Ni quantum dot-embedded and N-doped biomass-derived porous carbon as an efficient sulfur host for lithium–sulfur batteries
摘要
Biomass-derived carbon materials attract much attention due to their unique structure and renewable sources. Here, a novel three-dimensional (3D) interconnected N-doped porous carbon embedded with nickel quantum dots is synthesized by a combined freezing dry-activation strategy from waste pomelo peel. The activation temperature significantly affects the microstructure of biomass-derived carbon. Appropriately increasing temperature is beneficial for obtaining higher specific surface area/pore volume and larger pore size, but excessively high activation temperature will lead to microstructural collapse. The optimized porous carbon possesses high specific surface area (2042 m2 g−1) and pore volume (1.41 cm3 g−1) with high mesopore/micropore volume ratio (2.36). Both the uniformly distributed Ni quantum dots (3–5 nm) and the N doping facilitate to significantly improve the electron conductivity and polysulfide-adsorption ability. Furthermore, it benefits the conversion reaction of lithium polysulfides and retards the shuttle effect. As a result of these synergistic features, the pomelo peel-derived porous carbon displays a high initial discharge capacity (1316.5 mAh g−1 at 0.1 C), excellent rate capability of 550 mAh g−1 at 3 C, as well as good long-time cycling stability (372 mAh g−1 after 1000 cycles at 1 C, with a low-capacity decay rate of only 0.06% per cycle). This Ni quantum dot-modified carbon host with excellent electrochemical performance exhibits great potential for low-cost energy storage devices based on renewable biomass waste.
Graphical abstract