Jung Sub Kim

Si–Mn/Reduced Graphene Oxide Nanocomposite Anodes with Enhanced Capacity and Stability for Lithium-Ion Batteries

Although Si is a promising high-capacity anode material for Li-ion batteries (LIB), it suffers from capacity fading due to excessively large volumetric changes upon Li insertion. Nanocarbon materials have been used to enhance the cyclic stability of LIB anodes, but they have an inherently low specific capacity. To address these issues, we present a novel ternary nanocomposite of Si, Mn, and reduced graphene oxide (rGO) for LIB anodes, in which the Si-Mn alloy offers high capacity characteristics and embedded rGO nanosheets confer structural stability. Si-Mn/rGO ternary nanocomposites were synthesized by mechanical complexation and subsequent thermal reduction of mixtures of Si nanoparticles, MnO2 nanorods, and rGO nanosheets. Resulting ternary nanocomposite anodes displayed a specific capacity of 600 mAh/g with ∼90% capacity retention after 50 cycles at a current density of 100 mA/g. The enhanced performance is attributed to facilitated Li-ion reactions with the MnSi alloy phase and the formation of a structurally reinforced electroconductive matrix of rGO nanosheets. The ternary nanocomposite design paradigm presented in this study can be exploited for the development of high-capacity and long-life anode materials for versatile LIB applications.

Si/Ti2O3/Reduced Graphene Oxide Nanocomposite Anodes for Lithium-Ion Batteries with Highly Enhanced Cyclic Stability

Silicon (Si) has attracted tremendous attention as a high-capacity anode material for next generation Li-ion batteries (LIBs); unfortunately, it suffers from poor cyclic stability due to excessive volume expansion and reduced electrical conductivity after repeated cycles. To circumvent these issues, we propose that Si can be complexed with electrically conductive Ti2O3 to significantly enhance the reversible capacity and cyclic stability of Si-based anodes. We prepared a ternary nanocomposite of Si/Ti2O3/reduced graphene oxide (rGO) using mechanical blending and subsequent thermal reduction of the Si, TiO2 nanoparticles, and rGO nanosheets. As a result, the obtained ternary nanocomposite exhibited a specific capacity of 985 mAh/g and a Coulombic efficiency of 98.4% after 100 cycles at a current density of 100 mA/g. Furthermore, these ternary nanocomposite anodes exhibited outstanding rate capability characteristics, even with an increased current density of 10 A/g. This excellent electrochemical performance can be ascribed to the improved electron and ion transport provided by the Ti2O3 phase within the Si domains and the structurally reinforced conductive framework comprised of the rGO nanosheets. Therefore, it is expected that our approach can also be applied to other anode materials to enable large reversible capacity, excellent cyclic stability, and good rate capability for high-performance LIBs.

Corrosion behaviour of Zr1−xTixV0.6Ni1.2M0.2 (M=Ni, Cr, Mn) AB2-type metal hydride alloys in alkaline solution

Abstract An examination is made of the discharge and cycle life of Zr 0.5 Ti 0.5 V 0.6 Ni 1.4 alloys when a fraction (0.2 at.%) of the Ni-component is substituted by Cr or Mn. In addition, the Zr:Ti component ratios are varied to extend the cycle life of high capacity, Mn-substituted Zr 1− x Ti x V 0.6 Ni 1.2 Mn 0.2 ( x =0.0, 0.25, 0.5, 0.75) alloys. The metallurgical microstructure is observed by X-ray diffraction analysis, scanning electron microscopy, and energy dispersive X-ray analysis. Active–passive potentiodynamic behaviour, as well as charge–discharge cycle characteristics, is evaluated, and dissolved V-species in the electrolytic solution is analyzed by inductively coupled plasma spectroscopy. The corrosion behaviour of the V–Cr or the V–Mn phase in the alkaline electrolyte solution is found to determine the cycle life of an AB 2 alloy. Cr-substituted (Zr 0.5 Ti 0.5 Ni 1.2 Cr 0.2 ) alloy, containing a V–Cr phase, is estimated to involve a dissolution rate of 0.028 wt.% vanadium per cycle in an alkaline electrolytic solution, while Mn-substituted (Zr 0.5 Ti 0.5 V 0.6 Ni 1.2 Mn 0.2 ) alloy, containing a V–Mn phase, is estimated to have a dissolution rate of 0.138 wt.% vanadium per cycle. For Mn-substituted alloys, an optimum Zr:Ti ratio of 3:1, i.e., Zr 0.75 Ti 0.25 V 0.6 Ni 1.2 Mn 0.2 , is found to have the most stable cycle life. The improvement in cycle life caused by increasing the Zr content in the alloy is attributed to increase in the corrosion resistance of the alloy due to less formation of the corrosive V–Mn phase.

Uniformly dispersed silicon nanoparticle/carbon nanosphere composites as highly stable lithium-ion battery electrodes

Engineered silicon and carbon composite materials have been demonstrated to be promising anode materials for lithium-ion batteries. In this paper, we demonstrate a facile approach to fabricating silicon/carbon composite electrodes via simple mixing of silicon nanoparticles (SNPs) and carbon nanospheres (CNSs). Size-monodisperse CNSs were obtained by the direct carbon conversion of polystyrene spheres. The mixture of SNPs with size-monodisperse CNSs allowed for a uniform dispersion with minimal SNP aggregation, which was evaluated through direct comparison of the SNP mixture with micrometer-sized carbon particles. This SNP/CNS composite electrode, containing 30 wt% SNPs, exhibited a reversible specific capacity of 1023 mA h g−1 at 100 mA g−1, which was more than three times higher than that of a bare CNS electrode. The capacity retention after 50 cycles was 73%, with a high Coulombic efficiency of 99%; in addition, the capacity retention was approximately 70% when the current density was increased tenfold. Specifically, the SNP/CNS electrode exhibited substantially less capacity fade than did SNPs dispersed in micrometer-sized carbon particles. Moreover, the SNP/CNS electrode exhibited improved capacity retention under high-current-density conditions compared to that of previously developed silicon/carbon composite anodes. We attributed this improved LIB performance to the uniform dispersion of SNPs in the CNS matrix, which resulted in stable SEI formation and effective accommodation of the volume change of silicon. We believe our CNS structures can be extended to other electrode-material systems that require a large volume change and good mass transport characteristics.

Si nanoparticles-nested inverse opal carbon supports for highly stable lithium-ion battery anodes

The confinement and uniform dispersion of Si nanoparticles (NPs) in a carbon matrix is a promising strategy to accommodate the problematic large volume change of high-capacity Si-based anodes during charging/discharging in lithium-ion batteries. Here, we introduced an inverse opal carbon (IOC) matrix for Si NPs dispersion. A macroporous, highly interconnected porous structure of IOCs allowed uniform dispersion of Si NPs by simple mixing, and large voids that surrounded the Si NPs. The Si NPs/IOC composite anode exhibited a specific capacity up to 1233 mA g−1 with 40 wt% Si NPs content, which was 4.1 times higher than the IOC anode. The capacity retention over 50 cycles for the Si NPs/IOC anode (40 wt% Si NPs/IOC) was as high as 81%, whereas the Si NPs anode revealed only 48% retention. The specific capacity was also maintained up to 70% as the current density increased 20-fold. These enhancement of the capacity retention and the current density were attributed to the efficient accommodation of the Si volume change in the IOC structure and facile charge transport in and through the IOC matrix. We believe this simple geometry-derived approach for the dispersion of nanoparticles may be advantageous in the practical application of high-capacitive nanomaterials for next-generation lithium ion battery (LIB) development.

3D Woven‐Like Carbon Micropattern Decorated with Silicon Nanoparticles for Use in Lithium‐Ion Batteries

Carbon/silicon composite materials are a promising anode substrate for use in lithium-ion batteries. In this study, we suggest a new architecture for a composite electrode made of a woven-like carbon material decorated with silicon nanoparticles. The 3D woven-like carbon (WLC) structure was fabricated using direct carbonization of multi-beam interference lithography polymer patterns. Subsequent solution coating was applied to decorate the WLC with silicon nanoparticles (SiNPs). The SiNP/WLC electrode exhibited a specific capacity of 930 mAh g(-1) , which is three times higher than the specific capacity of the bare electrode. Specifically, the SiNP/WLC electrode exhibited an outstanding retention capacity of 81 % after 50 cycles and a Coulombic efficiency of more than 98 %. This rate capability performance was attributed to the WLC structure and the uniform decoration of the SiNPs.

Population Pharmacokinetics of Liposomal Irinotecan in Patients With Cancer

Nanoliposomal irinotecan (nal‐IRI) is a liposomal formulation of irinotecan with a longer half‐life (t1/2), higher plasma total irinotecan (tIRI), and lower SN‐38 maximum concentration (Cmax) compared with nonliposomal irinotecan. Population pharmacokinetic (PK) analysis of nal‐IRI was performed for tIRI and total SN‐38 (tSN38) using patient samples from six studies. PK‐safety association was evaluated for neutropenia and diarrhea in 353 patients. PK‐efficacy association was evaluated from a phase III study in pancreatic cancer NAPOLI1. Efficacy was associated with longer duration of unencapsulated SN‐38 (uSN38) above a threshold and higher Cavg of tIRI, tSN38, and uSN38. Neutropenia was associated with uSN38 Cmax and diarrhea with tIRI Cmax. Baseline predictive factors were race, body surface area, and bilirubin. Analysis identified PK factors associated with efficacy, safety, and predictive baseline factors. The results support the benefit of nal‐IRI dose of 70 mg/m2 (free‐base; equivalent to 80 mg/m2 salt base) Q2W over 100 mg/m2 Q3W.

Ductile fracture simulation for A106 Gr.B carbon steel under high strain rate loading condition

This paper provides simulation of ductile crack growth under high strain rate loading condition using a stress-modified fracture strain models. The stress-modified fracture strain model is determined to be incremental damage in terms of stress triaxiality ( σ m / σ e ) and fracture strain ( e f ) for dimple fracture from tensile test result with FE analyses technique. In order to validate stress-modified fracture strain model in dynamic loading conditions, this paper compares FE results with test results fitted by Johnson-Cook model. The calibrated damage model predicts CT test result under high strain rate. Simulated results agree well with experimental data.

Laser shock peening simulation of mitigation on residual stress in Alloy 600

Laser shock peening simulation method especially for Alloy 600 penetration nozzles in pressurized water reactor is proposed. In order to simulate multiple laser peening process, the strain rate dependent stress-strain relationship with isotropic hardening model was considered. In this paper, we present analytical results about the effect of multiple laser peening on mitigation of tensile residual stress in Alloy 600.

212PTHE PROGNOSTIC ROLE OF SERUM CXCR4 IN METASTATIC OR RECURRENT COLORECTAL CANCER

ABSTRACT Aim: The CXCR4 is involved in several aspects of tumor progression including angiogenesis, metastasis, and survival. However, whether serum CXCR4 level in metastatic or recurrent colorectal cancer (CRC) has a prognostic role has been not evaluated. Methods: We analyzed serum samples from 55 patients with advanced CRC diagnosed between March 2008 and July 2011. Blood was collected before beginning systemic chemotherapy and serum CXCR4 levels were quantified by commercially available ELISA kit. Results: The median age of the 55 patients was 62 years (range: 39-82) and all patients received systemic chemotherapy of 2 or more line. The median serum CXCR4 level was 283.47pg/ml (range, 77.48-846.52). Patients with 2 or more of metastatic sites, liver metastasis, or over more normal level of CA 19-9 (37 248.0pg/ml) (p = 0.046). The median OS was 26.50 (95% CI, 17.37-35.63) and 17.03 (95% CI, 14.67-19.39) months. Univariate analysis showed that liver metastasis, no debulking operation and higher level of CXCR4 (>248.0) had significantly poor prognostic value regarding OS (p Conclusions: Serum CXCR4 level was positively correlated with disease burden (2 or more of metastatic sites, liver metastasis, or over more normal level of CA 19-9). And there was significant difference for OS according to the level of CXCR4. These findings suggested that CXCR4 might be useful as surrogate marker of clinical outcome in metastatic or recurrent CRC. Disclosure: All authors have declared no conflicts of interest.