Coal-based hierarchical porous carbon for lithium/potassium storage

Carbon-based materials exhibit the advantages of low-operating voltages and non-toxicity and are thus considered promising anode components for potassium-ion batteries (PIBs) and lithium-ion batteries (LIBs). Herein, hydrothermal treatment and KOH activation combined with high-temperature carbonization were employed to fabricate hierarchical porous carbon, in which the low-cost coal as the carbon source. The proposed material shows rich microporous structures that facilitate Li+/K+ adsorption/desorption and promote capacitive contributions, thus improving the dynamics of the electrochemical reaction. CBC-700 (carbonized at 700 °C), as an LIB anode material, delivers a specific capacity of up to 844 mAh g−1, maintains 597 mAh g−1 under 1000 mA g−1 current density, and exhibits excellent capacity reversibility. When applied as a PIB anode material, the reversible specific capacity is preferable, with a value of 314 mAh g−1, and the specific capacity at 500 mA g−1 is 235 mAh g−1, apart from exhibiting excellent capacity reversibility. Significantly, it is highly expected that the coal-based carbon shows potential as an anode for the large-scale production of highly efficient LIBs and PIBs.