다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

[신간의 별자리x] 우리/미술, 그리고 ‘슬픔의 박물관’

Li-ion battery materials: present and future

Research Development on Sodium-Ion Batteries

The lithium metal battery is strongly considered to be one of the most promising candidates for high-energy-density energy storage devices in our modern and technology-based society. However, uncontrollable lithium dendrite growth induces poor cycling efficiency and severe safety concerns, dragging lithium metal batteries out of practical applications. This review presents a comprehensive overview of the lithium metal anode and its dendritic lithium growth. First, the working principles and technical challenges of a lithium metal anode are underscored. Specific attention is paid to the mechanistic understandings and quantitative models for solid electrolyte interphase (SEI) formation, lithium dendrite nucleation, and growth. On the basis of previous theoretical understanding and analysis, recently proposed strategies to suppress dendrite growth of lithium metal anode and some other metal anodes are reviewed. A section dedicated to the potential of full-cell lithium metal batteries for practical applicatio...

Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review.

Lithium-ion batteries raise safety, environmental, and cost concerns, which mostly arise from their nonaqueous electrolytes. The use of aqueous alternatives is limited by their narrow electrochemical stability window (1.23 volts), which sets an intrinsic limit on the practical voltage and energy output. We report a highly concentrated aqueous electrolyte whose window was expanded to ~3.0 volts with the formation of an electrode-electrolyte interphase. A full lithium-ion battery of 2.3 volts using such an aqueous electrolyte was demonstrated to cycle up to 1000 times, with nearly 100% coulombic efficiency at both low (0.15 C) and high (4.5 C) discharge and charge rates.

"Water-in-salt" electrolyte enables high-voltage aqueous lithium-ion chemistries.

Carbon-coated olivine NaFePO4 (C-NaFePO4) spherical particles with a uniform diameter of ∼80 nm are obtained by chemical delithiation and subsequent electrochemical sodiation of carbon-coated olivine LiFePO4 (C-LiFePO4), which is synthesized by a solvothermal method. The C-NaFePO4 electrodes are identical (particle size, particle size distribution, surface coating, and active material loading, etc.) to C-LiFePO4 except that Li ions in C-LiFePO4 are replaced by Na ions, making them ideal for comparison of thermodynamics and kinetics between C-NaFePO4 cathode in sodium-ion (Na-ion) batteries and C-LiFePO4 in lithium-ion (Li-ion) batteries. In this paper, the equilibrium potentials, reaction resistances, and diffusion coefficient of Na in C-NaFePO4 are systematically investigated by using the galvanostatic intermittent titration technique (GITT), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), and compared to those of the well-known LiFePO4 cathodes in Li-ion batteries. Due to the lower diffusion coefficient of Na-ion and higher contact and charge transfer resistances in NaFePO4 cathodes, the rate performance of C-NaFePO4 in Na-ion batteries is much worse than that of C-LiFePO4 in Li-ion batteries. However, the cycling stability of C-NaFePO4 is almost comparable to C-LiFePO4 by retaining 90% of its capacity even after 100 charge–discharge cycles at a charge–discharge rate of 0.1 C.

Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries

Molybdenum disulfide (MoS2 ) is a promising anode for high performance sodium-ion batteries due to high specific capacity, abundance, and low cost. However, poor cycling stability, low rate capability and unclear electrochemical reaction mechanism are the main challenges for MoS2 anode in Na-ion batteries. In this study, molybdenum disulfide/carbon (MoS2 /C) nanospheres are fabricated and used for Na-ion battery anodes. MoS2 /C nanospheres deliver a reversible capacity of 520 mAh g(-1) at 0.1 C and maintain at 400 mAh g(-1) for 300 cycles at a high current density of 1 C, demonstrating the best cycling performance of MoS2 for Na-ion batteries to date. The high capacity is attributed to the short ion and electron diffusion pathway, which enables fast charge transfer and low concentration polarization. The stable cycling performance and high coulombic efficiency (∼100%) of MoS2 /C nanospheres are ascribed to (1) highly reversible conversion reaction of MoS2 during sodiation/desodiation as evidenced by ex-situ X-ray diffraction (XRD) and (2) the formation of a stable solid electrolyte interface (SEI) layer in fluoroethylene carbonate (FEC) based electrolyte as demonstrated by fourier transform infrared spectroscopy (FTIR) measurements.

An advanced MoS2 /carbon anode for high-performance sodium-ion batteries.

Selenium-impregnated carbon composites were synthesized by infusing Se into mesoporous carbon at a temperature of 600 °C under vacuum. Ring-structured Se8 was produced and confined in the mesoporous carbon, which acts as an electronic conductive matrix. During the electrochemical process in low-cost LiPF6/EC/DEC electrolyte, low-order polyselenide intermediates formed and were stabilized by mesoporous carbon, which avoided the shuttle reaction of polyselenides. Exceptional electrochemical performance of Se/mesoporous carbon composites was demonstrated in both Li-ion and Na-ion batteries. In lithium-ion batteries, Se8/mesoporous carbon composite cathodes delivered a reversible capacity of 480 mAh g–1 for 1000 charge/discharge cycles without any capacity loss, while in Na-ion batteries, it provided initial capacity of 485 mAh g–1 and retained 340 mAh g–1 after 380 cycles. The Se8/mesoporous carbon composites also showed excellent rate capability. As the current density increased from 0.1 to 5 C, the capacit...

Selenium@mesoporous carbon composite with superior lithium and sodium storage capacity.

Sodium ion batteries (SIBs) have been considered as a top alternative to lithium ion batteries due to the earth abundance and low cost of sodium compared with lithium. Among all proposed anode materials for SIBs, red phosphorus (P) is a very promising candidate because it has the highest theoretical capacity (∼2600 mAh/g). In this study, a red P–single-walled carbon nanotube (denoted as red P–SWCNT) composite, in which red P is uniformly distributed between tangled SWCNTs bundles, is fabricated by a modified vaporization-condensation method. Benefiting from the nondestructive preparation process, the highly conductive and mechanically strong SWCNT network is preserved, which enhances the conductivity of the composite and stabilizes the solid electrolyte interphase. As a result, the red P–SWCNT composite presents a high overall sodium storage capacity (∼700 mAh/gcomposite at 50 mA/gcomposite), fast rate capability (∼300 mAh/gcomposite at 2000 mA/gcomposite), and stable long-term cycling performance with 80...

Chao Luo

Papers

"Water-in-salt" electrolyte enables high-voltage aqueous lithium-ion chemistries.

Comparison of electrochemical performances of olivine NaFePO4 in sodium-ion batteries and olivine LiFePO4 in lithium-ion batteries

An advanced MoS2 /carbon anode for high-performance sodium-ion batteries.

Selenium@mesoporous carbon composite with superior lithium and sodium storage capacity.

Red Phosphorus–Single-Walled Carbon Nanotube Composite as a Superior Anode for Sodium Ion Batteries