Kyu Tae Lee 교수

New metastable olivine phases of sodium metal phosphates, Na[Mn1–xMx]PO4 (M = Fe, Ca, Mg), nanorods are synthesized by a simple solid-state reaction at low temperature (≤100 °C) by means of a topotactic molten salt reaction that converts NH4[Mn1–xMx]PO4•H2O (M = Fe, Ca, Mg) to Na[Mn1–xMx]PO4. Their crystal structures are characterized via XRD Rietveld refinement and electron diffraction. A full range of solid solution behavior was observed for olivine Na1–xMn0.5Fe0.5PO4, in contrast to that of L

Motivated by new applications including electric vehicles and the smart grid, interest in advanced lithium ion batteries has increased significantly over the past decade. Therefore, research in this field has intensified to produce safer devices with better electrochemical performance. Most research has focused on the development of new electrode materials through the optimization of bulk properties such as crystal structure, ionic diffusivity, and electric conductivity. More recently, researche

Abstract A new polyanion‐based compound, Na 3.12 M 2.44 (P 2 O 7 ) 2 (M = Fe, Fe 0.5 Mn 0.5 , Mn) is synthesized and examined as a cathode for Na ion batteries. Off‐stoichiometric synthesis induces the formation of a Na‐rich phase, Na 3.32 Fe 2.34 (P 2 O 7 ) 2 ‐ a member of the solid solution series Na 4‐α Fe 2+α/2 (P 2 O 7 ) 2 (2/3 ≤ α ≤ 7/8) ‐ which delivers a reversible capacity of about 85 mA h g −1 at ca. 3 V vs. Na/Na + and exhibits very stable cycle performance. Above all, it shows fast k

The concept of surface-initiated growth of oxides on functionalized carbons is introduced as a method to inhibit the dissolution of polysulfide ions in Li–S battery cathode materials. MOx (M: Si, V) thin layers are homogeneously coated on nanostructured carbon–sulfur composites. The coating significantly inhibits the dissolution of polysulfides on cycling, resulting in enhanced cycle performance and coulombic efficiency of the Li–S battery.

SnSe alloy is examined for the first time as an anode for Na-ion batteries, and shows excellent electrochemical performance including a high reversible capacity of 707 mA h g(-1) and stable cycle performance over 50 cycles. Upon sodiation, SnSe is changed into amorphous NaxSn nanodomains dispersed in crystalline Na2Se, and SnSe is reversibly restored after desodiation.

Mild-acid Zn-MnO₂ batteries have been considered a promising alternative to Li-ion batteries for large scale energy storage systems because of their high safety. There have been remarkable improvements in the electrochemical performance of Zn-MnO₂ batteries, although the reaction mechanism of the MnO₂ cathode is not fully understood and still remains controversial. Herein, the reversible dissolution/deposition (Mn²⁺/Mn⁴⁺) mechanism of the Mn

Law and order: When metal phthalocyanines are used as the carbon precursor, pseudo-solid-state in situ chemical vapor deposition on mesoporous silica yields highly graphitic mesoporous carbon materials (see TEM image) with ordered pore structure, high surface area, and high pore volume. This simple synthetic route is suitable for bulk production, and the high degree of graphitization is enhanced by the catalytic action of the metal. Detailed facts of importance to specialist readers are publishe

Lithium-oxygen (Li-O₂) batteries are desirable for electric vehicles because of their high energy density. Li dendrite growth and severe electrolyte decomposition on Li metal are, however, challenging issues for the practical application of these batteries. In this connection, an electrochemically active two-dimensional phosphorene-derived lithium phosphide is introduced as a Li metal protective layer, where the nanosized protective layer on Li metal suppresses electrolyte decompositi

Abstract Remarkable improvements in the electrochemical performance of Si materials for Li‐ion batteries have been recently achieved, but the inherent volume change of Si still induces electrode expansion and external cell deformation. Here, the void structure in Si‐encapsulating hollow carbons is optimized in order to minimize the volume expansion of Si‐based anodes and improve electrochemical performance. When compared to chemical etching, the hollow structure is achieved via electroless etchi

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTCointercalation of Mg2+ Ions into Graphite for Magnesium-Ion BatteriesDong-Min KimDong-Min KimSchool of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, 1, Gwanak-ro, Gwanak-gu, Seoul 08826, Republic of KoreaMore by Dong-Min Kimhttp://orcid.org/0000-0003-0676-8208, Sung Chul JungSung Chul JungDepartment of Physics, Pukyong National University, Busan 48513, Republic of KoreaMore by Sung Chul Jung, Se

All-solid-state batteries (ASSBs) have received much attention because of their high energy density and safety. However, the safety of argyrodite-type Li6PS5Cl (LPSCl)-based ASSBs is still not assured because their thermal stability has been assessed under selected mild conditions. Herein, we introduce the poor thermal stability of LPSCl with Ni-rich layered oxide cathode materials as the trigger of thermal runaway. The charged composite cathode pellets containing Li1–xNi0.8Co0.1Mn0.1O2 and LPSC

Abstract Various doped materials have been investigated to improve the structural stability of layered transition metal oxides for lithium‐ion batteries. Most doped materials are obtained through solid state methods, in which the doping of cations is not strictly site selective. This paper demonstrates, for the first time, an in situ electrochemical site‐selective doping process that selectively substitutes Li + at Li sites in Mn‐rich layered oxides with Mg 2+ . Mg 2+ cations are electrochemical

Homogeneous-sized LiMPO(4) (M = Fe, Mn) nanorods and bulk particles were synthesized, and the thermodynamic characteristics of their mixtures as electrodes were analyzed to study the lithiation/delithiation mechanism for the general case of nanoparticles with a heterogeneous particle size distribution. We show that ionic transport occurs between nano and bulk particles in a cell at equilibrium, due to their electrochemical potential difference that originates from their different thermodynamic p

Advanced porous separators with thin selective skin layers to reduce the hydrogen permeation are developed for applications in alkaline water electrolysis. A thin skin layer based on crosslinked polyvinyl alcohol (cPVA) is fabricated on a porous substrate by a facile and scalable ultrasonic spray coating process. As the number of ultrasonic spraying cycles increases, the resulting separator demonstrates a decrease in the large-diameter pore fraction, an increase in the bubble-point pressure, and