Silicon anodes usually endure low initial coulombic efficiency (ICE) in applications for lithium-ion batteries (LIBs), although the volume expansion and structural stability has been greatly improved under many efforts in the recent years. During the first charge and discharge, a large number of lithium ions can participate in the formation of a solid electrolyte interface (SEI) on anode surface, such as LiF, Li 2 CO 3 and many Li-based compounds, resulting in low efficiency, particularly as the nanosized silicon is widely applied to solve the volume effect. Herein, we find that the lithium difluorophosphate (LiPO 2 F 2 , LiDFP) additive shows some special properties, which greatly improve the reversible capacity in the first discharge. The silicon nanoparticles can deliver an ICE of 70.6 % with 2 wt% LiDFP in the electrolyte, which is increased by 17.7 % compared with the cell without LiDFP (ca. 52.9 %). By comparing the XPS and NMR results, it appears the LiDFP may reduce the number of lithium ions involved in the SEI reaction in the electrolyte during the first discharge, and thus the ICE can be improved.

We demonstrate a transparent stretchable supercapacitor based on a nanocomposite electrode consisting of silver nanowires (AgNWs) and poly­(3,4-ethylenedioxythiophene)-poly­(styrenesulfonate) (PEDOT:PSS) modified with ethylene glycol. The addition of ethylene glycol (EG) in the PEDOT:PSS solution can dramatically enhance the conductivity of the polymer film. Furthermore, the solvent treatment induces the reorganization of the polymer chains, leading to better distribution of PEDOT:PSS on the AgNW network. With the EG-enhanced AgNWs/PEDOT:PSS electrode, an 87% transmittance of the nanocomposite electrode can be achieved at a wavelength of 550 nm and a pseudo capacitance of 113 ± 18 F/g (areal capacitance = 2.83 ± 0.46 mF cm–2) can be achieved at a scan rate of 10 mV/s. When it was stretched with a tensile strain of 40%, the capacitance of the transparent supercapacitor even increased, owing to closer electrode contact. This work provides a facile way to produce highly transparent and stretchable electrodes using EG-enhanced nanocomposite for a stretchable portable power source of transparent electronics.

Ba 0.6 Sr 0.4 Ti O 3 (BST) thin films were prepared on MgO buffered Pt(111)∕Ti∕SiO2∕Si substrates by pulsed laser deposition. The crystallographic structure, interface characteristics, and dielectric properties of BST thin films are strongly dependent on MgO thickness. BST thin films exhibit (111) preferred orientation when MgO layer is thicker than 5nm. The MgO layer can mitigate the interdiffusion between BST and Pt, causing the dielectric loss and leakage current of BST thin films to decrease significantly. The dielectric loss, tunability, and the largest figure of merit of BST thin films on 10nm MgO achieve 0.009, 30%, and 33.4, respectively.

No abstract

Fe-doped Ba(0.6)Sr(0.4)TiO3 (BST) thin films were prepared on Pt/Si substrates by the pulsed-laser deposition method. The concentrations of Fe dopants vary from 0.1 mol% to 1.0 mol%. Our results indicate that a certain amount of Fe dopants can decrease the dielectric loss of BST thin films without causing the significant reduction of the tunability. The leakage current of BST thin films also was reduced by the addition of Fe dopants. BST thin films doped with 0.3 mol% Fe ions show a minimum dielectric loss of 0.88% at 10(6) Hz, which is 1.7% for the undoped BST films. Moreover, the 0.3 mol% Fe-doped BST films reveal a maximum figure of merit (FOM) of 51, indicating the improved comprehensive dielectric and tunable properties.