bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Stiffness in Anodes and Cathodes for Lithium Ion Batteries
Authors: Gewirth Andrew A. , Tavassol Hadi , Jones Elizabeth M. C. , Esbenshade Jennifer , Sottos Nancy R. 
Published: February 2020

Higher power and charging rates are essential for large scale adoption of lithium-ion batteries in transportation applications. While lithium-ion batteries are ubiquitous in portable electronics, their performance and lifetime suffer during high rate charging and high power discharging. In such extreme electrochemical conditions, the mechanical response of electrode materials governs their degradation behavior. Here, we present a new technique to probe the electrochemically-induced mechanics of electrodes by calculating the electrochemical stiffness of electrodes via coordinated in situ stress and strain measurements. Through the electrochemical stiffness, we elucidate inherent and rate-dependent mechanical responses of graphitic battery electrodes. We find that stress and strain are asynchronous as shown in the figure. In particular, stress development is found to lead strain development as different graphite-lithium intercalation compounds are formed. Additionally, our analysis reveals inversely scaled rate-dependent behaviors for stress and strain responses. Stress scales as scan rate while strain scales with charge (or, equivalently, capacity). These measurements provide a new paradigm for understanding mechanical effects in intercalation systems, such as batteries. Stress arises as resistance to lithiation, while strain arises as a consequence of lithiation. Electrochemical stiffness measurements provide new insights into the origin of the rate-dependent chemo-mechanical degradations, and provide a probe to evaluate advanced battery electrodes.
We also report on our efforts to stabilize LiMn2O4 (LMO) -- a low cost cathode material for a Li-ion battery These cathodes suffer from significant capacity fade with cycling. This capacity fade is in part associated with the dissolution of Mn from the cathode material. To prevent this dissolution, we coated LMO particles with a Au shell by a simple and scalable electroless deposition. Characterization by SEM, TEM, EELS, and AFM showed that the Au shell was approximately 3 nm thick. The Au shell prevented much of the Mn from dissolving in the electrolyte with 82% and 88% less dissolved Mn in the electrolyte at room temperature and 65 ºC, respectively, as compared to the uncoated LMO. These Au coated cathode materials show great improvement in reducing Mn dissolution and extending electrochemical performance through hundreds of cycles over uncoated LMO.

Figure 1
The Evolution of a High Capacity Electrode
Authors: Wang YuHuang , Sun Chuan-Fu 
Published: February 2020

Silicon can store Li+ at a capacity 10 times as high as that of graphite anodes. However, to harness this remarkable potential for electrical energy storage, one must address the multifaceted challenge of volume change inherent to high capacity electrode materials. In this talk, we present novel chemical strategies to address this challenge. Based on fundamental understanding of nanostructure interface, we have synthesized non-cracking silicon-carbon nanotube composite electrodes that electrically connect amorphous silicon beads. This synthesis is made possible by a propagative chemistry which creates regular bands of alkylcarboxyl groups along the nanotubes. The functional bands anchor the beads such that they exhibit a symmetric “radial breathing” around the CNT string, remaining crack-free and electrically connected throughout lithiation-delithiation cycling. We further show that, solely by chemical tailoring of the Si-C interface with atomic oxygen, the cycle life of the electrodes can be substantially improved, by 300%, even at high mass loadings. The evolution of this work culminates in the design and fabrication of a high capacity composite electrode that is weavable. The engineered andoe simultaneously attains high areal capacity (3.86 mAh/cm2), high specific capacity (922 mAh/g based on the mass of the entire electrode), and excellent cyclability (80% retention of capacity after 160 cycles), which are among the highest reported.
This work was mainly supported as part of Nanostructures for Electrical Energy Storage (NEES), an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award Number DESC0001160. We acknowledge cumulative contributions from many collaborators particularly K. Karki, M. Okada, H. Liao, H. Zhu, Z. Jia, E. Baker, Y. Zhang, K. Gaskell, A. Ghemes, P. Wang, J. Cumings, L. Hu, Y. Inoue, T. Li, Y. Qi, and G. W. Rubloff.
Studies on Dielectric Properties of Annealed RF-Sputtered ZrO2 Thin Films
Authors: Mendoza Raul R. , Skaria Giji , Prakash Adithya , Velez Victor H. , Sundaram Kalpathy B 
Published: February 2020

Dielectrics play an important role in semiconductor devices when it is used as gate insulator MOS transistors or in memory applications [1]. SiO2 has been one of the most typically used dielectrics due to its good properties like electrical and thermodynamic stability. It provides a great Si-SiO2 interface used in MOS transistors, and has high quality isolation electrical characteristic. Despite its benefits, there comes a point where continuous device scaling sets a limit to what materials can be used. Therefore, other high-k gate dielectric materials have to be found in order to go below 1.5nm thickness when SiO2 is used for the 45nm node technology. ZrO2 is one of the high-k materials that can be used as a possible solution [2].
ZrO2 possesses some interesting characteristics like relatively high-k and wide bandgap. In addition, its crystal structure changes at different temperatures, going from monoclinic to tetragonal and then to cubic as the temperature raises. Even though the monoclinic structure is stable and occurs at room temperature, the other two are not. This presents some problems, which create phase instability leading to stresses and cracking of the material. However, by introducing certain rare earth oxide based dopants as for example Yttria (Y2O3), stable phases for the tetragonal and cubic structures can be achieved, as well as increasing the permittivity constant of the dielectric [3,4].
In this work, ZrO2 thin films are deposited on glass substrates to find various properties. The films are prepared in an RF magnetron sputtering system using a 99.5% pure yttria-stabilized zirconium oxide target. ZrO2 based metal/insulator/metal (MIM) structures are fabricated using Aluminum as the top and bottom electrodes. Various electrical properties are investigated for the ZrO2 films prepared under different deposition and annealing conditions.
REFERENCES
[1] G. D. Wilk, R. M. Wallace, J. M. Anthony, “High-κ gate dielectrics: Current status and materials properties considerations” Journal of Applied Physics, Vol 89, 2001

[2] M. K. Bera, C. K. Maiti, "Reliability of Ultra-thin Zirconium Dioxide (ZrO2) Films on Strained-Si" Physical and Failure Analysis of Integrated Circuits, 2006.

[3] S. M. Hwang, S. M. Lee, K. Park, M. S. Lee, J. Joo, J. H. Lim, H. Kim, J. J. Yoon, Y. D. Kim “Effect of annealing temperature on microstructural evolution and electrical properties of sol-gel processed ZrO2 /Si films” Applied Physics Letters 98, 2011

[4] H. García, H. Castán, S. Dueñas, E. Pérez, L. Bailón, “Electrical characterization of MIS capacitors based on DY203-doped Zr02 dielectrics”, Electron Devices (CDE), 2015
(Invited) Li Rich FCC Materials As High Capacity Cathodes
Authors: Ren Shuhua , Chen Ruiyong , Fichtner Maximilian 
Published: February 2020

In 2014, we developed a new type of compound based on lithium-rich metal oxyfluoride of Li2MO2F.[1] The novel material exhibits an outstandingly high capacity of 420 mAh g-1 with small lattice expansion and shrinkage of only 3% upon cycling owing to its stable rock salt host structure. Lithium, occupying 2/3 of the cation sites, is highly mobile. The structure stabilizes well after nearly two Li+ depletion. The flexibility of the host structure means a paradigm change in the Li+ storage, which opens new possibilities for obtaining higher storage capabilities both gravimetrically and volumetrically. Particularly, high volumetric energy densities up to 4600 Wh L-1were achieved.
The first generation of materials (M=V) [2] has recently been expanded by Cr as an alternative transition metal.[3] This presentation will address the first and the second generation of materials, where pure V and Cr compounds as well as systems with mixtures of the two metals have been synthesized and tested. It will be shown that Cr leads to higher discharge potentials, which are about 0.5 V above those of the pure V compounds. Moreover, the smaller cation enables higher packing densities of Li so that the theoretical gravimetric and volumetric energy densities of the respective Li rich fcc compound are high at average 2.8 V.

References

[1] (a) R. Chen, et al. EP patent application EP 14160894.3 (2014); (b) R. Chen et al., 226th ECS Meeting Cancun, Mexico (2014).
[2] R. Chen et al., Disordered lithium-rich oxyfluoride as a stable host for enhanced Li+ intercalation storage, Advanced Energy Materials (2015) 5, 1401814.
[3] S. Ren et al., Improved voltage and cycling for Li+intercalation in high-capacity disordered oxyfluoride cathodes, (2015) submitted.
[MF1]

Figure 1
Layered Cathode Materials with Controlled Particle Assembly for High Energy Lithium-Ion Batteries
Authors: Lin Feng , Li Yuyi , Nordlund Dennis , Liu Yijin , Weng Tsu-Chien , Xin Huolin , Doeff Marca 
Published: February 2020

Stoichiometric layered lithium transition metal oxides (LiNi1-x-yMnxCoyO2) represent a family of cathode materials suitable for high-energy lithium ion batteries. However, their structural instability (e.g., surface reconstruction from the layered structure to a rock-salt/spinel mixed structure) when charged to high voltages impedes efforts to improve their energy densities. Here, we report on a study of LiNi1-x-yMnxCoyO2 materials prepared by a spray pyrolysis technique to provide improved cycling performance.
The as-prepared LiNi1-x-yMnxCoyO2 materials assemble into spherical structures that consist of nanosized primary particles. Revealed by transmission electron microscopy, these primary particles are “fused” together to form atomically disordered interfaces that may allow for lithium and electron diffusion. LiNi1-x-yMnxCoyO2 materials with different ratios of transition metals were synthesized, i.e., LiNi1/3Mn1/3Co1/3O2, LiNi0.4Mn0.4Co0.2O2, LiNi0.5Mn0.3Co0.2O2, LiNi0.6Mn0.2Co0.2O2, most of which show improved electrochemical performance (i.e., discharge capacity, capacity retention) compared to the counterparts synthesized by the conventional co-precipitation method, although different thermal treatment protocols are needed after the spray pyrolysis process. Surface reconstruction was quantified by soft X-ray absorption spectroscopy to investigate the surface phase transition of the LiNi1-x-yMnxCoyO2 materials after electrochemical cycling, and it is found that the materials prepared by spray pyrolysis have thinner surface passivation layers (a rock-salt/spinel mixed structure), which accounts for better capacity retention. This study suggests that morphological engineering by spray pyrolysis may offer an efficient pathway towards stable high-energy layered cathode materials.
(Invited) Understanding Surface and Structural Changes in High Energy Density Electrodes By NMR and Computational Studies
Authors: Grey Clare P , Michan Alison , Leskes Michal , Seymour Ieuan 
Published: February 2020

This talk will focus on two different topics. The first involves the use of NMR spectroscopy to characterize the SEI formed on silicon and carbon electrodes. By using a multinuclear NMR approach in combination with a series of double resonance and two-dimensional NMR experiments, we identify many of the organic and inorganic components that are formed on silicon anodes. Preliminary comparisons with the SEI on carbons will be made. The second topic involves a study of layered materials by using a combination of NMR spectroscopy and DFT methods. The use of DFT methods to calculate NMR shifts for these materials is challenging, particularly for partially delithiated (disordered) materials. Our strategies in this area will be discussed, along with computational approaches to explore structural transformations.
(Invited) Effects of Crystalline Structure on the Electrochemical Properties of High Voltage Spinel Cathode Materials
Authors: Wu She-huang , Su Shou-Huang , Shiu Je-Jang 
Published: February 2020

LiNi0.5Mn1.5O4 powders were prepared via a spraying-dry method followed by heating at temperatures between 600 and 1000oC for 8 hours in air with oven cooling. In order to eliminate the particle size effects, 900oC samples were annealed at 700oC under air for various durations. The crystalline structure of the prepared samples were investigated from their high resolution neutron powder diffraction data collected with Echidna at ANSTO and refined with Rietica Ver. 1.77. The results of Rietveld refinement for the NPD patterns manifest that the 700oC prepared sample contains 85% of ordered P4332 and 15% of disordered Fd
m phases whereas the powders prepared at temperatures higher than 800oC prevailed with disordered Fd
m phase (72`75%) with amount of rock-salt LixNi1-xO increases from 1 to 4% with heating temperature. For the annealed samples, the molar fraction of the ordered phase increases with increasing duration of annealing and converts completely into ordered phase after annealing for 60 hours. It suggests that the phase conversion and LixNi1-xO evolution/dissolution are reversible [1]. From the results of capacity retention study of the cells comprised with the prepared powders, it was found that sample prepared at 900oC with oven cooling exhibits the most promising performance among the prepared powders. These results are different from those reported by Fang et al. [2], however, they are similar to those reported previously that the disordered phase has better electrochemical properties than the ordered phase [3-5]. Though various reasons had been suggested [3, 6-7], the effects of crystalline structure on the cycling performance of high voltage spinel are still not clear. In this study, the effects are hope to reveal from the results of dissolution study for transition metals upon storage and cycling, linear sweep voltammetry for electrolyte oxidation on high voltage spinel, cyclic voltammetry for Li+ ion diffusivity, and the phase evolution detected by high resolution TEM for the fresh and cycled electrodes and in-situ NPD study.
Reference:
[1] L. Cai, Z. Liu, K. An, and C. Liang, J. Mater. Chem. A, 1,6908 (2013).
[2] H. Fang, Z. Wang, B. Zhang, X. Li and G. Li, Electrochem. Commun., 9, 1077 (2007).
[3] J. H. Kim, S. T. Myung, C. S. Yoon, S. G. Kang and Y. K. Sun, Chem. Mater., 16, 906 (2004).
[4] A. Bhaskar, N. N. Bramnik, A. Senyshyn, H. Fuess and H. Ehrenberg, J. Electrochem. Soc., 157, A689 (2010).
[5] K. Takahashi, M. Saitoh, M. Sano, M. Fujita and K. Kifune, J. Electrochem. Soc., 151, A173 (2004).
[6] M. Kunduraci, J. F. Al-Sharab and G. G. Amatucci, Chem. Mater., 18, 3585 (2006).
[7] X. H. Ma, B. Kang and G. Ceder, J. Electrochem. Soc., 157, (2010).
The Effect on Electrochemical Properties By the Content of Mn3+ of High-Voltage Spinel LiNi0.5Mn1.5O4 Cathode Material for Highly Stable Lithium-Ion Batteries
Authors: Li Jie , Liu Haidong , Wang Jun 
Published: February 2020

High voltage spinel LiNi0.5Mn1.5O4 (LNMO) is considered as one of the most promising cathode material for next generation lithium ion batteries, which can greatly meet the rapid increasing demand of power sources applied into portable electronic devices and electric vehicles. The electrochemical performance of LNMO is greatly affected by the morphology and lattice structure. In order to improve the long-term cycling stability, particularly at elevated temperature, one of effective methods is to tune the amount of Mn3+ in LNMO for controlling the stability of spinel lattice structure due to complex interactions on the interface of electrode material and the electrolyte on the high operating voltage.
In this work, the influence of different content of Mn3+ in LNMO on electrochemical properties is displayed by truncated octahedral LNMO obtained by controlling synthetic conditions of heating atmosphere and temperature cooling rate. Superior truncated octahedral LNMO materials were synthesized with tuned Mn3+ content through heating under oxygen atmosphere and controlling the cooling conditions of natural cooling and a cooling rate of 5 oC/min, respectively. The material synthesized under O2 shows the smallest amout of Mn3+, while the one with natural cooling has the highest amount. The LNMO material obtained under O2 shows the best electrochemical stability with about 96% capacity retention after 500 cycles at 0.5C (1C = 147 mA/g). The material obtained at 5 oC/min shows about 90% of capacity retention after 2000 C cycles at 1C, while the one obtained with natural cooling can reach up to 88% of capacity retention after 500 cycles at 0.5C at 60 oC. Therefore, the Ni-Mn disordering intrinsically related to the Mn3+ amount has a great effect on the electrochemical performance of LNMO. More experimental details and measurement results will be exhibited later.
Reference:
1. Xiao, J., Chen, X., Sushko, P., et al, Adv. Mater. 2012, 24, 2109.
2. Chemelewski, K. R.; Lee, E.; Li, W.; Manthiram, A. Chem. Mater. 2013, 25, 2890.
Advanced Performances of Full Concentration Gradient Li[Ni0.65Co0.08Mn0.27]O2 Cathode Materials for Lithium Ion Batteries
Authors: Jun Do-Wook , Park Kang-Joon , Lim Byung-Beom , Yoon Chong seung , Sun Yang-Kook 
Published: February 2020

Full concentration gradient (FCG) cathode material which consists of Ni-rich core Li[Ni0.89Co0.01Mn0.10]O2 and Ni-less outer layer Li[Ni0.61Co0.09Mn0.30]O2 was synthesized by co-precipitation method.1,2 A gradually changing concentration gradients for Ni, Co, and Mn extended from the core to the surface within a single cathode particle with an average composition of Li[Ni0.65Co0.08Mn0.27]O2. We have evaluated electrochemical and thermal properties of the FCG cathode material and compared it with the conventional cathode (CC) material, Li[Ni0.65Co0.08Mn0.27]O2 without the concentration gradient. The BET surface area measurement demonstrated the presence of high-density primary particles in the FCG cathode material. The FCG cathode exhibited higher discharge capacity, excellent cycle retention and superior thermal stability compared to the CC Li[Ni0.65Co0.08Mn0.27]O2 cathode material.1

References

1. H.-J. Noh, Z. Chen, C. S. Yoon, J. Lu, K. Amine, and Y.-K. Sun, Chem. Mater., 25, 2109 (2013).
2. M. H. Lee,Y. J. Kang, S. T.Myung, andY. K. Sun, Electrochim. Acta. 50, 939 (2004).
Electrospun Hollow Glassy Carbon-Reduced Graphene Oxide Nanofibers with Encapsulated ZnO Nanoparticles : A Free-Standing Anode for Li-Ion Batteries
Authors: Shilpa Shilpa , Basavaraja Basavanakote M , Majumder Subhasish B , Sharma Ashutosh 
Published: February 2020

Although zinc oxide (ZnO) has a high theoretical capacity for lithium storage, its poor cyclability due to the huge volume changes during charge–discharge cycles result in particle pulverization and detachment from the current collector. In this work, a novel anode architecture for Li-ion batteries is fabricated by encapsulating ZnO nanoparticles in the hollow core of glassy carbon–reduced graphene oxide (C–rGO) electrospun composite nanofibers. A one-step, co-axial electrospinning method is used to synthesize a mat of core–shell structured composite nanofibers composed of rGO embedded in poly(acrylonitrile) (shell) and a ZnO nanoparticle precursor with a carrier polymer (core). Subsequent calcination and carbonization produce a mechanically stable anode material, which is used directly as a free-standing anode without any binder and current collector. The ZnO–C–rGO nanofiber composite was characterized by SEM, TEM, RAMAN and XRD techniques. The electrochemical performance of the composite was studied by galvanostatic charge–discharge measurements at different current densities, slow scan cyclic voltammetry (CV) and impedance measurements. Incorporation of an rGO network in the glassy nanofiber shell enhances both the capacity and electrical conductivity of the mat electrode resulting in faster electron kinetics, and thus, an improved rate capability. The interior void spaces combined with the mechanical strength and flexibility of the C–rGO shell act as a structural buffer effectively relieving the volumetric stresses generated during charge–discharge cycles. The synergistic effect of the metal oxide, rGO and the core–shell design results in a high capacity of 815mAh/g at a current density of 50mA/g with a capacity retention of almost 80% after 100 cycles, thus demonstrating significant potential as an anode substitute for next generation Li-ion batteries.
(Invited) Li Intercalation into Multi-Layers Transition Metal Carbides and Carbonitrides "Mxenes" in Li-Ion Batteries
Authors: Naguib Michael 
Published: February 2020

Two-dimensional, 2D, transition metal carbides and carbonitrides, so called MXenes, consist of nearly closed packed layers of early transition metals “M” with “X” atoms (X stands for carbon or nitrogen) filling the octahedral sites with a nominal composition of Mn

+1
Xn
where n = 1, 2, or 3. Depending on the value of n, the thickness of the Mn

+1
Xn
change; if n = 1 the MXene layer consists of a single block of octahedra (3 atoms thick). If n = 2 the MXene layer consists of 2 octahedra blocks; if n = 3, consists of 3 blocks of octahedra. The surface of as-synthesized MXenes is terminated by a mixture of moieties viz. O, OH, and F (this mixture is referred hence after by Tx). To date, the following MXenes were successfully synthesized: Ti2CTx, Nb2CTx, V2CTx, (Ti0.5,Nb0.5)2CTx, Ti3C2Tx, (V0.5,Cr0.5)3C2Tx, Ti3CNTx, Ta4C3Tx, and Nb4C3Tx.
Unlike conventional 3D transition metal carbides and nitrides which are known to be inert for Li, MXenes were found to be electrochemically active as host materials for Li-ions. The latter intercalate/de-intercalate reversibly between the MXenes layers during the electrochemical cycling in Li batteries. This was confirmed by in situ XRD studies during electrochemical lithiation and de-lithiation. When they were tested as electrode materials for Li-ion batteries (LIBs), each MXene showed its own electrochemical voltage window. In principle, some MXenes could function as cathodes and some as anodes for LIBs. MXenes electrodes exhibited an excellent capability to handle high cycling rates with good capacity. This was explained by a low Li diffusion barrier in case of MXene compared to other electrode materials such as graphite. MXenes powders can be cold pressed into freestanding thick discs resulting in electrodes with high areal capacities exceeding 5 mAh/cm2. Most of the research conducted –experimentally- on MXenes as electrodes for LIBs was limited to the as-synthesized MXene without further control of the surface termination. However, ab initio calculations predict that controlling the surface termination could enhance the performance. Herein the progress in the synthesis of MXenes and controlling their surface termination, in addition to their performance as electrode materials in LIBs will be discussed.