To meet the power needs of soft and portable electronics, such as wearable and small-sized electronic devices, development of the flexible energy storage devices with high volumetric capacitance is urgent. In fact, electrode materials are an important component of high-performance energy storage devices. Herein, we develop a flexible and free-standing paper electrode with ultrahigh volumetric performance based on layered 2D Ti₃C₂T_x by first etching, then immersing in LiCl solution, and finally vacuum-assisted filtration. This paper electrode achieves a volumetric capacitance of 892 F cm⁻³, which is comparable to the best datum reported previously for Ti₃C₂T_x clay, and also exhibits excellent cyclic performance without capacitance loss after 10 000 cycles. The paper electrodes with ultrahigh volumetric capacitance, outstanding flexibility and stability demonstrate their potential applications as high-performance power sources in wearable and small-sized electronic devices.