bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spontaneous Formation of Diazonium Salts Thin Films on Silicon Electrodes
Authors: Peiris Malwattage Chandramalika Rukmali , Ciampi Simone , Darwish Nadim 
Published: February 2020

Future of electronics will require using single molecule as the active component in electric circuitry. In that vein our group and others have developed single molecule switches1,2, single molecular diodes3, single molecular resistors and transistors4. All these previous studies utilized alkynes, amines, thiols as anchoring groups to metals (mostly on gold (Au)). Despite the popularity of the S-Au linkers, they are mechanically unstable and their contact resistance is variable which complicates device fabrication. To realize molecular electronics devices a change towards more robust contacts is needed. In this study, we show that molecular contacts of o-Dianisidine bis(diazotized) zinc double salt (bis diazo) on silicon (Si) can be made electrochemically and also spontaneously without the need of external electric field (Figure 1a) and can be potentially extended to other types of electrodes. The thin films were characterized electrochemically by spontaneously attaching ferreocene to the distal end of the bis diazo molecule and by using X-ray Photoelectron Spectroscopy (XPS), X-ray Reflectometry (XRR), Atomic Force Microscopy (AFM). Furthermore, electrochemical reduction of bis diazo molecule on different crystalline faces of Si were studied (Figure 1b). We found that Si <111> reduction wave occurs at more positive potential then that observed for Si <100>. To confirm these assignments we have created Si <111> pyramids on Si <100> surface by anisotropic etching in 20% KOH solution. By doing so, we have created a mixed <111/100> surface that can probe in-situ the difference in the electrochemical reduction between the two crystal faces (Figure 1 c). These types of diazonium salts could be used as molecular diodes, devices since they can spontaneously attach to both gold and silicon.
References

N. Darwish, M. N. Paddon-Row and J. J. Gooding, Acc. Chem. Res., 47, 385 (2013).

N. Darwish, A. C. Aragonès, T. Darwish, S. Ciampi and I. Díez-Pérez, Nano Lett., 14, 7064 (2014).

A. C. Aragonès, N. Darwish, S. Ciampi, F. Sanz, J. J. Gooding and I. Diéz-Pérez, Nat. Commun., 8 (2017).

M. L. Perrin, E. Burzurí and H. S. J. van der Zant, Chem. Soc. Rev., 44, 902 (2015).

Figure 1. a) Cyclic voltammogram of a thin film of bis diazo spontaneously grafted on n-type Si <111> (resting in a solution of bis diazo for 2 h on Si <111> surface and then exposed to a solution of ferreocene, scan at 0.2 V/s) b) Cyclic voltammetry of a the reduction of bis diazo on n-type Si <111> (red line (a)) and <100> (black line (b)) at scan rate 0.05 V/ s c) Potential difference in the electrochemical reduction between the two crystal faces on the pyramid surface .

Figure 1
Functionalized GaAs Photocathodes for Spin-Dependent Charge Transfer Studies
Authors: Tamski Mika , Blumenschein Felix , Roussel Christophe , Ansermet Jean-Philippe 
Published: February 2020

Chiral-Induced Spin Selectivity (CISS) is a well-documented phenomenon occurring at electrochemical interfaces, where chiral functional groups can hinder the transfer of electrons with a specific spin state, while allowing the electrons with an opposite spin state to be transferred to the electroactive species in the solution.1,2

Spin dependent electron transfer has also been observed at p-GaAs/electrolyte interface without chiral functionalities, relying on the spin selectivity between polarised electrons in the conduction band (CB) of the p-GaAs and spin-oriented radical species in the solution.3,4

Here we report spin-dependent charge transfer in electrochemistry, where the spin selectivity is achieved by manipulating the electron spins of a radical redox mediator in the sample solution using microwaves (MW) under resonance conditions. This work has required us to characterise the photocathodic behaviour of p-GaAs in contact with methyl viologen radical cation (MV+•) in organic solvents under very low light intensities, a domain not traditionally covered in semiconductor electrochemistry.
We have also contrasted the behaviour of the bare p-GaAs to biphenyl- and peptide-functionalised surfaces, showing that the parasitic valence band (VB) and surface state (SS) mediated processes can be completely avoided. In the future, we hope that these functionalised surfaces allow us to increase the spin-dependent signal intensity, as the probability of electron’s spin state relaxing due to parasitic processes can be minimised.

Figure 1
Recent Progresses in Ionic Liquid-Based Electrolytes for Hybrid Multivalent Metals Secondary Batteries
Authors: Pagot Gioele , Vezzù Keti , Nale Angeloclaudio , Negro Enrico , Greenbaum Steven , Di Noto Vito 
Published: February 2020

The seeking of stable and high-performing electrolytes is the major bottleneck to the development of future secondary batteries belonging to the so-called beyond Li-ion technology. In particular, electrolytes able to reversibly deposit and strip multivalent metals seem to be the answer to the growing energy demand requested by the Electric Vehicles market. Indeed, the multi-electron chemistry could ensure a higher energy value per moles of active material.
In this concern, Ionic Liquids (ILs) are considered attractive materials thanks to their low volatility, negligible flammability and good electrochemical performance in the metal reversible deposition processes [1-3]. Indeed, it was recently demonstrated that these electrolytes are able to deposit and strip magnesium/metal alloys with Coulombic efficiencies higher than 99%, overpotentials lower than 50 mV vs. Mg/Mg2+ and remarkable current densities (Fig. 1).
In this report, an overview on the most recent progresses in IL-based electrolytes for hybrid multivalent metals secondary batteries will be given. A detailed description of the interplay between structure and conductivity of ionic species will be presented. Finally, the relationships existing among metal ion speciation, long-range charge migration processes and electrochemical performances of these materials will be elucidated.

References:
[1] G. Pagot, F. Bertasi, K. Vezzù, E. Negro, S. Greenbaum and V. Di Noto, under submission.
[2] G. Pagot, F. Bertasi, K. Vezzù, F. Sepehr, X. Luo, G. Nawn, E. Negro, S.J. Paddison and V. Di Noto, Electrochim. Acta 2017, 246, 914-923.
[3] F. Bertasi, C. Hettige, F. Sepehr, X. Bogle, G. Pagot, K. Vezzù, E. Negro, S.J. Paddison, S.G. Greenbaum, M. Vittadello and V. Di Noto ChemSusChem 2015, 8, 3069-3076.

Figure 1
Proton Dissociation and Transfer in Protic Ionic Liquids (PILs)
Authors: Zhu Zhenghao , Luo Xubo , Paddison Stephen J. 
Published: February 2020

Protic ionic liquids (PILs) have attracted significant attention due to their promising properties and potential use in various applications. Recent studies revealed exceptionally strong decoupling of proton conductivity from structure relaxation in a mixture of lidocaine with phosphoric acid.1 Proton conductivity in this mixture even exceeds that of phosphoric acid at the same viscosity. Both lidocaine and phosphoric acid have proton donor and acceptor sites that facilitates the formation of a well-connected hydrogen bond network contributing to their high proton diffusivity. Thus, it is necessary to study the effects of the molecular geometry of both the acid and base, the number of the proton donating and accepting sites on the acid and base, and the solvation on the proton dissociation and transfer.
In this study, fully optimized structures of pairs and clusters of the phosphoric acids (PAs) with different bases (lidocaine, imidazole, creatinine, and trimethylammonium) were determined through ab initio electronic structure calculations at the B3LYP/6-311G** level of theory in both the gas phase and the SMD model. The molecular binding energies of PA and the base molecules were calculated from both the uncorrected and zero point energies (ZPEs) corrected total electronic energies based on the same level of theory. Subsequently, potential energy surface (PES) scans for the transfer of a proton for pairs and clusters of the acids with various bases were performed at the same level of theory to study the effects of different bases and the number of PAs on the dissociation of PA and the proton transfer energetics. The results reveal that dissociated protons are generally more favorable in the SMD model since the continuum solvation model stabilizes the charge separation.

Reference:

1. Z. Wojnarowska, Y. Wang, K. J. Paluch, A. P. Sokolov, M. Paluch, Observation of highly decoupled conductivity in protic ionic conductors. Phys.Chem.Chem.Phys
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, 16, 9123-9127.
High Energy SAXS-Waxs Studies on the Fluid Structure of Molten LiCl-Li Solutions
Authors: Guo Jicheng , Merwin Augustus , Benmore Chris , Mei Zhi-Gang , Hoyt Nathaniel C. , Williamson Mark A. 
Published: February 2020

Molten mixtures of lithium chloride and metallic lithium (LiCl-Li) play an essential role in the electrolytic reduction of various metal oxides. These mixtures possess unique high temperature physical and chemical properties that have been researched for decades. However, due to their extreme chemical reactivity, no study to date has been capable of definitively proving the basic physical nature of Li dissolution in molten LiCl. In this study, the evolution of structures of the molten LiCl-Li, as metallic Li is electrochemically introduced into the melt, is investigated in situ using synchrotron radiation based high energy wide angle X-ray scattering (WAXS) and small-angle X-ray scattering (SAXS). The scattering results indicate the presence of Cl- ion “cages” with size of approximately 7.9Å, which suggests the formation of Li nanoclusters as previous reported. The structure factor of the melt derived from the SAXS results is in agreement with that obtained from ab-initio molecular dynamics (AIMD) simulation of lithium nanoclusters (Li4, Li6 and Li8) in LiCl. A physical model based on the formation and suspension of metallic Li nanocluster in lithium chloride is proposed to explain various phenomena exhibited by these solutions that were previously unexplainable.
The submitted abstract has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357. The U.S. Government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the Government. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan. http://energy.gov/downloads/doe-public-access-plan
(Invited) Discovery of New Capacity Fade Mechanism in Lixsn Batteries with Derivative Operando (dOp) NMR Spectroscopy
Authors: Lorie Lopez Jose L. , Grandinetti Philip J. , Co Anne C. 
Published: February 2020

Tin, silicon and other intermetallic forming electrodes have large volumetric lithium capacities—nearly 10 times that of graphite. Such a high capacity combined with their low cost make intermetallics promising materials for the next generation of rechargeable batteries. Unfortunately, severe capacity fade remains the greatest obstacle in their commercial use. For example, in 2005 Sony introduced their NEXELION battery technology using nanostructured SnCo electrodes but eventually had to pull these batteries from the market due to substantial capacity loss with cycling. While a major reason for capacity fade in these electrodes is thought to be cracking from large volume changes during transitions between intermetallic phases, little evidence for cracking in nanostructured electrodes has been found; and the mechanism for capacity fade in nanostructured intermetallic electrodes has remained a mystery.
Using derivative operando (dOp) 7Li NMR we have discovered a mechanism for capacity fade in LixSn nanoparticle electrodes that may solve this mystery. In short, the capacity fade in nanoparticle electrodes is the result of nanopar- ticles losing contact with the carbon/PVDF binder. Yet, it occurs in a peculiar way which causes the cell to reach full capacity at the end of every cycle on lithiation. In other words, capacity fade only occurs during delithiation. We present clear NMR evidence showing that particle disconnection occurs during the delithiation (volume contraction of the electrode particles) process. During lithiation (volume expansion of the electrode particles) our NMR data further reveals that connected particles are surprisingly pushed back into contact with the disconnected particles which then rejoin the circuit and allow the cell to reach full capacity on lithiation. Our dOp 7Li NMR spectra also reveal the structural transformation pathways between Li-Sn intermetallics during lithiation and delithiation of Sn nanoparticles. The disconnecting particles are associated with LixSn phases undergoing large decreases in diameters on delithiation, i.e., Sn, Li2Sn5, LiSn, and Li7Sn3. The Li–Sn phases observed are somewhat consistent with the structural evolution expected from the equilibrium binary phase diagram, but there are some notable exceptions with the observation of a metastable phase Li2Sn3, and two vacancy rich metastable phases, Li7−ζSn3, and Li13−δSn5 during delithiation.
Although this new capacity fade mechanism is simple, we know no in-situ microscopy method capable of detecting and following such a disconnection-connection mechanism. Our approach clearly show the power of operando NMR spectroscopy for revealing such fundamental processes. These results point the way for future efforts in both industrial and academic research labs to reduce capacity fade in a wider range of nano-structured intermetallic electrodes, involving Si, Ge and Sb.

Figure 1
Tripling the Energy Density of Insertion-Type Electrode Materials for Rechargeable Alkali-Ion Batteries By Introducing Carefully Selected Dopants
Authors: Ma Yanjiao , Passerini Stefano , Bresser Dominic 
Published: February 2020

Targeting continuously increasing energy and power densities for the next generations of rechargeable alkali-ion batteries like lithium-ion and sodium-ion batteries (LIBs and SIBs), researchers worldwide are trying to develop new electrode materials which are capable of hosting more lithium/sodium ions per unit weight or volume.[1]–[4] Ideally, these new materials also allow for a fast delithiation/desodiation and, even more important, lithiation/sodiation, i.e., the charge step. This is a particular challenge for insertion-type materials, which are commonly used at present in commercial LIBs. In fact, it is frequently written that the insertion mechanism sets an intrinsic limit to the achievable lithium storage capacity.
Herein, we show that the introduction of carefully selected dopants provides the chance to double or even triple the capacity of insertion-type lithium- and sodium-ion anodes. Based on an in-depth characterization down to the atomic scale, we will moreover provide general guidelines for achieving such improvement and, eventually, present also their employment in high-performance lithium-ion and sodium-ion full-cells, offering an outstanding combination of high energy and high power, as shown in Figure 1 and Table 1.
[5]–[12]

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[12] J. Xu, Y. Li, L. Wang, Q. Cai, Q. Li, B. Gao, X. Zhang, K. Huo, P.K. Chu, Nanoscale
2016, 8, 16761.

Figure 1
X-Ray Photoelectron Study of the Binder/Electrode Interface on Silicon Anodes for Lithium Ion Batteries
Authors: Johnson Richard , Waller Gordon H. , Nadimpalli Siva 
Published: February 2020

Polymeric binders are a critical component of all composite electrodes used in today's lithium ion batteries (LIB). Binders keep active material and conductive additive mixture together, while also adhering this mixture to the current collector. At the particle level the binder forms bridges between particles of active material. Failure of these bridges contributes to electrical isolation of active material and thus poor cyclic life. the mechanical strength of these binder bridges is of key interest to understand the failure mechanisms of LIBs. Failure of binder bridges is highlighted in LIBs that incorporate Li-alloy forming anode materials such as Si which are known to degrade due to expansion and contraction during cycling. Meanwhile, the formation of solid electrolyte interphase (SEI) can also exacerbate capacity loss in novel anode materials, however the contribution of the binder to SEI formation and stability of alloying anodes has not been emphasized. Favorable interface properties between binder and active material resulting in good adhesion is desirable for anodes which encounter larger stresses during cycling.
The objective of this study is to understand the effect different polymer binders have on the nature, formation, and location of the SEI layer of silicon based anodes. In this study crystalline Si wafers coated with thin films of CMC and PVDF binders were utilized. No conductive additives were used. Half cells containing either bare crystal Si or a wafer with a thin film of CMC or PVDF were cycled in a standard lithium-ion electrolyte (1 molar LiPF6 in 1:1:1 vol. ratio of EC:DC:DMC) to form a stable SEI. After cycling, the cells were opened in an inert atmosphere and x-ray photoelectron spectroscopy (XPS) was carried out to analyze and compare the surface chemistries. Depth profiling was then conducted utilizing C-60 fullerene ions opposed to the conventional Ar ion milling probe due to the known issue of chemical degradation caused by the Ar ion milling. In addition, the morphology of the substrates and binder films were characterized by SEM.
Preliminary results indicate that binder layers on the order of hundreds of nm thick do not impede the lithiation and delithiation of Si (Figure 1A) but do play a role in the SEI composition (Figure B-D). These results can help inform the optimization of current and advanced composite electrodes for commercial LIB.

Figure 1
(Invited) Towards the Realization of Sustainable High-Performance Lithium-Ion Batteries: Aqueous Processing of Cobalt-Free High-Energy Cathodes
Authors: Kuenzel Matthias , Kazzazi Arefeh , Kim Guk-Tae , Bresser Dominic , Passerini Stefano 
Published: February 2020

The recently rising awareness for a more sustainable cell manufacturing can be expected to gain even more momentum in sight of the announcements from major car manufacturers across Europe and North America to entirely electrify their fleet within the next half-decade1,2. The implementation of aqueous electrode processing strategies for lithium-ion cathodes is a key step to realize the environmentally benign battery production. To achieve this ambitious goal, most studies focus on the development of non-toxic and abundant active materials and specifically, the implementation of nature-derived, inexpensive binders in combination with the use of water as dispersion agent and solvent provides the great possibility to spare energy-intensive drying procedures and costly dry-room conditions, and thus, will turn the whole battery fabrication more eco-efficient 3,4.
What could easily be established for graphite anodes – employing water-soluble natural polymers as binder, thus, abolishing the need of toxic and rather costly N-methyl-2-pyrrolidone (NMP) as processing solvent3,5 – appears more complicated for transition metal oxide-based and imperatively cobalt-free cathode materials, which suffer from lithium leaching and transition metal dissolution when getting in contact with water, which has, so far, rendered the use of aqueous binders very challenging6,7.
In our group we recently demonstrated the general feasibility for the aqueous processing of several lithium-ion cathode materials, such as high-voltage LiNi0.5Mn1.5O4, by introducing a complementary approach, of suitable processing additives to stabilize the active material surface as well as the electrode/electrolyte/current collector interface8. Moreover, we extended our investigations to various binder systems and cathode materials in order to advance the aqueous electrode preparation and move from the well-established lab-scale process towards the fabrication of commercial-scale lithium-ion batteries9.

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A. Kwade et al., Nat.
Energy, 3, 290–300 (2018) http://www.nature.com/articles/s41560-018-0130-3.

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N. Loeffler et al., ChemSusChem, 9, 1112–1117 (2016).

M. Kuenzel et al., ChemSusChem, 11, 562–573 (2018).

A. Kazzazi et al., ACS Appl. Mater. Interfaces, 10, 17214–17222 (2018).