Ungyu Paik

Silicon is a promising candidate for electrodes in lithium ion batteries due to its large theoretical energy density. Poor capacity retention, caused by pulverization of Si during cycling, frustrates its practical application. We have developed a nanostructured form of silicon, consisting of arrays of sealed, tubular geometries that is capable of accommodating large volume changes associated with lithiation in battery applications. Such electrodes exhibit high initial Coulombic efficiencies (i.e

Rationally designed FeS₂@carbon yolk–shell nanoboxes exhibit impressive electrochemical performance when evaluated as an anode material for sodium-ion batteries.

Exploring new materials with high efficiency and durability is the major requirement in the field of sustainable energy conversion and storage systems. Numerous techniques have been developed in last three decades to enhance the efficiency of the catalyst systems, control over the composition, structure, surface area, pore size, and moreover morphology of the particles. In this respect, metal organic framework (MOF) derived catalysts are emerged as the finest materials with tunable properties an

Crystalline–amorphous phase boundary engineering can be an effective strategy to develop cost-effective and high-performance electrocatalysts for water splitting.

Sb@C coaxial nanotubes have been designed and synthesized using a facile strategy starting with Sb₂S₃nanorods. The as-obtained Sb@C nanotubes exhibit unprecedented sodium storage properties.

Recent advances in materials, mechanics, and electronic device design are rapidly establishing the foundations for health monitoring technologies that have "skin-like" properties, with options in chronic (weeks) integration with the epidermis. The resulting capabilities in physiological sensing greatly exceed those possible with conventional hard electronic systems, such as those found in wrist-mounted wearables, because of the intimate skin interface. However, most examples of such emerging cla

A template-engaged strategy is used to synthesize nanostructured metal phosphides with different compositions. Among the as-synthesized metal phosphides, nickel cobalt phosphides quasi-hollow nanocubes exhibit the best electrocatalytic activity for hydrogen evolution reaction in terms of lower overpotential and smaller Tafel slope in alkaline solution.

Epidermal electronics with advanced capabilities in near field communications (NFC) are presented. The systems include stretchable coils and thinned NFC chips on thin, low modulus stretchable adhesives, to allow seamless, conformal contact with the skin and simultaneous capabilities for wireless interfaces to any standard, NFC-enabled smartphone, even under extreme deformation and after/during normal daily activities.

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.

Problems related to tremendous volume changes associated with cycling and the low electron conductivity and ion diffusivity of Si represent major obstacles to its use in high-capacity anodes for lithium ion batteries. We have developed a group IVA based nanotube heterostructure array, consisting of a high-capacity Si inner layer and a highly conductive Ge outer layer, to yield both favorable mechanics and kinetics in battery applications. This type of Si/Ge double-layered nanotube array electrod

A class of thin, lightweight, flexible, near‐field communication (NFC) devices with ultraminiaturized format is introduced, and systematic investigations of the mechanics, radio frequency characteristics, and materials aspects associated with their optimized construction are presented. These systems allow advantages in mechanical strength, placement versatility, and minimized interfacial stresses compared to other NFC technologies and wearable electronics. Detailed experimental studies and theor

This article overviews the recent progress in TiO₂ (i) as an anode material for Li ion batteries and (ii) as a supplemental material in lithium batteries.

Titanium dioxide (TiO(2)) is one of the most promising anode materials for lithium ion batteries due to low cost and structural stability during Li insertion/extraction. However, its poor rate capability limits its practical use. Although various approaches have been explored to overcome this problem, previous reports have mainly focused on the enhancement of both the electronic conductivity and the kinetic associated with lithium in the composite film of active material/conducting agent/binder.

Titanium niobium oxide (TiNb 2 O 7 ) has been recognized as a promising anode material for lithium‐ion batteries (LIBs) in view of its potential to operate at high rates with improved safety and high theoretical capacity of 387 mAh g −1 . However, it suffers from poor Li + ion diffusivity and low electronic conductivity originated from its wide band gap energy ( E g > 2 eV). Here, porous TiNb 2 O 7 microspheres (PTNO MSs) are prepared via a facile solvothermal reaction. PTNO MSs have a partic