bluuebunny/crossref_metadata_2025_split huggingface dataset:
Graphene Induced Growth of Single Crystalline Sb2MoO6 Sheets and the Sodium Storage Performance
Authors: Liu Qing 
Published: February 2020

Ternary oxides have been widely investigated as excellent anode candidates for LIBs with good cycling and rate capability. In the initial lithiation process, the ternary oxides decompose into Li-alloying metal particles distributed in the matrix of the second inert metal nanoparticles and Li2O. The matrix can act as effective buffer layer and alleviate the aggregation of nanoparticles. Therefore, some ternary oxide anodes for LIBs show greatly improved cyclability and rate performance.
Meanwhile, according to some reported publications, single crystalline materials, which has crystallographically oriented structure with few grain boundaries, can facilitate electron and ion transport compared with the amorphous or polycrystalline counterpart.
Inspired by the above strategies, we reported here a single crystalline Sb2MoO6/reduced graphene oxides composite as anode for SIBs. Interestingly, the Sb2MoO6 particles grow into large single crystalline sheets with the induction of graphene oxide in the hydrothermal process, and the obtained Sb2MoO6/RGO composites exhibit excellent electrochemical performance, delivering a high capacity of 430 mAh g-1 at 0.05 A g-1 and maintains 270 mAh g-1 at high current density of 4 A g-1. A capacity retention of 93.2% can be acquired after 220 cycles at 0.2 A g-1. To the best of our knowledge, the single crystalline Sb2MoO6/RGO composites is investigated as anode for SIBs for the first time.

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Bio-Inspired Surface Layer for the Cathode Material of High-Energy Density Sodium-Ion Batteries
Authors: Jo Chang Heum , Myung Seung-Taek 
Published: February 2020

P2-Cathode materials for sodium battery are usually active in the range of 2–4.3 V, but the decomposition of the electrolytic salt above 4 V versus Na+/Na is common. Arguably, the one of the concerns is the formation of HF after the reaction of the salts with water molecules, which are present as an impurity in the electrolyte. This HF ceaselessly attacks the active materials and gradually causes the failure of the electrode via electric isolation of the active materials. In this study, we report a bio-inspired b-NaCaPO4 nanolayer on a P2-type layered Na2/3[Ni1/3Mn2/3]O2 cathode material. The coating layers successfully scavenge HF and H2O, and excellent capacity retention was achieved with the b-NaCaPO4-coated Na2/3[Ni1/3 Mn2/3]O2 electrode. This retention was possible because a less acidic environment was produced in the Na cells during prolonged cycling. The intrinsic stability of the coating layer also assisted in delaying the exothermic decomposition reaction of the de-sodiated electrodes. We suggest formation and reaction mechanisms for the coating layers responsible for the excellent electrode performance. The suggested technology is promising for use with cathode materials in rechargeable sodium batteries to mitigate the effects of acidic conditions in Na cells.
P2-type layered Na2/3[Ni1/3Mn2/3]O2 powders were synthesized by a conventional solid-state method. Na2CO3, Mn2O3, and NiO were thoroughly mixed. And then it was calcined at 1,000 °C for 12 h in air and then quenched, after which the pellet was immediately transferred into an Ar-filled glove box to minimize the adsorption of water and exposure to the CO2 in the air. Calcium nitrate and phosphoric acid were first dissolved in anhydrous ethanol at room temperature, and the as-synthesized active materials were added slowly to the solution. Then, the solution containing the active material was stirred continuously at 80 °C in a dry room, accompanied by the slow evaporation of the solvent. The as-prepared and bare Na2/3[Ni1/3Mn2/3]O2 powders were heated at 700 °C for 2 h in air. Also, the coated powders were characterized by XRD, SEM, and HR-TEM. Electrochemical properties of coated powders were examined by galvanostatic cycle test and electrochemical impedance spectroscopy.
b-NaCaPO4
coatings shows uniform coating layers, as observed by TEM. Thickness of coating layer is of about 10nm. Electrochemical test with half cells in voltage range of 2.5 - 4.3 V at 25 oC indicates that coated materials have better capacity retention and coulombic efficiency, rate capability, and low resistance. Thin coating layers seem to effective to improve the electrochemical properties. Also, b-NaCaPO4 coatings give decrease of residual sodium and byproduct on the surface of particle, as confirmed by ToF-SIMS. Details will be mentioned at the conference site.

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Si Nanoparticles: Its Stability in Aqueous Slurries and the Optimization of Oxide Layer Thickness for Optimal Electrochemical Performance
Authors: Zhang Linghong , Liu Yuzi , Key Baris , Trask Stephen E. , Yang Zhenzhen , Lu Wenquan 
Published: February 2020

For the silicon particles used as anode for lithium ion batteries, there is always a native oxide layer on the surface, whose role on electrochemical performance of silicon electrode need to be understood. The actual thickness of the oxide layer may also vary due to the manufacturing processes. As the size of the silicon particle becomes smaller, this oxide layer will play a more important role as it takes up a larger volume and weight percentage. Previous study suggests that the presence of oxide layer harms the initial performance of the silicon anodes in a non-aqueous system. However, the effect of the oxide layer on the long cycling performance of the electrodes has not been well studied.
Here we investigated the effect of oxide layer on the electrochemical performance of silicon anodes by growing the oxide layer of Si nanoparticles in a controlled manner. Si nanoparticles with an average size of 80 nm was used. LiPAA and carbon black was used to fabricate the electrodes. Brunauer-Emmett-Teller (BET) surface analysis, transmission electron microscopy as well as Fourier-transform infrared spectroscopy were performed to characterize the silicon nanoparticles. The stability of the silicon nanoparticles with different oxide layer thickness during electrode fabrication process was compared. Electrochemical performance of the silicon electrodes of different thicknesses was also analyzed and compared.
Acknowledgement
We gratefully acknowledge the support from the U.S. Department of Energy’s (DOE) office of Energy Efficiency & Renewable Energy (EERE) Vehicle Technologies Office. This work is performed at Argonne National Laboratory, a U.S. Department of Energy Office of Science Laboratory operated under Contract No. DE-AC02-06CH11357
Highly Stretchable Conductive Binder Based on PEDOT:PSS for High Performance Si Anode
Authors: Wang Lei , Fu Huo Kai 
Published: February 2020

Silicon (Si) is a promising anode material in advanced high-energy-density lithium-ion batteries (LIBs) due to its large theoretical capacity of 4200 mAh g-1, however, the high volume change cause the pulverization and unstable solid-state interface layer. How to maintain the structural integrity and high electronic conductivity during cycling is the major challenge for high-capacity Si anodes. Binder plays a key role in maintaining the mechanical integrity of electrodes in lithium-ion batteries. However, the existing binders typically exhibit poor stretchability or low conductivity at large strains, which are not suitable for high rate and high-capacity silicon (Si)-based anodes undergoing severe volume changes during cycling. Herein, we report a novel stretchable conductive polymer that possesses inherent high conductivity, excellent stretchablity and ductility. The polymer can be stretched up to 400% in volume and 250% in length without conductivity loss and mechanical fracture. The Si anode composed of the polymer and Si nanoparticles exhibited excellent cycle performance with a high discharge capacity (1500 mAh g-1 for over 700 cycles) as well as high areal capacity (5.13 mAh cm-2). The highly stretchable conductive binder provides a new perspective for designing next-generation high-capacity and high-power batteries.
References:
[1] L. Wang, T. Liu, et al. Adv. Funct. Mater. DOI: 10.1002/adfm.201704858.
[2] L. Wang, K. Huo et al. Nanoscale 7 (2015) 13840.
[3] K. Huo, L. Wang et al. J. Mater. Chem. A 4 (2016) 7585.
[4] W. Zeng, L. Wang et al. Adv. Energy Mater. DOI: 10.1002/aenm.201702314.
Effects of Local Tortuosity and Porosity Heterogeneities on Charge and Discharge Performance of Li-Ion Batteries
Authors: Forouzan Mehdi M , Wheeler Dean R , Mazzeo Brian A 
Published: February 2020

Local variations of mechanical, structural, transport, and kinetic properties, referred to as heterogeneity (generated by a non-optimized manufacturing process [1]), can detrimentally affect battery life and performance, especially at high cycling rates and low temperatures, in a number of manners. The distribution of current density across an electrode surface can be non-uniform as a consequence of electrode heterogeneity. A high local charging rate (especially at local low temperature) may lead to local lithium plating, resulting in capacity fade and shorter cycle life. Additionally, deviation of local charging-discharging rate from the average rate results in variation in local state of charge (SOC, Li concentration in active material). For a given chemistry and application, there is an SOC operation range (lower and upper bounds) beyond which capacity loss and damage occur. Therefore, highly heterogeneous electrodes may cause “hot” and “cold” spots, in terms of SOC, leading to non-uniform aging within the cell. Another negative effect of local inhomogeneity is non-uniform utilization of active materials, resulting is decreased volumetric and gravimetric energy density of a Li-ion battery.
In this work, we introduce a computationally efficient Newman-type model to further understand and quantify the effects of local inhomogeneities, particularly non-uniform ionic and electronic impedance. As shown in Fig. 1, we imitate the real heterogeneity of the cell by a system consisting of three localized Li-ion domains, each with specific properties ion-transport associated with “cold” (high tortuosity and low porosity [2]), “middle” (moderate tortuosity and porosity), and “hot” (low tortuosity and high porosity) spots. The properties for each of the domains are obtained experimentally through a combination of SEM/FIB and localized conductivity measurements. The three simulated domains are treated as separate cells electrically connected in parallel. This approach can simplify mathematical treatment and significantly reduces intensive computation requirements needed for true 3D modeling.
[1] M.M. Forouzan, C.-W. Chao, D. Bustamante, B.A. Mazzeo, D.R. Wheeler, Journal of Power Sources, 312 (2016) 172-183.
[2] M.M. Forouzan, M. Wray, L. Robertson, D.R. Wheeler, J. Electrochem. Soc., 164 (2017) A3117-A3130.
Figure 1: Heterogeneity of the NMC electrode using SEM/FIB images and equivalent circuit used in the Newman-type model.

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Improvement of Thermal Stability of Lithium Ion Pouch Type Cell
Authors: Sung Changhun , Kim Hyejung , Kim Cheon-Soo , Kim Min Gyu , Jeong Kyeong-Min 
Published: February 2020

Thinner design of smart phone continuously would need to the high energy density lithium-ion batteries. Lithium-ion batteries are composed of four major component, cathode, anode, electrolyte and separator. Each components’s reaction by pyrolysis and interaction between components are causative of exothermic reaction of lithium ion batteries.
We investigated causes of exothermic reaction of lithium ion batteries having thermal analysis, surface analysis and structure analysis by dismantling two kinds of 3.2Ah lithium-ion batteries composed of most commercialized LiCoO2 cathode material and Graphite anode material.
In LiCoO2 cathode material, Li ions are oxidized by charge process, it exists as Li0.5CoO2. Near 230oC, structure of Li0.5CoO2 is changed, it causes exothermic reaction. EXAFS, structure analysis, showed change of two kind of Li0.5CoO2 structure according to temperature change. By investigating Co-Co and Co-O bond, we can find that structure stability as temperature increasing is different as status of LiCoO2 such as Mg doping.
Surface analysis showed surface status of cathode material and distribution of anode SEI layer. Especially, in case of anode, Alkyl Carbonate is considered as important factor of thermal stability because it makes exothermic reactions as it decomposed. We identified how thick the alkyl carbonates were deposited and we found difference of exothermic value by DSC thermal analysis between two kinds of graphite of lithium ion batteries.
These analysis data indicate which part is important for thermal stability and investigate exothermic reaction mechanism of Cell components. We made sure structure change of cathode material and distribution of Alkyl carbonate in anode SEI layer is important for thermal runaway of Cell. These results suggest improvement direction for increasing of thermal stability.
In-Situ STM Studies on Li- and Na- Intercalation Batteries
Authors: Seidl Lukas , Schneider Oliver , Stimming Ulrich 
Published: February 2020

The processes of SEI formation and of intercalation are still not well understood on the molecular level. Scanning probe techniques are capable of analysing these processes under in-situ conditions.
The SEI-formation on graphitic electrodes operated as an Li+-ion battery anode in a standard 1 M LiPF6 EC/DMC (1 : 1) electrolyte has been studied using in-situ electrochemical scanning tunnelling microscopy (EC-STM)1. Two different modes of in situ study were applied, one, which allowed to follow topographic and crystallographic changes (solvent co-intercalation, graphite exfoliation, SEI precipitation on the HOPG basal plane) of the graphite electrode during SEI-formation, and the second, which gave an insight into the SEI precipitation on the HOPG basal plane in real time. From the in situ EC-STM studies, not only conclusions about the SEI-topography could be drawn, but also about the formation mechanism and the chemical composition, which strongly depend on the electrode potential. It was shown that above 1.0 V vs. Li/Li+ the SEI-formation is still reversible, since the molecular structure of the solvent molecules remains intact during an initial reduction step. During further reduction, the molecular structures of the solvents are destructed, which causes irreversible charge losses.
The reversible intercalation of solvated Na-ions into graphite and the concomitant formation of ternary Na-graphite intercalation compounds (GICs) is studied by EC-STM and other in-operando techniques2. Linear ethylene glycol dimethyl ether homologes (“glymes”) Gx with x+1 O-atoms were used as solvents, where x is 1-4. The intercalation mechanism of Na+(Gx)y-complexes was investigated with the focus on phase transitions and diffusion rates of the Na+(Gx)y-complexes inside the graphite lattice. For the four shortest glymes (G1 to G4), it is found by XRD that an intermediate stage 2 Na-GIC (NaC48) is formed upon partial sodiation of the graphite electrode. At full sodiation a stage 1 Na-GIC (NaC18, 112 mAh g-1) is obtained for G1, G2 and G4, while the G3-system is also forming a stage 1 Na-GIC but with less Na incorporated (NaC30, 70 mAh g-1). Phase transitions of a battery electrode upon ion-intercalation are visualised by STM on the atomic scale for the first time. In addition, local diffusion rates of the intercalated species inside the electrode were determined, a unique approach to determining kinetic effects in batteries on the atomic scale. The formation of a solid electrolyte interphase (SEI) is observed in EC-STM.

Lukas Seidl, Sladjana Martens, Jiwei Ma, Ulrich Stimming, Oliver Schneider "In-Situ Scanning Tunneling Microscopy of the SEI Formation on Graphite Electrodes for Li-Ion Batteries" Nanoscale, 2016, 8, 14004;

Seidl, N. Bucher, E. Chu, S. Hartung, S. Martens, O. Schneider and U. Stimming, "Intercalation of solvated Na-ions into graphite", Energy Environ. Sci.,2017, 10, 1631.
Free-Standing Binder-Free Multi-Wall Carbon Nanotube/Silicon Anodes for Lithium-Ion Batteries
Authors: Luanwuthi Santamon , Babenko Vitaliy , Naylor Andy , Roberts Matthew R. , Hong Jindui , Kasemchainan Jitti , Bruce Peter G. , Grobert Nicole 
Published: February 2020

Silicon is of interest owing to its high theoretical capacity (4200 mAh/g). However, its enormous volume expansion of silicon during cycling is one of the main reasons for the rapid capacity fading and pulverisation of the anode commonly observed.
Here, freestanding multi-wall carbon nanotube (MWCNT)/silicon anodes were prepared using so-called MWCNT buckypapers (BPs) as current collectors instead of the traditional metallic foils. To prepare the anodes, silicon was deposited on these MWCNT BPs to form silicon nanoparticles (SiNPs) and subsequent annealing resulted in the formation of a connecting SiC interface preventing the SiNPs from detaching. An amorphous carbon coating was applied in order to enhance electrical conductivity and overall integrity of these hierarchical anode materials.
The morphology and chemical composition of the Si-BP anodes were characterised by means of SEM, TEM, EDX, STEM, XRD, RAMAN, etc. Cycling tests of these binder and additive-free anodes revealed an areal capacity of 0.55 mAh/cm2 after 300 cycles with 99.7% of Columbic efficiency and showed that the presence of the SiC interface and a-C coating played a crucial role in improving their rate capability and stability.
Core-Shell Structured SiOx-TiO2@C Nanocomposites As High-Rate and Long-Cycle Anode for Lithium Ion Batteries
Authors: Li Zhaolin , Zhao Hailei , Lv Pengpeng 
Published: February 2020

Silicon suboxide (SiOx, 0˂x˂2) is one of the promising anode materials for lithium-ion batteries (LIBs) due to its high specific capacity, low operating voltage (˂0.4 V) and rich abundance [1]. SiOx produces inert components (lithium oxide and lithium silicate) and nano-Si particles during initial lithiation/delithiation process. The former can act as buffer matrix to significantly reduce the volume change of nano-sized Si. Therefore, compared to pure Si, SiOx electrode shows relatively good cycling stability and thus appears promising for high energy density Li-ion batteries. Nevertheless, the poor intrinsic electronic and ionic conductivity of SiOx often leads to a low specific capacity and inferior rate capability [2]. In addition, the SiOx electrode cannot withstand long-period cycling due to the inevitable volume variation of SiOx.
In this work, we prepared core-shell SiOx-TiO2/C nanoparticles with unique watermelon-like structured by a simple sol-gel combined with a following carbon coating process. Ultrafine TiO2 nanocrystals are homogeneously distributed inside SiOx particles, forming SiOx-TiO2 dual-phase cores, which are coated with outer carbon shells. The incorporation of TiO2 component can effectively enhance the electronic and lithium ionic conductivities, release the structure stress caused by alloying/dealloying of Si component and maximize the capacity utilization by decreasing the O/Si ratio (x value). The synergetic combination of these advantages enables the synthesized SiOx-TiO2@C nanocomposite to have outstanding electrochemical performances, including high specific capacity, excellent rate capability and stable long term cycleability. A stable specific capacity of ~910 mAh g-1 is achieved after 200 cycles at the current density of 0.1 A g-1 . These results suggest the synthesized SiOx-TiO2/C composite is a promising high performance anode material for lithium ion batteries.
MOF-Derived Carbons As Ordered Isoreticular Structures for High Performance Sodium-Ion Battery Anode
Authors: Ingersoll Nolan , Underwood Robert , Warren Roseanne 
Published: February 2020

Sodium-ion batteries present many advantages over lithium-ion batteries for large-scale, stationary energy storage, including higher abundance, lower cost, and simpler processing procedures of sodium compared to lithium. To date, the low energy density and long-term instability of sodium-ion batteries have prevented them from being commercially viable. One of the main research challenges for sodium-ion batteries is finding high capacity anode materials with good voltage window and cycle life when combined with sodium electrolytes. Early research on sodium-ion battery anodes strived to mimic electrode materials from lithium-ion batteries such as graphitic carbons; other simple structured carbons were then studied including hard carbons, petroleum cokes and carbon black1. However, these structures do not allow the larger sodium ion to diffuse and intercalate as easily as the smaller lithium ion. Research efforts have since broadened to structured carbons such as pyrolized glucose2, carbon microspheres3, silica templated carbon4, and others. These structures moderately improve performance but still face limitations including low available surface area, poor cycle performance, and complex fabrication.
We propose the application of metal organic framework-derived carbons (MOFDCs) as a large surface area, highly porous, and electrochemically stable material for the sodium-ion battery anode. MOF material is a tunable sacrificial template that, when carbonized, produces ordered, porous structures highly conducive to diffusion and intercalation of sodium ions. Here, we present two MOF structures that are used as sacrificial templates for carbonization, MOF-5 and ZIF-8. After carbonization, the materials were characterized via scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) (Figure 1) to confirm complete carbonization and structural consistency with the starting MOF material. Open cell charge-discharge tests (Figure 2) were performed using a sodium metal cathode and NaClO4 electrolyte to provide initial confidence in cycle stability and capacity. This work will present detailed characterization of MOF-5 and ZIF-8-derived carbons as sodium-ion battery anode materials, including charge-discharge measurements, cycle performance testing, rate performance testing, and electrochemical impedance spectroscopy measurements.
[1] M. M. Doeff, Y. P. Ma, S. J. Visco, L. C. Dejonghe, J. Electrochem. Soc. 1993, 140, L169.
[2] R. Alcantara, P. Lavela, G. F. Ortiz, J. L. Tirado, Electrochem. Solid-State Lett. 2005, 8, A222.
[3] Kun Tang et. al., Adv Energy Mater. 2012, 2, 873-877.
[4] S. Wenzel, T. Hara, J. Janek, P. Adelhelm, Energy Environ. Sci. 2011, 4, 3342.

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First-Principles Approach to Lithium Diffusion in Silicon
Authors: Kumar Vishank , Di Stefano Davide , Rignanese Gian-Marco , Gonze Xavier 
Published: February 2020

Silicon has drawn a strong interest for its possible application as anode material for the next generation Li-ion batteries. The capacity of silicon is 10 times higher than graphite, however the kinetics of lithiation and delithiation of Si has not yet been fully understood. In this work, the temperature dependent diffusion coefficient of Li has been calculated, in bulk Si and LiSi phase, in the transition state theory framework. The energy barriers and pre-exponential factors have been obtained from total energy and phonon calculations, respectively, using the density functional theory (DFT). In LiSi case with multiple vacancy mediated diffusion pathways, kinetic monte carlo (KMC) simulations were used to calculate the effective diffusion coefficient.
Our results are in good agreement with the experimental data and suggest that in Li-Si system, quantum mechanical effects are only marginally significant. The current study shows a theoretical approach, which is computationally efficient and quantitatively accurate, to fill the gap due to limited studies of Li diffusion in lithiated LixSi phases.