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.

As high capacity cathodes for Li-ion and Na-ion batteries, carbon bonded and encapsulated selenium composites (C/Se) with a high loading content of 54% Se were synthesized by the in situ carbonization of a mixture of perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) and selenium (Se) in a sealed vacuum glass tube. Because Se is physically encapsulated and chemically bonded by carbon, the shuttle reaction of polyselenide is effectively mitigated. The in situ formed C/Se composites exhibit superior cycling stability for both Li-ion and Na-ion batteries in carbonate-based electrolytes. The reversible capacity of the in situ formed C/Se composites is maintained at 430 mA h g−1 after 250 cycles in Li-ion batteries and 280 mA h g−1 after 50 cycles in Na-ion batteries at a current density of 100 mA g−1.

In situ formed carbon bonded and encapsulated selenium composites for Li–Se and Na–Se batteries

Organic compounds are desirable alternatives for sustainable lithium-ion battery electrodes. However, the electrochemical properties of state-of-the-art organic electrodes are still worse than commercial inorganic counterparts. Here, a new chemistry is reported based on the electrochemical conversion of nitro compounds to azo compounds for high performance lithium-ion batteries. 4-Nitrobenzoic acid lithium salt (NBALS) is selected as a model nitro compound to systemically investigate the structure, lithiation/delithiation mechanism, and electrochemical performance of nitro compounds. NBALS delivers an initial capacity of 153 mAh g-1 at 0.5 C and retains a capacity of 131 mAh g-1 after 100 cycles. Detailed characterizations demonstrate that during initial electrochemical lithiation, the nitro group in crystalline NBALS is irreversibly reduced into an amorphous azo compound. Subsequently, the azo compound is reversibly lithiated/delithiated in the following charge/discharge cycles with high electrochemical performance. The lithiation/delithiation mechanism of azo compounds is also validated by directly using azo compounds as electrode materials, which exhibit similar electrochemical performance to nitro compounds, while having a much higher initial Coulombic efficiency. Therefore, this work proves that nitro compounds can be electrochemically converted to azo compounds for high performance lithium-ion batteries.

Azo Compounds Derived from Electrochemical Reduction of Nitro Compounds for High Performance Li-Ion Batteries.

Na3V2(PO4)3 (NVP) has been considered as a very promising cathode material for sodium-ion batteries (SIBs) due to its typical NASICON structure, which provides an open and three dimensional (3D) framework for Na+ migration. However, the low electronic conductivity of NVP limits its rate capability and cycling ability. In this study, carbon coated hollow structured NVP/C composites are synthesized via a template-free and scalable ultrasonic spray pyrolysis process, where the carbon coated NVP particles are uniformly decorated on the inner and outer surfaces of the porous hollow carbon spheres. When evaluated as a cathode material for SIBs, the unique NVP/C porous hollow sphere cathode delivers an initial discharge capacity of 99.2 mA h g−1 and retains 89.3 mA h g−1 after 300 charge/discharge cycles with a very low degradation rate of 0.035% per cycle. For comparison, the NVP/C composite, prepared by the traditional sol–gel method, delivers a lower initial discharge capacity of 97.4 mA h g−1 and decreases significantly to 71.5 mA h g−1 after 300 cycles. The superior electrochemical performance of NVP/C porous hollow spheres is attributed to their unique porous, hollow and spherical structures, as well as the carbon-coating layer, which provides a high contact area between electrode/electrolyte, high electronic conductivity, and high mechanical strength.

Scalable synthesis of Na3V2(PO4)3/C porous hollow spheres as a cathode for Na-ion batteries

Strategies in Structure and Electrolyte Design for High‐Performance Lithium Metal Batteries

Lithium sulfur batteries (LSBs) are promising next-generation rechargeable batteries due to the high gravimetric energy, low cost, abundance, nontoxicity, and high sustainability of sulfur. However, the dissolution of high-order polysulfide in electrolytes and low Coulombic efficiency of Li anode require excess electrolytes and Li metal, which significantly reduce the energy density of LSBs. Quasi-solid-state LSBs, where sulfur is encapsulated in the micropores of carbon matrix and sealed by solid electrolyte interphase, can operate under lean electrolyte conditions, but a low sulfur loading in carbon matrix (<40 wt %) and low sulfur unitization (<70%) still limit the energy density in a cell level. Here, we significantly increase the sulfur loading in carbon to 60 wt % and sulfur utilization to ∼87% by dispersing sulfur in an oxygen-rich dense carbon host at a molecular level through strong chemical interactions of C-S and O-S. In an all-fluorinated organic lean electrolyte, the C/S cathode experiences a solid-state lithiation/delithiation reaction after the formation of solid electrolyte interphase in the first deep lithiation, completely avoiding the shuttle reaction. The chemically stabilized C/S composite retains a high reversible capacity of 541 mAh⋅g-1 (based on the total weight of the C/S composite) for 200 cycles under lean electrolyte conditions, corresponding to a high energy density of 974 Wh⋅kg-1 The superior electrochemical performance of the chemical bonding-stabilized C/S composite renders it a promising cathode material for high-energy and long-cycle-life LSBs.

https://www.pnas.org/content/pnas/117/26/14712.full.pdf

Chao Luo

Papers

In situ formed carbon bonded and encapsulated selenium composites for Li–Se and Na–Se batteries

Azo Compounds Derived from Electrochemical Reduction of Nitro Compounds for High Performance Li-Ion Batteries.

Scalable synthesis of Na3V2(PO4)3/C porous hollow spheres as a cathode for Na-ion batteries

Strategies in Structure and Electrolyte Design for High‐Performance Lithium Metal Batteries

A chemically stabilized sulfur cathode for lean electrolyte lithium sulfur batteries