Realizing Formation and Decomposition of Li2O2 on Its Own Surface with a Highly Dispersed Catalyst for High Round-Trip Efficiency Li-O2 Batteries  Li-Na Song, Lian-Chun Zou, Xiao-Xue Wang, Nan Luo, Ji-Jing Xu, Ji-Hong Yu  iScience  Volume 14, Pages 36-46 (April 2019) DOI: 10.1016/j.isci.2019.03.013 Copyright © 2019 The Authors Terms and Conditions

iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions

Figure 1 Scheme for the Fabrication of RuNCs@RCC3 (A) Synthesis of the CC3R cage by a [4 + 6] cycloimination and the reduction of CC3R to RCC3 cage by NaBH4. (B) Schematic illustration of the encapsulation of Ru nanoclusters inside the RCC3 matrix using a reverse double-solvent approach. iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions

Figure 2 Morphological and Structural Characterization of RuNCs@RCC3 (A) FESEM image of RCC3. See also Figure S7. (B and C) Scanning electron microscopic (B) and TEM (C) images of RuNCs@RCC3. See also Figures S8 and S9. Scale bars, 1 μm in (A), 2 μm in (B) and 500 nm in (C). (D–F) FTIR patterns (D), PXRD patterns (E), and N2 adsorption-desorption isotherms (F) of RCC3 and RuNCs@RCC3. See also Figures S2 and S10. (G and H) Ru 3d XPS spectrum (G) and N 1s XPS spectrum (H) of the RuNCs@RCC3. (I) 1H NMR spectra of RCC3 and RuNCs@RCC3. See also Figure S4. iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions

Figure 3 Electrochemical Performance and Characterization of Discharged Products (A) First charge-discharge curves of lithium-oxygen (Li-O2) cells at a current density of 100 mA g−1, and a specific capacity limit of 500 mAh g−1. (B) Photographs of the pristine electrolyte (left), RuNCs@RCC3 (middle), and RuNPs/RCC3 (right) catalysts in CH2Cl2/TEGDME (v/v, 1/2) at different stages (Cm = 6.67 mg/mL). (C) An electrochemical mechanism for the aggregation of Li2O2 on the surface of the CNT with RuNCs@RCC3, versus without catalyst. (D and E) The rate capability (D) of the Li-O2 cells with three types of catalysts at different current densities. Galvanostatic discharge and recharge curves (E) of the Li-O2 cells with three kinds of catalysts at a current density of 100 mA g−1. See also Figures S12 and S13. (F and G) FESEM image of the discharged CNT cathode without catalyst (F) and with RuNCs@RCC3 (G) at a current density of 200 mA g−1 and a specific capacity of 2,000 mAh g−1. The inset of (G) represents the corresponding enlarged FESEM image. See also Figure S14. iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions

Figure 4 Cycle Stability and Characterization of Charged Products (A–C) FESEM images of the recharged CNT cathode with RuNCs@RCC3 at a current density of 200 mA g−1 and charge capacities of 500 (A), 1,000 (B), and 2,000 mAh g−1 (C). Insets in (A–C) show the corresponding enlarged FESEM images. (D) FESEM image of the recharged CNT cathode with RuNPs at a current density of 200 mA g−1 with a charge capacity of 1,000 mAh g−1. (E and F) Schematic of the Li2O2 oxidation mechanism in electrolyte with RuNCs@RCC3 (E) and without catalyst (F). (G) Variation of the terminal voltage upon the discharge of the Li-O2 cells at a current density of 200 mA g−1 and a specific capacity limit of 500 mAh g−1 with three types of catalysts. See also Figure S19. iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions

Figure 5 Cathode Morphology upon Cycling (A–F) FESEM images of the recharged CNT cathode without catalyst at a current density of 200 mA g−1 and a charge capacity of 1,000 mAh g−1 after the fifth recharging (A) and the 20th recharge (B). FESEM images of the recharged CNT cathode with RuNPs at a current density of 200 mA g−1 and a charge of 1,000 mAh g−1 after the fifth(C) and the 20th recharge (D). FESEM images of the recharged CNT cathode with RuNCs@RCC3 at a current density of 200 mA g−1 and a charge capacity of 1,000 mAh g−1 after the fifth recharge (E) and the 20th recharge (F). (G) 1H NMR spectra of the CNT cathodes without catalyst or with RuNCs@RCC3 after the fifth and 20th recharge. The spectra for TEGDME, HCO2Li, and CH2CO2Li are also shown for reference. See also Figure S20. iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions

Figure 6 The Morphology and Crystallinity of the Discharged Product upon Cycling (A–D) FESEM images of the fifth (A) and the 20th (B) discharged CNT cathodes without catalyst at a current density of 200 mAh g−1 and a specific capacity of 1,000 mAh g−1. FESEM images of the fifth (C) and the 20th (D) discharged CNT cathodes with RuNCs@RCC3 at a current density of 200 mA g−1 and a specific capacity of 1,000 mAh g−1. Insets in (C and D) show the corresponding enlarged FESEM images. (E and F) PXRD patterns of the discharge products on the CNT cathodes without catalyst (E) and with RuNCs@RCC3 (F). See also Figure S17. iScience 2019 14, 36-46DOI: (10.1016/j.isci.2019.03.013) Copyright © 2019 The Authors Terms and Conditions