bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical and Structural Characteristics of Type I and Type II Silicon Clathrate Anodes
Authors: Li Ying , Raghavan Rahul , Wagner Nicholas , Chan Candace K. 
Published: February 2020

Lithium-ion batteries are one of the most promising energy storage devices due to their high energy density, long cycle life, high voltage, and excellent rate capability. Si is a promising anode material due to its extremely large theoretical capacity of 3579 mAh/g at room temperature. However, the practical use of Si anodes is hindered by the structural failure upon lithium insertion/extraction processes and the low intrinsic electric conductivity.
In our group, we have investigated several different silicon clathrate materials, which have cage-like structures, as anode materials of Li-ion battery. The work to be presented here will discuss the electrochemical and structure characteristics of both type-I and type-II silicon clathrate anodes.
Type-I clathrates, which are synthesized using thermal annealing and arc-melting methods, are made of two pentagonal dodecahedra (Si20) cages and six tet-rakaidecahedra (Si24 cages) per unit cell and crystallize in the Pm3n space group. Results show that ternary type-I clathrates have the ability to allow lithium insertion and removal without a large volume change or pulverization. Type-II clathrates, which are synthesized by thermal decomposition of the Zintl compound, are made of sixteen pentagonal dodecahedra plus eight hexakaidecahedra (Si28 cages) per unit cell and crystallize in the Fd3m space group. Results show that upon electrochemical lithiation the type-II clathrates become amorphous and transform into c-Li15Si4 at low potentials, then remain an amorphous silicide after delithiation. Ex-situ X-ray diffraction, X-ray photoelectron spectroscopy and nuclear magnetic resonance are also employed to understand the structural changes upon lithiation, delithiation and prolonged cycling.
Measurements of SOH Using Stack Stress
Authors: Cannarella John , Arnold Craig B. 
Published: February 2020

In previous ageing studies in which the stack stress of commercially available lithium-ion (LCO/C) pouch cells is monitored during cycling [1], we observe that stack stress (Figs 1a and 2a) is linearly related to cell SOH (Figs 1b and 2b) as shown in Figs 1c and 2c [2]. The increase in stack stress is attributed to irreversible volumetric expansion of the anode which we assume to be related to SOH. This suggests the possibility of using stress to measure SOH, a method whose simplicity provides a distinct advantage to conventional computationally intense methods which rely on complex physical models of the underlying cells. Stack stress could be used as a standalone SOH monitoring system, or integrated into existing battery management systems to increase management fidelity. In this talk we investigate the origins of the stress-SOH relationship.
We report the following data from ageing studies of cells cycled under different conditions: temporal stack stress evolution, capacity evolution, non-destructive differential voltage spectroscopy analysis, and destructive post-mortem analysis. All of the temporal stress and capacity data show a t1/2 dependence suggestive of a diffusion limited mechanism such as SEI growth, as seen in Figs. 1d and 2d. This assertion is corroborated by the differential voltage spectroscopy measurements and destructive post mortem analysis, which also show evidence of a SEI growth mechanism. Stack stress is also observed to increase in cells held at 4.2V in the absence of cycling as shown in Fig. 2a, supporting the notion of a chemical mechanism. Based on the assumptions of an SEI growth mechanism, we present simple scaling arguments which predict a linear relationship between stack stress and SOH. We discuss the implications for this method and model as it applies to battery management systems and fundamental ageing studies.
REFERENCES
[1]. J. Cannarella, C. B. Arnold, “Stress evolution and capacity fade in constrained lithium-ion pouch cells,” J. Power Sources
245 (2014) 745-751.
[2]. J. Cannarella, C. B. Arnold, "State of health and charge measurements in lithium-ion batteries using mechanical stress," submitted.

FIGURE CAPTIONS

Figure 1. Data from a cell aged by cycling under a C/2 CCCV scheme showing (a) stack stress as a function of cycle, (b) C/10 capacity as a function of accumulated cycles, (c) stack stress as a function of SOH, and (d) t1/2 dependence of the C/10 capacity data.

Figure 2. Data from a cell aged by holding at 4.2V at room temperature and periodic cycling at C/10 to measure capacity showing (a) stack stress as a function of time, (b) C/10 capacity as a function of time, (c) stack stress as a function of SOH, and (d) t1/2 dependence of the C/10 capacity data.
ACKNOWLEDGEMENTS
Support was provided by the DoD through the NDSEG Program and by the Siebel Energy Challenge. J. C. also acknowledges the Rutgers-Princeton IGERT in Nanotechnology for Clean Energy.
In-Situ Nanomechanical Measurement of High-Capacity Battery Materials Using MEMS Cantilevers
Authors: Cheng Mark Ming-Cheng 
Published: February 2020

This paper investigates a bilayer cantilever for a sensitive and quantitative measurement of the mechanical stress of high-capacity battery materials during electrochemical cycles. Silicon is a promising candidate for anode materials thanks to its high specific capacity (4200 mAh/g). One of the main challenges for silicon anode is the large volume expansion (~400%), causing material degradation and pulverization of the electrode [1-2]. In-situ characterization of stress evolution is critical because it enables the development of nanostructures and nanocomposites in order to enhance mechanical integrity [3-4].
As shown in Fig 1, the bilayer cantilever consists of an active material and copper. Copper is used as a mechanical structure because of its good mechanical properties as well as its popular use as a current collector in anode. During lithiation, where lithium ions are inserted in silicon, the anode is subjected to compressive stress and the cantilever curls up. Similarly, the anode experiences tensile stress during delithiation and the cantilever curls down. The bending of a bilayer cantilever is described by a Timoshenko beam theory. The active material (250nm α-Si) was used as a working electrode, and faced lithium metal (as a counter and a reference electrode). A separator was placed between two electrodes in order to prevent an electrically short circuit. Electrolytes (1 mol LiPF6in ethylene carbonate and dimethyl carbonate with 1:1 ratio) were filled in the chamber. A white light interferometry was used to determine the deformation of the cantilever during electrochemical cycles that was controlled by a potentiostat. Figure 2 shows the voltage vs. time and a corresponding stress profile during the first five cycles. Interestingly, during the first lithiation, the stress did not increase rapidly when the voltage was larger than 300mV, indicating the formation of solid-electrolyte interfaces (SEI). SEI was a result of the decomposition of electrolytes. When the voltage was smaller than 300mV, compressive stress reached -0.3GPa. Then the compressive stress slightly decreased at a lower voltage, probably due to the material cracking. The tensile stress appeared during delithiation. As we observed, the anode material experienced a dynamic change of stress during the first five cycles. Figure 3 shows the surface morphology of silicon anode before and after cycling. Silicon was initially uniformly coated, but many cracks were generated during electrochemical cycles due to mechanical stress.

REFERENCES:

[1] A. Magasinski, et al., Nat
.
Mater
., vol. 9, pp. 353-358, 2010.
[2] R. Teki, et al., Small, vol. 5, pp. 2236-2242, 2009.
[3] S.J. Lee, et al., J. Power Sources, vol. 97-8, pp. 191-193, 2001.
[4] V.A. Sethuraman, et al, J. Power Sources, vol. 195, pp. 5062-5066, 2010.
Electrolytes and Interphases for Beyond Li-Ion Chemistries
Authors: Xu Kang 
Published: February 2020

With the intrinsic limit of energy density being approached in Li ion chemistry, there have been extensive efforts aiming at breaking out this limit set by the storage mechanism where only one Li+ could be accommodated per transition metal element. Among the so-called “beyond Li ion” chemistries, in which inert masses are kept at minimum, the electrode integrity is often sacrificed for high specific capacities, which presents severe challenge to the electrode/electrolyte interphases. Understanding the interactions between these new materials and electrolytes and the concomitant interphases would play significant roles in determining their future successes.
This presentation will overview the electrolyte and interphase in these nascent battery chemistries, while emphasizing the most recent breakthroughs achieved in electrolytes and interphasial chemistry in Li/S system..
A Technical and Operational Perspective on the DOE Energy Innovation Hub in Fuels from Sunlight, the Joint Center for Artificial Photosynthesis
Authors: Lewis Nathan S. 
Published: February 2020

The design of highly efficient, non‐biological, molecular‐level energy conversion “machines” that generate fuels directly from sunlight, water, and carbon dioxide is both a formidable challenge and an opportunity that, if realized, could have a revolutionary impact on our energy system. Basic research has already provided enormous advances in our understanding of the subtle and complex photochemistry behind the natural photosynthetic system, and in the use of inorganic photo‐catalytic methods to split water or reduce carbon dioxide–key steps in photosynthesis. Yet we still lack sufficient knowledge to design solar fuel generation systems with the required efficiency, scalability, and sustainability to be economically viable.
In the DOE Energy Innovation Hub, the Joint Center for Artificial Photosynthesis, we are developing an artificial photosynthetic system that will only utilize sunlight and water as the inputs and will produce hydrogen and oxygen as the outputs. We are taking a modular, parallel development approach in which the three distinct primary components-the photoanode, the photocathode, and the product-separating but ion-conducting membrane-are fabricated and optimized separately before assembly into a complete water-splitting system. The design principles incorporate two separate, photosensitive semiconductor/liquid junctions that will collectively generate the 1.7-1.9 V at open circuit necessary to support both the oxidation of H2O (or OH-) and the reduction of H+ (or H2O). The photoanode and photocathode will consist of rod-like semiconductor components, with attached heterogeneous multi-electron transfer catalysts, which are needed to drive the oxidation or reduction reactions at low overpotentials. This talk will discuss a feasible and functional prototype and blueprint for an artificial photosynthetic system, composed of only inexpensive, earth-abundant materials, that is simultaneously efficient, durable, scalably manufacturable, and readily upgradeable, including both the operational and technical scope of the JCAP Hub, as well as technical results towards this goal that has recently been developed at Caltech.
New Titanate Negative Electrode Materials for Na-Ion Batteries
Authors: Fielden Ryan I , Obrovac Mark N 
Published: February 2020

Introduction

Lithium-ion batteries are widely used because they are lightweight, have a high energy density, and can be cycled many times. Sodium-ion has shown promise as a potentially lower cost, more sustainable battery chemistry [1]. Titanates have been investigated for use as anode materials in Na and Li cells [2]. However they are non-conductive, requiring the use of large amounts of carbon black to cycle [3]. We have found new titanate phases that can reversibly intercalate Na as bulk micron-sized particles without the need for large amounts of carbon black.

Experimental

Samples were synthesized via heating precursors to 900 °C for 10 hours in argon. A 10 % Na excess was added due to the volatility of Na at these elevated temperatures. Products were found to be air or moisture sensitive. Samples for X-ray diffraction measurement were loaded under argon into an air-tight sample holder with an aluminized Mylar window. The sample holder was purged with He gas during XRD measurement. Electrodes comprising active materials, carbon black and PVDF binder in a 80:10:10 weight ratio were cast using NMP as a solvent and dried at 120°C. Electrodes were cycled in 2325 coin type cells at a rate of C/10 (assuming a 100 mAh/g capacity) using Na metal counter/reference electrodes and 1M NaPF6in PC electrolyte.

Results and Discussion

Figure 1 shows a voltage curve of a new titanate negative electrode material. In-situ XRD shows that reversible Na-insertion occurs via an intercalation mechanism in which the titanate's volume only expands by 1.6% after full sodiation. The volumetric capacity of the titanate is 400 Ah/L, which is comperable to that of hard carbon.
To our knowledge, this is the first demonstration of intercalation of sodium into bulk oxides at such low voltages without the use of large amounts of carbon black. The use of these new titanate phases presents a new strategy towards making negative electrodes for Na-ion cells, from which high energy density bulk intercalation materials may be developed.

References:
[1] M.D. Slater et al., Adv. Funct. Mater., 23(2012) 947-958.
[2] L. Zhao, Journal of Power Sources, 242(2013) 597-603.
[3] P. Senguttuvan et al., Chem. Mat., 23(2011) 4109.
Figure 1 Voltage curve of a new titanate negative electrode vs. sodium metal.
Application of a New Co-Polyimide Binder Material to Improved High-Temperature Performance for Lithium-Ion Batteries
Authors: Choi Jaecheol , Song Seonghyun , Cho Insung , Cho Kuk Young , Lee Yong Min 
Published: February 2020

Lithium-ion batteries (LIBs) have been widely used for mobile IT devices and various electric vehicles (xEVs). Especially, since large-format LIBs are operated in the severe environments like -30 or 60 oC, their electrochemical performances and safety should be secured for at least 10 years. Recently, Yoon et al. reported that the degradation was closely related to the contact loss at the electrode/current collector interface and between active material particles1. Thus, the dimensional stability of electrode should be maintained even at high temperatures.
In this study, the effects of a thermally stable co-polyimide-based polymeric binder on the performance of a cathode electrode are investigated. The introduction of co-polyimide (P84) into a conventional polymeric binder system based on polyvinylidene fluoride (PVdF) enhances the cycle performance under high temperature conditions (60 oC). Because of the inherent mechanical and thermal stabilities of the co polyimide, P84 retains outstanding adhesive/cohesive strength within the electrode composite, as well as between the electrode composite and the aluminium current collector. These findings are further supported by electrochemical impedance spectroscopic analysis, scanning electron microscope, and studies using a Surface and Interfacial Cutting Analysis System (SAICAS®) 2.

References

[1] T. Yoon, S. Park, J. Mun, J.H. Ryu, W. Choi, Y.-S. Kang,J.-H. Park, and S.M. Oh, J. Power Sources 215(2012) 312-316
[2] B. Son, M.-H. Ryou, J. Choi, T. Lee, H. K. Yu, J. H. Kim, and Y. M. Lee, ACS Appl. Mater. Interfaces, 6 (2014) 526-531

Acknowledgements

This research was financially supported by Chungcheong Leading Industry Promotion Project of the Korean Ministry of Trade. The authors also thank Sungmoon Systech Corp. in Korea for SAICAS® measurement.
Synthesis and Characterization of Flexible and Free-Standing Carbon Nanotube, Graphene Films and Their Composites for Li-Ion Batteries
Authors: Mery Adrien , Luais E. , Autret C. , Van F. Tran , Ghamouss F. 
Published: February 2020

The objective of this communication is to present our results on the synthesis and the characterization of flexible and free standing films made from Carbon Nanotube (CNT), reduced graphene oxide (rGO) [1] and their composites (CNT/rGO). The films were obtained by filtration method from aqueous suspension of CNT, rGO, or CNT/rGO. The obtained materials are used as negative electrode in Li-ion systems. CNT films with a thickness below 50 µm are integrated on an electrodeposited Cu current collector (15 µm thick) according to the method describe by
Luais et al

[2], whereas CNT or CNT/rGO flexible free standing films with a thickness of 50 µm can be directly used without the need of a metallic current collector as anode material for battery cycling. All results will be discussed on the basis of SEM observations (as synthetized films and after cycling for post-mortem characterizations), Raman spectroscopy analysis, galvanostatic cycling, and electrochemical impedance spectroscopy. CNT free standing electrodes exhibit specific discharge capacities up to 300 mA.h.g-1 at C/20 and 200 mA.h.g-1at 5C. The effect of rGO/CNT ratio in composite electrodes will be presented as an improvement of the electrochemical performances compared to CNT free standing electrodes.

Figure : a-Evolution of the specific capacity of CNT free standing film in Li-ion half-cell. SEM images of b1: as synthetized free standing CNT film, and b2: after cycling in EC/PC/3DMC 1M LiPF6 electrolyte; Photographs of c1: a flexible free-standing film, and c2: the same film roll up around a plastic rod

[1] Qian Cheng, Jie Tang, Jun Ma, Han Zhang, Norio Shinya, Lu-Chang Qin, CARBON 49 (2011) 2917–2925
[2] E.Luais, J. Sakai, S. Desplobain, G. Gautier, F. Tran-Van, F.Ghamouss. Journal of Power Sources, 242, 2013,166-170
Template-Free Electrochemical Synthesis of Cuprous Oxide and Its Application to Anode of Lithium Ion Batteries
Authors: Shin Jeong Ho , Park Sun Hwa , Hyun Seungmin , Park Hyun Min , Song Jae Yong 
Published: February 2020

Cu2O has been investigated as a candidate of the promising anode materials for Lithium ion batteries (LIB) due to its several advantages such as reversible mechanism with Li ion, relatively low-cost, non-toxicity, and higher theoretical capacity than graphite. However, the Li ion charge and discharge (C-D) processes accompany huge volume expansion and shrinkage, by which mechanical stresses are induced and lead to poor C-D cycle life due to the failure of the contacts between anode material and current collector. In order to avoid the drawbacks of large volume change in anode material, several efforts have been taken to use Cu2O nanopowders as an anode. However, the usage of nanopowders requires additional conductive carbon sources or binders which are disadvantageous in simplifying fabrication process and lowering cost.
In this talk, we present a template-free and surfactant-free electrochemical nanosynthesis of single crystalline Cu2O nanostructures. The electrochemical growth of Cu2O nanostructures originated from filamentary effect related to the electric field enhancement on the pyramidal Cu2O grains in an ultra-dilute CuSO4 aqueous electrolyte. The synthesized Cu2O nanorods showed much more excellent electrochemical properties as an anode material for LIBs than Cu2O films; the electrochemical capacities exceptionally increased from 340 to 1249 mAh/g during 500 cycles exceeding the theoretical capacity of Cu2O. The capacity enhancement was due to the phase transformation from Cu2O to CuO, nanostructuring from nanorods to fragmented nanoparticles, and progressive generation of electroactive polymeric gel-like layer on the surface of the nanoparticles. The present nanostructuring of Cu2O is expected to contribute to the development of higher capacity LIBs in near future.
Characterization of a Lithium Ion Battery Based on Carbon-Coated Lithium Sulfide Cathode and Electrodeposited Silicon Based Anode
Authors: Agostini Marco , Liu Jun , Jeong Moongook , Nara Hiroki , Momma Toshiyuki , Scrosati Bruno , Sun Y.-K. , Osaka Tetsuya , Hassoun Jusef 
Published: February 2020

In the latest years there has been an increasing interest in the wide spread of electric vehicles (EVs) and hybrid vehicles (HEVs) with the final goal of the reduction of greenhouse gas emission and atmosphere pollution in large metropolitan areas. Clearly, the success of this operation depends on the availability of an efficient power source for the electric engine. Due to his high energy density, the lithium-ion battery is as an ideal candidate.
1
However, although appropriate for the consumer electronic market, the present lithium-ion battery technology is still inadequate for the electric road transportation one. Improvements in energy density and safety, as well as reduction in cost, are mandatory steps to meet the EV and HEV severe targets.
2
To achieve these operative improvements, battery chemistries alternative to intercalation are required.
3-4
A very promising example is provided by the lithium-sulfur battery, characterized by a conversion chemistry leading to high specific energy, i.e. of about 2600 Wh kg-1,combined with the low cost of the earth abundant sulfur. However, several issues still prevent the practical development of this battery, including the solubility of polysulfides in the course of the discharge process and the high resistance, almost insulating nature of both reactants and products; furthermore the safety hazard associated with the use of lithium metal as anode. These issues have been recently addressed by modifying the electrolyte formulation and developing microstructured/nanostructured carbon conductive matrixes.
5
Despite the replacement of the lithium metal anode with an alternative material is mandatory to assure the practical development of Li/S battery, surprisingly there are not many examples of efficient Li-ion sulfur batteries. In this work we report a new type of rechargeable lithium-ion battery based on the combination of a high capacity Si-O-C anode with a high-rate Li2S-MCMB (Mesophase Carbon Micro Beads) composite in a tetraglyme electrolyte. We show that this Si/Li2S battery operates around 1.4V, delivering a very stable capacity of about 280 mAh gLi2S-1 with a resulting theoretical energy density of the order 400 Wh kgLi2S-1.
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[2] M. Armand and J.M. Tarascon, Nat. 2008, 451, 652.
[3] K. Cai, M.K. Song, E.J. Cairns, Y. Zhang, Nano Lett. 2012, 12, 6474.
[4] Y.K. Sun, S.T. Myung, B.C. Park, J. Prakash, I. Belharouak, K. Amine, Nat. Mater. 2009, 8(4),
320.
[5] X. Ji, K.T. Lee, L.F. Nazar, Nat Mater. 2009, 8(6), 500.