Integration of nickel–cobalt double hydroxide nanosheets and polypyrrole films with functionalized partially exfoliated graphite for asymmetric supercapacitors with improved rate capability

Abstract

High-rate asymmetric supercapacitors (ASCs) made of abundant and low-cost electrode materials and operating in safe aqueous electrolytes could be attractive for electrochemical energy storage. Here, we design a new type of ASC by using pseudo-capacitive nanomaterials, Ni-Co double hydroxide (Ni-Co DH) nanosheets and polypyrrole (PPy) film, for cathode and anode, respectively which were integrated with functionalized partial-exfoliated graphite (FEG) current collector.Benefiting from the "super highway" for fast electron/ion transportation in the hybrid systems, the as-prepared electrodes exhibit superior rate capability (2442 and 2039 F/g at 1 and 50 A/g, with 83.5% retention for Ni-Co DH; 560 and 441 F/g at 1 and 50 A/g, with 79% retention for PPy). The assembled ASC displays a high specific capacitance (261 F/g at 1 A/g) and excellent rate capability, 77% of its initial capacitance can be retained when the current density increases 30 times from 1 to 30 A/g. An energy density of 61.3 Wh/kg can be achieved by the ASC at 0.65 kW/kg. Even at an ultra-high power density of 19.5 kW/kg, the ASC can still deliver a high energy density of 47.2 Wh/kg. Through careful control of charges which can be stored in anode and cathode, cycling stability of the ASC is much improved, 91% capacitance retention can be achieved after 5000 charge-discharge cycles. These features demonstrate a new avenue for developing high-performance pseudocapacitive electrodes and rational assembly strategies for high power/energy density charge storage devices with good cycling stability.A high-rate asymmetric supercapacitor (ASC) was developped by employing high rate pseudo-capacitive nanomaterial/graphene hybrid electrode for both electrodes.

Recent Overviews in Functional Polymer Composites for Biomedical Applications

“…The conducting polymers have been integrated with carbon nanomaterials such as carbon nanotubes (CNTs), graphene oxide (GO), and reduced graphene oxide (rGO) to enhance cycling stability, electrical conductivity, and provide high surface area [28,29,30,31]. Similarly, metal oxides or hydroxides could be composited with a polymer matrix to increase capacitance and provide better cyclic stabilities [32,33,34]. In addition, such conductive reinforcement materials (i.e., CNTs, graphite, carbon fibers, and metals), when added to a polymer matrix, resulted in polymer composites with improved thermal conductivity.…”

Peanut-Shell-like Porous Carbon from Nitrogen-Containing Poly-N-phenylethanolamine for High-Performance Supercapacitor

“…In addition, we also tried four-unit capacitor device in series to drive three color LEDs, and most interestingly, the LEDs can keep light for 70 min when the device is only charged for 10 s, which far exceeds previous reports. [44][45][46] The capacitance performance of a supercapacitor depends on the specific surface and the (electronic and ionic) conductivity of its electrode material. Usually, high surface area and high conductivity make great contributions to excellent capacitive property.…”

A Review on Nano-/Microstructured Materials Constructed by Electrochemical Technologies for Supercapacitors

“…The seamless integration between the top layer and the graphite bottom ensured fast electron conduction pathways. Besides improving electrolyte wettability, the oxygen moieties served as anchoring sites for depositing guest materials for polyaniline [ 27 ], polypyrrole [ 105 ], manganese oxides [ 86 ], vanadium oxides [ 37 ], iron oxides [ 35 , 106 ], nickel–cobalt double hydroxides [ 106 ], and molybdenum-based materials [ 28 ].

Fig.

…”