Organic sodium-ion batteries (SIBs) are potential alternatives of current commercial inorganic lithium-ion batteries for portable electronics (especially wearable electronics) because of their low cost and flexibility, making them possible to meet the future flexible and large-scale requirements. However, only a few organic SIBs have been reported so far, and most of them either were tested in a very slow rate or suffered significant performance degradation when cycled under high rate. Here, we are focusing on the molecular design for improving the battery performance and addressing the current challenge of fast-charge and -discharge. Through reasonable molecular design strategy, we demonstrate that the extension of the π-conjugated system is an efficient way to improve the high rate performance, leading to much enhanced capacity and cyclability with full recovery even after cycled under current density as high as 10 A g(-1).

Na-ion batteries are a potential substitute to Li-ion batteries for energy storage devices. However, the poor electrochemical performance, especially capacity and rate capability are the major bottlenecks to future development. Here we propose a performance-oriented electrode structure, which is 1D nanostructure arrays with large-scale high ordering, well vertical alignment, and large interval spacing. 10 Benefiting from these structure merits, a great enhancement on electrochemical performance could be achieved. To Sb as an example, we firstly report large-scale highly ordered Sb nanorod arrays with uniform large interval spacing (190 nm). In return for this electrode design, high ion accessibility, fast electron transport, and strong electrode integrity are presented here. Used as additive-and binder-free anode for Na-ion batteries, Sb nanorod arrays showed a high capacity of 620 mAh g -1 at the 100th cycle 15 with a retention of 84% up to 250 cycles at 0.2 A g -1 , and superior rate capability for delivering reversible capacities of 579.7 and 557.7 mAh g -1 at 10 and 20 A g -1 , respectively. A full cell coupled by P2-Na 2/3 Ni 1/3 Mn 2/3 O 2 cathode and Sb nanorod arrays anode was also conducted, which showed a good cycle performance up to 250 cycles, high rate capability up to 20 A g -1 , and large energy density up to 130 Wh kg -1 . These excellent electrochemical performances shall pave a way to develop more applications of Sb 20 nanorod arrays in energy storage devices. 65 friendly. 17 The abundance of Sb in the Earth's crust is estimated at 0.2 to 0.5 parts per million. In addition, Sb has been found in over 100 mineral species. Sb is considered a promising anode material for SIBs due to its large Na storage capacity of 660 mAh g -1 , good electronic conductivity, and moderate operating voltage. 17 70 However, the practical application of Sb is mainly hindered by Journal Name, [year], [vol], 00-00 | 7 65 cell was tested with a voltage range of 1.4-4.0 V at a large current density of 0.5 A g -1 (with respect to the anode weight) using 1.0 M NaClO 4 in EC-PC-5% FEC electrolyte. According to the This journal is © The Royal Society of Chemistry [year] [journal], [year], [vol], 00-00 | 10 Broader contextDue to the lower cost and larger abundance of Na, Na-ion batteries have been a potential alternative to Li-ion batteries for energy storage devices. The development of electrode materials or structures with good electrochemical performance is currently key task in Na-ion batteries research. In this work, we presented a performance-oriented 1D nanostucture arrays with large-scale high ordering, well vertical 5 alignment, and large interval spacing, fabricated by a facile and cost-effective nanoimprinted AAO templating technique, might be successfully used as an electrode and showed an excellent electrochemical performance. This arrays conceptual design is universial to most of electrode materials. Taking antimony (Sb) as an example, large-scale higly ordered Sb nanorod arrays with uniform large interval spac...

Organic sodium‐ion batteries (SIBs) are one of the most promising alternatives of current commercial inorganic lithium‐ion batteries (LIBs) especially in the foreseeable large‐scale flexible and wearable electronics. However, only a few reports are involving organic SIBs so far. To achieve fast‐charge and fast‐discharge performance and the long‐term cycling suitable for practical applications, is still challenging. Here, important factors for high performance SIBs especially with high capacity and long‐term cyclability under fast‐charge and fast‐discharge process are investigated. It is found that controlling the solubility through molecular design and determination of the electrochemical window is essential to eliminate dissolution of the electrode material, resulting in improved cyclability. The results show that poly(vinylidenedifluoride) will decompose during the charge/discharge process, indicating the significance of the binder for achieving high cyclability. Beside of these, it is also shown that decent charge transport and ionic diffusion are beneficial to the fast‐charge and fast‐discharge batteries. For instance, the flake morphology facilitates the ionic diffusion and thereby can lead to a capacitive effect that is favorable to fast charge and fast discharge.

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spectrum of solar radiations, a key point for PEC water splitting is to explore photoelectrode materials with a high-effi cient solar light utilization. Since the pioneering work demonstrated by Fujishima and Honda in 1972, TiO 2 has been extensively investigated as a photoanode material, attributing to its advantages of high photochemical stability, cost effectiveness, and nontoxicity. [ 2 ] However, in view of the large band gap (3.2 eV for anatase and 3.0 eV for rutile), low electron mobility (1 cm 2 V −1 s −1 ) and short minority carrier (hole) diffusion length (10-100 nm) of TiO 2 , its practical application for PEC is restricted. [ 3 ] Thus, many efforts have been devoted to address this issue. [ 4 ] In particular, owning to the signifi cant capability of decoupling light absorption and charge carrier collection, and shortening minority carrier diffusion distance compared to bulk structures, 1D nanostructures (e.g., nanorod, [ 5 ] nanowire, [ 6 ] and nanotube [ 7 ] of TiO 2 have been intensively studied. Additionally, rational construction of complex hierarchical TiO 2 nanostructures, such as branched nanowire array [ 8 ] and nanotube photonic crystal, [ 9 ] can further increase the light absorption effi ciency and contact surface areas, thus enhance the PEC performance accordingly. Although the TiO 2 nanostructuring could effi ciently transfer the holes at the TiO 2 /electrolyte interface via diffusing across the axial direction of the nanostructures, the low mobility of electrons in TiO 2 is still an obstacle because they must transport along the radial direction to reach to the current collector. [ 8a ] As previously demonstrated, core/ shell nanostructures, in which the core acts as a conductive path, could be an excellent candidate to facilitate the electrons separation and transportation simultaneously in the axial direction. [ 10 ] Furthermore, in order to promote the solar light utilization of the TiO 2 -based core/shell nanostructures, introducing surface plasmon resonance (SPR) of Au nanoparticles (NPs) is a promising approach, ascribing to the advantages of its visible light absorption and good stability. [ 11 ] However, most of the existing TiO 2 -based core/shell nanostructures require complex multistep fabrication processes and the structure could only be roughly adjusted, which make it diffi cult to quantitatively optimize the charge carrier collection. [ 12 ] Meanwhile, although the Constructing core/shell nanostructures with optimal structure and composition could maximize the solar light utilization. Here, using an Al nanocone array as a substrate, a well-defi ned regular array of AZO/TiO 2 core/shell nanocones with uniformly dispersed Au nanoparticles (AZO/TiO 2 /Au NCA) is successfully realized through three sequential steps of atomic layer deposition, physical vapor deposition, and annealing processes. By tuning the structural and compositional parameters, the advantages of light trapping and short carrier diffusion from the core/shell nanocone array, as well as the surface plasmo...

Oxygen vacancies (OVs) are reported for the first time as an effective strategy to boost the electrochemical performance for amorphous electrode materials of sodium-ion batteries (SIB). Amorphous SnO2 is used as a model anode material to demonstrate the significant impact of OVs owing to the high attention it has received in the SIB field. Amorphous SnO2 ordered arrays are fabricated using the nanoimprinted anodic aluminum oxide (AAO) template and atomic layer deposition, and OVs are confined in the material by annealing the arrays in the N2 atmosphere. The OVs-containing amorphous SnO2 ordered arrays, used as binder-and conductive additive-free anodes, exhibit high reversible capacity and good cycle life by retaining the capacities of 376 mAh g-1 after 100 cycles at 0.05 A g-1 and 220 mAh g-1 after 800 cycles at 1 A g-1 as well as great rate capability by maintaining the capacities of 210 mAh g-1 at 10 A g-1 and 200 mAh g-1 at 20 A g-1. Electrochemical kinetic study reveals that the presence of OVs greatly enhances charge transfer/transport in the amorphous SnO2, thereby boosts the performance comparing with the OVs-free counterpart. This work highlights the importance of modulating defects in amorphous electrode materials towards promoted sodium storage.

Plasmonic nanostructures have been widely incorporated into different semiconductor materials to improve solar energy conversion. An important point is how to manipulate the incident light so that more light can be efficiently scattered and absorbed within the semiconductors. Here, by using a tunable three-dimensional Au pillar/truncated-pyramid (PTP) array as a plasmonic coupler, a superior optical absorption of about 95% within a wide wavelength range is demonstrated from an assembled CdS/Au PTP photoanode. Based on incident photon to current efficiency measurements and the corresponding finite difference time domain simulations, it is concluded that the enhancement is mainly attributed to an appropriate spectral complementation between surface plasmon resonance modes and photonic modes in the Au PTP structure over the operational spectrum. Because both of them are wavelength-dependent, the Au PTP profile and CdS thickness are further adjusted to take full advantage of the complementary effect, and subsequently, an angle-independent photocurrent with an enhancement of about 400% was obtained. The designed plasmonic PTP nanostructure of Au is highly robust, and it could be easily extended to other plasmonic metals equipped with semiconductor thin films for photovoltaic and photoelectrochemical cells.