Supercapacitors, emerging as energy storage devices, face challenges in practical applications due to their relatively low energy density. In this study, we fabricate a novelty supercapacitor cathode composed of Co9S8, conductive phosphorusdoped carbon (P–C), and layered double hydroxides (LDH). The incorporation of a conductive layer significantly enhances charge transfer, capacity, and electrochemical stability, ultimately elevating the electrochemical performance of the cathode. The fabricated Co9S8@ P–C@NiCo-LDH demonstrates an exceptional area-specific capacitance of 3.9 F cm− 2 at a current density of 2 mA cm− 2, along with remarkable cyclic stability, maintaining 98.9% of their capacity after 2000 cycles. The flexible asymmetric all-solid-state supercapacitor (AAS) assembled with Co9S8@ P–C@NiCo-LDH and activated carbon (AC) exhibits a remarkable energy density of 0.065 mWh cm− 2, corresponding to 325.0 W h kg− 1. Moreover, it maintains excellent cycling stability even at elevated current densities of 10 mA cm− 2. Following 5000 consecutive charge/discharge cycles, the AAS device maintains approximately 91.1% of its initial specific capacity. The AAS device successfully powered a 3V white LED for 5 min, further emphasizing its practicality.

Preparation and performance study of flexible all-solid-state Co9S8@P–C @ NiCo-LDH   AC asymmetric supercapacitors
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Materials
        2.2 Preparation of Co9S8@P–C
        2.3 Preparation of Co9S8@P–C@NiCo-LDH
        2.4 Preparation of the anode electrode
        2.5 Preparation of PVALiOH polymer gel electrolytes and the all-solid flexible capacitor
        2.6 Material measurements
        2.7 Electrochemical measurements
    3 Results and discussion
    4 Conclusion
    Acknowledgements 
    References

• Guanru Chang(School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, People’s Republic of China)
• Min Guo(School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, People’s Republic of China)
• Lei Wang(School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, People’s Republic of China)
• Kunzhen Li(School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, People’s Republic of China)
• Chang Zhu(School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, People’s Republic of China)
• Hui Zhang(School of Chemistry and Chemical Engineering, Huangshan University, Huangshan 245041, People’s Republic of China)