Fast and Large Lithium Storage in 3D Porous VN Nanowires–Graphene Composite as a Superior Anode Toward High‐Performance Hybrid Supercapacitors

Abstract

Li‐ion hybrid capacitors (LIHCs), consisting of an energy‐type redox anode and a power‐type double‐layer cathode, are attracting significant attention due to the good combination with the advantages of conventional Li‐ion batteries and supercapacitors. However, most anodes are battery‐like materials with the sluggish kinetics of Li‐ion storage, which seriously restrict the energy storage of LIHCs at the high charge/discharge rates. Herein, vanadium nitride (VN) nanowire is demonstated to have obvious pseudocapacitive characteristic of Li‐ion storage and can get further gains in energy storage through a 3D porous architecture with the assistance of conductive reduced graphene oxide (RGO). The as‐prepared 3D VN–RGO composite exhibits the large Li‐ion storage capacity and fast charge/discharge rate within a wide working widow from 0.01–3 V (vs Li/Li+), which could potentially boost the operating potential and the energy and power densities of LIHCs. By employing such 3D VN–RGO composite and porous carbon nanorods with a high surface area of 3343 m2 g−1 as the anode and cathode, respectively, a novel LIHCs is fabricated with an ultrahigh energy density of 162 Wh kg−1 at 200 W kg−1, which also remains 64 Wh kg−1 even at a high power density of 10 kW kg−1.

Porous One‐Dimensional Nanomaterials: Design, Fabrication and Applications in Electrochemical Energy Storage

“…Layered hydrogen titanates also deliver pseudocapacitive behavior in both nanotube and nanowire forms, [316,317,328] which have an open layered structure with large interlayer spacing (0.8 nm) and enable fast Li + ion intercalation. [330][331][332][333][334][335][336][337][338] Nitrogen-rich CNT/C composites were tested as electrodes in lithium ion capacitors (LICs), and demonstrated a capacity of >200 mAh g −1 for 600 cycles. Similar results have been observed with sodium titanate in non-aqueous electrolytes.…”

Construction of SnO2−Graphene Composite with Half-Supported Cluster Structure as Anode toward Superior Lithium Storage Properties

“…Although both SnO 2 @C@half-rGO//gpC and SnO 2 @C/rGO//gpC benefit from the mesopores inside the SnO 2 clusters and the conductive rGO matrix outside, the half-open structure gives SnO 2 @C@half-rGO a larger exposed surface than SnO 2 @C/rGO for the high-speed transfer of Li + .

Figure 7Ragone chart of SnO 2 @C@half-rGO//gpC and SnO 2 @C/rGO//gpC. The performance is compared with reported similar LIHC systems including Fe 3 O 4 /graphene//3D-graphene 32 , VN-RGO//AC 33 , porous NbN//AC 34 , MnO@graphene//HNC 35 , SnO 2 /Cu/CNT//AC 36 , Li 4 Ti 5 O 12 //activated bottom-up graphene 37 , and Li 3 V 2 (PO 4 ) 3 -C//AC 38 .

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

“…where a and b are appropriate values, obeying the power law [42]. The obtained b values can classify electrochemical reaction kinetics mechanism: b = 0.5 symbolizes a diffusion-controlled insertion process and b = 1 represents a surface capacitive behavior [2,30].…”