The Surface Coating of Commercial LiFePO_4 by Utilizing ZIF-8 for High Electrochemical Performance Lithium Ion Battery

The requirement of energy-storage equipment needs to develop the lithium ion battery(LIB) with high electrochemical performance. The surface modification of commercial LiFePO_4(LFP) by utilizing zeolitic imidazolate frameworks-8(ZIF-8) offers new possibilities for commercial LFP with high electrochemical performances.In this work, the carbonized ZIF-8(C_(ZIF-8)) was coated on the surface of LFP particles by the in situ growth and carbonization of ZIF-8. Transmission electron microscopy indicates that there is an approximate 10 nm coating layer with metal zinc and graphite-like carbon on the surface of LFP/C_(ZIF-8) sample. The N_2 adsorption and desorptionisotherm suggests that the coating layer has uniform and simple connecting mesopores. As cathode material, LFP/C_(ZIF-8) cathode-active material delivers a discharge specific capacity of 159.3 m Ah g^(-1) at 0.1 C and a discharge specific energy of 141.7 m Wh g^(-1) after 200 cycles at 5.0 C(the retention rate is approximate 99%). These results are attributed to the synergy improvement of the conductivity,the lithium ion diffusion coefficient, and the degree of freedom for volume change of LFP/C_(ZIF-8) cathode. This work will contribute to the improvement of the cathode materials of commercial LIB.

Silver Nanowire Electrodes: Conductivity Improvement Without Post-treatment and Application in Capacitive Pressure Sensors

Transparent electrode based on silver nanowires(Ag NWs) emerges as an outstanding alternative of indium tin oxide film especially for flexible electronics. However, the conductivity of Ag NWs transparent electrode is still dramatically limited by the contact resistance between nanowires at high transmittance. Polyvinylpyrrolidone(PVP) layer adsorbed on the nanowire surface acts as an electrically insulating barrier at wire–wire junctions, and some devastating post-treatment methods are proposed to reduce or eliminate PVP layer, which usually limit the application of the substrates susceptible to heat or pressure and burden the fabrication with high-cost, time-consuming, or inefficient processes. In this work, a simple and rapid pre-treatment washing method was proposed to reduce the thickness of PVP layer from 13.19 to0.96 nm and improve the contact between wires. Ag NW electrodes with sheet resistances of 15.6 and 204 X sq-1have been achieved at transmittances of 90 and 97.5 %, respectively. This method avoided any post-treatments and popularized the application of high-performance Ag NW transparent electrode on more substrates. The improved Ag NWs were successfully employed in a capacitive pressure sensor with high transparency, sensitivity, and reproducibility.

Low haze transparent electrodes and highly conducting air dried films with ultra-long silver nanowires synthesized by one-step polyol method

Transparent electrodes made of silver nanowires （AgNWs） exhibit higher flexibility when compared to those made of tin doped indium oxide （ITO） and are expected to be applied in plastic electronics. However, these transparent electrodes composed of AgNWs show high haze because the wires cause strong light scattering in the visible range. Reduction of the wire diameter has been proposed as a way to weaken light scattering, although there have seldom been any studies focusing on the haze because of the difficulty involved in controlling the wire diameter. In this report, we show that the haze can be easily reduced by increasing the length of AgNWs with a large diameter. Ultra-long （u-long） AgNWs with lengths in the range of 20-100 μm and a maximum length of 230 μm have been successfully synthesized by adjusting the reaction temperature and the stirring speed of a one-step polyol process. Compared to typical AgNWs （with diameter and length of 70 nm and 10 μm, respectively） and ITO, a transparent electrode consisting of u-long AgNWs 91 nm in diameter demonstrated a low haze of 3.4%-1.6% and a low sheet resistance of 24-109 Ω/sq. at a transmittance of 94%-97%. Even when fabricated at room temperature without any post-treatment, the electrodes composed of u-long AgNWs achieved a sheet resistance of 19 Ω/sq, at a transmittance of 80%, which is six orders of magnitude lower than that of typical AgNWs.

Facile fabrication of stretchable Ag nanowire/polyurethane electrodes using high intensity pulsed light

Silver nanowires （AgNWs） have emerged as a promising nanomaterial for next generation stretchable electronics. However, until now, the fabrication of AgNW- based components has been hampered by complex and time-consuming steps. Here, we introduce a facile, fast, and one-step methodology for the fabrication of highly conductive and stretchable AgNW/polyurethane （PU） composite electrodes based on a high-intensity pulsed light （HIPL） technique. HIPL simultaneously improved wire-wire junction conductivity and wire-substrate adhesion at room temperature and in air within 50 μs, omitting the complex transfer-curing-implanting process. Owing to the localized deformation of PU at interfaces with AgNWs, embedding of the nanowires was rapidly carried out without substantial substrate damage. The resulting electrode retained a low sheet resistance （high electrical conductivity） of 〈10 Ω/sq even under 100% strain, or after 1,000 continuous stretching-relaxation cycles, with a peak strain of 60%. The fabricated electrode has found immediate application as a sensor for motion detection. Furthermore, based on our electrode, a light emitting diode （LED） driven by integrated stretchable AgNW conductors has been fabricated. In conclusion, our present fabrication approach is fast, simple, scalable, and cost- efficient, making it a good candidate for a future roll-to-roll process.

Oxidation-enhanced bonding strength of Cu sinter joints during thermal storage test

With the development in next-generation semiconductor power devices,the power devices based on silicon carbide(SiC)and gallium nitride(GaN)are expected to replace the traditional Si-based power devices[1–6].However,the foreseeable harsh operating environment such as heavy thermal-load or extremely temperature cycle required more reliable interconnection technology[4,7-9].