Hollow carbon nanocages toward long cycle lifespan lithium/sodium-ion half/full batteries

Richly electron-deficient BCxO3−x anodes with enhanced reaction kinetics for sodium/potassium-ion batteries

“…Compared with the CNC anode (Table S5, ESI †), the BCNC anode displays a much lower charger transfer resistance (R ct ) of 181.9 O, which decreases to 172.2 O even after 1000 cycles, because B-doping makes carbon nanocages electron deficient and results in large charge transfer from Na to the carbon substrate. 4,50,62 Remarkably, the Na storage of BCNCs outperforms those of some other SIB anodes reported so far in the literature (ESI, † Table S6 and Fig. 4g).…”

“…The hollow cage-like morphologies with thin shells could effectively reduce the ion diffusion length in the solid phase, thus achieving better electrochemical kinetics to ensure excellent rate performance. 40,49,50 The elemental mapping images of BCNCs (Fig. 1i-l) suggest the presence and uniform distributions of C, B, and O elements in the nanocages, confirming that boron elements have been successfully incorporated into the carbon nanocage structure.…”

“…The hierarchically mesoporous structure of BCNCs can buffer the volume variation during discharge/ charge cycles, stabilizing the Na-ion transfer, and accommodating the charge in the electrochemical reaction zones. 41,50 The FT-IR spectra of Fig. 2e show that the B-O binding in the edge of BCNCs was detected at 883.7 cm À1 , originating from the BC x O 3Àx structures.…”

“…Both anodes exhibit excellent cycling stability, implying that the cage-like nanostructure with plentiful mesopores has robust structural stability and could relieve the volume variation upon cycles. 50 Notably, the BCNC anode exhibits a much larger reversible capacity than that of CNCs, suggesting that B-doping could effectively activate the inert electronic structure in the carbon skeleton due to the electron-deficient nature of boron atoms, resulting in remarkable charge transfer between sodium and the substrate, thus improving the Na + storage capability. 26,29,34 From Fig.…”

“…[44][45][46][47][48] Song et al 49 designed hollow carbon nanocages as the anodes for PIBs, demonstrating excellent cyclability due to the strain relaxation of a hollow cage-like structure during K + insertion/extraction. Recently, Huang et al 50 reported a series of hollow carbon nanocages towards long cycle lifespan SIBs, which exhibit excellent rate performance. Accordingly, integrating the merits of the architectural and electron structure design, hollow carbon nanocages with enriched electron deficiencies are more desirable as an anode for high-performance SIBs and PIBs.…”