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Ring-opening metathesis polymerization (ROMP) of buckybowl corannulene-based oxa-norbornadiene monomer is shown to give rise to polymeric nanomaterials with an average pore size of about 1.4 nm and a surface area of 49.2 m2/g. Application in supercapacitor devices show that the corannulene-based nanomaterials exhibit a specific capacitance of 134 F·g–1 (1.0 V voltage window) in a three-electrode cell configuration. Moreover, the electrode assembled from these materials in a symmetric configuration (1.6 V voltage window) exhibits long-term cyclability of 90% capacitance retention after undergoing 10000 cycles. This work demonstrates that ROMP is a valuable method in synthesizing nanostructured corannulene polymers, and that materials based on the nonplanar polycyclic aromatic motif represents an attractive active component for fabrication of devices targeted at electrochemical energy storage applications. Accepted version

We introduce a green synthesis approach for high-performance sodium-ion battery anodes that does not involve hydrothermal treatment or excessive energy use. Wet chemistry involving ammonium peroxostannate intermediate coating of reduced graphene oxide can be done at low temperature without excessive use of solvents. The process is practically waste-free and does not involve acid waste. Thermal treatment is required only for the solid material. The electrode exhibited very high stability and the charging capacity was reduced from 320 to 310 mA h g–1 after 2000 cycles at 3 A g–1. Moreover, the synthesis protocol demonstrated here is highly versatile with different, alternative pathways that provide many degrees of freedom in the process sheet design and in material composition.

Generally, a cost-effective electrocatalytic process that offers an efficient electrochemical energy conversion and storage necessitates a rational design and selection of structure as well as comp...

The reversibility of metal anode is a fundamental challenge to the lifetime of rechargeable batteries. Though being widely employed in aqueous energy storage systems, metallic zinc suffers from dendrite formation that severely hinders its applications. Here we report texturing Zn as an effective way to address the issue of zinc dendrite. An in‐plane oriented Zn texture with preferentially exposed (002) basal plane is demonstrated via a sulfonate anion‐induced electrodeposition, noting no solid report on (002) textured Zn till now. Anion‐induced reconstruction of zinc coordination is revealed to be responsible for the texture formation. Benchmarking against its (101) textured‐counterpart by the conventional sulphate‐based electrolyte, the Zn (002) texture enables highly reversible stripping/plating at a high current density of 10 mA cm−2, showing its dendrite‐free characteristics. The Zn (002) texture‐based aqueous zinc battery exhibits excellent cycling stability. The developed anion texturing approach provides a pathway towards exploring zinc chemistry and prospering aqueous rechargeable batteries. National Research Foundation (NRF) Accepted version The authors appreciate the financial support by National Research Foundation of Singapore (NRF) investigatorship award number NRF-NRFI2017-08 (NRF2016NRF-NRFI001-22). The authors would like to acknowledge the Facility for Analysis, Characterization, Testing and Simulation, Nanyang Technological University, Singapore, for use of their electron microscopy/X-ray facilities.

The reversibility of metal anode is a fundamental challenge to the lifetime of rechargeable batteries. Though being widely employed in aqueous energy storage systems, metallic zinc suffers from dendrite formation that severely hinders its applications. Here we report texturing Zn as an effective way to address the issue of zinc dendrite. An in-plane oriented Zn texture with preferentially exposed (002) basal plane is demonstrated via a sulfonate anion-induced electrodeposition, noting no solid report on (002) textured Zn till now. Anion-induced reconstruction of zinc coordination is revealed to be responsible for the texture formation. Benchmarking against its (101) textured-counterpart by the conventional sulphate-based electrolyte, the Zn (002) texture enables highly reversible stripping/plating at a high current density of 10 mA cm-2 , showing its dendrite-free characteristics. The Zn (002) texture-based aqueous zinc battery exhibits excellent cycling stability. The developed anion texturing approach provides a pathway towards exploring zinc chemistry and prospering aqueous rechargeable batteries.

We report the synthesis of TiS2 by chemical vapour transport and evaluated as insertion host for Na-ion battery. The half-cell assemblies are fabricated to study the Na-insertion properties. The Na/TiS2 cell displayed a reversible capacity of ∼146 mAh g–1 at 0.1 C rate which corresponds to ∼0.61 mol. Na. Excellent cycling stability, and rate performance are noted for TiS2. Cyclic voltammetry and impedance measurements supports the charge storage mechanism and interfacial properties, respectively. Operando studies are also conducted to ensure the structural stability of the insertion host. Furthermore, the Li-insertion properties are also conducted to support the electrochemical activity of the host matrix prepared by chemical vapour transport.

Coconut shell derived mesoporous carbon (CS-AC) is explored as prospective supercapacitor component in Li-ion and Na-ion capacitors (LIC and NIC) along with pre-lithiated/sodiated natural plant derived hard carbon (HC) as battery element. Though, there is no obvious variation from the capacitive properties of CS-AC, but an obvious difference is evident for battery component in single electrode configuration. Based on such performance, the mass loading has been adjusted during the fabrication of LIC and NIC. Prior to this, HC is pre-lithiated/sodiated for LIC/NIC assembly. The CS-AC and pre-treated HC based materials registered the maximum energy density of ∼121 and ∼82 Wh kg−1 for LIC and NIC assemblies, respectively. An excellent long-term cycleability of ∼83% retention is noted for LIC after 8000 cycles, whereas NIC showed inferior performance (∼60%) under similar testing conditions. Multilayer surface film is the main reason for such performance which has been clearly revealed from the impedance measurements. First, the CS-AC is prepared by hydrothermal carbonization and subsequent chemical activation with ZnCl2 to yield high specific surface area and pore volume of 1795 m2 g−1 and 2.2 cm3 g−1, respectively, in which 71% originated from mesoporous region.

The development of anodes with high capacity, long cycle life and good rate capability is essential to expedite the commercialization of sodium-ion batteries for practical applications, including grid storage and electric vehicles (EV). Herein, we report the facile solvothermal synthesis of nanostructured iron distannide (FeSn2) intermetallic particles as an alloy-type anode and the improvement of its cycle life by fabricating FeSn2-graphite composites by a ball-milling process. The influence of graphite concentration on the sodium storage properties is studied. The composite anode delivered over 400 mAh g−1 sodiation capacity over 200 cycles at a specific current of 100 mA g−1. In addition, the composite anode exhibited excellent rate performance at higher current rates. This result would certainly pave the way for the development of high-performance anodes that would realize low-cost sodium-ion batteries with a longer calendar life.

The commercialization of Na-ion batteries demands the development of technologically feasible and economically viable electrodes, in particular anodes. Herein, we report the facile synthesis of nanostructured FeSn 2 by a hydrothermal route and the formulation of composites with different carbonaceous materials like Super P, graphite, and graphene via high-throughput ball-milling. The influence of the carbonaceous matrix on the electrochemical performance of the alloy anode is investigated in half-cell assembly. Amongst, FeSn 2 -Graphite composite exhibits excellent cycling stability with a reversible capacity of 333 mAh g −1 obtained after 100 cycles at a specific current of 100 mA g −1 . The composite also displayed a good rate performance even at high current rates of 1 A g −1 which is a desirable feature for high power applications such as hybrid electric vehicles. The outstanding electrochemical performance of the composite anodes is ascribed to the effective encapsulation of the alloy particles in the carbonaceous matrix, which sustains the volume change and facilitates excellent Na-storage capability.

Generally, a cost-effective electrocatalytic process that offers an efficient electrochemical energy conversion and storage necessitates a rational design and selection of structure as well as composition of active catalytic centers. Herein, we achieved an unprecedented surface morphology and shape tuning to obtain hollow NiCo

The increasing energy demands have prompted research on conversion and alloying materials, offering high lithium and sodium storage capacities. However, most of these materials suffer from huge volume expansion and degradation over the thousands of charging and discharging cycles required for commercial applications. In this study, we demonstrate a facile route to synthesize FeSbO

To facilitate the commercialization of sodium-ion batteries (SIBs), advanced electrode materials with high sodiation capacities and enhanced cycling stabilities are essential. Herein, we investigate the effect of Fe incorporation into SnSb to generate a new ternary nanocrystalline composite based anode, which improves the cycling stability and performance of SIBs. We ensure a high-throughput synthetic approach via a rapid-solidification technique for efficient and industrially viable Fe–Sn–Sb alloy synthesis. Interestingly, the new ternary system possesses nanocrystalline domains that helped to alleviate the stresses induced upon the sodiation/desodiation reactions and thereby enhanced the performance. The Fe1.0–SnSb anode delivered a capacity of ∼500 mA h g−1 at a specific current density of 50 mA g−1 for over 120 cycles and a full-cell was designed, which could deliver one of the highest reported energy densities of ∼826 W h kganode−1. The promising electrochemical results assert the significance of microstructural engineering of alloying anodes and open up new avenues of research into rapidly solidified alloys for energy storage applications. NRF (Natl Research Foundation, S’pore) Accepted version

The increasing energy demands have prompted research on conversion and alloying materials, offering high lithium and sodium storage capacities. However, most of these materials suffer from huge volume expansion and degradation over the thousands of charging and discharging cycles required for commercial applications. In this study, we demonstrate a facile route to synthesize FeSbO4 nanocrystals that possess theoretical lithium and sodium storage capacity of 1220 mAh g–1. Operando X-ray diffraction studies reveal the electrochemically induced amorphization of the nanocrystals upon alkali-ion storage. We achieved specific storage capacities of ∼600 mAh g–1 for lithium and ∼300 mAh g–1 for sodium, respectively. The disparity in the lithium and sodium electrochemistry arises from the unique lithiation/sodiation pathways adopted by the nanocrystals. This study offers new insights into the chemistry and mechanism of conversion- and alloying-based energy storage materials that would greatly assist the development of next-generation active materials for energy storage. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Accepted version

Efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are required for metal air batteries, to replace costly metals, such as Pt and Ir/Ru based compounds, which are typically used as benchmarks for ORR and OER, respectively. Isolated single atomic sites coordinated with nitrogen on carbon supports (M-N-C) have promising performance for replacement of precious metal catalysts. However, most of monometallic M-N-C catalysts demonstrate unsatisfactory bifunctional performance. Herein, a facile way of preparing bimetallic Fe and Co sites entrapped in nitrogen-doped hollow carbon nanospheres (Fe,Co-SA/CS) is explored, drawing on the unique structure and pore characteristics of Zeolitic imidazole frameworks and molecular size of Ferrocene, an Fe containing species. Fe,Co-SA/CS showed an ORR onset potential and half wave potential of 0.96 and 0.86 V, respectively. For OER, (Fe,Co)-SA/CS attained its anodic current density of 10 mA cm at an overpotential of 360 mV. Interestingly, the oxygen electrode activity (ΔE) for (Fe,Co)-SA/CS and commercial Pt/C-RuO is calculated to be 0.73 V, exhibiting the bifunctional catalytic activity of (Fe,Co)-SA/CS. (Fe,Co)-SA/CS evidenced desirable specific capacity and cyclic stability than Pt/C-RuO2 mixture when utilized as an air cathode in a homemade Zinc-air battery. Ministry of Education (MOE) This work was supported by the AcRF Tier 1 grant (RG105/19), provided by Ministry of Education in Singapore. H.H. and J.C. like to thank National Natural Science Foundation of China (Grant No. 11874044).

Electrochemical deposition (ECD) is a promising and efficient technique for film assembly and electrode fabrication in energy storage and conversion devices. Herein, reduced graphene oxide (ErGO) with high porosity was driven by high-voltage ECD to form a binder-free capacitor electrode for lithium ion capacitors (LICs). The high voltage was used to drive the continuous and constant reduction of graphene oxide as well as for generation hydrogen, which was responsible for the porous structure. The latter not only prevented the severe stacking problem of reduced graphene oxide (rGO) but also facilitated the mass transfer of the electrolyte for the capacitive adsorption/desorption. One of the advantages of ECD is that it allows controlling very well the thickness and weight of the electrochemically deposited layer. Therefore, the effect of film thickness on the capacitive performance was also investigated. We found that increasing the film thickness did not linearly increase the areal capacitance, which was attributed to the resistive electrolyte diffusion through internal pores. Furthermore, a good capacitance as high as 168 F g−1 at 0.1 A g−1 was obtained by combining ErGO with V2O5 nanoparticles, benefiting from the integration of the high surface area of ErGO and the redox activity of V2O5.

Herein, we report additive- and binder-free pristine amorphous vanadium oxide (a-VOx) for Li- and Na-ion battery application. Thin films of a-VOx with a thickness of about 650 nm are grown onto stainless steel substrate from crystalline V2O5 target using pulsed laser deposition (PLD) technique. Under varying oxygen partial pressure (pO2) environment of 0, 6, 13 and 30 Pa, films bear O/V atomic ratios 0.76, 2.13, 2.25 and 2.0, respectively. The films deposited at 6‑30 Pa have a more atomic percentage of V5+ than that of V4+ with a tendency of later state increased as pO2 rises. Amorphous VOx films obtained at moderate pO2 levels are found superior to other counterparts for cathode application in Li- and Na-ion batteries with reversible capacities as high as 300 and 164 mAh g−1 at 0.1 C current rate, respectively. At the end of the 100th cycle, 90% capacity retention is noticed in both cases. The observed cycling trend suggests that more is the (V5+) stoichiometric nature of a-VOx better is the electrochemistry. Electronic supplementary material The online version of this article (10.1186/s11671-018-2766-0) contains supplementary material, which is available to authorized users.

Novel materials with high lithium-storage capacities are indispensable to substantially increase the gravimetric and volumetric energy densities of lithium-ion batteries. In this context, metal thiophosphites (MTPs) possessing a layered structure are considered ideal candidates to serve as alkali-ion hosts. Herein, the lithium storage properties of layered tin thiophosphite (SnPS3) crystals have been investigated in coin-cell configuration. The results reveal that SnPS3 undergoes a conversion and alloying reaction to deliver high lithiation capacities. The SnPS3 anode delivered a significant lithiation capacity of ∼800 mAh g-1 at a specific current of 100 mA g-1. Moreover, the layered structure was able to accommodate the volume changes upon (de)lithiation as evident from its excellent cycling stability. Additionally, the SnPS3 anode demonstrated excellent rate capability as well and delivered ∼315 mAh g-1 at a high specific current of 2 A g-1. Furthermore, the lithium-storage mechanism was investigated through cyclic voltammetry and ex situ X-ray diffraction and X-ray photoelectron spectroscopy studies. Studies of SnPS3 anode in a full cell configuration by coupling with commercial LiNi0.33Co0.33Mn0.33O2 cathode are also presented. The outstanding electrochemical performance demonstrated by the SnPS3 anode calls for further research into this novel class of metal thiophosphites for energy storage applications. National Research Foundation (NRF) Accepted version National Research Foundation of Singapore (NRF) Investigatorship award number NRF2016NRF-NRFI001-22.

Figure S11. SEM images of bare 304 SS. Figure S12. XRD patterns of a-VOx films deposited under different pO2 conditions in comparison with 304 SS. Figure S13. GC profiles of a-VOx-13Pa (a, b) and a-VOx-30Pa (c, d) at 0.1 C. Figure S14. Li-ion battery CV profile of bare 304 SS at 0.1 mV s−1. Figure S15. Li-ion battery CV (a and c) at 0.1 mV s−1 and GC at 0.1 C profiles of crystalline V2O5 (b and d). Figure S16. Na-ion battery CV profiles about 10 cycles of a-VOx films at 0.1 mV s−1 after 100th GC cycling. (DOCX 1728 kb)

Sodium-ion batteries (SIBs) have received renewed interest in recent years and are projected as an alternative to the existing lithium-ion battery (LIB) system. Research on SIBs is impelled by the low cost and abundant supply of sodium resources, the similar electrochemistry of SIBs and LIBs and the competing electrochemical performance achieved in recent years. Significant progress has been made in the development of alloying anodes for SIBs which offer high gravimetric and volumetric energy densities when compared to the conventional intercalation based anodes. Recent progress in the field of advanced operando and ex situ characterization techniques as well as theoretical computational studies has shed light on the sodiation mechanism of these alloying anodes. Herein, we review the recent developments in alloying anodes for SIBs. Primarily Sn, Sb, and P based alloying anodes are focused on and the progress in Bi, Ge and Si is also discussed. We focus on the sodiation mechanism of these alloying anodes, recently revealed by means of advanced experimental and computational tools, to enable the design of efficient strategies for enhanced electrochemical performance. We also discuss synthetic methodologies and novel approaches adopted for alloying anodes to mitigate the challenges faced during the (de)sodiation cycles. The future outlook and issues to be addressed to realize the practical implementation of alloying anodes are also discussed. NRF (Natl Research Foundation, S’pore) Accepted version

Owing to the high theoretical sodiation capacities, intermetallic alloy anodes have attracted considerable interest as electrodes for next-generation sodium-ion batteries (SIBs). Here, we demonstrate the fabrication of intermetallic Fe–Sb alloy anode for SIBs via a high-throughput and industrially viable melt-spinning process. The earth-abundant and low-cost Fe–Sb-based alloy anode exhibits excellent cycling stability with nearly 466 mAh g–1 sodiation capacity at a specific current of 50 mA g–1 with 95% capacity retention after 80 cycles. Moreover, the alloy anode displayed outstanding rate performance with ∼300 mAh g–1 sodiation capacity at 1 A g–1. The crystalline features of the melt-spun fibers aid in the exceptional electrochemical performance of the alloy anode. Further, the feasibility of the alloy anode for real-life applications was demonstrated in a sodium-ion full-cell configuration which could deliver a sodiation capacity of over 300 mAh g–1 (based on anode) at 50 mA g–1 with more than 99% Coulombic efficiency. The results further exhort the prospects of melt-spun alloy anodes to realize fully functional sodium-ion batteries. Accepted version