Recently there is strong interest in lightweight, flexible, and wearable electronics to meet the technological demands of modern society. Integrated energy storage devices of this type are a key area that is still significantly underdeveloped. Here, we describe wearable power devices using everyday textiles as the platform. With an extremely simple "dipping and drying" process using single-walled carbon nanotube (SWNT) ink, we produced highly conductive textiles with conductivity of 125 S cm(-1) and sheet resistance less than 1 Omega/sq. Such conductive textiles show outstanding flexibility and stretchability and demonstrate strong adhesion between the SWNTs and the textiles of interest. Supercapacitors made from these conductive textiles show high areal capacitance, up to 0.48F/cm(2), and high specific energy. We demonstrate the loading of pseudocapacitor materials into these conductive textiles that leads to a 24-fold increase of the areal capacitance of the device. These highly conductive textiles can provide new design opportunities for wearable electronics and energy storage applications.

Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (⍀/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30 -47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithiumion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices.conformal coating ͉ carbon nanotubes ͉ nanomaterial ͉ solution process P rintable solution processing has been exploited to deposit various nanomaterials, such as fullerene, carbon nanotubes (CNTs), nanocrystals, and nanowires for large-scale applications, including thin-film transistors (1-3), solar cells (4, 5), and energy-storage devices (6, 7), because the process is low-cost while maintaining the unique properties of the nanomaterials. In these processes, flat substrates, such as glass, metallic films, Si wafers, and plastics, have been used to hold nanostructure films. Nanostructured materials are usually first capped with surfactant molecules so that they can be well-dispersed as separated particles in a solvent to form ''ink.'' The ink is then deposited onto the flat substrates, followed by surfactant removal and solvent evaporation. To produce high-quality films, significant efforts have been spent on ink formulation and rheology adjustment. Moreover, because the surfactants are normally insulating, and thus limit the charge transfer between the nanomaterials, their removal is particularly critical. However, this step involves extensive washing and chemical displacement, which often cause mechanical detachment of the film from the flat substrate. Polymer binders or adhesives have been used to improve the binding of nanomaterials to substrates, but these can also cause an undesirable decrease in the film conductivity. These additional procedures increase the complexity of solution processing and result in high cost and low throughput. Here, we exploit paper substrates used in daily life to solve these issues a...

These authors contributed equally to this work. Integration of electronics onto existing, widely used paper could bring unprecedented opportunities for consumer electronics.1Ϫ3 These devices can be paperthin, flexible, lightweight and manufactured by a low cost, roll-to-roll printing process. Power sources are needed for the operation of the paper electronics, and ideally, a power source directly integrated onto paper would be preferred for easy system integrations. On the other hand, secondary Li-ion batteries are key components in portable electronics due to their high power and energy density and long cycle life. 4 In these devices, metal strips, mainly copper (ϳ10 mg/cm 2 ) and aluminum (5 mg/cm 2 ), are used as current collectors. Recently, solution-processed carbon nanotube (CNT) thin films have been widely studied and applied as electrodes for optoelectronics due to their high conductivity and flexibility. 3,5 CNT thin films on plastic substrates have been explored as current collectors for supercapacitors. 6 We recently demonstrated that paper coated with CNTs or silver nanowires can be used to replace heavy metals in supercapacitors and Li-ion batteries. 7 The CNT films on substrate function effectively as current collectors and enable some new properties for devices.In this paper, we integrated all of the components of a Li-ion battery into a single sheet of paper with a simple lamination process. Free-standing, lightweight CNT thin films (ϳ0.2 mg/cm 2 ) were used as current collectors for both the anode and cathode and were integrated with battery electrode materials through a simple coating and peeling process. The double layer films were laminated onto commercial paper, and the paper functions as both the mechanical support and Li-ion battery membrane. Due to the intrinsic porous structure of the paper, it functions effectively as both a separator with lower impedance than commercial separators and has good cyclability (no degradation of Li-ion battery after 300 cycles of recharging). After polymer sealing, the secondary Li-ion battery is thin (Ͻ300 m), mechanically flexible, and has a high energy density. Such flexible secondary batteries will meet many application needs in applications such as interactive packaging, radio frequency sensing, and electronic paper.CNT thin films were coated onto stainless steel (SS) substrates with a solutionbased process. Aqueous CNT ink was prepared with 10% by weight sodium dodecylbenzenesulfonate (SDBS) as the surfactant. 8 The concentration of CNT is 1.7 mg/mL. The CNT ink was applied to the SS substrate with a doctor blade method.

A new zinc-ion battery based on copper hexacyanoferrate and zinc foil in a 20 mM solution of zinc sulfate, which is a nontoxic and noncorrosive electrolyte, at pH 6 is reported. The voltage of this novel battery system is as high as 1.73 V. The system shows cyclability, rate capability, and specific energy values near to those of lithium-ion organic batteries based on Li4 Ti5 O12 and LiFePO4 at 10 C. The effects of Zn(2+) intercalation and H2 evolution on the performance of the battery are discussed in detail. In particular, it has been observed that hydrogen evolution can cause a shift in pH near the surface of the zinc electrode, and favor the stabilization of zinc oxide, which decreases the performance of the battery. This mechanism is hindered when the surface of zinc becomes rougher.

Water desalination is an important approach to provide fresh water around the world, although its high energy consumption, and thus high cost, call for new, efficient technology. Here, we demonstrate the novel concept of a "desalination battery", which operates by performing cycles in reverse on our previously reported mixing entropy battery. Rather than generating electricity from salinity differences, as in mixing entropy batteries, desalination batteries use an electrical energy input to extract sodium and chloride ions from seawater and to generate fresh water. The desalination battery is comprised by a Na(2-x)Mn(5)O(10) nanorod positive electrode and Ag/AgCl negative electrode. Here, we demonstrate an energy consumption of 0.29 Wh l(-1) for the removal of 25% salt using this novel desalination battery, which is promising when compared to reverse osmosis (~ 0.2 Wh l(-1)), the most efficient technique presently available.