Hansu Kim

Li-air(O2) and Li-S batteries have gained much attention recently and most relevant research has aimed to improve the electrochemical performance of air(O2) or sulfur cathode materials. However, many technical problems associated with the Li metal anode have yet to be overcome. This review mainly focuses on the electrochemical behaviors and technical issues related to metallic Li anode materials as well as other metallic anode materials such as alkali (Na) and alkaline earth (Mg) metals, includi

TiO2 nanofibers, TiO2 hollow nanofibers, and nitridated TiO2 hollow nanofibers were synthesized using a simple electrospinning method and subsequent nitridation treatment. The nitridated TiO2 hollow nanofibers showed twice higher rate capability compared to that of pristine TiO2 nanofibers at 5 C. This improvement is mainly attributed to shorter lithium ion diffusion length and high electronic conductivity along the surface of nitridated hollow nanofibers.

The reaction mechanism of lithium insertion into was studied using various analytic techniques including electrochemical measurements, X‐ray diffraction (XRD), and Auger electron spectroscopy (AES). Electrochemical tests demonstrated that 1 mol reacted with 3.9 mol Li from which the initial capacity obtained was approximately 1370 mAh/g. Ex situ XRD and AES data showed that lithium intercalated into the lattice first followed by alloying with Si and Mg. The degradation mechanism of during cyclin

In order to develop high capacity electrode materials with next generation Li-ion batteries, intensive research effort has been actively devoted to satisfy the power demands for electronic devices, electric vehicles and energy storage units for renewable energy. This review focuses on high capacity Si based nanostructured anode materials composed of Si and various inactive phase materials. This review is devoted mainly to their electrochemical performances and technical issues when they were emp

Abstract To overcome the lithium storage barriers of current lithium‐ion batteries, it is imperative that conventional low capacity graphite anodes be replaced with other higher capacity anode materials. Silicon is a promising alternative anode material due to its huge energy densities; however, its lithium‐concentration‐dependent volumetric changes can induce severely adverse effects that lead to drastic degradations in capacity during cycling. The dealloying of Si–metal alloys is recently sugg

2D nanoscale oxides have attracted a large amount of research interest due to their unique properties. Here, a facile synthetic approach to prepare graphene‐mimicking, porous 2D Co 3 O 4 nanofoils using graphene oxide (GO) as a sacrificial template is reported. The thermal instability of graphene, as well as the catalytic ability of Co 3 O 4 particles to degrade carbon backbones, allow the fabrication of porous 2D Co 3 O 4 nanofoils without the loss of the 2D nature of GO. Based on these results

We demonstrated room temperature cross-linkable gel polymer electrolytes (GPE) prepared by in situ cationic polymerization of tri(ethylene glycol) divinyl ether (TEGDVE) with LIBF4 that yields protonic acid and Lewis acid as an acidic initiating system by the reaction with water as an impurity in the liquid electrolyte. FTIR analysis reveals that TEGDVE in the liquid electrolyte is successfully polymerized into gel polymer electrolyte. The resulting gel polymer electrolyte showed promising elect

Lithiation–delithiation reactions in Li‐ion batteries do exhibit a huge electrochemically driven volume change of the anode material between the lithium‐free and lithiated‐host states, which results in a gradually fading capacity. Minimizing this volume change of the electrode during cycling is essential to achieve stable electrochemical behavior and thus for innovating design of electrode materials for Li storage. Here, ordered mesoporous CoSn intermetallic anode materials with various Co/Sn at

Mesoporous transition metal dichalcogenides with 2D layered crystallinity, synthesized through a melting-infiltration assisted nano-replication, exhibit excellent electrochemical performances for lithium-storage.

Porous Si of up to 200 μm in thickness has been used to fabricate high-performance spiral inductors on heavily doped Si substrates (0.007 /spl Omega/-cm). Spiral inductors with L/spl sim/5.7 nH are fabricated demonstrating Q <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> /spl sim/29 at 7 GHz and f/sub r/>20 GHz. The resonant frequency (f/sub r/) increases with increasing porous Si thickness and saturates beyond 120 μm. A corresponding dec

Si-based high-capacity materials have gained much attention as an alternative to graphite in Li-ion battery anodes. Although Si additions to graphite anodes are now commercialized, the fraction of Si that can be usefully exploited is restricted due to its poor cyclability arising from the large volume changes during charge/discharge. Si/SiO _x nanocomposites have also shown promising behavior, such as better capacity retention than Si alone because the amorphous SiO _x helps