Biomass‐Derived Carbon Materials as Prospective Electrodes for High‐Energy Lithium‐ and Sodium‐Ion Capacitors

Biomass-derived carbon materials have received special attention as efficient, low-cost, active materials for charge-storage devices, regardless of the power system, such as supercapacitors and rechargeable batteries. In this Minireview, we discuss the influence of biomass-derived carbonaceous materials as positive or negative electrodes (or both) in high-energy hybrid lithium-ion configurations with an organic electrolyte. In such hybrid configurations, the electrochemical activity is completely different to conventional electrical double-layer capacitors; that is, one of the electrodes undergoes a Faradaic reaction, whilst the counter electrode undergoes a non-Faradaic reaction, to achieve high energy density. The use of a variety of biomass precursors with different properties, such as surface functionality, the presence of inherent heteroatoms, tailored meso-/microporosity, high specific surface area, various degrees of crystallization, calcination temperature, and atmosphere, are described in detail. Sodium-ion capacitors are also discussed, because they are an important alternative to lithium-ion capacitors, owing to the low abundance and high cost of lithium. The electrochemical performance of carbonaceous electrodes in supercapacitors and rechargeable batteries are not discussed.