes. During fatigue of lithium ion batteries material changes occur as well as changes in the cell balancing. Both have consequences for the redox reactions within the system and have to be considered for lifetime prediction. We investigated analytically kinetic laws of the reversible (charge and discharge processes) and irreversible (fatigue processes) reactions. With Kinetic Monte Carlo simulations the elementary steps were upscaled. Due to this it is possible to predict quantitatively the changes of the materials as well as changes in the cell balancing during operation of a battery. This provides information to design better materials for lithium ion batteries as well as it helps to select materials for each application specifically.
Rational Design of Metal Oxide-Carbon Yolk-Shell Nanostructures for Lithium Ion Batteries
Authors: Guo Shaojun
Published: February 2020

The development of high-capacity and long-life anode materials for lithium ion batteries (LIBs) is highly important for future portable electronic devices and hybrid electric vehicles. In this talk, I will present my recent advances on how to rationally design new classes of stable anode nanomaterials for boosting the performance of LIBs. I will start with speaking on the development of hydrothermal technique for the synthesis of MnO/C nanopeapods with sufficient internal void space for greatly enhancing the capacity, rate capability and long-term stability of LIBs. Then, I will move to another novel structure-Fe3O4@Fe3C core@shell nanoparticles-carbon yolk-shell nanospindles for long-lived lithium ion storage.
First Principles Investigation of Stable LiMn2O4 Surfaces for Lithium-Ion Batteries
Authors: Kim Soo , Aykol Muratahan , Wolverton Chris
Published: February 2020

The spinel LiMn2O4 (LMO) has been widely studied as a lithium-ion battery cathode to replace the currently-used LiCoO2 materials due to its low cost and fast Li+ diffusivity.[1]  However, a severe capacity fading during LMO cycling occurs because of the Mn dissolution, possibly initiating from the cathode surface. Thus, it is essential to completely understand the stable LMO surface structure to overcome current limitations and further to suppress the Mn dissolution in LMO.

  In this work, we investigate the effects of surface termination, slab reconstruction, relaxation schemes, magnetic ordering, and different U value for Mn to determine the relative stabilities of the LMO surfaces. We find that it is necessary to relax all atomic positions with symmetry-broken DFT calculations to fully capture the local variation of Mn-O and Li-O polyhedral clusters to obtain the most consistent surface energies. We finally comment on the possible implication of our work on the future surface studies of the mixed-valence transition metal complex oxides such as the LMO system.

Acknowledgement: This work has been supported by Northwestern-Argonne Institute of Science and Engineering (NAISE) and by The Dow Chemical Company.

Reference: [1] R. J. Gummow, A. Kock, M.M. Thackeray, Solid State Ionics
1994, 69, 59.

Figure 1
Long-Term High-Efficient Cus and Cu2s Cathodes for Lithium-Ion Batteries
Authors: Meng Xiangbo , Ren Yang , Sun Chengjun , Elam Jeffrey W
Published: February 2020

Lithium-ion batteries (LIBs) based on intercalation, such as C/LiCoO2, are dominant in consumer electronics, mainly ascribed to their superiority over their competitors in energy density. To meet our expectations for use in electrical vehicles (EVs), however, LIBs need to further improve their capability in energy density. In this context, intensive investigation has been undertaking for new battery materials of high capacities. A new reactivity concept named “conversion reaction” was first reported with transition metal oxides 1 at the very beginning of the 21st century. Since then, more and more binary compounds were discovered having the similar electrochemical reactions in LIBs, such as metal sulfides, metal fluorides, and metal nitrides 2. In comparison to the intercalation-based materials, the conversion-based materials can generally provide much higher capacities and this makes these new classes of materials important candidates for new battery technologies.

CuS has been regarded as one promising cathode material via conversion reactions, featuring a theoretical capacity of 560 mAh/g, flat discharge plateaus, and good electrical conductivity. In spite of these advantages, CuS was reported with severe capacity fading 3. To circumvent this technical hurdle, Chung and Sohn 4 discovered that narrowing voltage window could help improve cycleability of CuS in LIBs, but CuS still could not sustain long-term high-efficient discharge-charge cycling. In comparison to CuS, there were even fewer studies reported on Cu2S. In this talk, we are going to present our recent progress on both CuS and Cu2S cathodes. We confirmed that a suitable selection on voltage windows is essential for securing reliable cycleability of the CuS and Cu2S cathodes. On the other hand, we found current collectors also have some effects on the LIB cathodes. To explore the underlying mechanism, we applied advanced synchrotron-based techniques of in situ X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) to track time-resolved structural changes of CuS and Cu2S during discharge-charge cycles. Based on all these efforts, we developed a set of conditions for achieving long-term high-efficient CuS (see figure 1) and Cu2S cathodes in LIBs. In addition, the electrochemical characteristics of CuS and Cu2S also will be comparatively discussed. This work is potentially significant for developing next-generation high-energy batteries for EVs.

 

References:

         (1)    Poizot, P.; Laruelle, S.; Grugeon, S.; Dupont, L.; Tarascon, J. M. Nature
2000, 407, 496.

         (2)    Cabana, J.; Monconduit, L.; Larcher, D.; Palacin, M. R. Adv Energy Mater
2010, 22, E170.

         (3)    Debart, A.; Dupont, L.; Patrice, R.; Tarascon, J. M. Solid State Sciences
2006, 8, 640.

         (4)    Chung, J. S.; Sohn, H. J. Journal of Power Sources
2002, 108, 226.

Figure 1
Mapping of Ageing Mechanisms in Cylindrical LiFePO4/Graphite Batteries Cycled Under Deep Discharge Steps
Authors: Aguesse Frederic , Sarasketa-Zabala Elixabet , Bekaert Emilie , Lopez Carmen , Kubiak Pierre , Rodriguez-Martinez Lide M
Published: February 2020

Li-ion batteries are good candidates for electric vehicles and stationary applications due to their high power and energy density. Despite significant improvement over the last decade, lifetime and safety remain major issues for large-scale applications. Thus, a better understanding of factors governing battery lifetime and performance loss is crucial. Various types of Li-ion batteries are commercially available and their characteristics and performance depend strongly on the combination of active materials, cell design and manufacturing process. Therefore, the determination of specific degradation mechanisms and their correlation with cell performances is crucial for working on cell concepts that can meet target lifetimes [1-3].

In this work, cycling performance fade of LiFePO4-based cylindrical batteries is evaluated under deep charge/discharge steps (100% DOD). The cycling conditions were chosen to represent highly demanding condition of operation, which covers the analysis of ageing phenomena under the largest possible operating DOD. Diagnostic evaluation of the ageing mechanisms included in-situ electrochemical measurements, and ex-situ destructive physico-chemical and electrochemical analyses of cell components. A thorough study on the degradation mechanisms in different areas of the battery is realised in order to establish a geometrical mapping of the cell degradation. This allows identifying areas of inhomogeneous degradation along the jelly-roll of the battery. Degradation mechanisms were evaluated by microstructural (SEM) and crystallographic (XRD) analyses. Elemental analysis of the electrode composition was determined by EDS and ICP techniques. The electrochemical performances of selected areas of the harvested electrodes were determined by galvanostatic testing in half-cell configuration. These results were combined with non-destructive cell electrochemical measurements to provide a global view of the main degradation processes.

[1] M. Safari and C. Delacourt, Journal of the Electrochemical Society, 2011. 158(12): p. A1436-A1447.

[2] M. Dubarry and B.Y. Liaw, Journal of Power Sources, 2009. 194(1): p. 541-549.

[3] D.P. Abraham, J. Liu, C.H. Chen, Y.E. Hyung, M. Stoll, N. Elsen, S. MacLaren, R. Twesten, R. Haasch, E. Sammann, I. Petrov, K. Amine, and G. Henriksen, Journal of Power Sources, 2003. 119-121: p. 511-516.
Preparation of Graphite from Fish Scales
Authors: Huang Yaqin , Gao Mengyao , Wang Weikun
Published: February 2020

Graphite with relatively high specific capacity (372mAh g-1), cycling efficiency and low irreversible charge is nowadays the choice of the lithium-ion batteries [1,2]. In order to improve the electrochemical performance of graphite, many reports focused on the selection of suitable carbon precursors with easy graphitization [3,4]. In this work, fish scale with a layer-by-layer structure inspired us to prepare graphite from it. The advantages are as follows: 1) it is as an abundant food waste; 2) collagen as its main composition has high carbon content (about 50%); 3) the preparation process could be easy. The fish scales have been carbonized at 900℃ with a heating rate of 3℃ min-1 under a flowing N2. The obtained carbon was diluted by acid and then graphited at 2800℃. The BET surface area of the as-prepared fish-scale-based graphite is 5 m2 g-1 and the Raman ID/IG ratio only remains 0.04 (Fig. 1a) which illustrates a low degree of defects and a high degree of crystallinity. The initial discharge specific capacity is 310 mAh g-1 and keeps 300 mAh g-1 with the coulombic efficiency 99.6% after 150 cycles (Fig. 1b). These results state that the fish-scale-based graphite is a promising material for the anode of lithium-ion batteries. 

Fig. 1 (a) Raman spectra (514 nm laser) and (b) Cycle performance and corresponding Coulombic efficiency at a current density of 50 mA g-1 for the fish-scale-based graphite.

Acknowledgments

Financial support from the National Natural Science Foundation of China (no.51272017 and 51432003) is gratefully appreciated. 

[1] M. Armand and J. -M. Tarascon, Nature, 451, 652 (2008).

[2] N. A. Kaskhedikar and J. Maier, Adv. Mater. , 21, 2664 (2009).

[3] I. Cameán, A. B. García, I. Suelves, J. L. Pinilla, M. J. Lázaro, and R. Moliner, J. Power Sources, 198, 303 (2012).

[4] C. Ma, Y. Zhao, J. Li, Y. Song, J. Shi, Q. Guo, and L. Liu, Carbon, 64, 553 (2013).

Figure 1
(Invited) Record-Performance In(Ga)As MOSFETS Targeting ITRS High-Performance and Low-Power Logic
Authors: Rodwell Mark J , Huang Cheng-Ying , Lee Sanghoon , Chobpattana Varistha , Thibeault Brian , Mitchell William , Stemmer Susanne , Gossard Arthur
Published: February 2020

We review recent development of In(Ga)As-channel MOSFETs. Low-effective mass InAs and InGaAs channels, combined with thin gate dielectrics, provide high transconductance, but off-state leakage can be high due to band-band and source-drain tunneling currents.
 This leakage is reduced through thin 2.5-3nm channels, and through InGaAs or wide-bandgap InP vertical field spacers in the raised, regrown source and drain.  
Planar UTB devices with 2.7nm thick strained InAs channels and lightly-doped InGaAs spacers in the raised regrown source and drain provide, at 25nm gate length, record 0.5mA/µm on-current at 100nA/µm off-current  (ITRS HP specification) and 500mV VDD.  1 µm gate length FETs show 61mV/decade subthreshold swing at 0.1 Volts VDD.  Targeting the ITRS LP specification, we have developed InGaAs-channel MOSFETs with lightly-doped InP wide-bandgap spacer layers in the raised source and drain.  At 30nm gate length, these show a minimum 60 pA/µm off-current, approximately 100:1 smaller than a similar device using InGaAs source/drain spacers. A FET using InP spacers,  with 45 nm gate length, shows  0.15 mA/µm on-current at 1nA/µm off-current  (ITRS GP specification) and 500mV VDD.  We will discuss ongoing efforts to further increased on-current and decrease off-current in short-gate-length III-V MOSFETs.
Effect of Design and Rare-Earth Doping of the Structural, Optical, Electrical and Light Emitting Properties of Si-Based Superlattices Developed for Photonic Application
Authors: Khomenkova L. , Pratibha Nalini R. , Labbe Christophe , Carrada Marzia , Portier Xavier , Gourbilleau Fabrice
Published: February 2020

Nowadays, silicon-based nanostructures attract great attention due to their wide functionality. However, in spite of a lot of efforts forwarded on the investigation of Si-based nanomaterials, additional research is still required in order to design their optical properties for optoelectronic, photovoltaic or memory applications. The structural disorder is one of the main issues that may reduce the efficiency of device operation in the applications area of every nanomaterial.

Undoped and rare-earth (RE) doped Si-rich-SiO2 (SiOx) composite films and multilayers were recently investigated [1-3]. An efficient RE emission was achieved in Er- and, later, Nd-doped SRSO films due to an interaction of RE ions with Si-nanoclusters (Si-ncs). Although, a multilayer (ML) approach offers a precise control of Si-ncs distribution via a tuning of SRSO thickness, RE-doped SRSO-based MLs are not well addressed. This work presents the benefits of ML approach to achieve high efficiency and to control RE emission from Nd-doped SiOx/SiNx-based MLs grown by RF magnetron sputtering. Their properties were studied by means of XRD, TEM, PL and PL excitation methods versus deposition conditions, annealing treatment and ML design (doping, thickness of alternated sublayers (silicon oxide, nitride)). In each type of ML structures, either one or both sublayers were doped with Nd ions to investigate the effect of selective or full doping on PL emission. The results will be summarized and compared with those of Nd-doped SiOx/SiO2 MLs. It will be showed that comparable Nd PL emission can be obtained for both types of ML structures. Besides, fabrication approach allowed the PL emission to be achieved from as-grown samples. However, the highest Nd PL intensity was obtained after an annealing at about 700°C in nitrogen flow, whereas the formation of crystallized Si-ncs occurs at 1000-1100°C. The mechanism of Nd ions' excitation (i.e. an interaction with Si-ncs as well as with matrix defects, if any) will be discussed in details based on PL excitation spectra and PL life-time data. These results reveal potential photonic applications of Nd-doped MLs.

This work was supported by French National Agency (ANR) through DAPHNES project.

1. Pratibha Nalini R., Khomenkova L., Debieu O., Cardin J., Dufour C., Carrada M., Gourbilleau F.,Nanoscale Research Letters, 7, 124 (2012).

2. Cueff S., Labbé C., Khomenkova L., Jambois O., Pellegrino P., Garrido B., Frilay C., Rizk R., Mater. Sci. Eng. B. 177, 725 (2012).   

3. E. Talbot, R. Lardé, P. Pareige, L. Khomenkova, K. Hijazi, F. Gourbilleau, Nanoscale research letters 8, p.39 (8 pages) (2013).
Light Emitting Properties of Si-Rich-Si3N4 Films Grown By PECVD Method
Authors: Torchynska Tetyana V. , Casas Espinola Jose Luis , Polupan Georgiy , Vergara Hernandez Erasto , Khomenkova Larysa , Slaoui A
Published: February 2020

Bandgap engineering of Si-based materials through the control of the distribution of Si nanoclusters’ (Si-ncs) offered future applications of Si-based nanostructured materials in optoelectronics as low-cost, miniaturized, and CMOS-compatible, light-emitting and photovoltaic devices. In the past, most efforts were concentrated on the development of luminescent Si-ncs embedded in SiO2 host. However, its insulating nature remains a barrier for the production of future electrically pumped LEDs and efficient photovoltaic cells. This detrimental aspect can be coped with a medium of higher conductivity and lower band gap, for instance, Si nitride. Tunable room temperature visible light emission from Si-ncs embedded in Si nitride matrices has been recently demonstrated.

Present work deals with the Si-rich Silicon nitride films were grown by PECVD technique on silicon substrates. The film stoichiometry was controlled via variation of NH3/SiH4 ratio from R=0.45 up to 1.0. Thermal treatment was performed at 1100°C for 30min in nitrogen flow to form Si-ncs. To control structural and light emitting properties of the films Raman scattering, X-ray diffraction (XRD), Transmission electron microscopy (TEM) and photoluminescence (PL) methods were used. The evolution of PL spectra with the temperature of measurements from 20 to 300 K was studied also aiming at the determination of the types of optical transitions. 

The PL spectra were found to be complex and the shape and magnitude of PL spectra depends on silicon nitride stoichiometry. The increase of gas ratio from R=0.63 to R=1 results in the shift of PL peak position from 1.6 eV up to 2.7 eV. Analysis of the temperature dependence of PL spectra revealed the presence of several PL components with the maxima at 2.9-3.0 eV, 2.5-2.7 eV, 1.9-2.2 eV and 1.8-1.9 eV. The peak position of the former three PL components unchanged with the decrease of temperature of the measurements. This allows describing all these components to the defects of silicon nitride host. At the same time, PL band peaked at 1.8-1.9 eV showed high-energy shift with sample cooling and can be ascribed to the exciton recombination inside Si-ncs. The presence of these latter was confirmed by Raman scattering spectra and TEM images. The nature of light emitting defects in silicon nitride, the mechanism of photoluminescence and the way for the optimization of light emitting properties are discussed.
Pulse Width Modulation for Reducing Pulsed MOS Capacitor Measurement Time
Authors: Safarnezhad Hendijani Mohamad , Zahedi Sayedehgolnaz
Published: February 2020

Carrier lifetime in silicon is a direct measure of its deep-level defect density. This parameter is therefore widely used for process screening purposes to check for unwanted contaminations such as metallic impurities. The dynamics of semiconductor industry requires the development of novel approaches to reduce the measurement time of commonly established carrier lifetime measurement techniques for more efficient screening in process lines. The pulsed MOS capacitor (MOS-C) is the most popular technique for measuring the generation lifetime (τg
) where τg
is being extracted from the capacitance transient response (C-t) of a MOS capacitor device when pulsed from accumulation into deep-depletion and as it moves from the non-equilibrium deep-depletion into the inversion. Although accurate and easy to implement, the pulsed MOS capacitor takes a long time to accomplish. For clean wafers the time for a single measurement can easily reach several hours. This becomes specifically problematic when the goal is to map the whole wafer area. Many attempts have been made to reduce the lifetime measurement times. The challenge, however, is to maintain the accuracy while trying to reduce the test time. It will showed that by using a dynamic pulse train and exploiting the pulse width, the pulsed MOS-C technique can be implemented not only to reduce the measurement time. If the accumulation pulse in the pulsed MOS technique is applied at a high frequency the device response will become substantially short resulting in a reduced measurement time. Interestingly, this approach will not cause any compromise in the accuracy with which the lifetime is measured.  TCAD simulations and experimental results will be presented to show the effect of the accumulating pulse width on the C-t transient of a typical MOS device.
Atomic Level Simulation of Ridge Reconstruction and Passivation in GaAs Nanopillars
Authors: Yu Ted H. , Ratsch Christian
Published: February 2020

State-of-the-art semiconductor nanopillars are an exciting new topic, due to their unique properties that can be used in a number of microelectronic applications.  Nanopillars can be grown into microarrays that can maximize surface to volume ratio, ideal for photo-voltaics1, 2.  Recently, it was shown that sulfur passivation with sulfur, improved GaAs nanopillar conversion efficiency 2-3 times2.  A theoretical understanding on how sulfur can remove mid-gap states in GaAs nanopillar is needed to further improve this process.

    In this work, we report our density functional theory (DFT) modeling3 result of 18 different hexagonal shaped GaAs nanopillar that is periodic in the vertical direction.  Our model examines energetics and band gaps of the pillars to form a theory on the chemical mechanism for sulfur passivation on nanopillars.  Three different stacking are studied, wurtzite, zinc blende, and polytype (ABCB) which contains 50% wurtzite and 50% zinc blende.  The nanopillars also differ by their diameter and the way they terminate at the ridges.  We theorize that sulfur passivation is mostly effective on the ridges of the nanopillars and that stacking faults play a role in the mid-gap states that exist before passivation. 

    Further study of our electronic structures, looking at the density of states, show mid-gap states inherent in GaAs ridges passivated by the presence of sulfur.  This is because there are dangling bonds along the ridges of the nanopillar that exists when there are stacking faults.  We look at many different ways sulfur can react with the ridges.  The energetically favorable configuration satisfies the octet rule and eliminates most of the midgap states.

Figure 1:  Geometry and density of State for polytype (ABCB) nanopillar before and after sulfur passivation.

References:

1.            G. Mariani, A. C. Scofield, C. H. Hung and D. L. Huffaker, Nat. Commun. 4 (1497), doi:  10.1038/ncomms2509 (2013).

2.            G. Mariani, R. B. Laghumavarapu, B. T. de Villers, J. Shapiro, P. Senanayake, A. Lin, B. J. Schwartz and D. L. Huffaker, Appl Phys Lett 97 (1), 013107 (2010).

3.            T. H. Yu, L. Yan, W. You, R. B. Laghumavarapu, D. L. Huffaker and C. Ratsch, Appl Phys Lett 103, 173902 (2013).

Figure 1
Template-directed Synthesis of Ag2S-Fe2O3 Heterostructures
Authors: Chen Yingjie , Liu Shiben , Zhao Mei , Yu Liyan , Dong Hongzhou , Dong Lifeng
Published: February 2020

Controlled synthesis of optical-magnetic nanostructures has attracted more and more interest due to their simultaneous optical properties and magnetic manipulating. Ag2S nanocrystals, with a low (~1.0 eV) band gap at room temperature, have become one of the most commonly studied semiconductor nanocrystals. Due to their excellent photoelectric and thermoelectric properties, Ag2S nanocrystals have been widely used in photocatalysis, near-infrared fluorescence imaging, and photoconductive cells. In addition, Fe2O3 nanoparticles with or without interior voids have both magnetic and photocatalytic properties. Thus, the integration of Ag2S and Fe2O3 nanoparticles may lead to further improvements of their optical performance. However, it still remains a difﬁcult task to prepare these desired hybrids in a controllable fashion.

Herein, we demonstrated the synthesis of nanocomposites containing silver sulfide and iron oxide materials by the sulfidation of silver-iron oxide nanotemplates with elemental sulfur as sulfur resource. In the presence of oleylamine, the sulfidation of silver-iron oxide heteromers retained similar nanostructures as templates, indicating an in-situ sulfidation of silver. TEM images, UV-Vis absorption spectra and XRD patterns of as-prepared Ag-Fe2O3 and Ag2S-Fe2O3 nanoparticles synthesized by sulfidation with elemental sulfur were shown in this paper. These investigations would help us to understand the sulfidation and growth process of nanomaterials and control their synthesis for a given application.
Invited: III-Nitride Semiconductor Nanowire Resonant Tunneling Diodes
Authors: Lu Wu , Shao Ye
Published: February 2020

Resonant tunneling devices (RTDs) have attracted considerable interests because of their extremely high switching speeds and potential applications in multi-logic circuits. Due to the large conduction band offset, strong piezoelectric and spontaneous polarization, III-nitride wide band gap semiconductors are promising materials for resonant tunneling devices. However, III-nitride thin film structures always suffer from a large density of threading dislocations due to the large lattice matches between themselves and also substrates. Therefore negative differential resistances (NDR) reported in thin film III-nitride devices are a result of trap-assisted tunneling. III-nitride heterojunction nanowires have the potential to address this issue because that the large surface-to-volume ratio and small cross sections allows semiconductor nanowires accommodate much higher lattice mismatch with an efficient elastic strain relaxation thereby inhibiting the formation of dislocations. In this work, we demonstrate III-nitride nanowire RTDs with high tunneling current density and peak-to-valley current ratio. We started with growth of n-GaN/AlN/i-GaN/AlN/n-GaN double barrier heterojunction nanowres by plasma assisted molecular beam epitaxy. The I-V characteristics show clear NDR features at both room temperature and cryogenic temperatures. Significantly, NDR happens in both forward and backward voltage sweeps at the same bias, which is a strong evidence that NDR is a result of tunneling resonance as designed rather trap-assisted tunneling reported in III-N thin film heterostructures. A maximum peak to valley current ratio (PVCR) of 41 and a maximum resonant peak current density of 106 A/cm2 have been demonstrated. To our best knowledge, this is higher than any reported PVCR values in AlN/GaN RTDs. The details of the design, simulation, growth, and fabrication of such III-nitride heterojunction nanowire RTDs will be discussed in this talk.
Metallization Reliability and Defectivity in Compound Semiconductors
Authors: Kilgore Steve
Published: February 2020

Compound semiconductor devices are in mass volume production yet our understanding of reliability and defectivity of III-V materials is still evolving.  Process-induced defects in electroplated Au interconnect metallization on GaAs devices were detected during the course of reliability testing.  Abnormally high lognormal sigmas (σ > 0.7) indicated the existence of a bi-modal failure mechanism.  A distinct early lifetime failure mode was observed along with the intrinsic electromigration metallization wear-out failure mode.  Increased temperature stress showed only a slight acceleration on the early failure mechanism but selection of a higher resistance degradation failure percentage criterion reduced the extent of these early failures.  Physical characterization of the electroplated Au film revealed as-deposited nanoscale voids. Elimination of these voids through process improvement as well as suggested mechanisms for the early failures is discussed.