Dual-salt Assisted Strategy to Construct Soft-Hard Composite Porous Carbon for High-performance Potassium-ion Batteries

Non-graphitized carbons attract interest as anode materials for high performance batteries. Therefore, a 3D soft and hard carbon composite material with controlled pores via dual-salt assisted strategy was fabricated and applied to potassium ion batteries (PIBs). The eutectic salt plays an important role as template while inhibiting the graphitization of carbon. The obtained porous composite material has a connected pore structure and a large interlayer spacing, which is beneficial to the diffusion and insertion of potassium ions. The material exhibits considerable potassium storage performance in terms of high reversible capacity, excellent rate capability and long cycling stability. The storage mechanism of potassium has been also explored. The present study provides a new insight for the development of anode materials for potassium ion batteries. A 3D soft and hard carbon composite with controlled porous structure was fabricated via a dual-salt assisted strategy. Benefit from the particular structure, i.e., macropore characteristics, moderate SSA and number of defects, the obtained sample exhibits considerable potassium storage performance in terms of high reversible capacity (400.4 mAh g−1), excellent rate capability (114.9 mAh g−1 at 5 A g−1) and long cycling stability.