Ozone‐Functionalized Carbon Nanotube Mat for Composite Structural Supercapacitor Electrodes and Structural Interleave

ABSTRACT Composite structural supercapacitors require good electrochemical and mechanical performance to complement current battery technology within future lightweight vehicle applications. Carbon nanotube (CNT) mat electrode materials are ideal, readily available candidates for developing mechanically robust devices. The current research has examined the treatment of the CNT mat electrodes using ozonolysis, to increase adhesion to the polymer matrix and enhance energy storage capacity. When the CNT mat is used as a ply interleave in a unidirectional carbon fiber composite, the oxygen functional groups on the CNT surface from 6 h of ozonolysis improved the interlaminar shear strength from 95 to 111 MPa. Supercapacitor coin cell studies showed that ozonolysis of the CNT mat for 22 h increased the electrode specific energy from 6.9 Wh kg ⁻¹ at 0.168 kW kg ⁻¹ to 19.2 Wh kg ⁻¹ at 0.121 kW kg ⁻¹ . Both of these enhanced characteristics are exploited when the CNT mat is integrated into conventional composite materials to produce localized structural supercapacitors. An unconventional method, whereby resin in the prepreg separator layer is replaced with ionic liquid prior to manufacture, enables a discrete ionogel region to form, creating the active electrochemical area. Samples sectioned near the active electrochemical region were used to assess the change in mechanical strength, with in situ electrochemical testing confirming the region exhibited an energy storage capability.