Preparation and electrochemical performance of potassium intercalated K2MnS2

In this study, potassium-intercalated manganese sulfide (K2MnS2) is prepared on nickel foam (NF) using the electrochemical deposition method successfully by directly introducing potassium ions into manganese sulfide (MnS2). The electrochemical behavior of K2MnS2 involving the release and insertion of potassium-ion during charging and charging in 1 M KOH electrolyte, differs substantially from the reaction mechanism of MnS2. Comparative analysis of the electrochemical performance of K2MnS2/NF and MnS2/NF electrode materials is conducted in 1 M LiOH, 1 M NaOH and 1 M KOH electrolytes. The results indicate that K2MnS2/NF exhibits a higher mass specific capacitance than MnS2/NF in 1 M KOH electrolyte, confirming the effectiveness of potassium ion-embedding and disembedding. Furthermore, an asymmetric aqueous supercapacitor is assembled using K2MnS2/NF as the positive electrode and graphene (G)/NF as the negative electrode. The aqueous supercapacitor demonstrates a notable energy density of 22.0 Wh kg−1 at a power density of 2.7 kW kg−1, coupled with excellent cycling performance (159.3 % over 5, 000 cycles). The synthesis of K2MnS2 holds significant implications for the development of potassium-ion supercapacitors with enhanced energy densities.