Controlled synthesis of MnO2 nanoparticles for aqueous battery cathodes: polymorphism–capacity correlation
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Polymorphs of MnO2 are known to have different electrochemical activity, with gamma (γ) and akhtenskite (ε) polymorphs often considered as the most active phases for aqueous battery cathodes. However, most synthetic samples contain a mixture of polymorph phases, which makes understanding of the structure-property correlations more complicated. In this paper, we report on a systematic study that correlates synthesis parameters with the morphology, phase composition and reversible storage capacity of the resulting nanoparticles. Rietveld analysis of X-ray powder diffraction patterns was used to accurately describe fractional composition of multi-phase nanoparticles. It was demonstrated that through control of the synthesis parameters desired phase compositions and nanoparticle morphologies can be achieved. The key synthesis parameters were found to be the concentration of Mn2+ precursor which strongly affects both the morphology and the crystalline structure of the products, and the time of reaction. The presence of surfactant only impacts the crystalline phase composition of the MnO2 nanoparticles and has insignificant effect on the morphology. It was also demonstrated that nanoparticles with higher fraction of the akhtenskite polymorph show higher reversible capacities in LiOH electrolyte (~210 mAh/g) compared to other MnO2 phase compositions (~120 mAh/g).
KeywordsSodium Dodecyl Sulfate MnO2 Rietveld Refinement Pyrolusite Ostwald Ripening
We thank Dr. James Kaduk for helpful discussions on XRD analysis. This research was funded by US Department of Energy, Advanced Research Funding Agency—Energy (ARPA-E) (award #AR000387). Use of the Argonne National Laboratory, Center for Nanoscale Materials and Electron Microscopy Center are supported by the US Department of Energy, under Contract No. DE-AC02- 06CH11357.
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Conflict of interest
The authors declare that they have no conflict of interest.
- 7.Linden D, Reddy T (2002) Handbook of batteries. McGraw-Hill, New YorkGoogle Scholar
- 10.Wolfenstine J, Foster D, Behl W, Gilman S (1998) Gas evolution and self-discharge in Li/MnO2 primary batteries. Army Research Laboratory, AdelphiGoogle Scholar
- 12.Hill LI, Verbaere A, Guyomard D (2002) Synthesis of alpha-, beta-, and low defect gamma-manganese dioxides using the electrochemical-hydrothermal method and study of their Li insertion behavior. J New Mater Electrochem Syst 5(2):129–134Google Scholar
- 13.Vodyanitskii YN (2004) Formation of manganese oxides in soils. Eurasian Soil Sci C/C Pochvovedenie 37(6):572–584Google Scholar
- 19.Liu X, Chen C, Zhao Y, Jia B (2013) A review on the synthesis of manganese oxide nanomaterials and their applications on lithium-ion batteries. J Nanomater 2013:1–7Google Scholar
- 33.Wang EI, Lin L, Bowden WL (1996) Electrochemical cell comprising gamma MnO2 cathode having filamentary protrusions. J Power Sources 63(2):294Google Scholar
- 35.Larson AC, Von Dreele RB (2000) General structure analysis system (GSAS); Report LAUR 86-748. Los Alamos, NM, Los Alamos National LaboratoryGoogle Scholar
- 37.Karlsruhe F. ICSD https://icsd.fiz-karlsruhe.de/search/index.xhtml. Accessed 21 Oct 2016