Controlling the internal microstructure and overall morphology of building blocks used to form hybrid materials is crucial for the realization of deterministically designed architectures with desirable properties. Here, integrative spray-frozen (SF) assembly is demonstrated for forming hierarchically structured open-porous microspheres (hpMSs) composed of Fe3O4 and reduced graphene oxide (rGO). The SF process drives the formation of a radially aligned microstructure within the sprayed colloidal droplets and also controls the overall microsphere morphology. The spherical Fe3O4/rGO hpMSs contain interconnected open pores, which, when used as a lithium-ion battery anode, enables them to provide gravimetric and volumetric capacities of 1069.7 mAh g−1 and 686.7 mAh cm−3, much greater than those of samples with similar composition and different morphologies. The hpMSs have good rate and cycling performance, retaining 78.5% capacity from 100 to 1000 mA g−1 and 74.6% capacity over 300 cycles. Using in situ synchrotron X-ray absorption spectroscopy, the reaction pathway and phase evolution of the hpMSs are monitored enabling observation of the very small domain size and highly disordered nature of FexOy. The reduced capacity fade relative to other conversion systems is due to the good electrical contact between the pulverized FexOy particles and rGO, the overall structural integrity of the hpMSs, and the interconnected open porosity.
|Journal||Advanced Energy Materials|
|Publication status||Published - 2019 Feb 7|
Bibliographical noteFunding Information:
S.Y. and S.-M.B. contributed equally to this work. This work was supported by both the National Research Foundation (NRF) funded by the Ministry of Science, ICT and Future Planning (No. 2018M3D1A1058624 [Creative Materials Discovery Program]) and the R&D Convergence Program (CAP-15-02-KBSI) of the National Research Council of Science & Technology, Republic of Korea. This work was technically supported by the Korea Basic Science Institute. The work done at the Brookhaven National Lab was supported by the U.S. Department of Energy, the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, through the Advanced Battery Materials Research (BMR) Program, under Contract No. DE-SC0012704. The work done at the University of Illinois at Urbana-Champaign was supported by the National Science Foundation Engineering Research Center for Power Optimization of Electro Thermal Systems (POETS) with cooperative agreement EEC-1449548.
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
All Science Journal Classification (ASJC) codes
- Renewable Energy, Sustainability and the Environment
- Materials Science(all)