In-situ Synthesis of Mixed-valence Manganese Oxide@S, P Self-codoped Carbon@Reduced Graphene Oxide Composites by Enhanced Surface Interaction for High-Performance all-solid-state Supercapacitors

By enhancing surface interaction between metal oxide particles and carbon-based materials,it can effectively improve Faraday capacitance and conductivity, ultimately achieving high energy density with sufficient redox reactions in supercapacitors. Through a gentle biomineralization process and subsequent thermal reduction strategy, we successfully prepared the graphene oxide (GO) wrapping mixed-valence manganese oxides (MnO x ) and S, P self-codoped carbon matrix porous composite (MnOx@SPC@reduced graphene oxide (RGO)).During the biomineralization process of engineered Pseudomonas sp. (M1) cells, GO nanosheets functioned as the ‘soil’ to adsorb Mn 2+ ion and uniformly disperse biogenic Mn oxides (BMO). After undergoing annealing, the MnOx nanoparticles were evenly wrapped with graphene, resulting in the creation of the MnO x @SPC@RGO3 composite. This composite possesses strong C—O—Mn bond interfaces, numerous electroactive sites, and a uniform pore structure. By optimizing the synergistic interaction between the highly conductive graphene and the remarkable surface capacitance of MnO x , the MnO x @SPC@RGO3 electrode, with its intercalation Faraday reactions mechanism of Mn 2+ ↔ Mn 3+ and Mn 3+ ↔ Mn 4+ transformations, exhibits an outstanding specific capacity (448.3 F g −1 at 0.5 A g −1 ), multiplying performance (340.5 F g −1 at 10 A g −1 ), and cycling stability (93.8% retention after 5000 cycles).Moreover, the asymmetric all-solid-state supercapacitors of MnO x @SPC@RGO3//PC exhibit an exceptional energy density of 64.8 W·h kg −1 and power density of 350 W kg −1 , as well as a long lifespan with capacitance retention of 92.5 % after 10000 cycles. In conclusion, the synthetic route utilizing biomineralization and thermal reduction exhibits significant potential for exploiting high-performance electrode materials in all-solid-state supercapacitor applications.