Critical Role of Aromatic C(sp²)-H in Boosting Lithium-Ion Storage

Exploring high-sloping-capacity carbons is of great significance in the development of high-power lithium-ion batteries/capacitors (LIBs/LICs). Herein, an ion-catalyzed self-template method is utilized to synthesize the hydrogen-rich carbon nanoribbon (HCNR), achieving high specific and rate capacity (1144.2/471.8 mAh g^-1 at 0.1/2.5 A g^-1). The Li⁺ storage mechanism of the HCNR is elucidated by in situ spectroscopic techniques. Intriguingly, the protonated aromatic sp²-hybridized carbon (C(sp²)-H) can provide additional active sites for Li⁺ uptake via reversible rehybridization to sp³-C, which is the origin of the high sloping capacity. The presence of this sloping feature suggests a highly capacitance-dominated storage process, characterized by rapid kinetics that facilitates superior rate performance. For practical usage, the HCNR-based LIC device can deliver high energy/power densities of 198.3 Wh kg^-1/17.9 kW kg^-1. This work offers mechanistic insights on the crucial role of aromatic C(sp²)-H in boosting Li⁺ storage and opens up new avenues to develop such sloping-type carbons for high-performance rechargeable batteries/capacitors.