Optimized TiO Subcompounds and Elastic Expanded MXene Interlayers Boost Quick Sodium Storage Performance

Abstract

To develop quick‐charge sodium‐ion battery, it is significant to optimize insertion‐type anode to afford fast Na+ diffusion rate and excellent electron conductivity. First‐principles calculations reveal the TiO subcompound superiority for Na+ diffusion following Ti(II)O > Ti(III)O > Ti(IV)O. Hence, in situ growth of amorphous TiO subcompounds with rich oxygen defects based on Ti3C2Tx‐MXene is developed. Meanwhile, the composite presents expanded MXene interlayer spacing and much enhanced conductivity. The synergistic effect of enhanced electron/ion conduction gives a high capacity of 107 mAh g−1 at 50 A g−1, which gives 50% and 150% increasements compared with one counterpart without valence adjustment and another one without MXene expansion. It only needs 20 s (at 30 A g−1) to complete the discharge/charge process and obtains a capacity of 144.5 mAh g−1, which also shows a long‐term cycling stability at quick‐charge mode (121 mAh g−1 after 10000 cycles at 10 A g−1). The enhanced performance comes from fast electron transfer among TiO subcompounds contributed by rich‐defect amorphous TiO2–x, and a reversible change of elastic MXene with interlayer spacing between 1.4 and 1.9 nm during Na+ insertion/extraction process. This study provides a feasible route to boost the kinetics and develop quick‐charge sodium‐ion battery.

Modulation of physical and chemical connections between SiOx and carbon for high-performance lithium-ion batteries

“…Additionally, a broad diffraction peak around 22.3° was indexed to the amorphous SiO x [25] in SiO x /C. Raman spectra shown in Supplementary Figure 3 confirmed the low crystallinity SiO x with a broad peak at 459 cm -1 [26] , consistent with XRD data. The presence of carbonaceous materials in the three previously mentioned samples was confirmed by D and G bands at approximately 1,324 and 1,564 cm -1 , respectively, [Figure 2B].…”

A Universal Approach for Sustainable Urea Synthesis via Intermediate Assembly at the Electrode/Electrolyte Interface

“…The scanning electron microscopy (SEM) images in Figure S1 confirmed the successful fabrication of TiO 2 with a nanosheet morphology. Additionally, the lattice distance of 0.347 nm observed in the high-resolution transmission electron microscopy (HR-TEM) image (Figure S2) corresponds to the (101) planes of anatase TiO 2 , [15] which is further supported by the X-ray diffraction (XRD) pattern in Figure S3.…”

“…The potential of electrocatalytic CÀ N coupling in the synthesis of isotope-labelled urea under ambient conditions was also demonstrated. The results of further quantitative analysis showed that the urea production rates obtained using 14 N and 15 N as nitrogen sources were almost the same, indicating that the urease decomposition method and the NMR method were reliable for quantitative analysis of urea products (Figure S26). The contrast experiment results confirmed that urea products came from the co-electrolysis process (Figure S27).…”

“…In the spectra shown in Figure S22 and S23, the CO( 14 NH 2 ) 2 and the isotope-labelled CO( 15 NH 2 ) 2 can be distinguished based on the single broad peak at around 5.68 ppm and the double peak at around 5.60 ppm and � 5.75 ppm, respectively. [1a] Co-electrolysis experiments were conducted with 14 NO 3 À and 15 NO 3 À as nitrogen sources respectively, and the NMR measurement results suggested that the nitrogen atoms in urea products were indeed derived from nitrate feedstock (Figure S24 and S25). The potential of electrocatalytic CÀ N coupling in the synthesis of isotope-labelled urea under ambient conditions was also demonstrated.…”