A flexible carbon nanotube@V_(2)O_(5) film as a high-capacity and durable cathode for zinc ion batteries

Aqueous zinc-ion batteries(ZIBs)are receiving a continuously increasing attention for mobile devices,especially for the flexible and wearable electronics,due to their non-toxicity,non-flammability,and low-cost features.Despite the significant progress in achieving higher capacities for electrode materials of ZIBs,to endow them with high flexibility and economic feasibility is,however,still a significant challenge remaining unsolved.Herein,we present a highly flexible composite film composed of carbon nanotube film and V_(2)O_(5)(CNTF@V_(2)O_(5))with high strength and high conductivity,which is prepared by simply impregnating a porous CNT film with an aqueous V_(2)O_(5)sol under vacuum.For this material,intimate incorporation between V_(2)O_(5)and CNTs has been achieved,successfully integrating the high zinc ion storage capability with high mechanical flexibility.As a result,this CNTF@V_(2)O_(5)film delivers a high capacity of 356.6 m Ah g^(-1)at 0.4 A g^(-1)and excellent cycling stability with 80.1%capacity retention after 500 cycles at 2.0 A g^(-1).The novel strategy and the outstanding battery performance presented in this work should shed light on the development of high-performance and flexible ZIBs.

Electrochemical performance of all-solid lithium ion batteries with a polyaniline film cathode

We have prepared a high-density polyaniline（PANI） paste（50 mg/m L）, with similar physical properties to those of paints or pigments. The synthesis of PANI is confirmed by Fourier transform infrared（FT-IR） spectroscopy. The morphologies of PANI, doped PANI, and doped PANI paste are confirmed by scanning electron microscopy（SEM）. Particles of doped PANI paste are approximately 40–50 nm in diameter, with a uniform and cubic shape. The electrochemical performances of doped PANI paste using both liquid and solid polymer electrolytes have been measured by galvanostatic charge and discharge process. The cell fabricated with doped PANI paste and the solid polymer electrolyte exhibits a discharge capacity of ～87 μAh/cm2（64.0 m Ah/g） at the second cycle and～67 μAh/cm2（50.1 m Ah/g） at the 100 th cycle.

Three-dimensional knotting of W_(17)O_(47)@PEDOT:PSS nanowires enables high-performance flexible cathode for dual-functional electrochromic and electrochemical device

An efficient integration of electrochromic and electrochemical devices into one flexible entity enables both energy storage and energy-saving dual-functionalities.For this purpose,achieving both high electrochromic and electrochemical performance is the key aspect.Herein,a new 3D architecture is successfully made by knotting W_(17)O_(47)@PEDOT(poly(3,4-ethylenedioxythiophene)):PSS(poly(styrenesulfonate))nanowires with NaWO_(3)nanoknots,and interestingly,the 3D W_(17)O_(47)/(NaWO_(3)-knots)@PEDOT:PSS cathode thus-made simultaneously exhibits a large optical modulation(79.7%at 633 nm),an ultra-long cycling life(76%of original optical modulation retained after 12400 cycles),and a high areal capacitance(55.1 mF cm^(-2)at 0.1 mA cm^(-2)).Our density functional theory(DFT)calculations demonstrate that the much improved dual-functional performance is correlated to the raised electronic conductivity and ion adsorption at the W_(17)O_(47)/(NaWO_(3)nanoknots)interface,together with the ion adsorption of PEDOT:PSS in the 3D-knotted architecture.As a proof-of-concept application,different-sized flexible dual-functional electrochromic/electrochemical devices(FDEDs)were assembled and investigated for various application scenarios,including a smart window(15 cm×10 cm),a wearable wristband(20 cm×2.5 cm),and a smart eyeglass.The smart window made of the FDED enables a large temperature difference of 27.6℃ confirm-tested in model houses,where the energy source also powers three light-emitting diodes(LEDs).The understandings of the key governing principles in the electrodes and dual-functionalities provide a timely foundation for the new generation flexible multifunctional devices.

Surface-assembled highly flexible Na_(3)(VOPO_(4))_(2)F nanocube cathode for high-rate binder-free Na-ion batteries

Flexible Na-ion storage cathodes are still very few due to the challenge in achieving both reliable mechanical flexibility and excellent electrochemical performances.Herein,a new type of flexible Na_(3)(VOPO_(4))_(2)F cathode with nanocubes tightly assembled on carbon cloth is fabricated by a facile solvothe rmal method for the first time.The cathode is able to exhibit superior rate capability and stable cycling performa nce up to 1000 cycles,due to the surface-assembling of crystalline nanocubes on carbon fibers.In addition,it shows good mechanical flexibility,nearly no capacity decay is observed after continuous bending of 500 times.With this novel cathode and a directly-grown Na_(2)Ti_(2)O_(5) anode,a fully binde r-free Na-ion battery is assembled.It can deliver a high wo rking voltage and increased gravimetric energy/power densities(maximum values:220.2 Wh/kg;5674,7 W/kg),and can power a LED indicator at bending angles fro m 0° to 180°.