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

Abstract

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.