Proof of Aerobically Autoxidized Self-Charge Concept Based on Single Catechol-Enriched Carbon Cathode Material

The self-charging concept has drawn considerable attention due to its excellent ability to achieve environmental energy harvesting,conversion and storage without an external power supply.However,most self-charging designs assembled by multiple energy harvesting,conversion and storage materials increase the energy transfer loss;the environmental energy supply is generally limited by climate and meteorological conditions,hindering the potential application of these selfpowered devices to be available at all times.Based on aerobic autoxidation of catechol,which is similar to the electrochemical oxidation of the catechol groups on the carbon materials under an electrical charge,we proposed an air-breathing chemical self-charge concept based on the aerobic autoxidation of catechol groups on oxygen-enriched carbon materials to ortho-quinone groups.Energy harvesting,conversion and storage functions could be integrated on a single carbon material to avoid the energy transfer loss among the different materials.Moreover,the assembled Cu/oxygen-enriched carbon battery confirmed the feasibility of the air-oxidation self-charging/electrical discharging mechanism for potential applications.This air-breathing chemical self-charge concept could facilitate the exploration of high-efficiency sustainable air self-charging devices.

Self-charging power textiles integrating energy harvesting triboelectric nanogenerators with energy storage batteries/supercapacitors

Lightweight and flexible self-charging power systems with synchronous energy harvesting and energy storage abilities are highly desired in the era of the internet of things and artificial intelligences,which can provide stable,sustainable,and autonomous power sources for ubiquitous,distributed,and low-power wearable electronics.However,there is a lack of comprehensive review and challenging discussion on the state-of-the-art of the triboelectric nanogenetor(TENG)-based self-charging power textiles,which have a great possibility to become the future energy autonomy power sources.Herein,the recent progress of the self-charging power textiles hybridizing fiber/fabric based TENGs and fiber/fabric shaped batteries/supercapacitors is comprehensively summarized from the aspect of textile structural designs.Based on the current research status,the key bottlenecks and brighter prospects of self-charging power textiles are also discussed in the end.It is hoped that the summary and prospect of the latest research of self-charging power textiles can help relevant researchers accurately grasp the research progress,focus on the key scientific and technological issues,and promote further research and practical application process.

Nanogenerator-Based Self-Charging Energy Storage Devices

One significant challenge for electronic devices is that the energy storage devices are unable to provide su cient energy for continuous and long-time operation,leading to frequent recharging or inconvenient battery replacement.To satisfy the needs of next-generation electronic devices for sustainable working,conspicuous progress has been achieved regarding the development for nanogenerator-based self-charging energy storage devices.Herein,the development of the self-charging energy storage devices is summarized.Focus will be on preparation of nanomaterials for Li-ion batteries and supercapacitors,structural design of the nanogenerator-based self-charging energy storage devices,performance testing,and potential applications.Moreover,the challenges and perspectives regarding self-charging energy storage devices are also discussed.

Self-Powered Piezo-Supercapacitors Based on ZnO@Mo-Fe-MnO_(2)Nanoarrays

The development of self-charging supercapacitor power cells(SCSPCs)has profound implications for smart electronic devices used in different fields.Here,we epitaxially electrodeposited Mo-and Fe-codoped MnO_(2)films on piezoelectric ZnO nanoarrays(NAs)grown on the flexible carbon cloth(denoted ZnO@Mo-Fe-MnO_(2)NAs).A self-charging supercapacitor power cell device was assembled with the Mo-and Fe-codoped MnO_(2)nanoarray electrode and poly(vinylidenefluoride-co-trifluoroethylene)(PVDF-Trfe)piezoelectric film doped with BaTiO_(3)(BTO)and carbon nanotubes(CNTs)(denoted PVDF-Trfe/CNTs/BTO).The self-charging supercapacitor power cell device exhibited an energy density of 30μWh cm^(-2)with a high power density of 40 mW cm^(-2)and delivered an excellent self-charging performance of 363 mV(10 N)driven by both the piezoelectric ZnO nanoarrays and the poly(vinylidenefluoride-co-trifluoroethylene)piezoelectric film doped with BaTiO_(3)and carbon nanotubes.More intriguingly,the device could also be self-charged by 184 mV due to residual stress alone and showed excellent energy conversion efficiency and low self-discharge rate.This work illustrates for the first time the self-charging mechanism involving electrolyte ion migration driven by both electrodes and films.A comprehensive analysis strongly confirmed the important contribution of the piezoelectric ZnO nanoarrays in the self-charging process of the self-charging supercapacitor power cell device.This work provides novel directions and insights for the development of selfcharging supercapacitor power cells.

Recent trends,challenges,and perspectives in piezoelectric-driven self-chargeable electrochemical supercapacitors

The increasing demand for wearable electronic devices has resulted in tremendous progress in research on energy harvesting and storage devices/technologies.Energy storage devices require a power source to charge them,whereas energy harvesting devices require a storage compartment to store the harvested energy for sustainable delivery.Recently,a piezoelectrically driven self-charging supercapacitor power cell(SCSPC)was developed to harvest and store electrical energy in a solitary system to determine the potential impact of these two types of energy devices for wearable electronic applications.This review describes the recent advances in piezoelectric-driven SCSPCs in terms of device configuration,piezoelectric separator,electrolyte types,electrode materials,current collectors,and system integration.This review focuses specifically on the principles and mechanism of the self-charging process that occurred in the SCSPCs and the use of a promising piezo electrochemical spectroscopic tool to realize the piezo electrochemical energy transfer and storage process in the SCSPCs.Further,the current challenges and new perspectives for future developments in the emerging area of SCSPCs or integrated energy devices are discussed.

A survey of hybrid energy devices based on supercapacitors

Developing multifunctional energy storage systems with high specific energy, high specific power and long cycling life has been the one of the most important research directions. Compared to batteries and traditional capacitors, supercapacitors possess more balanced performance with both high specific power and long cycle-life. Nevertheless, regular supercapacitors can only achieve energy storage without harvesting energy and the energy density is still not very high compared to batteries. Therefore, combining high specific energy and high specific power,long cycle-life and even fast self-charging into one cell has been a promising direction for future energy storage devices. The multifunctional hybrid supercapacitors like asymmetric supercapacitors, batteries/supercapacitors hybrid devices and self-charging hybrid supercapacitors have been widely studied recently. Carbon based electrodes are common materials used in all kinds of energy storage devices due to their fabulous electrical and mechanical properties. In this survey, the research progress of all kinds of hybrid supercapacitors using multiple effects and their working mechanisms are briefly reviewed. And their advantages and disadvantages are discussed. The hybrid supercapacitors have great application potential for portable electronics, wearable devices and implantable devices in the future.

Wearable energy harvesting-storage hybrid textiles as on-body self-charging power systems

The rapid development of wearable electronics requires its energy supply part to be flexible,wearable,integratable and sustainable.However,some of the energy supply units cannot meet these requirements at the same time,and there is also a capacity limitation of the energy storage units,and the development of sustainable wearable self-charging power supplies is crucial.Here,we report a wearable sustainable energy harvesting-storage hybrid self-charging power textile.The power textile consists of a coaxial fiber-shaped polylactic acid/reduced graphene oxide/polypyrrole(PLA-rGO-PPy)triboelectric nanogenerator(fiber-TENG)that can harvest low-frequency and irregular energy during human motion as a power generation unit,and a novel coaxial fiber-shaped supercapacitor(fiber-SC)prepared by functionalized loading of a wet-spinning graphene oxide fiber as an energy storage unit.The fiber-TENG is flexible,knittable,wearable and adaptable for integration with various portable electronics.The coaxial fiber-SC has high volumetric energy density and good cycling stability.The fiber-TENG and fiber-SC are flexible yarn structures for wearable continuous human movement energy harvesting and storage as on-body self-charging power systems,with light-weight,ease of preparation,great portability and wide applicability.The integrated power textile can provide an efficient route for sustainable working of wearable electronics.

Integration of micro-supercapacitors with triboelectric nanogenerators for a flexible self-charging power unit

The rapid development of portable and wearable electronic devices has increased demand for flexible and efficient energy harvesting and storage units. Conventionally, these are built and used separately as discrete components. Herein, we propose a simple and cost-effective laser engraving technique for fabricating a flexible self-charging micro-supercapacitor power unit （SCMPU）, by integrating a triboelectric nanogenerator （TENG） and a micro-supercapacitor （MSC） array into a single device. The SCMPU can be charged directly by ambient mechanical motion. We demonstrate the ability of the SCMPU to continuously power light-emitting diodes and a commercial hygrothermograph. This inves- tigation may promote the development of sustainable self-powered systems and provide a promising new research application for supercapacitors.

Flexible self-charging power units for portable electronics based on folded carbon paper

The urgent demand for portable electronics has promoted the development of high-efficienc）9 sustainable, and even stretchable self-charging power sources. In this work, we propose a flexible self-charging power unit based on folded carbon （FC） paper for harvesting mechanical energy from human motion and power portable electronics. The present unit mainly consists of a triboelectric nanogenerator （FC-TENG） and a supercapacitor （FC-SC）, both based on folded carbon paper, as energy harvester and storage device, respectively. This favorable geometric design provides the high Young＇s modulus carbon paper with excellent stretchability and enables the power unit to work even under severe deformations, such as bending, twisting, and rolling. In addition, the tensile strain can be maximized by tuning the folding angle of the triangle-folded carbon paper. Moreover, the waterproof property of the packaged device make it washable, protect it from human sweat, and enable it to work in harsh environments. Finally, the as-prepared self-charging power unit was tested by placing it on the human body to harvest mechanical energy from hand tapping, foot treading, and arm touching, successfully powering an electronic watch. This work demonstrates the impressive potential of stretchable self-charging power units, which will further promote the development of high Young＇s modulus materials for wearable/portable electronics.

A water-evaporation-induced self-charging hybrid power unit for application in the Internet of Things

A self-charging hybrid power unit has been developed by integrating a water-evaporation-induced nano- generator with a flexible nano-patterned supercapacitor. The nanogenerator can harvest environmental thermal energy and mechanical energy through the water evaporation process, and the supercapacitor can be charged simultaneously. The former offers stable electrical power as output, whereas the Ppy- based supercapacitor shows a capacitance of 12.497 m F/cm^2 with 96.42% retention after 4,000 cycles. After filling the power unit with water as the fuel, it can be fully charged in about 20 min. The power unit can be flexibly integrated with electronic devices such as sensor nodes and wireless transmitters employ- ing the Internet of Things. This new approach can offer new possibilities in continuous future operation of randomly distributed electronic devices incorporated in the Internet of Things.

Review:Multiple Functionalities of Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries are a kind of attractive power supply devices due to their high energy, environmental benignity, and intrinsic safety. In recent years, tremendous enthusiasm has been devoted to the functionalities of aqueous zinc-ion batteries, aiming to extend their potential applications in multiple dimensions and multiple scales. Here, the latest advances in the design, construction, and performance evaluation of aqueous zinc-ion batteries are summarized. The focus is on various functionalities such as flexibility, self-healing, self-charging, and miniaturization. We also highlight the materials and structures that have been engineered to realize these functionalities. Finally, we offer some general insights into the challenges and chances in such exciting field.

Sustainable wearable energy storage devices self-charged by human-body bioenergy

Charging wearable energy storage devices with bioenergy from human-bodymotions, biofluids, and body heat holds great potential to construct self-powered body-worn electronics, especially considering the ceaseless nature ofhuman metabolic activities. To bridge the gap between human-body bioen-ergy and storage of energy, wearable triboelectric/piezoelectric nanogenerators(TENGs/PENGs), biofuel cells (BFCs), thermoelectric generators (TEGs) havebeen designed to harvest energy from body-motions, biofluids, and body heat,respectively. Researchers have explored various strategies using bioenergy har-vesters to charge wearable supercapacitors and batteries to relieve or even fullyeliminate the recharging process from external power stations, thus, makingwearable electronics more sustainable, autonomous, and user friendly. In thisarticle, we review the advances in the design of sustainable energy storagedevices charged by human-body energy harvesters. The progress in multifunc-tional wearable energy storage devices that cater to the easy integration withhuman-body energy harvesters will be summarized. Then, the focus is laid onthe integrating strategies (single-cell strategy and separated-cell strategy), devicedesign, materials selection, and characteristics of different self-charging human-body energy harvesting-storage systems. Finally, the challenges that impedethe wide application of human-body energy harvesters charged supercapaci-tors/batteries and prospects will be discussed both from materials and structuraldesign aspects.

Hierarchical polypyrrole@cobalt sulfide-based flexible on-chip microsupercapacitors with ultrahigh energy density for selfcharging system

Herein,we prepare the unique hierarchical polypyrrole@cobalt sulfide(PPy-hs@CoS)hollow sphere-based nanofilms as interdigitated electrodes for flexible on-chip micro-supercapacitors(MSC).Benefiting from the excellent flexibility and high electrical conductivity of PPy-hs combined with the great electrochemical activity of CoS,such PPy-hs@CoS composite material can not only inhibit the volume expansion of PPy but also promote the diffusion of the electrolyte ions.The PPy-hs@CoS filmbased electrode delivers a greatly improved specific capacitance and small resistance.Density functional theory calculations infer that OH−prefers to bind to PPy on CoS@PPy and confirms the synergistic effect of each component for enhanced reaction kinetics.A quasi-solid-state on-chip flexible asymmetric MSC based on PPy-hs@CoS and activated carbon(AC)microelectrodes exhibits large areal-specific capacitance(131.9 mF/cm2 at 0.3 mA/cm2),ultrahigh energy density(0.041 mWh/cm2@0.224 mW/cm2 and 25.6 mWh/cm3@140.6 mW/cm3),and long cycle lifespan.We demonstrate the possibility to scale up the PPy-hs@CoS nanofilm microelectrode by arranging two of our asymmetric MSC in series and parallel connections,which respectively increase the output voltage and current.A self-charging system by connecting our asymmetric MSCs with a piece of commercial solar cells is developed as a potential possible mode for future highly durable and high-voltage integrated electronics.

Dual occupations of sulfur induced band flattening and chemical bond softening in p-type S_(y)Co_(4)Sb_(12-2y)S_(2y) skutterudites

The electronegative filling in skutterudites not only broadened the scope of filling atoms,but also facilitated the preparation of p-type skutterudites.However,the introduction of a single sulfur atom in the Co_(4)Sb_(12) cannot be achieved without charge compensation through the traditional equilibrium method.In the present study,the dual occupations of S-atoms by self-charge compensation were shown as the most stable forms under high pressure,and a series of p-type S_(y)Co_(4)Sb_(12-2y)S_(2y) skutterudites was successfully prepared by high-pressure-high-temperature(HPHT)method.The electronic structures and transport properties of as-obtained materials were investigated,and the related mechanisms were explored.The results suggested that the presence of S-impurities led to flattening of the electronic band that led to a higher Seebeck coefficient.The S-doped Co_(4)Sb_(12) displayed lower elastic modulus,elastic constant,and Debye temperature,thus indicating the chemical bond softening in skutterudites.The thermal conductivities of S_(y)Co_(4)Sb_(12-2y)S_(2y) compounds reduced monotonously with the increase in Scontent.This study provides a new and promising avenue for optimizing the thermoelectric properties of p-type Co_(4)Sb_(12).