A Highly Flexible Supercapacitor Based on MnO2/RGO Nanosheets and Bacterial Cellulose-Filled Gel Electrolyte

Abstract

The flexible supercapacitors (SCs) of the conventional sandwich-type structure have poor flexibility due to the large thickness of the final entire device. Herein, we have fabricated a highly flexible asymmetric SC using manganese dioxide (MnO2) and reduced graphene oxide (RGO) nanosheet-piled hydrogel films and a novel bacterial cellulose (BC)-filled polyacrylic acid sodium salt-Na2SO4 (BC/PAAS-Na2SO4) neutral gel electrolyte. Apart from being environmentally friendly, this BC/PAAS-Na2SO4 gel electrolyte has high viscosity and a sticky property, which enables it to combine two electrodes together. Meanwhile, the intertangling of the filled BC in the gel electrolyte hinders the decrease of the viscosity with temperature, and forms a separator to prevent the two electrodes from short-circuiting. Using these materials, the total thickness of the fabricated device does not exceed 120 μm. This SC device demonstrates high flexibility, where bending and even rolling have no obvious effect on the electrochemical performance. In addition, owing to the asymmetric configuration, the cell voltage of this flexible SC has been extended to 1.8 V, and the energy density can reach up to 11.7 Wh kg−1 at the power density of 441 W kg−1. This SC also exhibits a good cycling stability, with a capacitance retention of 85.5% over 5000 cycles.

Pastes and hydrogels from carboxymethyl cellulose sodium salt as supporting electrolyte of solid electrochemical supercapacitors

“…For example, aerogels made of cellulose nanofibers, which were used as aqueous electrolyte nanoreservoirs, combined with graphene oxide or multi-walled carbon nanotubes electrodes displayed a SC of 207 or 178 F/g, respectively (Gao et al, 2013a;Gao et al, 2013b;). More recently, MnO 2 and reduced graphene oxide nanosheet-piled hydrogel electrodes were combined with bacterial cellulose-filled polyacrylic acid gel electrolyte, a SC of 27 F/g being obtained (Fei et al, 2017). In a very recent study (Jiao et al, 2018), a solid electrolyte made of nanofibrillated cellulose combined with polystyrene sulfonic acid, as proton transported polymer, was sandwiched between two paper-based electrodes, the resulting SC (81.3 F/g) being comparable to those achieved in this work.…”

Synthesis of a NiMoO4/3D-rGO Nanocomposite via Starch Medium Precipitation Method for Supercapacitor Performance

“…Generally, three types of electrode materials-carbon materials, metal oxide, and conducting polymers-have been used for supercapacitors [3]. However, transition metal oxides and hydroxides, such as NiO [4], Ni(OH) 2 [5][6][7], MnO 2 [8,9], MoO 3 [10], and Co 3 O 4 [11], are mostly employed as the supercapacitors material. These types of electrode materials are low cost and naturally abundant, with significant specific capacity based on redox reactions and high electrochemical activity [12].…”

An Overview of Bacterial Cellulose in Flexible Electrochemical Energy Storage

“…BC couldb ea lso used for the preparation of gel electrolytes, which was conducive to reducing the thickness of the separator and thus increasing the volumetric density. [32,33] By using rehydrated BC as the skeleton, aB Cg el polymer electrolyte (GPE) was successfully prepared through an environmental friendly approach by using the freeze-dried BC membrane to absorb the commercially available LIBsl iquid electrolyte (1.0 m LiPF 6 in 50:50 v/v EC/DMC). [33] Owing to factorsi ncluding the excellent mechanical properties and unique 3D nanofibrous structure of BC,t he as-prepared BC-GPE, with ah igh tensile strength of 39.06 MPa and high ionic conductivity of 4.04 10 À3 Scm À1 ,e xhibited ah igh initial capacity of 141.2 mAh g À1 (current density:0 .5 C) with no significant fading after 150 cycles in aLiFePO 4 /BC-GPE/Li battery.…”