RESUMEN
A high-rate lithium ion battery electrode consisting of nanostructured copper-doped TiO2 films, synthesized using a single-step, template-free aerosol chemical vapor deposition technique, is reported herein. A narrowing of the band gap of the copper-doped films from 2.92 to 1.93 eV corresponds to a large increase in electronic conductivity, overcoming a major drawback of pristine TiO2 in electronic applications. Lithium-ion batteries using copper-doped films as the negative electrode exhibit improved charge retention at ultra-high charge rates, up to 50C. Additionally, over 2000 charge-discharge cycles at a rate of 10C, the copper-doped TiO2 electrodes display higher stable cycling capacities. Cyclic voltammetry (CV) and a galvanostatic intermittent titration technique (GITT) provide insight into the chemical diffusion of Li+ in the TiO2 matrix, with copper-doped TiO2 electrodes exhibiting an order of magnitude higher value in CV measurements over pristine TiO2. GITT provided the state-of-charge (SoC) resolved chemical diffusion coefficient of Li+ and suggests that a minimum value occurs at a moderate SoC of 60%, with values near the extremes being over two orders of magnitude higher. Both techniques indicate increased Li+ mobility due to copper-doping, supporting improved electrochemical performance in ultra-high rate battery testing.
RESUMEN
Current state-of-the-art synthetic strategies produce conducting polymers suffering from low processability and unstable chemical and/or physical properties stifling research and development. Here, we introduce a platform for synthesizing scalable submicron-sized particles of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT). The synthesis is based on a hybrid approach utilizing an aerosol of aqueous oxidant droplets and monomer vapor to engineer a scalable synthetic scheme. This aerosol vapor polymerization technology results in bulk quantities of discrete solid-state submicron particles (750 nm diameter) with the highest reported particle conductivity (330 ± 70 S/cm) so far. Moreover, particles are dispersible in organics and water, obviating the need for surfactants, and remain electrically conductive and doped over a period of months. This enhanced processability and environmental stability enable their incorporation in thermoplastic and cementitious composites for engineering chemoresistive pH and temperature sensors.
RESUMEN
We demonstrate a flexible and light-weight supercapacitor based on bacterial nanocellulose (BNC) incorporated with tin oxide (SnO2) nanoparticles, graphene oxide (GO) and poly(3,4-ethylenedioxyiophene)-poly(styrenesulfonate) (PEDOT:PSS). The SnO2 and GO flakes are introduced into the fibrous nanocellulose matrix during bacteria-mediated synthesis. The flexible PEDOT:PSS/SnO2/rGO/BNC electrodes exhibited excellent electrochemical performance with a capacitance of 445 F g-1 at 2 A g-1 and outstanding cycling stability with 84.1% capacitance retention over 2500 charge/discharge cycles. The flexible solid-state supercapacitors fabricated using PEDOT:PSS/SnO2/rGO/BNC electrodes and poly(vinyl alcohol) (PVA)-H2SO4 coated BNC as a separator exhibited excellent energy storage performance. The fabrication method demonstrated here is highly scalable and opens up new opportunities for the fabrication of flexible cellulose-based energy storage devices.