Boosting K+ capacitive storage in dual-doped carbon crumples with B-N moiety via a general protic-salt synthetic strategy

Abstract

The heteroatom co-doped carbonaceous anodes have readily attracted great attention in potassium-ion batteries (PIBs), owing to their augmented carbon interlayer distances and increased K+ storage sites to induce enhanced capacity value. Nevertheless, the synergistic effect of dual-doped heteroatoms is still unclear and lacks systematic explorations. In addition, traditional synthetic routes are cumbersome with template removal step, which are normally deficient in product scalability. Herein, a generic protic-salt strategy is devised to realize sulfur-, phosphorus- or boron-nitrogen dual-doped carbon (SNC, PNC, or BNC) via varying the types of protic precursors (e.g., the acid). Throughout comprehensive instrumental probing and theoretical simulation, it is identified that the presence of B-N moiety can harvest high adsorption capability of K+ and hence exhibit more obvious pseudo-capacitance behavior than bare N-doped carbon counterpart. As a PIB anode, the BNC electrode displays an impressive reversible capacity (360.5 mAh g(-1) at 0.1 A g(-1)) and cycle stability (125.4 mAh g(-1) at 1 A g(-1) after 3000 cycles). In situ/ex situ characterizations further reveal the origin of the excellent electrochemical properties of the BNC electrode. Such a tailorable protic-salt derived anode material offers new possibilities to advance PIB devices.