Highly Conductive Carbon Nanotube‐Graphene Hybrid Yarn

Abstract

An effi cient procedure for the fabrication of highly conductive carbon nanotube/ graphene hybrid yarns has been developed. To start, arrays of vertically aligned multi-walled carbon nanotubes (MWNT) are converted into indefi nitely long MWNT sheets by drawing. Graphene fl akes are then deposited onto the MWNT sheets by electrospinning to form a composite structure that is transformed into yarn fi laments by twisting. The process is scalable for yarn fabrication on an industrial scale. Prepared materials are characterized by electron microscopy, electrical, mechanical, and electrochemical measurements. It is found that the electrical conductivity of the composite MWNT-graphene yarns is over 900 S/cm. This value is 400% and 1250% higher than electrical conductivity of pristine MWNT yarns or graphene paper, respectively. The increase in conductivity is asssociated with the increase of the density of states near the Fermi level by a factor of 100 and a decrease in the hopping distance by an order of magnitude induced by grapene fl akes. It is found also that the MWNT-graphene yarn has a strong electrochemical response with specifi c capacitance in excess of 111 Fg −1 . This value is 425% higher than the capacitance of pristine MWNT yarn. Such substantial improvements of key properties of the hybrid material can be associated with the synergy of MWNT and graphene layers in the yarn structure. Prepared hybrid yarns can benefi t such applications as high-performance supercapacitors, batteries, high current capable cables, and artifi cial muscles.

Fast and Reversible Actuation of Metallic Muscles Composed of Nickel Nanowire‐Forest

“…[23,24] These experiments show that mechanical resonances as well as hydrodynamic drag affect the bending amplitude and higher frequencies. In addition, at −0.1 to 0.3 V, the Nyquist plot shows sharp increase of −Z″ with Z′ (Figure 3c), which is close to the behavior of pure capacitors (corresponding to vertical lines of the −Z″ against Z′ plot), indicating the capacitive-double-layer-charging process, [25] which correspond to the linear increase [2] of strain versus potential at the low potential regime observed in Figure 3a.…”

Ternary composite solid-state flexible supercapacitor based on nanocarbons/manganese dioxide/PEDOT:PSS fibres

“…The introduction of other nanostructured carbons (ordered mesoporous carbons, graphenes) into CNT fibres combines the advantages of both materials [10]. Examples of fibres made from different carbons include a reduced graphene oxide (rGO)/CNT fibre [11], hybrid CNT/ ordered mesoporous carbon fibre [10] and CNT/graphene yarn [12] to mention but a few. On the other hand, combining pseudocapacitive materials such as transition metal oxides or conducting polymers with nanostructured carbons results in excellent supercapacitors due to the synergistic effects of increased electrical conductivity and specific capacitance [13].…”

Flexible Electrodes and Electrolytes for Energy Storage

“…All lead to improved electrochemical properties. These functional materials can be deposited on CNTs membrane via filtration [ 110 , 111 ], in situ polymerization [ 112 ], and even electrospinning [113].…”