RESUMO
In situ electrochemical activation brings unexpected electrochemical performance improvements to electrode materials, while the mechanism behind is still needed to study deeply. Herein, an in situ electrochemically approach is developed for the activation of heterointerface MnOx /Co3 O4 by inducing Mn-defect, wherein the Mn defects are formed through a charge process that converts the MnOx with poor electrochemical activities toward Zn2+ into high electrochemically active cathode for aqueous zinc-ion batteries (ZIBs). Guided by the coupling engineering strategy, the heterointerface cathode exhibits an intercalation/conversion dual-mechanism without structural collapse during storage/release of Zn2+ . The heterointerfaces between different phases can generate built-in electric fields, reducing the energy barrier for ion migration and facilitating electron/ion diffusion. As a consequence, the dual-mechanism MnOx /Co3 O4 shows an outstanding fast charging performance and maintains a capacity of 401.03 mAh g-1 at 0.1 A g-1 . More importantly, a ZIB based on MnOx /Co3 O4 delivered an energy density of 166.09 Wh kg-1 at an ultrahigh power density of 694.64 W kg-1 , which outperforms those of fast charging supercapacitors. This work provides insights for using defect chemistry to introduce novel properties in active materials for highly for high-performance aqueous ZIBs.
RESUMO
Herein, for the first time, a pre-intercalated non-metal ion (NH4 + ) with rich oxygen vacancies stabilized tunnel WO3 is proposed as a new intercalation anode to construct Zn-metal-free rocking-chair ZIBs. With the ethylene glycol additive in the aqueous electrolyte, the Zn2+ solvation structure can be regulated and the side reaction of hydrogen evolution can also be suppressed. Owing to the integrated synergetic modification, a high-rate and ultra-stable aqueous Zn-(NH4 )x WO3 battery can be constructed, which exhibits an improved specific capacity (153 mAh g-1 at 0.1 A g-1 ), excellent rate performance (when the current density increases to 3 A g-1 , the specific capacitance is still 86 mAh g-1 ), and a high cycle stability with 100% capacity retention after 2,200 cycles under 5 A g-1 . Ex situ X-ray diffraction and XPS reveal the reversible insertion/extraction of Zn2+ in (NH4 )x WO3 . The assembled (NH4 )x WO3 //MnO2 rocking-chair ZIBs delivers excellent capacity of 82 mAh g-1 at 0.1 A g-1 , impressive cyclic stability. Additionally, the flexible (NH4 )x WO3 //MnO2 ZIBs can power the electrochromic device-based PANI/WO3 with high color contrast and fast response time. This study provides new insight for developing high-performance rechargeable aqueous ZIBs.
RESUMO
The current study explored the slide-lengthening potentials of double and triple hemisections and the biomechanical effects of different inter-hemisection distances. Forty-eight porcine flexor digitorum profundus tendons were divided into double- and triple-hemisection groups (Groups A and B) and a control group (Group C). Group A was divided into Group A1 (distance between hemisections were the same as Group B) and Group A2 (distance between hemisections corresponded to the greatest distance between hemisections in Group B). Biomechanical evaluation, motion analysis, and finite element analysis (FEA) were performed. Failure load of intact tendon was significantly highest among groups. When the distance was 4 cm, the failure load of Group A increased significantly. When the distance between the hemisections was 0.5 or 1 cm, the failure load of Group B was significantly lower than Group A. Tendon elongation and failure load of Group B were significantly lower than those in Group A when the greatest distance between hemisections was the same. Consequently, Double hemisections had a similar lengthening ability to that of triple hemisections with the same distance, but better when the distances between extreme hemisections matched. However, the driving force for the initiation of lengthening may be greater.
Assuntos
Procedimentos Ortopédicos , Tendões , Animais , Suínos , Projetos Piloto , Cadáver , Tendões/cirurgia , Movimento (Física) , Fenômenos BiomecânicosRESUMO
Ammonium ions feature a light molar mass and small hydrated radius, and the interesting interaction between NH4+ and host materials has attracted widespread attention in aqueous energy storage, while few studies focus on high-performance NH4+ storage anodes. Herein, we present a high-performance inset-type anode for aqueous ammonium-ion batteries (AIBs) based on Bi2SeO5 nanosheets. A reversible NH4+/H+ co-intercalation/deintercalation accompanied by hydrogen bond formation/breaking and a conversion reaction mechanism in layered Bi2SeO5 is proposed according to ex situ characterizations. Accordingly, the optimized Bi2SeO5 anode has a high reversible capacity of 341.03 mAh g-1 at 0.3 A g-1 in 1 M NH4Cl electrolyte and an impressive capacity retention of 86.7% after 7000 cycles at 3 A g-1, which is related to the existence of oxygen vacancies that enhance ion/electron transfer and promote the formation of hydrogen bonds between NH4+ and the host material. When the rocking-chair ammonium-ion battery is assembled using a MnO2 cathode, the device delivers an ultrahigh capacity of 140.73 mAh g-1 at 0.15 A g-1 and energy density of 207.13 Wh kg-1 at the power density of 2985.07 W kg-1. This work provides a promising strategy for designing high-performance anodes for next-generation AIBs.
RESUMO
Hollow/porous nanomaterials are widely applicable in various fields. The last few years have witnessed increasing interest in the nanoscale Kirkendall effect as a versatile route to fabricate hollow/porous nanostructures. The transformation of Cu-Co Prussian blue analogue (CuCo-PBA) and FeFe-PBA nanocubes into CuO/Co3O4 and Fe2O3 nanoframes is based on two types of nanoscale Kirkendall effect, which are related to solid-solid interfacial oxidation and solid-gas interfacial reaction, respectively. Both CuO/Co3O4 and Fe2O3 nanoframe electrodes exhibit high reversible discharge capacity, good rate performance and long cycling stability. Moreover, an asymmetric supercapacitor (ASC) is assembled by using CuO/Co3O4 as a cathode and Fe2O3 as an anode, respectively. The ASC can be operated in a wide potential range of 1.4 V with a large specific capacity of 181.8 F g-1, a high energy density of 48.77 W h kg-1 (at 751.2 W kg-1), an outstanding power density of 3657.8 W kg-1 (at 32.9 W h kg-1) and a good capacity retention (73.68%) after 6000 galvanostatic charge-discharge cycles, together with excellent flexibility. The ASC in series can power a LED and work stably under water conditions, delivering excellent practicability.
RESUMO
The rapid development of human-machine interfaces and artificial intelligence is dependent on flexible and wearable soft devices such as sensors and energy storage systems. One of the key factors for these devices is the design of a flexible electrode with high sensitivity, fast response time, and a wide working range. Here, we report the fabrication of strain sensors and all-solid-state flexible supercapacitors using Co@N-CNT/MXenes as an electrode material. The manufactured sensor shows a high tensile range (strain up to 200%) and high stability. The resistance change caused by the fingers touching the sensor can be used to transmit the Morse code information. Flexible supercapacitors serving as power supply demonstrate excellent cycling stability (85 000 cycles) and coulombic efficiency (99.7%) for their high surface area and pseudocapacitance. A self-powered integrated system composed of the strain sensor and flexible supercapacitor is fabricated and operates stably in a wide strain sensing test range. Moreover, the flexible solar-charging self-powered integrated system could be attached to the human body for stable human motion detection. This study clearly shows that appropriate selection of a single functional material to enable it to be used in multi-functional sensors and supercapacitors can simplify the process and reduce the cost of manufacturing wearable devices.