ABSTRACT
The graphene with 3D porous network structure is directly laser-induced on polyimide sheets at room temperature in ambient environment by an inexpensive and one-step method, then transferred to silicon rubber substrate to obtain highly stretchable, transparent, and flexible electrode of the all-solid-state planar microsupercapacitors. The electrochemical capacitance properties of the graphene electrodes are further enhanced by nitrogen doping and with conductive poly(3,4-ethylenedioxythiophene) coating. With excellent flexibility, stretchability, and capacitance properties, the planar microsupercapacitors present a great potential in fashionable and comfortable designs for wearable electronics.
ABSTRACT
Storing pulsed energy harvested by triboelectric nanogenerators (TENGs) from ambient mechanical motion is an important technology for obtaining sustainable, low-cost, and green power. Here, we introduce high-energy-density Li-S batteries with excellent performance for storing pulsed output from TENGs. The sandwich-structured sulfur composites with multi-walled carbon nanotubes and polypyrrole serve as cathode materials that suppress the shuttle effect of polysulfides and thus preserve the structural stability of the cathode during Li-ion insertion and extraction. The charging time and energy storage efficiency of the Li-S batteries are directly affected by the rotation rates of the TENGs. The average storage efficiency of the batteries for pulsed output from TENGs can exceed 80% and even reach 93% at low discharge currents. The Li-S batteries also show excellent rate performance for storing pulsed energy at a high discharge current rate of 5 C. The high storage efficiency and excellent rate capability and cyclability demonstrate the feasibility of storing and exploiting pulsed energy provided by TENGs and the potential of Li-S batteries with high energy storage efficiency for storing pulsed energy harvested by TENGs.
ABSTRACT
A flexible and low-cost triboelectric nanogenerator (TENG) based on a patterned aluminum-plastic film and an entrapped cantilever spring leaf is developed as a self-powered sensitive triboelectric sensor for sleep-body movement monitoring. The working mechanism and the impact factors of electric output performance were systematically investigated and elaborated. Due to the patterned nanostructures of the recently designed TENG, both the output voltage and current are greatly enhanced, and thereby the sensitivity of the device is significantly improved. The self-powered and sensitive device has been demonstrated as a smart body motion sensor of sleep monitoring for diagnosis of sleep disorders due to its high sensitivity and excellent stability. This work may promote the application of self-powered TENGs for healthcare and be helpful for the development of real-time mobile healthcare services and smart external portable electronics.
Subject(s)
Electric Power Supplies , Nanostructures , Polysomnography , Electricity , NanotechnologyABSTRACT
There is intense interest in sodium-ion batteries as an alternative to lithium-ion batteries for electric storage applications because of the low-cost and abundant sodium resources. Na0.67Ni0.33-xMgxMn0.67O2 compounds (x = 0, 0.02, 0.05, 0.1, or 0.15) were prepared by a sol-gel method and used as a cathode for sodium-ion batteries. The X-ray powder diffraction measurements demonstrated that the obtained samples have a pure P2 phase. Na0.67Ni0.23Mg0.1Mn0.67O2 delivers an initial reversible capacity of 105 mAh g(-1) in the potential region from 2.0 to 4.5 V at a charge/discharge current density of 48 mA g(-1). Moreover, the cyclability is improved by doping Mg. The capacity of Na0.67Ni0.23Mg0.1Mn0.67O2 can remain at approximately 84.9 mAh g(-1) at a current density of 48 mA g(-1) after 100 cycles. The improved high rate performance of Na0.67Ni0.23Mg0.1Mn0.67O2 was attributed to the increased lattice parameters and d spacing of the Na(+) layer. Therefore, Mg-doped Na0.67Ni0.23Mg0.1Mn0.67O2 is a promising cathode for sodium-ion batteries with excellent rate and cyclic performance.
