Uniformly confined V 2 O 3 quantum dots embedded in biomass derived mesoporous carbon toward fast and stable energy storage

Rational composition and structural design of electrode substances are critical for lithium-ion batteries (LIBs) and supercapacitors (SCs) with good cycling steadiness and superb rate capability. Therefore, we report a novel electrode material consisting of V 2 O 3 quantum dots (QDs, about 6.64 nm) well-distributed on mesoporous carbon (MC) nanosheets. V 2 O 3 has high intrinsic conductivity and an open tunnel-like lattice structure, facilitating electron transfer and ion intercalation. The composite architectures can offer more electrochemical active sites, shorten ion/electron diffusion paths, and reduce volume swings during the charging/discharging process. The synergic effect of these merits significantly improves the reaction kinetics and prevents structural damage to the entire electrode. As a result, V 2 O 3 -QDs/MC nanosheets exhibit a large capacity/capacitance, excellent cycling steadiness, and high rate performance. For LIBs, V 2 O 3 -QDs/MC displays a great reversible capacity of 931 mAh g −1 at 0.2 A g −1 over 500 cycles and fast and stable lithium storage behaviors with 822 mAh g −1 at 2 A g −1 after 1000 cycles. For SCs, V 2 O 3 -QDs/MC manifests a considerable specific capacitance of 270 F g −1 at 1 A g −1 and satisfactory durability for at least 5000 cycles at 10 A g −1. This work informs a good structure design for constructing advanced metal oxide-based nanostructured electrode materials.