Highlights
Hierarchically structured Nb
2
O
5
microflowers consiste of porous and ultrathin nanosheets.
Nb
2
O
5
microflowers exhibit enhanced capacity and rate performance boosting Na ion storage.
...Planar NIMSCs with charge and kinetics matching show superior areal capacitance and lifespan.
Planar Na ion micro-supercapacitors (NIMSCs) that offer both high energy density and power density are deemed to a promising class of miniaturized power sources for wearable and portable microelectronics. Nevertheless, the development of NIMSCs are hugely impeded by the low capacity and sluggish Na ion kinetics in the negative electrode. Herein, we demonstrate a novel carbon-coated Nb
2
O
5
microflower with a hierarchical structure composed of vertically intercrossed and porous nanosheets, boosting Na ion storage performance. The unique structural merits, including uniform carbon coating, ultrathin nanosheets and abundant pores, endow the Nb
2
O
5
microflower with highly reversible Na ion storage capacity of 245 mAh g
−1
at 0.25 C and excellent rate capability. Benefiting from high capacity and fast charging of Nb
2
O
5
microflower, the planar NIMSCs consisted of Nb
2
O
5
negative electrode and activated carbon positive electrode deliver high areal energy density of 60.7 μWh cm
−2
, considerable voltage window of 3.5 V and extraordinary cyclability. Therefore, this work exploits a structural design strategy towards electrode materials for application in NIMSCs, holding great promise for flexible microelectronics.
Sodium and potassium ion batteries hold promise for next-generation energy storage systems due to their rich abundance and low cost, but are facing great challenges in optimum electrode materials for ...actual applications. Here, ultrathin nanoribbons of sodium titanate (M-NTO, NaTi1.5O8.3) and potassium titanate (M-KTO, K2Ti4O9) were successfully synthesized by a simultaneous oxidation and alkalization process of Ti3C2 MXene. Benefiting from the suitable interlayer spacing (0.90 nm for M-NTO, 0.93 nm for M-KTO), ultrathin thickness (<11 nm), narrow widths of nanoribbons (<60 nm), and open macroporous structures for enhanced ion insertion/extraction kinetics, the resulting M-NTO exhibited a large reversible capacity of 191 mAh g–1 at 200 mA g–1 for sodium storage, higher than those of pristine Ti3C2 (178 mAh g–1) and commercial TiC derivatives (86 mAh g–1). Notably, M-KTO displayed a superior reversible capacity of 151 mAh g–1 at 50 mA g–1 and 88 mAh g–1 at a high rate of 300 mA g–1 and long-term stable cyclability over 900 times, which outperforms other Ti-based layered materials reported to date. Moreover, this strategy is facile and highly flexible and can be extended for preparing a large number of MXene-derived materials, from the 60+ group of MAX phases, for various applications such as supercapacitors, batteries, and electrocatalysts.
High-energy-density lithium–sulfur (Li–S) batteries hold promise for next-generation portable electronic devices, but are facing great challenges in rational construction of high-performance flexible ...electrodes and innovative cell configurations for actual applications. Here we demonstrated an all-MXene-based flexible and integrated sulfur cathode, enabled by three-dimensional alkalized Ti3C2 MXene nanoribbon (a-Ti3C2 MNR) frameworks as a S/polysulfides host (a-Ti3C2–S) and two-dimensional delaminated Ti3C2 MXene (d-Ti3C2) nanosheets as interlayer on a polypropylene (PP) separator, for high-energy and long-cycle Li–S batteries. Notably, an a-Ti3C2 MNR framework with open interconnected macropores and an exposed surface area guarantees high S loading and fast ionic diffusion for prompt lithiation/delithiation kinetics, and the 2D d-Ti3C2 MXene interlayer remarkably prevents the shuttle effect of lithium polysulfides via both chemical absorption and physical blocking. As a result, the integrated a-Ti3C2–S/d-Ti3C2/PP electrode was directly used for Li–S batteries, without the requirement of a metal current collector, and exhibited a high reversible capacity of 1062 mAh g–1 at 0.2 C and enhanced capacity of 632 mAh g–1 after 50 cycles at 0.5 C, outperforming the a-Ti3C2–S/PP electrode (547 mAh g–1) and conventional a-Ti3C2–S on an Al current collector (a-Ti3C2–S/Al) (597 mAh g–1). Furthermore, the all-MXene-based integrated cathode displayed outstanding rate capacity of 288 mAh g–1 at 10 C and long-life cyclability. Therefore, this proposed strategy of constructing an all-MXene-based cathode can be readily extended to assemble a large number of MXene-derived materials, from a group of 60+ MAX phases, for applications such as various batteries and supercapacitors.
As post-lithium ion batteries, both sodium ion batteries (SIBs) and potassium ion batteries (PIBs) possess great potential for large scale energy storage. However, the improvements of both SIBs and ...PIBs for practical applications are facing great challenges in the development of high-performance electrode materials. Here, we demonstrate the fabrication of alkalized Ti3C2 (a-Ti3C2) MXene nanoribbons attained by continuous shaking treatment of pristine Ti3C2 MXene in aqueous KOH solution. Benefited from the expanded interlayer spacing of a-Ti3C2, narrow widths of nanoribbons as well as three-dimensional interconnected porous frameworks for enhanced ion reaction kinetics and improved structure stability, the resulting a-Ti3C2 anodes showed excellent sodium/potassium storage performance, for example, high reversible capacities of 168 and 136mAhg−1 at 20mAg−1 and 84 and 78mAhg−1 at 200mAg−1 were obtained for SIBs and PIBs, respectively. Notably, a-Ti3C2 possessed outstanding long-term cyclability at high current density of 200mAg−1, delivering a capacity of ~ 50mAhg−1 for SIBs and ~ 42mAhg−1 for PIBs after 500 cycles, which outperformed most of reported MXene based anodes for SIBs and PIBs. Moreover, this alkalization strategy could be extended as a universal approach for fabricating various alkalized MXene-based frameworks derived from a large family of MAX phases for numerous applications, such as catalysis, energy storage and conversion.
Alkalized Ti3C2 (a-Ti3C2) MXene nanoribbons were successfully synthesized by shaking treatment of Ti3C2 in KOH solution. Benefited from the expanded interlayer spacing, narrow widths of nanoribbons as well as 3D interconnected porous frameworks for enhanced ion reaction kinetics and improved structure stability, the resulting a-Ti3C2 anodes showed excellent sodium/potassium storage performance. Display omitted
•Alkalized Ti3C2 MXene nanoribbons (a-Ti3C2) with expanded interlayer spacing is synthesized by shaking treatment of Ti3C2 MXene in KOH solution.•a-Ti3C2 shows narrow widths of nanoribbons (6–22nm) as well as 3D interconnected porous frameworks.•a-Ti3C2 displays high capacities and superior cycling stability over 500 cycles for sodium/ potassium storage.
Battery-supercapacitor hybrid devices (BSHDs) are promising for certain applications requiring both high energy and power densities, but restricted by the electrolyte-consuming mechanism and ...imbalance of charge-storage capacity and electrode kinetics between battery-type and capacitor-type electrodes. Herein, a new prototype of rocking-chair lithium-ion BSHD with high energy and power densities is developed by employing pseudocapacitive T-Nb
2
O
5
with a porous nanoflower structure as the anode and battery-type LiNi
0.815
Co
0.15
Al
0.035
O
2
complexed in a three-dimensional interconnected conductive network as the cathode. Benefiting from the rational selection and optimization of the active material and electrode architecture, the anode and cathode exhibit exceptionally matched faradaic capacity and kinetics. Consequently, the BSHD delivers superior performance (165 W h kg
−1
at 105 W kg
−1
and 9.1 kW kg
−1
at 83 W h kg
−1
) to previously reported rocking-chair BSHDs and could surpass the state-of-the-art electrolyte-consuming BSHDs at the device level. Therefore, this work will open a new avenue towards high-performance BSHDs.
A lithium-ion battery-supercapacitor hybrid device with a rocking-chair mechanism is constructed and exhibits high energy and power densities by virtue of double matching of capacity and kinetics between the two faradaic electrodes.
The rapid development of a NH3 sensor puts forward a great challenge for active materials and integrated sensing systems. In this work, an ultrasensitive NH3 sensor based on two-dimensional (2D) ...wormlike mesoporous polypyrrole/reduced graphene oxide (w-mPPy@rGO) heterostructures, synthesized by a universal soft template method is reported, revealing the structure–property coupling effect of the w-mPPy/rGO heterostructure for sensing performance improvement, and demonstrates great potential in the integration of a self-powered sensor system. Remarkably, the 2D w-mPPy@rGO heterostructrure exhibits preferable response toward NH3 (ΔR/R 0 = 45% for 10 ppm NH3 with a detection limit of 41 ppb) than those of the spherical mesoporous hybrid (s-mPPy@rGO) and the nonporous hybrid (n-PPy@rGO) due to its large specific surface area (193 m2/g), which guarantees fast gas diffusion and transport of carriers. Moreover, the w-mPPy@rGO heterostructures display outstanding selectivity to common volatile organic compounds (VOCs), H2S, and CO, prominent antihumidity inteference superior to most existing chemosensors, superior reversibility and favorable repeatability, providing high potential for practicability. Thus, a self-powered sensor system composed of a nanogenerator, a lithium-ion battery, and a w-mPPy@rGO-based sensor was fabricated to realize wireless, portable, cost-effective, and light-weight NH3 monitoring. Impressively, our self-powered sensor system exhibits high response toward 5–40 mg NH4NO3, which is a common explosive to generate NH3 via alkaline hydrolysis, rendering it a highly prospective technique in a NH3-based sensing field.
Free‐standing 2D porous nanomaterials have attracted considerable interest as ideal candidates of 2D film electrodes for planar energy storage devices. Nevertheless, the construction of well‐defined ...mesopore arrays parallel to the lateral surface, which facilitate fast in‐plane ionic diffusion, is a challenge. Now, a universal interface self‐assembly strategy is used for patterning 2D porous polymers, for example, polypyrrole, polyaniline, and polydopamine, with cylindrical mesopores on graphene nanosheets. The resultant 2D sandwich‐structured nanohybrids are employed as the interdigital microelectrodes for the assembly of planar micro‐supercapacitors (MSCs), which deliver outstanding volumetric capacitance of 102 F cm−3 and energy density of 2.3 mWh cm−3, outperforming most reported MSCs. The MSCs display remarkable flexibility and superior integration for boosting output voltage and capacitance.
Superflatcaps: A universal interface self‐assembly strategy is reported for patterning 2D porous polymers with cylindrical pores on graphene nanosheets. The resultant 2D sandwich‐like nanohybrids show great potential for flexible planar micro‐supercapacitors.
Metal nitrides with high theoretical capacities and exceptional electrical conductivities hold great potentials as high-rate anode materials for lithium ion batteries (LIBs), but suffer from severe ...pulverization and air instability of electrodes. Herein, we developed a general strategy for synthesizing few-layer graphene encapsulated transition metal nitride (e.g., Fe2N) nanoparticles confined in three dimensional (3D) ultrathin carbon nanosheet frameworks (denoted as Fe2N@CNFs) via the iron nitrate accelerated polyvinylpyrrolidone (PVP) blowing and subsequent in-situ nitridation process, as high-rate anode for LIBs. Benefiting from the well-confined Fe2N nanoparticles by graphene shells for alleviating structural pulverization and air sensitivity, and 3D carbon nanosheet porous frameworks for fast electrolyte ion diffusion and fast electron transport, the resulting Fe2N@CNFs anodes exhibited high reversible capacity of 587 mA h g−1 at 0.1 A g−1, and remarkable rate capacity of 215 mA h g−1 at high current density of 10 A g−1, outperforming most reported metal nitride electrodes. When coupled with carbon-coated LiFePO4 cathode, the resulting full LIBs still delivered an initial discharge capacity of 243 mA h g−1 at 0.1 A g−1. Therefore, this work will pave a new way for rational construction of a series of high-performance metal nitride electrodes for energy-related devices.
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Printable supercapacitors are regarded as a promising class of microscale power source, but are facing challenges derived from conventional sandwich‐like geometry. Herein, the printable fabrication ...of new‐type planar graphene‐based linear tandem micro‐supercapacitors (LTMSs) on diverse substrates with symmetric and asymmetric configuration, high‐voltage output, tailored capacitance, and outstanding flexibility is demonstrated. The resulting graphene‐based LTMSs consisting of 10 micro‐supercapacitors (MSs) present efficient high‐voltage output of 8.0 V, suggestive of superior uniformity of the entire integrated device. Meanwhile, LTMSs possess remarkable flexibility without obvious capacitance degradation under different bending states. Moreover, areal capacitance of LTMSs can be sufficiently modulated by incorporating polyaniline‐based pseudocapacitive nanosheets into graphene electrodes, showing enhanced capacitance of 7.6 mF cm−2. To further improve the voltage output and energy density, asymmetric LTMSs are fabricated through controlled printing of linear‐patterned graphene as negative electrodes and MnO2 nanosheets as positive electrodes. Notably, the asymmetric LTMSs from three serially connected MSs are easily extended to 5.4 V, triple voltage output of the single cell (1.8 V), suggestive of the versatile applicability of this technique. Therefore, this work offers numerous opportunities of graphene and analogous nanosheets for one‐step scalable fabrication of flexible tandem energy storage devices integrating with printed electronics on same substrate.
A universal printing technology is demonstrated to fabricate graphene‐based linear tandem micro‐supercapacitors, with tailored planar device geometry and metal‐free current collectors and interconnects, on different substrates. The fabricated devices show high‐voltage output, remarkable flexibility, and outstanding electrochemical performance due to the advanced device geometry and high‐performance 2D nanosheets.
The rapid development of microelectronics and microsystems has stimulated the continuous evolution of high-performance and cost-effective micro-batteries. Despite their competitiveness with huge ...application potential, sodium ion micro-batteries (NIMBs) are still underdeveloped. Herein, we demonstrate one prototype of a quasi-solid-state planar ionogel-based NIMB constructed by separator-free interdigital microelectrodes of sodium titanate anode and sodium vanadate phosphate cathode, both of which are embedded into a three-dimensional interconnected graphene scaffold. Meanwhile, a novel NaBF 4 -based ionogel electrolyte with robust ionic conductivity of 8.1 mS cm −1 was used. Benefiting from the synergetic merits from the planar architecture, dominant pseudocapacitance contribution, and 3D multi-directional Na-ion diffusion mechanism, the as-assembled NIMBs exhibit high volumetric capacity of 30.7 mA h cm −3 at 1C, and high rate performance with 15.7 mA h cm −3 at 30C at room temperature and 13.5 mA h cm −3 at 100C at a high temperature of 100 °C. Moreover, the quasi-solid-state NIMBs present outstanding flexibility, tunable voltage and capacity output, and remarkable areal energy density of 145 μW h cm −2 (55.6 mW h cm −3 ). Therefore, this work will provide numerous chances to construct planar NIMBs for microsystems.
