Metallic layered germanium phosphide GeP5 for high rate flexible all-solid-state supercapacitors

In this study, high quality GeP5 crystals with two-dimensional (2D) layered structures and novel electrical conductivity of 2.4 × 106 S m−1 have been prepared under high-temperature high-pressure oriented growth technique (HTHP-OGT). The as-synthesized GeP5 nanoflakes, after liquid phase exfoliation, show promising potential for application as electrode materials in all-solid-state supercapacitors (ASSPs). The as-prepared GeP5-ASSP exhibits excellent electrochemical performances, including an ultrahigh scan rate of 1000 V s−1, a high specific capacitance of up to 35.86 F cm−3 at 5 mV s−1, a great power density of 397.24 W cm−3 and an energy density of 4.98 mW h cm−3. Moreover, the device can retain 83.7% and 88% of the initial capacitance retention at 180° bending and after 10 000 cycles, respectively, showing outstanding flexibility and superior cycling stability. These properties indicate the promising application of the metallic layered GeP5 for flexible energy storage devices.