Li-ion Hybrid Supercapacitors Research Articles

Etching-Assisted Crumpled Graphene and Graphene Wrapped Spiky Iron Oxide Particles for Li-Ion Hybrid Supercapacitor

From graphene oxide wrapped iron oxide particles with etching/reduction process, high-performance anode and cathode materials of lithium-ion hybrid supercapacitors are obtained in the same process with different etching conditions, which consist of partially etched crumpled graphene (CG) wrapped spiky iron oxide particles (CG@SF) for a battery-type anode, and fully etched CG for a capacitive-type cathode. The CG is formed along the shape of spikily etched particles, resulting in high specific surface area and electrical conductivity, thus the CG-based cathode exhibits remarkable capacitive performance of 210 F g−1 and excellent rate capabilities. The CG@SF can also be ideal anode materials owing to spiky and porous morphology of the particles and tightly attached crumpled graphene onto the spiky particles, which provides structural stability and low contact resistance during repetitive lithiation/delithiation processes. The CG@SF anode shows a particularly high capacitive performance of 1420 mAh g−1 after 270 cycles, continuously increases capacity beyond the 270th cycle, and also maintains a high capacity of 170 mAh g−1 at extremely high speeds of 100 oC. The full-cell exhibits a higher energy density up to 121 Wh kg−1 and maintains high energy density of 60.1 Wh kg−1 at 18.0 kW kg−1. This system could thus be a practical energy storage system to fill the gap between batteries and supercapacitors.

Integrated nanocomposite of LiMn2O4/graphene/carbon nanotubes with pseudocapacitive properties as superior cathode for aqueous hybrid capacitors

Aqueous rechargeable Li-ion hybrid supercapacitors are attracting increasing attention owing to their intrinsic advantages compared with nonaqueous counterpart and the combination of high energy and power densities in an individual device. However, the lack of satisfactory battery-type cathode materials with fast lithium ion storage limits the overall performance. Herein, we report a composite structure by incorporating LiMn2O4 nanoparticles in graphene/carbon nanotubes network (LiMn2O4@CNTs@graphene) as superior cathode for aqueous hybrid capacitors. LiMn2O4@CNTs@graphene nanocomposite shows high capacitance with ultrafast lithium diffusion, which is mainly boosted by pseudocapacitive behavior, making it a potential candidate for hybrid supercapacitors. Hybrid devices assembled with LiMn2O4@CNTs@graphene cathode and N/S co-doped activated carbon anode exhibit an optimized overall performance with a high energy density of 62.77Whkg−1 and high power density of 2967.96Wkg−1 as well as good cycling performance with the capacitance retention of 90.8% after 5000cycles.

ZnFe2O4@Carbon Core-Shell Nanoparticles Encapsulated in Reduced Graphene Oxide for High-Performance Li-Ion Hybrid Supercapacitors.

Li-ion hybrid supercapacitors (Li-HSCs) are attracting extensive attention because of their high energy/power densities. However, the performance of most Li-HSCs suffers from the limitation of the sluggish kinetics of battery-type anodes. Herein, we demonstrate that with dual protection of carbon and graphene, a three-dimensional, strongly coupled ZnFe2O4@C/reduced graphene oxide (RGO) composite anode provides an effective solution to this issue. The covalent C-O-M linkage between ZnFe2O4 nanoparticles and C/RGO promotes charge transfer and enhances structural stability. Two kinds of carbon-based buffering layers are able to well accommodate the volume change during charging/discharging, endowing the composite anode with high rate performance (692 mA h g-1 at 5 A g-1) and outstanding cycle life (98.3% of capacity retention after 700 cycles at 1 A g-1). The resulting ZnFe2O4@C/RGO//activated carbon Li-HSC shows an ultrahigh energy density of 174 W h kg-1, excellent power density of 51.4 kW kg-1 (at 109 W h kg-1), and superior cycle life (80.5% of retention capacity after 10 000 cycles at 5 A g-1).

Improved pseudocapacitive charge storage in highly ordered mesoporous TiO2/carbon nanocomposites as high-performance Li-ion hybrid supercapacitor anodes.

A Li-ion hybrid supercapacitor (Li-HSCs), an integrated system of a Li-ion battery and a supercapacitor, is an important energy-storage device because of its outstanding energy and power as well as long-term cycle life. In this work, we propose an attractive material (a mesoporous anatase titanium dioxide/carbon hybrid material, m-TiO2-C) as a rapid and stable Li+ storage anode material for Li-HSCs. m-TiO2-C exhibits high specific capacity (∼198 mA h g−1 at 0.05 A g−1) and promising rate performance (∼90 mA h g−1 at 5 A g−1) with stable cyclability, resulting from the well-designed porous structure with nanocrystalline anatase TiO2 and conductive carbon. Thereby, it is demonstrated that a Li-HSC system using a m-TiO2-C anode provides high energy and power (∼63 W h kg−1, and ∼4044 W kg−1).

Tunable synthesis of LixMnO2 nanowires for aqueous Li-ion hybrid supercapacitor with high rate capability and ultra-long cycle life

LixMnO2 nanowires with controllable morphology and excellent electrochemical performance are synthesized by a hydrothermal method with tunable lithium contents. Both double layer capacitive process and diffusion-controlled Faradaic process play roles in the charging-discharging process. Aqueous Li-ion hybrid supercapacitors are assembled using LixMnO2 nanowires as the positive electrode and activated carbon as the negative electrode. The hybrid devices deliver high energy density of 88.56 Wh kg−1 and 25.2 Wh kg−1 at the high power density of 151.8 W kg−1 and 2155.8 W kg−1, respectively. The device also shows superb cycling life with capacitance retention of 95.2% after 10,000 cycles and 85.2% after 20,000 cycles.

Nanostructured LiMn2O4 composite as high-rate cathode for high performance aqueous Li-ion hybrid supercapacitors

Nanostructured spinel LiMn2O4 and super P composite with much enhanced electrochemical performance especially ultrahigh rate capability as the cathode for aqueous hybrid supercapacitors is synthesized by ball milling commercial LiMn2O4 particles together with super P. The as-prepared composite delivers a high capacitance of 306 F g−1 at the current density of 1 A g−1 and superb rate ability of 228.6 F g−1 at 40 A g−1 in 1 M Li2SO4 aqueous electrolyte. The capacitance of the nanostructured composite is 3.5 times higher than that of pristine LiMn2O4 even being charged and discharged 80 times faster. The excellent performances are ascribed to the nanosized LiMn2O4 well dispersed into the conductive carbon matrix. LiMn2O4 and super P composite//active carbon hybrid supercapacitor is assembled and the energy density can reach up to 21.58 Wh kg−1 at 293.16 W kg−1 and 13 Wh kg−1 at 5200 W kg−1. The hybrid device also shows an excellent cycling performance, which retains 85% of the initial capacitance after 4500 cycles. This work provides an effectively facile way to produce high performance LiMn2O4-based cathodes for hybrid suercapacitors in practical applications.

Hybrid Li-Ion Electrochemical Capacitor Enabled By Highly Crumpled Nitrogen-Doped Graphene

Energy storage systems are vital components to the success of emerging technologies such as renewable resources harvesting technologies and electric vehicles. Commercially, rechargeable Li-ion batteries (LIBs) and electrochemical capacitors (ECs) share the majority of energy storage systems markets. While LIBs are known for high energy density (≈ 240 Wh/kg) and ordinary power density (≈ 1000 W/kg), ECs have high power density (>10000 W/kg) and cyclability (>100000 cycles) but low energy density (≈ 5 Wh/kg)1. For past two decades, a new energy storage device has been studied to hybridize the two technologies by combining an EC cathode and a rechargeable battery's anode and achieve a balanced performance2. The hybridized device is commonly known as hybrid electrochemical capacitor (h-EC) or asymmetrical electrochemical capacitors which is intended to have a power density higher than rechargeable batteries and energy density higher than ECs. The initial study of the designed system comprised of nanostructured Li4Ti5O12 negative electrode accompanied with activated carbon as positive electrode. The performance showed similar cyclability to non-aqoues EDLC electrodes and 500% energy storage improvement2. Unlike the negative electrode materials, positive electrodes are believed to be more sensitive in determining the overall performance of the h-ECs due to the huge gap between the capacity of electrodes half-cells2,3. Thus, higher capacitance positive electrodes are perused using higher surface area and/or pseudocapacitance properties. The primary material for the positive electrode is carbonaceous materials with by high surface areas, such as biomass-derived doped and un-doped activated carbon1,3–5, 3D graphene/carbon composite6. Nonetheless, heteroatom-doped graphene, which has shown to increase the conductivity and activate the pseudocapacitance feature to enhance the capacitance, has rarely been reported as a cathode for hybrid electrochemical capacitors7,8. Herein, we demonstrate a high energy density of 106.2 Wh/kg at high power density 14160 Wh/kg hybrid electrochemical cell by hybridizing highly crumpled nitrogen-doped graphene with carbon-coated nano-sized silicon [Figure 1a, b]. Furthermore, the crumpled nitrogen-doped graphene was synthesized by a two-step method which led to a surface area of 1200 m2/g and high pore volume 4.5 cm3/g9. In addition, the long cycling performance has shown a capacity retention of 78% after 5000 cycles at high rate 1A/g [Figure 1c]. Carbon coating silicon anode proved to be highly advantageous for both cycling the h-EC and storing energy at higher power density. While 88% was of the initial capacity was preserved for carbon-coated silicon, only 63% was maintained for bare nano-sized silicon after 1000 cycles [Figure 1d]. Reference: Yi, R. et al. High-performance hybrid supercapacitor enabled by a high-rate Si-based anode. Adv. Funct. Mater. 24, 7433–7439 (2014).Amatucci, G. G., Badway, F., Du Pasquier, A. & Zheng, T. An Asymmetric Hybrid Nonaqueous Energy Storage Cell. J. Electrochem. Soc. 148, A930 (2001).Li, B. et al. Nitrogen-doped activated carbon for a high energy hybrid supercapacitor. Energy Environ. Sci. 9, 102–106 (2016).Sun, F. et al. High-energy Li-ion hybrid supercapacitor enabled by a long life N-rich carbon based anode. Electrochim. Acta 213, 626–632 (2016).Jain, A. et al. Activated carbons derived from coconut shells as high energy density cathode material for Li-ion capacitors. Sci. Rep. 3, 3002 (2013).Zhang, F. et al. A high-performance supercapacitor-battery hybrid energy storage device based on graphene-enhanced electrode materials with ultrahigh energy density. Energy Environ. Sci. 6, 1623 (2013).Wei, D. et al. Synthesis of n-doped graphene by chemical vapor deposition and its electrical properties. Nano Lett. 9, 1752–1758 (2009).Mendoza-Sánchez, B. & Gogotsi, Y. Synthesis of Two-Dimensional Materials for Capacitive Energy Storage. Advanced Materials 6104–6135 (2016). doi:10.1002/adma.201506133Song, J., Yu, Z., Gordin, M. L. & Wang, D. Advanced Sulfur Cathode Enabled by Highly Crumpled Nitrogen-Doped Graphene Sheets for High-Energy-Density Lithium-Sulfur Batteries. Nano Lett. 16, 864–870 (2016). Figure 1

Melamine based, n-doped carbon/reduced graphene oxide composite foam for Li-ion Hybrid Supercapacitors

In this work, a compressible melamine-based carbon/reduced graphene oxide foam was synthesized using a simple one-step process. The nitrogen-rich melamine allows the final composite material to be rich in nitrogen, resulting in a higher conductivity and performance. The synergistic combination of nitrogen-doped carbon foam and reduced graphene oxide results in a compressible, free-standing, binder-free electrode with a capacity of 330 mAh g−1 at 0.1 mA g−1 that can be used in both Lithium-ion Hybrid Supercapacitors (LIHSs) and Lithium-ion Batteries (LIBs). The composite electrode can also be used as a current collector and scaffolding for other active materials. As a proof of concept, a LIHS was fabricated using the composite foam as a free-standing electrode in the anode and a current collector for activated carbon in the cathode. The resulting device has an energy density of 40 Wh kg−1 at 1 A that can be maintained for 800 charge and discharge cycles.

A free-standing Li4Ti5O12/graphene foam composite as anode material for Li-ion hybrid supercapacitor

The demand of highly efficient energy storage system has significantly increased along with the rapid development of electric vehicles and hybrid electric vehicles. However, the energy and power density of standard energy storage devices, such as Li-ion batteries or supercapacitors still cannot meet the requirement of the state-of-the-art electric vehicles. Herein, free-standing Li4Ti5O12/graphene foam (LTO/GF) composite is synthesized via a hydrothermal method, and applied as anode material for Li-ion hybrid supercapacitor. The as-synthesized LTO/GF delivers specific capacities of 186, 179 and 175 mAh g−1 at 0.2, 0.5 and 1 C, respectively. Li-ion hybrid supercapacitors have been assembled with LTO/GF as anodes and activated carbon as cathodes, which have energy densities of 46 and 26 Wh kg−1 at power densities of 625 and 2500 W kg−1, respectively. Furthermore, the hybrid supercapacitor exhibits a superior cycle performance with capacity retention of 83% after 4000 cycles at 1 A g−1. GF sponge substrate can speed up ions and electrons transport with short diffusion lengths and large electrode/electrolyte contact area. Hierarchically structured LTO/GF electrode is lightweight, flexible, and is promising for energy storage applications.

Synthesis and characterization of carbon coated LiCo1/3Ni1/3Mn1/3O2 and bio-mass derived graphene like porous carbon electrodes for aqueous Li-ion hybrid supercapacitor

For the fabrication of aqueous Li-ion hybrid supercapacitor, carbon coated LiCo1/3Ni1/3Mn1/3O2 (or LiCo1/3Ni1/3Mn1/3O2@C composite) is synthesized by polymeric precursor method with subsequent thermal decomposition procedures for carbon coating. Graphene like porous carbon is obtained by chemical activation from the biomass of Agave Americana. The XRD analysis reveals that LiCo1/3Ni1/3Mn1/3O2 is having a hexagonal layered structure and activated carbon exists in both amorphous and graphitic nature. The TEM image infers that LiCo1/3Ni1/3Mn1/3O2 particles having the non-uniform shape with sub-micron size and the LiCo1/3Ni1/3Mn1/3O2 particles are embedded into amorphous carbon cloud in the composite. The activated carbon shows the specific surface area of 1219 m2 g−1. Finally, the fabricated aqueous LiCo1/3Ni1/3Mn1/3O2@C‖AC hybrid supercapacitor delivers the specific capacitance of 56 F g−1 with good capacity retention even after 5000 cycles.

Design and Construction of Novel High-Performance Li-Ion Hybrid Supercapacitors Based on 3D Graphene Composites

Li-ion hybrid capacitors (LIHCs) as a novel and promising energy storage unit, consisting of a Li-ion battery type anode and an electrochemical double layer capacitance (EDLC) type cathode, has attracted enormous research attentions. However, it remains a significant challenge to obtain high-performance LIHCs due to most battery-type anodes with the sluggish kinetics of Li-ion storage and low specific capacitance of common capacitor-type cathodes. Thus, it is highly required to design and fabricate novel alternative high-performance battery type anode materials and capacitor-type cathode materials, able to deliver higher energies and power densities in organic electrolyte. In this work, a novel high-performance LIHCs is constructed by combining a Li-ion battery type anode (3D graphene/MoO3 nanocomposite) with a capacitor type cathode (3D graphene/PANI derived carbon material). Such a subtle design endow LIHCs with a wide voltage range of (3.8 V), a high energy density of 128.3 Wh·kg-1, and an ultra-long cycle life up to 3000 cycles with 87% capacity retention.

High-performance Li-ion hybrid supercapacitors based on microporous pyropolymer nanoplates and orthorhombic Nb2O5 nanocomposites

In this study, high-performance Li-ion hybrid supercapacitors (LIHSs) were realized by the sophisticated design of nanostructured electrode pairs demonstrating both energy and kinetic balance. Microporous pyroprotein nanoplates (M-PNPs) were fabricated by a controlled pyrolysis process using potassium hydroxide, to achieve high electrochemical performance in the cathodic voltage region of 2.0–4.5V vs. Li+/Li. M-PNP/T-Nb2O5 nanocomposites obtained by introducing niobium oxide (T-Nb2O5) nanoparticles on the surface of M-PNP also showed outstanding Li-ion storage kinetics in the anodic voltage range of 1.0–2.0 vs. Li+/Li. The LIHSs based on M-PNP and M-PNP/T-Nb2O5 nanocomposite samples used as the cathode and anode pair, respectively, exhibited a high specific energy of ∼47.5Whkg−1 at ∼280.0Wkg−1 and a high specific power of ∼10,000Wkg−1 at ∼22.3Whkg−1 with excellent cycling stability over 30,000 cycles.

Facile synthesis of T-Nb2O5 nanosheets/nitrogen and sulfur co-doped graphene for high performance lithium-ion hybrid supercapacitors

Li-ion hybrid supercapacitors (Li-HSCs) have attracted increasing attention as a promising energy storage device with both high power and energy densities. We report a facile two-step hydrothermal method to prepare the orthorhombic niobium oxide (T-Nb2O5) nanosheets supported on nitrogen and sulfur co-doped graphene (T-Nb2O5/NS-G) as anode for Li-HSCs. X-ray diffraction and morphological analysis show that the T-Nb2O5 nanosheets successfully and uniformly distributed on the NS-G sheets. The T-Nb2O5/NS-G hybrid exhibits great rate capability (capacity retention of 63.1% from 0.05 to 5 A g−1) and superior cycling stability (a low capacity fading of ~6.4% after 1000 cycles at 0.5 A g−1). The full-cell consisting of T-Nb2O5/NS-G and active carbon (AC) results in high energy density (69.2 W h kg−1 at 0.1 A g−1), high power density (9.17 kW kg−1) and excellent cycling stability (95% of the initial energy after 3000 cycles). This excellent performance is mainly attributed to the highly conductive NS-G sheets, the uniformly distributed T-Nb2O5 nanosheets and the synergetic effects between them. These encouraging performances confirm that the obtained T-Nb2O5/NS-G has promising prospect as the anode for Li-HSCs.

Filling and unfilling carbon capsules with transition metal oxide nanoparticles for Li-ion hybrid supercapacitors: towards hundred grade energy density

Li-ion hybrid supercapacitors (Li-HECs) facilitate effective combination of the advantages of supercapacitors and Li-ion batteries (LIBs). However, challenges remain in designing and preparing suitable anode and cathode materials, which often require tedious and expensive procedures. Herein, we demonstrated that hollow N-doped carbon capsules (HNC) with and without a Fe3O4 nanoparticle core can respectively function as the anode and the cathode in very-high-performance Li-HECs. The Fe3O4@NC anode exhibited a high reversible specific capacity exceeding 1530 mA h g−1 at 100 mA g−1 and excellent rate capability (45% capacity retention from 0.1 to 5 A g−1) and cycle stability (>97% retention after 100 cycles). Moreover, high rate performance was achieved in a full-cell using the HNC cathode. By combining the respective structural advantages of the components, the hybrid device with Fe3O4@NC//HNC exhibited a remarkable energy density of 185 W h kg−1 at a power density of 39 W kg−1. The hybrid device furnished a battery-inaccessible power density of 28 kW kg−1 with rapid charging/discharging within 9 s at an energy density of 95 W h kg−1.

Nitrogen doping in the carbon matrix for Li-ion hybrid supercapacitors: state of the art, challenges and future prospective

Li ion hybrid supercapacitors are summarized with an emphasis on the use of nitrogen doped graphene and activated carbons.

Rational design of Li3VO4@carbon core–shell nanoparticles as Li-ion hybrid supercapacitor anode materials

A Li-ion hybrid supercapacitor (Li-HSC) delivering high energy within seconds (excellent rate performance) with stable cycle life is one of the most highly attractive energy storage devices.

The synergic effect of activated carbon and Li3V1.95Ni0.05(PO4)3/C for the development of high energy and power electrodes

Exceptionally high specific capacities at ultrahigh charge/discharge currents have been obtained with a bi-material electrode prepared using Li3V1.95Ni0.05(PO4)3/C (LVNP/C) and activated carbon (AC) as coexisting active materials. Thanks to the amphoteric properties of LVNP/C, this electrode designated as LVNP/C-AC, has been evaluated both as positive and negative electrode in 1M LiPF6 in EC:DMC (1:1). At high specific currents (26.6Ag−1), the bi-material electrode delivers specific capacities as high as 61 and 24mAhg−1, between 3.0–4.3V and 3.0–1.5V vs Li/Li+, respectively. By contrast, the corresponding values for LVNP/C are 49 and 18mAhg−1. In both potential windows, the bi-material electrode shows an excellent cycling stability over 2000 cycles at 26.6Ag−1, with capacity retention of 95 and 89%, between 3.0–4.3 and 3.0–1.5V vs Li/Li+, respectively. The synergic effect of the activated carbon on the electrochemical performances of Li3V1.95Ni0.05(PO4)3/C is investigated by comparing the cyclic voltammetry, electrochemical impedance spectroscopy, electronic conductivity, galvanostatic cycling, and scanning electron microscopy of the bi-material electrode with the ones of LVNP/C. This study highlights the huge potentialities of this bi-material electrode for the development of high energy and high power Li-ion hybrid supercapacitors.

Advanced Li-Ion Hybrid Supercapacitors Based on 3D Graphene-Foam Composites.

Li-ion hybrid supercapacitors (LIHSs) have recently attracted increasing attention as a new and promising energy storage device. However, it is still a great challenge to construct novel LIHSs with high-performance due to the majority of battery-type anodes retaining the sluggish kinetics of Li-ion storage and most capacitor-type cathodes with low specific capacitance. To solve this problem, 3D graphene-wrapped MoO3 nanobelt foam with the unique porous network structure has been designed and prepared as anode material, which delivers high capacity, improved rate performance, and enhanced cycle stability. First-principles calculation reveals that the combination of graphene dramatically reduces the diffusion energy barrier of Li+ adsorbed on the surface of MoO3 nanobelt, thus improving its electrochemical performance. Furthermore, 3D graphene-wrapped polyaniline nanotube foam derived carbon is employed as a new type of capacitor-type cathode, demonstrating high specific capacitance, good rate performance, and long cycle stability. Benefiting from these two graphene foam-enhanced materials, the constructed LIHSs show a wide operating voltage range (3.8 V), a long stable cycle life (90% capacity retention after 3000 cycles), a high energy density (128.3 Wh·kg-1), and a high power density (13.5 kW·kg-1). These encouraging performances indicate that the obtained LIHSs may have promising prospect as next-generation energy-storage devices.

High-energy Li-ion hybrid supercapacitor enabled by a long life N-rich carbon based anode

Hybridizing battery and capacitor materials to construct hybrid supercapacitors has been regarded as a promising avenue to achieve high energy densities while maintaining high power-output. Herein, we report a lithium ion hybrid supercapacitor with high power and energy densities as well as excellent cycling stability, which is constructed of an N-rich carbon based anode and commercial activated carbon cathode. The N-rich carbon spheres (NRCS) possess high surface area, uniform mesoporous structure, and high level of N-doping, synergically enabling excellent lithium storage properties in terms of high capacity, fast rate capability and long cycling lifespan even at high current rate (638mAhg−1 after 2000 cycles at 2Ag−1). Benefitting from above merits of NRCS, the assembled hybrid supercapacitor delivers a high energy density of 105.8Whkg−1 at 650Wkg−1. Even when power density increases to 10800Wkg−1, 40.4Whkg−1 can be maintained. Long cycling life (capacity retention of 75% after 8000 cycles) is also demonstrated. This work offers a new platform for high-energy hybrid supercapacitors by assembling high-performance porous carbon based anode.

Li-ion capacitor based on activated rice husk derived porous carbon with improved electrochemical performance

We report the fabrication of a high energy-power density Li-ion hybrid supercapacitor (Li-HSC) using rice husk derived activated porous carbon as cathode and insertion type Li4Ti5O12 (LTO) as anode. Nanoporous carbon chemically activated with KOH (RHDPC-KOH) and H3PO4 (RHDPC- H3PO4) exhibited high surface area and improved porosity characteristics. With optimized electrode mass loading, the fabricated Li-HSC exhibited excellent electrochemical properties with a maximum energy density of ∼57 Whkg−1 and ∼37Whkg−1 for LTO/RHDPC-KOH and LTO/RHDPC-H3PO4 configuration respectively. The obtained energy density of 45Whkg−1 for RHDPC-KOH −based Li-HSC, even at a high power density of ∼4.3kWkg−1, is far superior to several porous carbon-based Li-ion capacitors reported. Furthermore, the device showed excellent cyclability with capacity retention of ∼92% of initial capacity even after 2000 cycles, at high current density of 2 Ag−1.