Self-templated synthesis of hollow hierarchical porous olive-like carbon toward universal high-performance alkali (Li, Na, K)-ion storage

Alkali (Li, Na, K)-ion batteries have attracted tremendous attention in current power supply systems. However, it remains a great challenge to explore universal anodes for the desired de-/intercalation of these three alkali-metal ions (Li+, Na+, K+). Herein, hollow hierarchical porous olive-like carbon (HHPOC) structure is prepared through a self-templated strategy and post acid-etching treatment. The unique hollow hierarchical porous structure can facilitate the electrolyte penetration, shorten the transport pathway of ions, and endure well the volume change during the insertion/extraction of alkali ions. Meanwhile, the abundant self-doped N/O heteroatoms provide sufficient active sites for Li+/Na+/K+ storage, thereby resulting in a capacitive-dominating storage mechanism for the HHPOC electrode especially in sodium/potassium ion batteries. The HHPOC electrode delivers high reversible discharge capacity of 1121.8 mA h g−1 at 0.1 A g−1 for lithium-ion battery, 386.8 mA h g−1 at 0.1 A g−1 for sodium-ion battery, and 305.6 mA h g−1 at 0.1 A g−1 for potassium-ion battery. Moreover, the HHPOC electrode exhibits promising cycling stability with negligible capacity decay over 800 cycles at 1 A g−1 for the three alkali-ion batteries. Therefore, this work provides a new perspective for the development of universal carbon anodes with efficient Li+/Na+/K+ storage and the delicate structural design of biomass carbon materials.