Battery-Supercapacitor Hybrid Devices: Recent Progress and Future Prospects

Abstract

Design and fabrication of electrochemical energy storage systems with both high energy and power densities as well as long cycling life is of great importance. As one of these systems, Battery-supercapacitor hybrid device (BSH) is typically constructed with a high-capacity battery-type electrode and a high-rate capacitive electrode, which has attracted enormous attention due to its potential applications in future electric vehicles, smart electric grids, and even miniaturized electronic/optoelectronic devices, etc. With proper design, BSH will provide unique advantages such as high performance, cheapness, safety, and environmental friendliness. This review first addresses the fundamental scientific principle, structure, and possible classification of BSHs, and then reviews the recent advances on various existing and emerging BSHs such as Li-/Na-ion BSHs, acidic/alkaline BSHs, BSH with redox electrolytes, and BSH with pseudocapacitive electrode, with the focus on materials and electrochemical performances. Furthermore, recent progresses in BSH devices with specific functionalities of flexibility and transparency, etc. will be highlighted. Finally, the future developing trends and directions as well as the challenges will also be discussed; especially, two conceptual BSHs with aqueous high voltage window and integrated 3D electrode/electrolyte architecture will be proposed.

Keywords: battery‐supercapacitor hybrid; energy/power density; future prospects; multifunctional; recent progress.

Figure 1

Ragone plots of various rechargeable batteries and EDLC, and the comparison with BSHs.

Figure 2

a₁) CV at 5 mV s⁻¹ and a₂) Charge–discharge curves at 2 mA cm⁻² for amorphous MnO₂⋅nH₂O in KCl aqueous electrolyte. Reproduced with permission.31 Copyright 1999, Elsevier. b₁) CV at 10 mV s⁻¹ and b₂) charge–discharge curves for 1T phase MoS₂ electrode. Reproduced with permission.40 Copyright 2015, Nature Publishing Group. c1) CV profiles and c2) cycling stability of Ti₃C₂T_x electrode. Reproduced with permission.41 Copyright 2014, Nature Publishing Group.

Figure 3

General energy storage mechanism and device structure of BSHs.

Figure 4

Various types of BSHs and their electrode and electrolyte materials.

Figure 5

Typical voltage profiles for a) symmetric activated carbon‐based SC and b) activated carbon//Li‐doped carbon BSH. Reproduced with permission.42 Copyright 2006, The Electrochemical Society.

Figure 6

a) Charge–discharge profiles of LiNi_0.5Mn_1.5O₄ cathode in the potential range of 3.50–4.95 V. b) Cycling stability of LiNi_0.5Mn_1.5O₄//AC BSH in different cell voltage ranges. c) Charge–discharge profiles of 3.3 V LiNi_0.5Mn_1.5O₄//AC after 3000 cycles. Reproduced with permission.58 Copyright 2014, The Electrochemical Society.

Figure 7

a) Schematic illustration of a carbon//carbon Na‐ion BSH. b) SEM image of the porous nanosheet carbon. c) Ragone plots of the Na‐ion BSH at different working temperatures. Reproduced with permission.82 Copyright 2014, The Royal Society of Chemistry. d) Schematic and e) SEM images of V₂O₅/CNT nanocomposite. f) Ragone plots of V₂O₅/CNT‐based BSH and other devices. Reproduced with permission.83 Copyright 2012, American Chemical Society. g) CV curves of AC anode and Na_xMnO₂ cathode. h) Charge–discharge profiles and i) Ragone plots of Na_xMnO₂//AC BSH. Reproduced with permission.84 Copyright 2013, Elsevier.

Figure 8

a) CV curves of CoHCF. b) Ragone plots of CoHCF//CMS Na‐ion BSH. c) Wide channels in CoHCF allow for rapid insertion/removal of Na⁺. Reproduced with permission.88 Copyright 2015, Elsevier. d) Typical anodes and cathodes for aqueous Na‐ion BSHs.91

Figure 9

a) SEM and b) HRTEM images of NiMoO₄ nanosheets (NMO‐NS). c) Ragone plots of NMO‐NS//AC alkaline BSH device. Reproduced with permission.103 Copyright 2015, Wiley‐VCH. d) SEM image of (Cu,Ni)O nanowire array. e) Discharge curves and f) Ragone plot/cycling performance of (Cu,Ni)O//AC alkaline BSH. Reproduced with permission.106 Copyright 2016, The Royal Society of Chemistry. g) Schematic illustration of the synthesis process of CoMoO₄‐3D graphene hybrid electrode. h) Ragone plot of CoMoO₄//AC BSH. Reproduced with permission.107] Copyright 2014, Wiley‐VCH.

Figure 10

a) Schematic illustration of Fe₃O₄—C electrode's merits. b) Energy storage mechanism of Fe₃O₄—C electrode in KOH electrolyte. c) Comparative CV curves of Fe₃O₄—C anode and CNTs cathode in three‐electrode cells. Reproduced with permission.116 Copyright 2015, Wiley‐VCH. d) Typical CV and e) charge–discharge curves of Bi₂O₃ electrode in alkaline electrolyte. Reproduced with permission.117 Copyright 2014, Springer. f) SEM image of Bi₂O₃ nanosheet film. g) Energy storage mechanism of Bi₂O₃ in aqueous electrolytes. Reproduced with permission.5 Copyright 2016, The Royal Society of Chemistry.

Figure 11

a) Schematic illustration of redox‐additive BSH device of PVA‐H₂SO₄‐HQ//PVA‐H₂SO₄‐MB. Reproduced with permission.131 Copyright 2015, Elsevier. CVs for b) negative electrode and c) positive electrode in dihydroxybenzene‐modified acidic electrolytes. Reproduced with permission.132 Copyright 2015, The Royal Society of Chemistry. d) Redox potential of various organic and organometallic candidates. Reproduced with permission.129 Copyright 2015, The Royal Society of Chemistry.

Figure 12

Redox potential of various reversible inorganic redox couples. a) Reproduced with permission.130 Copyright 2015, Nature Publishing Group. b) Reproduced with permission.129 Copyright 2015, The Royal Society of Chemistry.

Figure 13

Na₂Fe₂(SO₄)₃//Ti₂CT_x BSH device. a) Charge–discharge curves of electrodes, b) charge–discharge plots at various rates, and c) cycling performance and coulombic efficiency for the full cell. Reproduced with permission.140 Copyright 2015, Nature Publishing Group. MnO₂//Bi₂O₃ BSH device. d) Schematic illustration, e) cycling performance, and f) Ragone plot. Reproduced with permission.141 Copyright 2015, Wiley‐VCH.

Figure 14

Flexible BSHs. a) Typical configuration of flexible BSH. b) SEM image of Li₄Ti₅O₁₂ nanowire array anode, the inset is digital photograph of the flexible Li₄Ti₅O₁₂//CNT BSH. c) Ragone plot of the device. Reproduced with permission.50 Copyright 2015, Nature Publishing Group. d–f) Electrochemical stability of CNTs//Fe₃O₄‐C BSH device under bending, high mechanical pressure and elevated temperature. Reproduced with permission.116 Copyright 2015, Wiley‐VCH. g) SEM image of CoO@PPy nanowire array cathode. h,i) The CoO@PPy//AC BSH powering rotation motor robustly and lighting LED indicator. Reproduced with permission.152 Copyright 2013, American Chemical Society.

Figure 15

a) Digital photographs, b) transmittance spectra, and c) absorbance at 550 nm versus thickness of flexible graphene films. Reproduced with permission.161 Copyright 2010, American Institute of Physics. d) Digital photographs and CV curves of transparent and stretchable graphene SC before and after stretching and bending. Reproduced with permission.169 Copyright 2013, American Chemical Society. e) Transmittance spectra, f) bending testing, and g) schematic illustration of transparent and flexible Co₃O₄ electrode/SC. Reproduced with permission.172 Copyright 2016, The Royal Society of Chemistry.

Figure 16

a) Conceptual illustration of future BSHs based on “water‐in‐salt” or hydrate‐melt electrolytes. b) The Li storage materials system that can be utilized with “water‐in‐salt” electrolyte. The comparison with the cases in simple aqueous electrolyte and organic carbonates electrolyte is also presented. Reproduced with permission.172 Copyright 2015, Science, AAAS. c) Schematic illustration of a conceptual flexible BSH using 3D nanostructure arrays as the electrode integrated with gel or polymer electrolyte.