Phys.org August 24, 2021 Due to the permanent loss of Li ions that occurs during the initial charge in the stabilization stage of the battery production the theoretical energy density that can be stored in the batteries has not been achieved. To overcome this issue researchers in South Korea have developed an electrode pre-treatment solution capable of minimizing the initial Li ion loss in graphite-silicon oxide composite anodes. After being dipped in the solution, the anode, which was composed of 50% SiOx, demonstrated negligible Li loss, enabling a full cell to exhibit near-ideal energy density. The work highlights the promise […]
Tag Archives: S&T South Korea
Single-step synthesis of solid-state sensors for detecting explosives
Nanowerk August 12, 2021 Most existing techniques to detect nitroaromatic compounds cannot be used in practical situations. Conventional methods available for the formulation of aggregation-induced emission (AIE) polymers are highly complicated, involving multi-step purification processes, proving detrimental in the application of AIE polymer-based probes. Researchers in South Korea have developed a single step protocol that produces tetraphenylethylene-hyperbranched polyglycidol (TPE-HPG) polymer solution that is added to water for formation of bright blue fluorescent TPE-HPG aggregated nanoparticles. Through empirical analysis, the researchers observed that the strong blue fluorescence of these nanoparticles is quenched by almost 95% on addition of 90 µM concentration […]
Tracking the movement of a single nanoparticle
Phys.org July 27, 2021 Researchers in South Korea have developed a fluorescence-based nanoparticle tracking analysis (NTA) system to characterize the size and protein expression of individual extracellular vesicles (EV). In this system, a sheet of lasers with four different wavelengths was shone onto the EVs according to a programmed schedule, providing scattering images intercalated by three fluorescent images. The size, ratio, and scattered light of thousands of individual particles were observed, and a six-dimensional value composed of three different fluorescence was obtained. They measured the distribution of specific proteins in EVs (e.g., exosomes) at individual particle levels and analyzed the […]
‘Wrapping’ anodes in 3D carbon nanosheets: The next big thing in li-ion battery technology
Science Daily July 22, 2021 The anodes of lithium ion batteries in use today have multiple inadequacies. Researchers in South Korea focused on manganese selenide (MnSe) for its high electrical conductivity. To prevent the drastic volume change it undergoes, they uniformly infused the MnSe nanoparticles into a three-dimensional porous carbon nanosheet matrix. In the new anode material (MnSe ⊂ 3DCNM), the carbon nanosheet scaffold provided MnSe nanoparticles with a high number of active sites and an enhanced contact area with the electrolyte and protected them from drastic volume expansion. They synthesized a variety of MnSe ⊂ 3DCNM materials. Among these, […]
Quantum laser turns energy loss into gain
Phys.org July 7, 2021 Parity-time reversal symmetry in non-Hermitian systems realizes spontaneous symmetry breaking. A team of researchers in South Korea have demonstrated that such direct coupling can remodel conventional photonic platforms of non-Hermitian systems into polaritonic platforms with a single component; thus, improving the degrees of freedom of both integration and design for the coupled system. In this system, they found that as energy loss increased, the amount of energy needed to induce lasing decreased. By controlling the degree of loss between the microcavity and the semiconductor substrate the threshold energy becomes smaller as energy loss increases. According to […]
Perovskite memory devices with ultra-fast switching speed
Science Daily June 22, 2021 Halide perovskite-based memory devices have limitations of slow switching speed which hinder their practical application in memory devices. Researchers in South Korea have successfully developed ultra-fast switching memory devices using halide perovskites by using a combined method of first-principles calculations and experimental verification. From a total of 696 compounds of halide perovskites candidates, Cs3Sb2I9 with a dimer structure was selected as the best candidate for memory application. They fabricated memory devices using the dimer-structured Cs3Sb2I9 to verify the calculation results. The devices were operated with an ultra-fast switching speed of 20 ns, which was more […]
Making batteries live longer with ultrathin lithium
Phys.org June 1, 2021 Lithium metal batteries (LMBs) have high energy density that exceeds lithium batteries (LIBs) by an order of magnitude. The key difference lies in the choice of anode material: LIBs use graphite leading to the formation of dendrites, whereas LMBs use lithium metal. Researchers in South Korea adopted a novel approach in which they pre-planted LiNO3 in the lithium metal powder (LMP) itself during the electrode fabrication process, allowing them to fabricate ~150-mm-wide and 20-μm-thick electrodes, which showed a coulombic efficiency of 96%. The addition of LiNO3 to LMP accomplished two things: it induced a uniform N-rich […]
Ultrafast, on-chip PCR could speed diagnosis during pandemics
Phys.org May 26, 2021 Researchers in South Korea have developed a plasmofluidic PCR chip comprising glass nanopillar arrays with Au nanoislands and gas-permeable microfluidic channels, which contain reaction microchamber arrays, a precharged vacuum cell, and a vapor barrier. The on-chip configuration allows both spontaneous sample loading and microbubble-free PCR reaction during which the plasmonic nanopillar arrays result in ultrafast photothermal cycling. After rapid sample loading, two-step PCR results for 40 cycles show rapid amplification in 264 s for lambda-DNA, and 306 s for plasmids expressing SARS-CoV-2 envelope protein. In addition, the in situ cyclic real-time quantification of amplicons clearly demonstrates […]
Researchers produce laser pulses with record-breaking intensity
Phys.org May 6, 2021 A team of researchers in South Korea demonstrated laser intensity exceeding 1023W/cm2 with the CoReLS petawatt (PW) laser. After wavefront correction and tight focusing with a two-stage adaptive optical system and an f/1.1 (=300mm) off-axis parabolic mirror, they obtained near diffraction-limited focusing with a spot size of 1.1 µm (FWHM). From the measurement of 80 consecutive laser shots at 0.1 Hz, they achieved a peak intensity of (1.1±0.2)×1023W/cm2, verifying the applicability of the ultrahigh intensity PW laser for ultrahigh intensity laser–matter interactions. From the statistical analysis of the PW laser shots, they identified that the intensity […]
A display that completely blocks off counterfeits
EurekAlert January 22, 2021 Researchers in South Korea have developed a device using nanostructures that is capable of encrypting full-color images depending on the polarization of light. The on and off states can be adjusted according to the polarization of the incident light. It displays full-color images during the on state and shows no images in the off state and it can switch between different images. According to the researchers this feature can be utilized as an anti-forgery device security label that appears to be a simple color image to the naked eye but reveals the serial number when a […]