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Lithium-ion hybrid supercapacitors combining the advantages of Li-ion batteries and supercapacitors have been the subject of extensive interest in the field of energy storage because of their high energy density at high power density. Herein, we report reduced graphene oxide (rGO) cross-linked mesoporous T-Nb2O5 nanospheres ( T-Nb2O5 MNSs/rGO) as high-performance Li+ intercalation pseudocapacitive material and mesoporous carbon-coated rGO (MC/rGO) as high-power electric double-layer capacitive material. The T-Nb2O5 MNSs/rGO anode material boasts a high reversible capacity of 181 mAh g−1 at a current density of 20 mA g−1, good cycle stability, with 85 % capacity retention after 1000 cycles, as well as excellent rate capability. The MC/rGO cathode material delivers a large capacity of 110 and 86 F g−1 at a current density of 500 and 10 000 mA g−1 in organic electrolyte in the voltage range of 3-4.5 V (vs. Li/Li+). The advanced Li-HSCs with a T-Nb2O5 MNSs/rGO anode combined with a MC/rGO cathode show the highest power density of 25 600 W kg−1 at 21 Wh kg−1, which is much higher than that of similar Li-HSC systems previously reported. Furthermore, the Li-HSCs exhibit an excellent cyclability, with 82 % capacitance retention after 4000 cycles. [ABSTRACT FROM AUTHOR]

The cellular piezoelectret generator (CPG) has drawn considerable attention as an emerging flexible energy harvester because of its advantages of a simple structure, easy assembly, a low cost, and eco-friendliness. To facilitate practical applications, an initial theoretical study of CPGs is presented in this work, in which the output characteristics of CPGs can be optimized through an appropriate choice of parameters, including the electret dielectric permittivity, device structure, polarization process, and external load. A good agreement with experimental results is achieved, verifying the validity of the theoretical study. The reported theory offers a complete interpretation of the dynamic working mechanism of CPGs and provides significant guidance for the design of a CPG with enhanced yield. [ABSTRACT FROM AUTHOR]

Self-powered and wearable electronics, which are away from the problems of batteries, can provide the sustainable and comfortable interactive service for people. In this work, cellular polypropylene piezoelectret, which is with excellent physical and electrical properties, is utilized to build the human body energy harvesting and self-powered human health monitoring systems. The cellular polypropylene piezoelectret flexible generator can reach a maximum peak power density of ≈52.8 mW m−2. Simultaneously, self-powered human body biological signals detecting sensors are demonstrated to detect the human physiological signals, such as coughing action and arterial pulses. This study strongly indicates the great compatibility and potential applications in human healthy monitoring may pave a new developing way for portable and wearable electronics systems. [ABSTRACT FROM AUTHOR]

The rapid development of electrical skin and wearable electronics raises the requirement of stretchable strain sensors. In this study, an active fiber-based strain sensor (AFSS) is fabricated by coiling a fiber-based generator around a stretchable silicone fiber. The AFSS shows the sensitive and stable performance and has the ability to detect the strain up to 25%, which is also demonstrated to detect finger motion states. It may play an essential role in future self-powered sensor system. [ABSTRACT FROM AUTHOR]

On page 1798, J. Zhou and colleagues present two kinds of pretreated cotton threads that are entangled to form an double helixes‐structure generator. The generator is then coiled around a silicone fiber to form an active fiber‐based strain sensor which shows sensitive and stable performance and has the ability to detect human body motions. This indicates potential applications in future self‐powered healthy monitor systems by detecting the mechanical deformation of the human body and surrounding environment. [ABSTRACT FROM AUTHOR]