Due to the high capacity of the three‐electron redox mechanism, Al‐ions‐based energy‐storage devices have the potential to provide a viable solution to meet the growing demand for powering electronic products. However, discovering suitable electrode materials for reversible insertion of Al ions remains a difficult task. Herein, it is reported that a classical conductive polymeric material poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS) can perform the reversible Al‐ions intercalation for aqueous electrochemical capacitors. The as‐prepared PEDOT:PSS film on a carbon cloth composite electrode exhibits a large magnitude of faradaic currents and sharp redox peaks in cyclic voltammetry (CV) curves in aluminum sulfate electrolyte, and delivers a high capacitance of 269 F g−1(78 mAh g−1). Diffusion‐controlled Al‐ions intercalation/deintercalation as the charge‐storage mechanism is demonstrated here, which is not observed in other ions‐based electrolytes (H+, Mg2+, Li+, Na+). An asymmetric electrochemical capacitor based on Al ions, composed of such an electrode and activated carbon electrode is assembled and displays a high energy density of 41.6 Wh kg−1at a power density of 0.24 kW kg−1, demonstrating a promising aqueous electrochemical capacitor with an advanced energy density via polyvalent ions intercalation.
Ion‐insertion capacitors show promise to bridge the gap between supercapacitors of high power densities and batteries of high energy densities. While research efforts have primarily focused on Li+‐based capacitors (LICs), Na+‐based capacitors (SICs) are theoretically cheaper and more sustainable. Owing to the larger size of Na+compared to Li+, finding high‐rate anode materials for SICs has been challenging. Herein, an SIC anode architecture is reported consisting of TiO2nanoparticles anchored on a sheared‐carbon nanotubes backbone (TiO2/SCNT). The SCNT architecture provides advantages over other carbon architectures commonly used, such as reduced graphene oxide and CNT. In a half‐cell, the TiO2/SCNT electrode shows a capacity of 267 mAh g−1at a 1 C charge/discharge rate and a capacity of 136 mAh g−1at 10 C while maintaining 87% of initial capacity over 1000 cycles. When combined with activated carbon (AC) in a full cell, an energy density and power density of 54.9 Wh kg−1and 1410 W kg−1, respectively, are achieved while retaining a 90% capacity retention over 5000 cycles. The favorable rate capability, energy and power density, and durability of the electrode is attributed to the enhanced electronic and Na+conductivity of the TiO2/SCNT architecture.
more » « less- Award ID(s):
- 1742828
- NSF-PAR ID:
- 10458922
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Functional Materials
- Volume:
- 30
- Issue:
- 5
- ISSN:
- 1616-301X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
more » « less
-
more » « less
Abstract The elemental sulfur electrode with Cu2+as the charge carrier gives a four‐electron sulfur electrode reaction through the sequential conversion of S↔CuS↔Cu2S. The Cu‐S redox‐ion electrode delivers a high specific capacity of 3044 mAh g−1based on the sulfur mass or 609 mAh g−1based on the mass of Cu2S, the completely discharged product, and displays an unprecedently high potential of sulfur/metal sulfide reduction at 0.5 V vs. SHE. The Cu‐S electrode also exhibits an extremely low extent of polarization of 0.05 V and an outstanding cycle number of 1200 cycles retaining 72 % of the initial capacity at 12.5 A g−1. The remarkable utility of this Cu‐S cathode is further demonstrated in a hybrid cell that employs an Zn metal anode and an anion‐exchange membrane as the separator, which yields an average cell discharge voltage of 1.15 V, the half‐cell specific energy of 547 Wh kg−1based on the mass of the Cu2S/carbon composite cathode, and stable cycling over 110 cycles.
-
more » « less
Abstract The elemental sulfur electrode with Cu2+as the charge carrier gives a four‐electron sulfur electrode reaction through the sequential conversion of S↔CuS↔Cu2S. The Cu‐S redox‐ion electrode delivers a high specific capacity of 3044 mAh g−1based on the sulfur mass or 609 mAh g−1based on the mass of Cu2S, the completely discharged product, and displays an unprecedently high potential of sulfur/metal sulfide reduction at 0.5 V vs. SHE. The Cu‐S electrode also exhibits an extremely low extent of polarization of 0.05 V and an outstanding cycle number of 1200 cycles retaining 72 % of the initial capacity at 12.5 A g−1. The remarkable utility of this Cu‐S cathode is further demonstrated in a hybrid cell that employs an Zn metal anode and an anion‐exchange membrane as the separator, which yields an average cell discharge voltage of 1.15 V, the half‐cell specific energy of 547 Wh kg−1based on the mass of the Cu2S/carbon composite cathode, and stable cycling over 110 cycles.
-
more » « less
Abstract A stable lean‐electrolyte operating lithium–sulfur (Li–S) battery based on a cathode of Li2S in situ electrocatalytically deposited from L2S8catholyte onto a support of metallic molybdenum disulfide (1T‐MoS2) on carbon cloth (CC) is created. The 1T‐MoS2significantly accelerates the conversion Li2S8catholyte to Li2S, chemically adsorbs lithium polysulfide (LiPSs) from solution, and suppresses crossover of the LiPSs to the anode. These experimental findings are explained by density functional theory calculations that show that 1T‐MoS2gives rise to strong adsorption of polysulfides on its surface and is electrocatalytic for the targeted reversible Li–S conversion reactions. The CC/1T‐MoS2electrode in a Li–S battery delivers an initial capacity of 1238 mAh g−1, with a low capacity fade of only 0.051% per cycle over 500 cycles at 0.5
C . Even at a high sulfur loading (4.4 mg cm−2) and low electrolyte/S (E/S) ratio of 3.7 µL mg−1, the battery achieves an initial reversible capacity of 1176 mA h g−1at 0.5C , with 87% capacity retention after 160 cycles. The post 500 cycles Li metal opposing 1T‐MoS2is substantially smoother than the Li opposing CC, with XPS supporting the role of 1T‐MoS2in inhibiting LiPSs crossover. -
more » « less
Abstract The growing demand for bioelectronics has generated widespread interest in implantable energy storage. These implantable bioelectronic devices, powered by a complementary battery/capacitor system, have faced difficulty in miniaturization without compromising their functionality. This paper reports on the development of a promising high‐rate cathode material for implantable power sources based on Li‐exchanged Na1.5VOPO4F0.5anchored on reduced graphene oxide (LNVOPF‐rGO). LNVOPF is unique in that it offers dual charge storage mechanisms, which enable it to exhibit mixed battery/capacitor electrochemical behavior. In this work, electrochemical Li‐ion exchange of the LNVOPF structure is characterized by operando X‐ray diffraction. Through designed nanostructuring, the charge storage kinetics of LNVOPF are improved, as reflected in the stored capacity of 107 mAh g−1at 20C. A practical full cell device composed of LNVOPF and T‐Nb2O5, which serves as a pseudocapacitive anode, is fabricated to demonstrate not only high energy/power density storage (100 Wh kg−1at 4000 W kg−1) but also reliable pulse capability and biocompatibility, a desirable combination for applications in biostimulating devices. This work underscores the potential of miniaturizing biomedical devices by replacing a conventional battery/capacitor couple with a single power source.
