bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of the Next Generation Anode Materials for Super-Efficient Lithium-Ion Batteries
Authors: Bakenov Zhumabay , Molkenova Anara , Zhexembekova Anar , Moldabayeva Azhar , Moldabayeva Marzhan , Kuanyshev Aidyn , Tayuekelev Medet , Beisbayeva Zhuldyz 
Published: February 2020

The global environmental and energy challenges demand for an immediate response through decarbonization of the energy sources by technological advances and implementation of renewable sources. From this point of view, the development of super-efficient battery technology has received an extensive attention for electrification of vehicles and grid integration of renewables [1]. Silicon materials have not only overwhelmed the electronics industry, but also can be nominated as a key technology towards achieving such super-efficiency in batteries due to its appealing features associated with the highest-known specific capacity (~4200 mAh g-1), profusion, and attractive cost. However, its promotion in the global market is impeded by low-conductive nature and high structural instability during cycling. The abovementioned restrictions can be surmounted through involvement of stable spinel Li4Ti5O12 (LTO) structure [2] and polyacrylonitrile (PAN) polymer conductive network [3] in the preparation of Si-based anode material with superior electrochemical properties. PAN is considered to be a carbon source with sufficiently large electrical conductivity, while LTO possesses extremely safe “zero-strain” Li-ion insertion/extraction properties. High energy ball milling and heat treatment procedures were employed in the solid-state synthesis of Si/LTO/PAN ternary composite. This presentation will discuss a systematic study on the effect of precursor nature, versatility of components ratios in the composite electrode structure and highlight the process parameters, which play an important role in overcoming problems of Si anode and improving its physical and electrochemical properties.

Acknowledgements

This work was supported by the project grant 5097/GF4 “Development of a novel quartz (SiO2) based anode material for Li-ion batteries” from the Ministry of Education and Science of the Republic of Kazakhstan.

References:

[1] S. Goriparti, C. Capiglia, J. Power Sources 257 (2014) 421-443.
[2] S. Jing, Y. Liang, L. Li, Y. Peng, H. Yang. Electrochimic. Acta 155 (2015) 125-131.
[3] W. Yuping, S. Fang, Y.Jiang. J. Power Sources 75 (1998) 201-206.
Preparation of Highly Porous Silicon As an Anode for Lithium Ion Batteries
Authors: Ngo Duc Tung , Kim Young-Jae , Park Chan-Jin 
Published: February 2020

The mobile world depends on lithium ion batteries (LIBs), which provide portable power for variety of applications, ranging from personal electronic devices such as laptops, mobile phones, digital cameras to electric vehicles due to the high energy density, low self-discharge and long cycle life of LIBs.
Nevertheless, current LIBs cannot still meet recent increased needs for higher energy density batteries from industries. Nowadays, LIBs can store more than double (200 Wh kg-1) energy density compared with the first commercial LIB. However, this value is still far from the goal in energy density of battery (400 Wh kg-1). Basically, this limitation of LIBs originates from their electrode materials; graphite as an anode and LiCoO2 as a cathode. Accordingly, to improve the energy and power densities of the LIBs, one of the easiest ways is to replace the conventional anode and cathode materials by other advanced materials with better capacity, rate capability, etc. In this context, Li alloys have emerged as a promising alternative candidate to replace graphite anode for LIBs due to the high specific capacity of the Li alloys. Although issues related to poor capacity retention of Li alloys caused by the large volume change during the lithiation/delithiation process have been addressed using new binders and electrolyte additives, the practical application of Li alloys as an anode is still a challenge, especially due to the limited rate capability of the Li alloys. Among the Li alloy based materials, silicon (Si) is considered the most suitable anode for LIBs due to the high theoretical capacity of 4200 mAh g-1 and low cost of Si.
In this work, we report the synthesis of highly monodisperse porous Si using a simple and scalable method. The porous nature of the Si enabled the homogeneous stress distribution within the structure during lithiation and delithiation, leading to the dramatic improvement in electrochemical stability. In particular, the high porosity offered the large electrolyte accessible surface area, the short Li-ion diffusion path, and the void spaces necessary for volume expansion. The porous silicon demonstrated the excellent reversible capacity and the minimal capacity fading for longer than 100 cycles at the high rate of C/10 (80% capacity retention with ~100% Coulombic efficiency). Further, this material exhibited the potential as an anode material for lithium-sulfur analogous battery.
Graphene Coated LiNi0.5Mn1.5O4 for High Power Positive Electrode Material of Lithium Batteries
Authors: Lee Chang-Woo , Kim Jun-Ho , Lee Hyun-Ju , Kim Jeom-Soo 
Published: February 2020

Recently, high power rechargeable lithium-ion batteries have become the dominant power source for xEVs (HEV, PHEV, and BEV). LiMn2O4 (LMO) is well known cathode material and adopted in the field required high power. However, the application of LMO is somewhat limited due to the low energy compared to other positive materials. One of strategies to improve the energy density is increasing their operation voltage by using high voltage positive material. Fortunately, a spinel LMO can be modified by replacing Mn with some portion of Ni to realize the high operation voltage, which is LiNi0.5Mn1.5O4. Ni-substituted spinel, LiNi0.5Mn1.5O4, has a voltage plateau around 4.7 V (vs. Li/Li+) which is 0.7 V higher than LMO has. One of the restrictions for LiNi0.5Mn1.5O4 as the positive electrode material is its relatively low electronic conductivity (~10-5 S/cm) which exerts negative effects on the power performance.
In this study, it has been attempted to improve the power capability of LiNi0.5Mn1.5O4 by enhancing surface conductivity. The homogeneous LiNi0.5Mn1.5O4 powder was obtained through the alcohol-assisted hydrothermal process followed by surface coating with the graphene. Two different process has been applied for graphene coating such as solution and mechanical method respectively. It will be discussed that the effect of graphene coating on the physical and electrochemical properties of LiNi0.5Mn1.5O4.

Figure 1
Interface Design with Conducting Polypyrrole Thin Film for Improving the Storage Property of Ni-Rich Materials
Authors: Cao Jingchao , Xiao Kesong 
Published: February 2020

Layered high nickel composites, such as LiNi0.9Co0.1O2, LiNi0.85Co0.1Al0.05O2 and LiNi0.8Co0.1Al0.1O2, are considered to be the most promising materials for hybrid electric vehicles, plus-in bybrid vehicles, and electric vehicles due to their large capacity, good C-rate capacity and long cycle life. However, the characteristics of rapidly moisture absorbing and residual alkaline substance such as Li2CO3 and LiOH limited their practical applications. Considered the long life of the cathode material is an important factor during its application, the storage property of Ni-rich materials has attracted much attention. It is obviously known that the Ni-rich composites easily absorbed H2O and CO2 after being exposed to air, and Li2CO3, LiOH and NiO-like species were identified to the major species formed on the surface. These impurities are believed to be responsible for storage loss.
Meanwhile, attempts have been made to reduce the storage loss by two approaches, ie.: (1) decreasing the nickel content on the surface of the compound, such as coating, core-shell structural design and gradient structural design; (2)storing the materials in an atmosphere without H2O and CO2. As a result, a marked improvement in storage properties is achieved. In our study, surface design with conducting polypyrrole thin film, which is just like a capsule shell, can avoid the indirect contact with atmosphere and protect the core materials form corrosion causing by HF attacking.
The PPy-coated cathode materials were prepared by the chemical polymerization with and p-toluenesulfonate as the dopant. H2O2 was chosen as the oxidant in order to avoid the introduction of other impurity ions. X-ray diffraction (XRD) was employed to identify the crystalline phase of the products. The surface species on the materials surface were identified through Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDXS). Transmission electron microscope (TEM) was used to identify the thickness of the thin film. To quantify the amount of the conducting thin film, thermogravimetric analysis (TGA) was carried on. Exposure test was carried out to determine the storage properties of pure and treatment composites. In order to measure the amount of residual alkaline substance on the surface, powders were soaked in water and the LiOH/Li2CO3were measured using titration method. All electrochemical properties of the composites were investigated by using coin cells (2016 type).
The results indicates that the Ni-rich composites designed with conducting thin film on the surface can effectively improve their storage properties. The amount of residual alkaline substance on the surface of powders coated with conducting thin film are greatly reduced after being exposed in air, compared with un-treatment powders. The thin film on the surface builds a conductive network, which is beneficial to improve their electrochemical properties as well.
Kraft Lignin - an Alternative Sustainable Binder Material for Green Li-Ion Batteries
Authors: Lu Huiran , Cornell Ann , Alvarado Fernando , Behm Mårten , Leijonmarck Simon , Li Jiebing , Tomani Per , Lindbergh Göran 
Published: February 2020

The binder material plays an important role in the electrodes for Li-ion batteries, keeping good electrochemical stability and adhesion with the current collectors. The conventional binder for the commercial Li-ion batteries is poly vinylidene fluoride (PVDF). However, it requires dissolving in an organic solvent, typically N-methyl-2-pyrrolidione (NMP), which is toxic and expensive.
Kraft lignin is a byproduct which is extracted from pulp and paper industries by the LignoBoost process [1]. Its utilization has gained considerable attention due to its reasonable cost, relatively high purity and being renewable. In this work, kraft lignin was used for the first time as a binder material in Li-ion batteries [2]. It is more environmental friendly and potentially less expensive compared to the PVDF binder. Electrodes, LiFePO4 positive and graphite negative electrodes bound by kraft lignin, were characterized using scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge cycles. Results show that the electrodes have good reversible capacities about 150 mAh g-1 for positive electrode and 300 mAh g-1 for negative electrode cycled at C/10, and fairly good rate capabilities. The negatives have a very high cycling stability with about 98% retention after 50 cycles cycled at C/4. It illustrates that lignin is a promising alternative sustainable binder material for green Li-ion batteries.
Reference
1. Tomani, P., The lignoboost process. Cellulose Chemistry & Technology, 2010. 44(1): p. 53.
2. Lu, H., et al., Lignin as a Binder Material for Eco-Friendly Li-Ion Batteries. Materials, 2016. 9(3): p. 127.

Figure 1
Reduced Graphene Oxide Sheets Attached Tin Oxalate Dihydrate As a High Capacity Anode for Lithium Ion Rechargeable Batteries
Authors: Park Jae sang , Myung Seung-Taek 
Published: February 2020

Lithium ion batteries have been widely applied as power sources for electronic devices to electric vehicle because of their high energy density, and long cycle life. Commercial graphite is the most commonly used as the anode material for lithium ion batteries. However graphite has its low theoretical capacity (372 mAh g-1). Therefore, to satisfy the growing power requirements, we need to explore alternative materials to replace graphite anode. For these reason, the silicon-based materials, transition metal oxides have been intensively investigated to replace the commercial graphite due to their high capacities, 700 ~ 1000 mAh g-1. Metal oxalate MC2O4 (M : Mn, Fe, Co, Ni, Sn, Cu, Zn) are also interesting because of high capacity. In this study, we synthesize tin oxalate by hydrothermal reaction, of SnCl2ㆍ6H2O (0.001 M), NaC2O4 (0.005 M), distilled water (9 ml), and ethylene glycol (EG, 16 ml) were mixed in a beaker and the mixed solution was stirred at room temperature for 6 h to form transparent solution. This solution was filled in a Teflon-lined autoclave (100ml capacity). This autoclave was sealed and heated at 100 oC - 200 oC for 12 h. After then, the autoclave was cooled to room temperature. The reacted solution were filtered and washed several times with de-ionized water and then dried at 80 oC for 24 h in a convection oven. Also, various contents of rGO were attached by layer by layer method. The obtained powder was analyzed by X-Ray diffraction (XRD, Rigaku, D-max 2000) using CuKα radiation. The XRD data were obtained with 0.03 step size and a 1 s count time. The particle morphologies of the products were analyzed by scanning electron microscopy (SEM, Hitachi, S-4700) and transmission electron microscopy (TEM, Hitachi, H-800). Electrochemical properties were measured in 2032 coin type cell. Electrodes were fabricated from a mixture of the prepared SnC2O4ㆍ2H2O powders (80 wt%), ketjen black (5 wt%), super-P (5 wt%) and polyacrylic acid (10 wt%) in distilled water. The obtained slurry was then applied onto Copper foil and dried in a vacuum oven at 80 oC for 1 h. The electrode was further dried over night at 80 oC under vacuum. The used electrode solution was 1M LiPF6 in a 3 : 7 volume mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) mixture.
The XRD pattern of the products showed single phase SnC2O4ㆍ2H2O and rGO attached both were obtained without impurity. The fabricated cells were charged and discharged in the range of 0 - 3 V applying a constant current of 100 mAg-1 at 25 oC. The bare sample delivered capacity approximately 643 mAh g-1 at initial charge. Also, the delivered capacities increased to 1170, 1220, 1440 mAh g-1 with increasing the amount of rGO (10, 20, 30 wt%). The rate capability demonstrate that the 30 wt% rGO composite SnC2O4ㆍ2H2O / rGO electrode delivered 467 mAh g-1 at 10 C-rate.

Figure 1
Modeling and Simulation of Negative Capacitance Gate on Ge FETs
Authors: Liao Yu-Hung , Fan Sheng-Ting , Liu C. W. 
Published: February 2020

In this work, a polysilicon-ferroelectric (FE) gate capacitor is proposed to be stacked on the Ge-MOSFET to simultaneously maintain the stability and the potential amplification in the sub-threshold region of a Negative Capacitance Field Effect Transistor (NCFET). Hence, the non-hysteresis ID-VG characteristics with sub-60mV/dec subthreshold slope (SS) can be designed. Based on the simulation results, a small signal capacitance model (Fig.1(b)) which includes the effects of gate-to-source/drain overlap, interface trap states at oxide/Ge, and polysilicon/FE/metal is presented.
In the sub-threshold region, the value of -CFE should be as close (but larger) to CMOS as possible to achieve large potential amplification. However, when the strong inversion of the MOS occurs and CMOS increases rapidly, -CFE > CMOS is still required to stabilize the NCFET.[1] The desirable properties can be achieved by utilizing the polysilicon capacitance (Cpoly) which is a function of the applied voltage. The magnitude of the effective CFE’ (=1/(1/CFE + 1/Cpoly)) approaches to CMOS capacitance closely at the subthreshold region and increases when strong inversion of Ge-MOSFET occurs (Fig.2(a)). Hence, a hysteresis-free steep SS NCFET is obtained.
The optimized hysteresis-free polysilicon-FE NCFET achieves SS as low as 43mV/dec in the simulation (Fig.2(b)). Its optimized SS is further improved when the direct S/D overlap with floating metal of Ge-MOSFET increases (Fig.2(b)). On the other hand, the trapped charges in the FE interface will compensate the polarization of the ferroelectric material, and thus degrade the negative capacitance. By tuning the FE thickness and adding fixed charges, its effect on CFE can be balanced through our optimization approach.
Reference:
[1] S. Salahuddin and S. Datta, Nano letters, vol. 8, no. 2, pp. 405–410 (2008).

Figure 1
Effects of Etching Variation on Ge/Si Channel Formation and Resulted Device Behavior
Authors: Chu Chun-Lin , Chen Bo-Yuan Chen , Luo Guang-Li , Li Mei-Yi 
Published: February 2020

As CMOS technology scales down to 22nm, traditional planar transistor architectures have reached a fundamental limit for the required short channel control necessary to continue scaling. For good channel control, 3D transistors such as FinFET, tri-gates, and gate-all-around (GAA) FETs are the preferred devices for the sub-20nm CMOS technologies and beyond. Beside the Si channel, Ge-based systems remain the most interesting for emergent device integration. The Ge epichannel directly on Si can be a low-cost solution for the future Si technology nodes, beside the bulk Ge and the SiGe graded buffer technologies. Ge integrated with Si is not straightforward since the 4% lattice mismatch between Ge and Si generates the misfit and threading dislocations. The misfits of the bottom Ge can be removal by anisotropic etching with sensitivity to the defects. The nearly defect-free Ge channel can be formed for GAA transistors. This work reviews the two major remaining challenges that Ge/Si based devices must overcome if they are to replace Si as the channel material, namely, heterogeneous integration of Ge on Si substrates, and developing a suitable gate stack. Next, adjusting the HBr/Cl2 plasma ratio and bias power, different fin-like field-effect transistor structures can be fabricated. This process allowed for better gate control than conventional rectangular fins due to the GAA Ge/Si Channel fabricated using the process. Etching decided that Ge is compared to Si materials in terms of p-channel device performance to review how it became the first choice for PMOS devices. Different Ge/Si device architectures, including surface channel and device behavior configurations, are reviewed. Finally, state-of-the-art Ge/Si device results and future prospects are also discussed.
(Invited) Selective Epitaxial Growth of High-P Si:P for Source/Drain Formation in Advanced Si nFETs
Authors: Rosseel Erik , Dhayalan Sathish Kumar , Hikavyy Andriy Yakovitch , Loo Roger , Profijt Harald Benjamin , Kohen David , Kubicek Stefan , Chiarella Thomas , Yu Hao , Horiguchi Naoto , Mocuta Dan , Barla Kathy , Thean Aaron , Bartlett Gregory , Margetis Joe , Bhargava Nupur , Tolle John 
Published: February 2020

As CMOS transistors are scaled down beyond N10, the metal/semiconductor contact resistance becomes a dominant contributor to the total parasitic resistance of the FinFET or Nanowire FET. The utilization of highly-P doped Si:P for the selective source/drain epitaxy was previously shown to be a key enabler to achieve a low contact resistivity in combination with a Ti silicide direct contact and Ge pre-amorphization1.
In this paper, we report on the microscopic properties of strained Si:P epitaxial layers with P concentrations up to ~ 4.6 %. We discuss the details of the microstructure and the manifestation of Phosphorus-Vacancy complexes at high Phosphorus concentrations. We analyze how a post-epi thermal budget like spike or laser annealing is modifying the microstructure and leads to an enhanced P activation and diffusion.
In a second part, we zoom in on the different integration aspects of the Si:P layer for advanced bulk finFETs with a sub 10nm fin width and 45nm fin pitch. We discuss the role of the different epi parameters and the benefit of the high-P concentration for the final device performance2.

Acknowledgements

The imec core CMOS program members, European commission, local authorities and imec pilot line are acknowledged for their support.

References

[1] H. Yu et al., 2015 Technical Digest – International Electron Devices Meeting, 2015, Vol. 21.7, p. 592.
[2] T. Chiarella et al., submitted to ESSDERC 2016

Figure 1
AlGaN/GaN High Electron Mobility Transistor Grown and Fabricated on Lattice Matched Metallic Layers
Authors: Ren Fan , Pearton Stephen J. , Ahn Shihyun , Lin Yi-Hsuan , Machuca Francisco , Weiss Robert , Welsh Alex , Smith David , Kravchenko Ivan 
Published: February 2020

AlGaN/GaN high electron mobility transistors (HEMTs) showed its promising features in high power and high frequency applications such as inverter units in hybrid electric vehicles, advanced radar systems, and satellite-based communication networks with its high density of sheet carrier concentration, high electron mobility, and radiation hardness. In order to lower the cost of HEMTs, larger diameters substrates are needed. Currently, the HEMT structures are grown on non-native sapphire, SiC and Si substrates or on native substrate of vapor phase epitaxy (VPE) GaN wafers. HEMTs grown on sapphire substrate suffer from poor heat dissipation and higher defect density due to the relative larger lattice mismatch to GaN. SiC has a very good thermal conductivity and is less lattice mismatch to GaN, but high quality semi-insulating SiC substrates are quite expensive. Although, Si substrates are fair low cost and available for larger diameter substrates, due to larger lattice mismatch to GaN, it requires to grow thick complex AlGaN buffers prior to the growth of GaN layer to reduce the threading dislocation density. These thick AlGaN layers are very defective and thermal resistive, which will hinder device heat dissipation. VPE grown GaN wafers are limited to 2-3” diameter and very expensive. Recently, it was reported that high quality GaN layers were grown by RF plasma-assisted molecular beam epitaxy (PA-MBE) or metal organic chemical vapor deposition (MOCVD) on high-quality, single crystal ZrTi refractory metal alloys deposited by plasma sputtering on c-plane sapphire and Si substrates. These ZrTi refractory metal alloys are not only lattice match to GaN, but have a similar coefficient of thermal expansion (CTE) as the CTE of GaN [1]. By employing these ZrTi alloys, there is no need to grow thick AlGaN buffer, both photonic and electronic GaN based device structure can be grown on large area Si substrates to achieve low cost GaN based device fabrication.
In this work, we have demonstrated AlGaN/GaN HEMTs grown on ZrTi refractory metal alloys, which were deposited on both Si and sapphire substrates. HEMTs with a gate dimension of 1 µm × 100 um were fabricated and characterized. Both dc and rf performance of AlGaN/GaN HEMTs fabricated on the ZrTi metal alloys will be presented.
1. “Epitaxial Growth of High Quality GaN Films on Lattice Matched Metallic Layers”, A.M. Dabiran, F. Machuca, I. De, and R. Weiss, ECS Trans. 66, 113-117 (2015).