Abstract

The integrated supercapacitors can remarkably reduce the interface contact resistance and avoid the delamination of multi-layer structure, while the mechanically stiff supercapacitors show a wide application prospect in the energy devices. Wood has unique hierarchical porous structure and high mechanical strength with the advantages of abundance and renewability. Here, a novel integrated and mechanically stiff all-in-wood supercapacitor is constructed with lignosulfonate/polypyrrole (Lig/PPy) hydrogel embedded in wood by in-situ polymerization of pyrrole in both sides of wood piece in the Lig/Py solution. Benefiting from strong interaction between Lig and wood, and high pseudo-capacitance of Lig, as well as the hierarchical porous structure of wood with vertical channels, as-prepared integrated Lig/PPy-Wood based supercapacitor (LPWS_74−4h) displays a high areal capacitance of 1062 mF cm⁻², high energy density of 47.2 µWh cm⁻² and favorable cyclic performance. Meanwhile, the LPWS_74−4h also shows impressive mechanical stiffness with a maximum compressive strength of 71 MPa. Particularly, LPWS_74−4h can maintain good electrochemical performance even if it is crushed into cake shape under high pressure (over 71 MPa). It is expected that such integrated and mechanically stiff all-in-wood supercapacitors with superior electrochemical performance to be a promising candidate for the next generation green and structural energy devices.

Graphic abstract

The integrated all-in-wood supercapacitors perfectly combine the conductive porous structure of Lig/PPy hydrogel with superior electrochemical performance and the unique hierarchical porous structure of wood with vertical channels. Impressive mechanical stiffness and superior electrochemical performance have been achieved.