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Potassium-based energy storage devices are attracting increasing attention as an alternative to lithium and sodium systems.

Rechargeable aqueous Zn–MnO2 batteries have been considered as one of the promising alternative energy technologies due to their high abundance, environmental friendliness, and safety of both Zn–metal anodes and manganese oxide cathodes.

There is a controversial issue based on the particle cracking of the Ni-rich layered oxide cathode materials whether it occurs at the primary particles or the grain boundary. Herein, we found that the microcracking of NMC811 does not occur at single crystalline primary particles even abused at a severe upper cell voltage of 4.7 V having a lot of gas evolution since the single-crystal NMC811 has superior mechanical stability. The capacity retentions determined at 1C rate and a 100% state of charge (SOC) are 80% and 50% after 1000 cycles for single crystal and polycrystal NMC811, respectively.

Scalable aqueous-based supercapacitors are ideal as future energy storage technologies due to their great safety, low cost, and environmental friendliness. However, the corrosion of metal current collectors e.g., aluminium (Al) foil in aqueous solutions limits their practical applications. In this work, we demonstrate a low-cost, scalable, and simple method to prepare an anti-corrosion current collector using a concept of hydrophobicity by coating the hydrophobic graphite passivation layer on the Al foil via a roll-to-roll coating technology at the semi-automation scale of production pilot plant of 18,650 cylindrical supercapacitor cells. All qualities of materials, electrodes, and production process are therefore in the quality control as the same level of commercial supercapacitors. In addition, the effects of the graphite coating layer have been fundamentally evaluated. We have found that the graphite-coated layer can improve the interfacial contact without air void space between the activated carbon active material layer and the Al foil current collector. Importantly, it can suppress the corrosion and the formation of resistive oxide film resulting in better rate capability and excellent cycling stability without capacitance loss after long cycling. The scalable supercapacitor prototypes here in this work may pave the way to practical 18,650 supercapacitors for sustainable energy storage systems in the future.

Although the Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode can store high electrical energy suitable for powering long-range electric vehicles, its poor cycling stability still hinders the practical application. Herein, a surface coating approach using a green scalable solvent-free mechanofusion process is introduced to prepare an infusing thin layer carbon nanosphere shell to improve the intrinsic drawbacks of NMC811 including poor electrical conductivity, Li+/Ni2+ cation mixing, parasitic reactions with electrolytes, and micro-crack formation. The in operando XRD of NMC811@carbon core@shell so-called NMC811cs reveals the smooth and fast phase transition through H1-H2-H3 with higher Li utilization and better stability even though it shows larger abrupt change in c lattice parameter compared to the pristine NMC811. In addition, the onset potential of CO2 and H2 evolution is found to be extended by the carbon coating as observed by an online Differential Electrochemical Mass Spectrometry. Finally, the practical application of the NMC811cs is demonstrated by the 18650 battery prototype which shows higher specific capacity and energy as well as excellent cycling stability compared to the pristine NMC811. This work provides both fundamental understanding and economical strategy towards highly stable and practical high-energy Li-ion batteries.

Transport phenomena and the solvation structure of lithium ions (Li+) and hexafluorophosphate anions (PF6−) in electrolytes with different fluoroethylene carbonate (FEC) concentrations as well as the electrochemical performance and safety of Ni-rich Li-ion battery cells at the 18650 cylindrical cell level are investigated. We have found that the electrolyte with an optimized FEC concentration (25% v/v) can effectively enhance the transport property in terms of the Li+ transference number and contact ion pair (CIP) ratio leading to high performance and safety of practical 18650 cylindrical LIBs.

Recently, graphene-based materials have become ubiquitous in electrochemical devices including electrochemical sensors, electrocatalysts, capacitive and membrane desalination and energy storage devices. However, many of the electrochemical properties of graphene (particularly the capacitance and ionic transport) are not yet fully understood. This paper explores the capacitance and ionic transport properties of size dependent graphene (from 100 nm to 1 μm) prepared through the liquid phase exfoliation of graphite in which the size of graphene was finely selected using a multi-step centrifugation technique. Our experiment was then expanded to include basal plane graphene using highly ordered pyrolytic graphite as a model electrode, describing the assumed theoretical graphene capacitance (quoted as 550 F g−1 or 21 μF cm−2) and the electrochemical surface area of the carbon-based materials. This work improves our understanding of graphene electrochemistry (capacitance and ion transport), which should lead to the continuing development of many high-performance electrochemical devices, especially supercapacitors, capacitive desalination and ion-based selective membranes.

A new approach using graphene as a conductive binder in electrical supercapacitors has recently been proposed. Graphene shows outstanding properties as a conductive binder, and can be used to replace conductive, additive, and polymer binders. However, graphene follows an EDLC behaviour, which may limit its electrochemical performance. In the process described in this work, we introduced WSe2 nanoflakes as a new approach to using pseudocapacitive materials as binders. The WSe2 nanoflakes were produced through liquid phase exfoliation of bulk WSe2, and the flake size was finely selected using a controlled centrifugation speed. The physical and electrochemical properties of the exfoliated WSe2 flakes were analysed; it was found that the smallest flakes (an average flake size of 106 nm) showed outstanding electrochemical properties, expanding our understanding of transition metal dichalcogenide (TMD) materials, and we were able to demonstrate the applicability of using WSe2 as a binder in supercapacitor electrodes. We also successfully replaced conductive additives and polymer binders with WSe2. The overall performance was improved: capacitance was enhanced by 35%, charge transfer resistance reduced by 73%, and self-discharge potential improved by 9%. This study provides an alternative application of using TMD materials as pseudo capacitive binders, which should lead to the continued development of energy storage technology.

Three-dimensional (3D) hierarchical reduced graphene oxide (rGO) aerogel with a finely tuned C/O ratio of 11.8 can be used for various applications because of its high specific surface area (925.27...

Nickel/cobalt-layered double hydroxides (NiCo-LDH) have been attracted increasing interest in the applications of anode materials for lithium ion battery (LIB), but the low cycle stability and rate performance are still limited its practice applications. To achieve high performance LIB, the surface-confined strategy has been applied to design and fabricate a new anode material of NiCo-LDH nanosheet anchored on the surface of Ti3C2 MXene (NiCo-LDH/Ti3C2). The ultra-thin, bended and wrinkled α-phase crystal with an interlayer spacing of 8.1 A can arrange on the conductive substrates Ti3C2 MXene directly, resulting in high electrolyte diffusion ability and low internal resistance. Furthermore, chemical bond interactions between the highly conductive Ti3C2 MXene and NiCo-LDH nanosheets can greatly increase the ion and electron transport and reduce the volume expansion of NiCo-LDH during Li ion intercalation. As expected, the discharge capacity of 562 mAh g−1 at 5.0 A g−1 for 800 cycles without degradation can be achieved, rate capability and cycle performance are better than that of NiCo-LDH (~100 mAh g−1). Furthermore, the density function theory (DFT) calculations were performed to demonstrate that NiCo-LDH/Ti3C2 system can be used as a highly desirable and promising anode material for lithium ion battery.

The ultra-fast charging batteries have become a bigger demand for electric vehicles. To achieve the fast charging system, the electrolyte system should be optimized with a high balance between ionic conductivity and chemical stability. In recent research, many compounds, including organic ester, formate, and nitrile, were introduced into carbonate-based electrolytes as a co-solvent. However, the understanding of how co-solvents and effect of functional groups improve the electrolyte properties is not yet disclosed. Here we investigate the role of co-solvent that affects electrolyte properties, especially the self-diffusion coefficient by using theoretical reactive molecular dynamics (RMDs) simulations coupled with the advancement in numerical method to compute the correlation between co-solvent properties and the self-diffusion coefficient. We found that the low electron affinity co-solvent and low-density molecule are the keys to improve the Li-ion diffusion in the carbonate-based electrolyte system. Hence, this work could lead the way for developing the new co-solvent for the ultra-fast charging demand.

The energy storage device with high energy and power densities with good cyclability is required. In principle, the energy density or specific energy of supercapacitor is proportional to the square of working potential window. In this work, different ionic liquids (ILs) with wide working potential windows are used as the electrolyte of supercapacitors using activated carbon. ILs of imidazolium-based structures with different sizes of alkyl chain (i.e., ethyl, propyl, butyl and pentyl) are synthesized to investigate their effects on the performance of supercapacitors. Also, we fabricated the 18650 cylindrical cells of symmetrical supercapacitors. The device with EMI-TFSI provides the highest performance following by PMITFSI, BMI-TFSI and PTMI-TFSI, respectively. This device reveals the specific capacitance of 3.44 F/g Cell (ca. 89 F a cell) and 22.28 F/g Active Material at an applied high current of 100 mA per cell. Moreover, optimum specific energy of this device (3.30 Wh kg-1 and 21.33Wh kg-1 as function of cell mass and active mass, respectively) is higher than PMI-TFSI, BMI-TFSI and PTMI-TFSI around 15, 80 and 85 %, respectively. The results elucidate that the size of alkyl chain of imidazolium cation play the importance role in electrochemical of device. We hope that these results may pave a way to design the structure of IL electrolyte for high energy storage in large-scale production.

Nickel metal hydride (NiMH) batteries are one type of batteries which are widely used commercially for various applications for example hybrid cars. NiMH battery consists of nickel hydroxide/oxyhydroxide (Ni(OH)2/NiOOH) cathode and lanthanum (La) alloy anode. Many recent studies focused on developing the storage capacity, the self-discharge, and the degradation of performance of NiMHs at a high temperature since they are cheaper than lithium-ion (Li-ion) batteries. Here, we have integrated the sunlight conversion and the storage abilities of Ni(OH)2 coated on transparent fluorene-doped tin oxide (FTO) glass for photoactive NiMH battery. This finding may lead to further develop novel photoactive NiMHs.

Even though PEO-based electrolytes have been interested as a solution for developing the next-generation lithium-based batteries, their performances are still far from the commercial need and requirement. One of the major challenges limiting the cycling performance of all-solid-state batteries is at the interfacial contact of the electrode and the ceramic electrolyte, not like in the case of liquid electrolyte. To address this poor solid-solid contact, we introduce a cathode composite concept by combining both ceramic filler and polymer with LiFePO4 (LFP) cathode material. Herein, the garnet (Li7La3Zr2O12, LLZO) ceramic is well mixed with LFP cathode material using a new solid-solid mixing process namely a mechano-fusion technique. PEO is also used as a binder during the cathode preparation. The PEO-based composited electrolyte layer (filled with LLZO) and the composite material used at the cathode are stacked layer-by-layer and hot-pressed. As a result, this composite concept produced by a scalable mechanofusion process could be useful for further develop high-performance the all-solid-state batteries.

Herein, we present the catalytic activity of CVD graphene on copper and nickel foam substrates towards electrochemical CO2 reduction (CO2R). As the result, the graphene on nickel foam (GP/NiF) shows the lower onset potential (-0.6 V vs. RHE) of CO2R process in 0.1 M KHCO3 under sat. CO2 atmosphere than that of copper foam (GP/CuF), -1.0 V vs RHE. When increasing the concentrations of KHCO3 from 0.1 to 2.0 M, the current density of the GP/NiF electrode increases due to the reduction of H+ or increase of pH.

Calendaring process is one of the most important part in the line production of 18650 lithium ion battery which densifies the electrode and promotes consistency to the metal current corrector. However, this process promotes the tortuosity of the void space network in the primary ion transportation and facilitate tradeoffs between electrode density and rate capability. The aim of this work to understanding the impact of density and porosity on electrode kinetics and authorizing cell designs with denser electrodes to improve capacity and energy density, this study investigates the effect of high and low limit of pressure force in the calendaring process between 400 and 2000 kg cm2 on the electrode properties such as density and porosity of LiNi0.8Co0.15Al0.05O2 (NCA) electrode. It was found that as the applied pressure force increased, the qualitative properties of NCA electrode are increased via the particle packing, porosity, and density. These factors directly affect to Li-ion diffusion in electrode and Li-ion depletion in the electrolyte interphases which will improve the energy density and power density. However, the overpressure force leads to increase in micro-cracking inside the NCA particle, tortuosity and over-packed of the NCA electrode which can obstructed the electrode capacity at high C-rates. Based on this result, the low-level compaction was proposed to mitigate the limiting factors. The development of the energy-power density in an 18650 cell was used to demonstrate how to further study into the electrode parameters in cell engineering.

Neutral aqueous supercapacitors are of interest due to their many advantages such as low-cost, non-flammable, and high ionic conductivity. Interestingly, the current collector is a critical part of these devices since it can be corroded in aqueous electrolytes. The Al foil is a widely used current collector for commercial organic supercapacitors due to its low-cost. However, it is corroded in aqueous electrolytes. To address this issue, we develop the graphite coating layer on the Al current collector to suppress the corrosion of Al and the formation of an oxide-resistive film on Al in an aqueous electrolyte. The corrosion testing was confirmed by the electrochemical impedance spectroscopy (EIS). Furthermore, the electrochemical performance of the as-prepared electrodes with and without the graphite coated layer was studied by using cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD). The as-prepared electrode with a graphite protective layer exhibits a higher specific capacitance as well as a higher rate capability. The capacitance fading upon increasing scan rate from 10 mV s-1 to 100 mV s-1 of graphite coated aluminium electrode was only 15%, while the capacitance of the unmodified electrode extremely faded up to 75%. The as-prepared electrode with a graphite protective layer can explicitly improve the cycling stability (retain 90 %) after 5,000 cycles at an applied current density of 1 A g-1, which is different from an unmodified electrode with rapid fading up to 55%. This finding may lead to practical neutral aqueous supercapacitors.

There are remarkedly increasing demands in electronic devices including the portable electronic devices and electric vehicles (EVs). Therefore, the energy storages that can store energy efficiently with both high energy and power densities with good cyclability as display in batteries and supercapacitors are needed. The hybrid energy storages are one of the energy storage devices merging the advantages of both batteries and supercapacitors to overcome those lacking properties in each device. Thus, the lithium-ion hybrid capacitors (LICs) are introduced consisting battery-type as negative electrode and supercapacitors-type as positive electrode. There are many selections of electrode materials that can be used in the LICs such as carbonaceous materials and lithium titanate (LTO). The cell configuration was developed and fabricated in organic electrolyte since coin-cell to cylindrical cell. Herein, the 18650 configuration is introduced as hybrid energy storage consisting LTO and activated carbon as negative and positive electrodes, respectively. Moreover, the additional additives in electrolyte are also studied and investigated to improve the electrochemical performances to the hybrid capacitors.

The practical application of Nickel-rich NMC811lithium-ion battery cylindrical cell type 18650 has been limited with its poor cycling stability due to transition metal dissolution, microcrack of NMC811 cathode, and thermodynamic instability of graphite anode. Herein, we study the effect of each electrolyte additive; VC, VEC, FEC, and PS, on the stability performance of the battery by varying the additive content at 1%, 2% and 3%. The study revealed the effect of electrolyte additives on the creation of stable SEI and CEI layers, which efficiently protected the surface of anode and cathode, respectively. It was found that high capacity retention of 61.98% can be obtained after 70 cycles, when 3%wt of VC, VEC, FEC, and PS was added. The average degradation rate of 0.54% per cycle was also observed. The improvement of cycling performance of the battery is confirmed.

An insight into the role of LiNO3 additive in an ether-based electrolyte for lithium sulfur battery has been presented. Herein, we proposed a formation mechanism of solid-electrolyte interphase on the surface of lithium metal anode by using the theoretical reactive force field (ReaxFF) simulation method. The interaction between the reactive lithium metal and nitrate ions results in the formation of LixNOy clusters, distributed homogeneously in both the SEI layer and electrolyte phase. Not only can these clusters be an efficient surface protection layer of lithium metal anode but also, they can suppress the lithium polysulfides shuttle effect by adsorbing liquid lithium polysulfide intermediates.

Photoactive bimetal oxide catalysts towards oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities have not yet been comprehensively investigated. Herein, this work presents the MnCo2O4 nanofiber using as a photo-electrocatalyst for OER and ORR. After irradiation with visible light, the MnCo2O4 decreases ca. 17.1% and 15.4% in overpotential of OER and ORR, respectively, while the overpotential of the Co3O4 is reduced ca. 8.6% and 6.4% towards OER and ORR processes, respectively. These results suggest that MnCo2O4 can enhance OER/ORR performances with two-fold higher than Co3O4 under the light illumination. Due to the mixed valence states of Mn2 + and Mn3 + in its spinel structure, the MnCo2O4 has lower band gap energy (1.7 eV) than the Co3O4 nanofiber (2.0 eV). This narrower band gap can facilitate electron transfer from the valence band to the conduction band. Moreover, the photogenerated MnCo2O4 * holes can accelerate the reaction with OH- and H2O which subsequently enhances OER performance.

A simple and chemical-free recycled carbon-ZnMn2O4 powder (composite) from the spent Zn-carbon batteries is proposed as an effective active material for the supercapacitor. This approach may amplify the economic and environmental benefits of the recycling process. We also synthesized the spherical MnOx nanoparticles by the calcination followed by the chemical treatment. Recycled composite and the MnOx nanoparticles were comprehensively characterized. Symmetrical supercapacitors with the composite and the MnOx nanoparticles show specific capacitances of 118 F g−1 and 88 F g−1 at 0.1 A g−1, respectively. Also, the supercapacitor with the composite offers a specific energy of 8.0 Wh kg−1 at 0.1 A g−1 while 4.3 Wh kg−1 is obtained for MnOx nanoparticles. The stable cell potential limits of 1.4 V and 1.2 V were established for the supercapacitors of the composite and MnOx nanoparticles with the capacitance retention of 83% and 96%, respectively at the end of 100,000 cycles at 2.5 A g−1. Also, the excellent energy efficiencies of 80% and 72% with the coulombic efficiency of 100% are estimated for the supercapacitors of the composite and the MnOx nanoparticles, respectively. Finally, in situ gas analysis of the symmetrical supercapacitors are carried out using the differential electrochemical mass spectrometry. The proposed approach may be more economical and the environmentally benign recycling of spent Zn-carbon battery for circular economy and sustainability.

A three-dimensional reduced graphene oxide (3D rGO) sponge with an ultra-high specific pore volume of 6.4 cm3g-1 and oxygen-containing (e.g., carboxyl) groups finely tuned was designed, synthesized, and employed as an ideal host of Li2S6 catholyte and related compounds for high-performance lithium-sulfur batteries (LSBs). To the best of our knowledge, the 3D rGO in this work exhibits the highest specific pore volume ever. The interconnected porous structure of 3D rGO can totally confine the lithium polysulfides overcoming the shuttle effect. Also, it can offer an excellent electrical conductivity and electrolyte transportation leading to high charge storage capacity. The as-fabricated LSB provides a high discharge capacity of 1607 mAh g−1 at 0.1C and a high areal capacity of 3.53 mAh cm−2. Even at a high sulfur loading content of 6.6 mg cm−2, high utilization (79.4%) of active materials at the 0.1C and low capacity fading rate of 0.065% per cycle at the 1.0C with 98% coulombic efficiency over 200 cycles are achieved. The 3D rGO sponge could be useful for high-energy battery applications.

A highly flexible and ionically conductive pre-lithiated perfluoro ionomer has been employed as a promising binder for the state-of-the-art Ni-rich (LiNi0.8Co0.15Al0.05O2, NCA) cathode. Such binder has been processed in two different solvent media concerning the solubility of surface residues (in ethanol and NMP), and their influence in electrochemical performances was compared. The binder dissolved in ethanol medium displays high initial coulombic efficiency in the formation cycle, followed by superior rate retention and cycling stability due to the significant solubility of lithium residues, when compared to the NMP mediated system. The operando XRD studies reveal that both systems undergo typical anisotropic crystallite alteration during the reversible lithium extraction; however, the ethanol-mediated electrode experiences a significantly low unit-cell volume change. The differential specific capacity studies also show that the electrode processed in ethanol is less prone to voltage decay, especially at the beginning of discharge, indicating improved lithium kinetics. In addition, the diffusion coefficient is found to be 5.69 × 10−9 cm2 s−1, related to the first anodic peak.

To solve the poor cycling stability of zinc ion batteries (ZIBs) caused by the growth of zinc (Zn) dendrites, a novel method of separator modification is proposed. Herein, graphene oxide (GO), which has many outstanding properties, is applied as a modified material to a glass fiber (GF) separator using a simple vacuum filtration method. A stable and dendrite-free Zn anode can be obtained after 500 cycles in a Zn//Zn symmetrical battery when using a modified separator (GF/GO1), which is mainly owing to the preferential growth of the non-protruding crystal planes of the zinc metal and the uniform nucleation of zinc ions under the action of GO. As proof of concept, full Zn//MnO2 batteries with a GF/GO1 separator exhibited a high specific capacity of 126 mA h g−1 at 0.1 A g−1, a high energy density of 327.5 W h kg−1 (power density of 0.517 W kg−1), and a high power density of 20.8 kW kg−1 (energy density of 253.8 W h kg−1), demonstrating significant improvements compared with the unmodified GF separator. Meanwhile, ZIBs with a GF/GO1 separator exhibited excellent long-term stability with less than 25% capacity fade over 500 cycles at a current density of 0.5 A g−1. ZIBs with a GF separator retain only 37% of their initial capacity after 100 cycles. Furthermore, the GF/GO1 separator can also help to improve the cycle performance and rate performance of lithium metal batteries and to achieve a dendrite-free lithium anode. Full batteries of Li//GF/GO1//LiCoO2 show improved rate and cycling capabilities. A higher energy density of 537.1 W h kg−1 at 0.04 kW kg−1 and higher power density of 1.4 kW kg−1 at 264.6 W h kg−1 can be achieved with a GF/GO1 separator, which is better than many Li metal batteries. This modification of the separator provides an effective approach to designing next-generation batteries exhibiting excellent rate and cycling capabilities, and high energy and power densities.

Pd-based catalysts are typically used in many applications; however, the effect of their oxide layer has not been fully investigated to date. Herein, by using experimental and theoretical approaches, we have found that the oxide layer significantly affects the electrocatalytic activity of Pd towards the ethanol oxidation reaction (EOR) in a basic solution. It alters the surface morphology and active sites of the catalyst, leading to different electrochemical kinetics and mechanistic pathways. Nanoscale PdO(101) layers on Pd(111) with the thickness of a few nanometers can strongly bind with ethanol and its intermediate species (i.e., acetaldehyde and acetic acid), leading to high current density being observed electrochemically. Also, the high surface roughness and active sites of the nanoscale PdO(101) layer can stabilize adsorbed intermediates, resulting in high autocatalytic decomposition and leading to overall productivity. This is an expected result since bulk PdO(101) is rather poor in terms of catalytic activity and productivity. Tuning the surface chemistry of metal catalysts with nanoscale oxide layers is a critical process in improving the electrocatalytic activity and productivity.

Lithium-sulfur battery (LSB) is considered as a potential candidate for future energy storage device due to its high specific capacity and energy density as well as the natural abundance of sulfur. However, poor capacity retention, polysulfide shuttle effect, and low electronic conductivity have hindered practical uses of the LSB. The introduction of interlayer has been proven to be a promising strategy to improve the overall performance of the LSB. Herein, the influence of various amine-based functional groups of carbon interlayer on lithium polysulfide (LPS) chemisorption was compared via electrochemical methods and density functional theory (DFT) calculations. The functionalized carbon interlayers with 4-aminobenzoic acid, 1,6-diaminohexane, p-phenylenediamine, 4-nitroaniline, and 4-aminothiophenol prepared by an amide coupling reaction show a strong contribution to reduce the polysulfide migration, resulting in the enhancement of overall LSB performances such as a superior capacity and high Coulombic efficiency along with long cyclability of the cells. The LSB with 4-aminobenzoic acid could achieve an initial specific capacity of 1694 mAh g−1 (0.1 C) with an extremely low capacity decay of 0.055% per cycle due to the cooperative interaction of H- and Li-bonds between 4-aminobenzoic acid-functionalized interlayer and polysulfides.

Insight into the influence of hydration energy of structural cations within birnessite-type layered MnO2 on charge storage mechanisms via redox reaction and intercalation/deintercalation processes ...

3D graphene oxide (GO) carbocatalyst-coated nickel foam substrate (GO@Ni) was synthesized by chemical vapor deposition (CVD) using methanol and water as material precursors. Interestingly, the GO@Ni has anti-corrosion property in an acidic electrolyte and high catalytic activity towards hydrogen evolution reaction (HER). Ni metal is easily corroded in the acid solution and cannot be used as an electrocatalyst in electrolysers for hydrogen generation. On the other hand, the GO@Ni with oxygen-containing functional groups exhibits a high HER catalytic activity with an overpotential of 83.2 mV at a current density of 10 mA cm−2. It can also be continuously tested under 1.0 M H2SO4 for 30 h without a corrosion issue of Ni substrate. In addition, the change in the morphological and structural properties of the GO@Ni after testing in H2SO4 was investigated by microscopy and spectroscopy techniques. The rate of hydrogen evolution was found to be in the order of 10−7 mol cm−2 s−1 as measured by an in situ electrochemical gas chromatography (GC). The GO@Ni electrode could be an alternative electrocatalyst in the electrolysers towards HER under acidic environment.

The safety of Li-ion batteries is one of the most important factors, if not the most, determining their practical applications. We have found that free carbonate-based solvent molecules in the hybrid electrolyte system can cause a severe safety concern. Mixing ionic liquids to the carbonate-based solvent as the co-solvent at fixed 1M LiPF6 salt can lead to free carbonate-based molecules causing poor charge storage performance and safety concerns.