Synthesis of cryptomelane type α-MnO2(KxMn8O16) cathode materials with tunable K+content: the role of tunnel cation concentration on electrochemistry

Poyraz, Altuğ S.; Huang, Jianping; Pelliccione, Christopher J.; Tong, Xiao; Cheng, Shaobo; Wu, Lijun; Zhu, Yimei; Marschilok, Amy C.; Takeuchi, Kenneth J.; Takeuchi, Esther S.

doi:10.1039/c7ta03476h

Cited by 101 publications

(112 citation statements)

References 76 publications

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“…37 However, the effect of tunnel cations on MnO 2 electrochemistry is still debated since lowering the stabilizing ion concentration has also been reported by another group to improve the battery performance of MnO 2 nanostructures. 38 Factors causing such seemingly inconsistent results could be that different methods of cation control and different characterization methods that result in various cation concentration ranges have been used in these associated studies. However, the above-mentioned complication in clarifying the role of tunnel cations makes this material system exceptionally interesting, and we believe more intensive work focusing on reliable cation control and compositional characterization should be devoted in the future to revealing the underlying mechanisms.…”

Section: Moving Toward Tunnel Homogeneitymentioning

confidence: 99%

Ordering Heterogeneity of [MnO6] Octahedra in Tunnel-Structured MnO2 and Its Influence on Ion Storage

Yuan

Liu

Byles

et al. 2019

Joule

150

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Correctly establishing a structure-property relationship is necessary to rationally develop energy materials for performance optimization. Bulk characterizations fall short of deciphering localized structural features at nanoscale and atomic scale. This work atomically resolves structural heterogeneity existing in single MnO 2 nanoparticles and demonstrates its significant effect on energy storage property, which was neglected by traditional bulk characterizations. Attention should thus be paid to controllable synthesis toward structural homogeneity with predictable/ tunable energy storage property and the proper choice of structural characterization tools. SUMMARY[MnO 6 ] octahedra are the structural units for a large family of manganese dioxides (MnO 2 ) possessing one-dimensional tunnel structures with extensive applications in catalysis and energy storage. Despite the long-range [MnO 6 ] ordering confirmed by conventional diffraction tools, surprisingly, the functional properties of a specific MnO 2 tunnel phase still vary significantly in literature with unclear structural origins. Here, we demonstrate the existence of tunnel heterogeneity featuring localized tunnel intergrowths within single MnO 2 nanoparticles via atomically resolved imaging. The degree of tunnel heterogeneity increases with the size increase of tunnels from b-MnO 2 (1 3 1 tunnel) to a-MnO 2 (2 3 2 tunnel), and to todorokite MnO 2 (3 3 3 tunnel). Furthermore, the tunnel heterogeneity within one MnO 2 nanoparticle significantly affects the energy storage kinetics even down to sub-nanometer scale. These findings are expected to call for renewed attention to the controlled synthesis of homogeneous tunnel-specific phases with predictable properties and to yield a more precise structure-property relationship in polymorphic materials.

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Section: Moving Toward Tunnel Homogeneitymentioning

confidence: 99%

Ordering Heterogeneity of [MnO6] Octahedra in Tunnel-Structured MnO2 and Its Influence on Ion Storage

Yuan

Liu

Byles

et al. 2019

Joule

150

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“…2). Poyraz et al [46] reported that the KxMn8O16 samples with low K + content, K0.32Mn8O16, have a lower decomposition temperature of 510 °C compared to T=580 °C for the samples with high K + content (K0.75Mn8O16). Fig.…”

Section: Elemental and Structural Studiesmentioning

confidence: 99%

“…We pay a special attention to characterize the crystal chemistry of α-type MnO2 prepared from redox reaction of potassium permanganate, which always contains a residual fraction of K + ions in the 2×2 tunnels preserving the structural stability of this material. Note that most of numerous works published in the literature neglect this aspect; only few papers consider the presence of potassium in the cryptomelane framework [44][45][46][47][48][49][50][51]. Two samples were prepared using a redox synthesis…”

Section: Introductionmentioning

confidence: 99%

Electrochemical performance of nanosized MnO2 synthesized by redox route using biological reducing agents

Abuzeid

Hashem

Kaus

et al. 2018

Journal of Alloys and Compounds

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For more than a century, manganese dioxides (MDOs) have been used as electrochemically active materials in energy storage and conversion applications. To reduce the cost and hazardous impact of synthesis, a redox method was used to prepare MnO2 using extracts of green (GT-MnO2) and black (BT-MnO2) tea as biological reducing agents. Polyphenols present in the extracts of tea not only reduce Mn 7+ ions but also act as "capping agents" to stabilize and prevent the produced MnO2 nanoparticles from degradation and aggregation. Elemental, structural properties and morphology of nanosized α-KxMnO2 were studied by thermogravimetric analysis, X-ray powder diffraction and Raman spectroscopy, which revealed the different crystallinity between GT-MnO2 and BT-MnO2 due to the strength of the antioxidant species. Electrochemical investigations highlight the beneficial presence of K + ions in (2×2) tunnels; with a higher concentration, α-K0.135MnO2 exhibits a discharge specific capacity of 155 mAh g-1 after 20 cycles at C/26 rate.

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“…Cryptomelane-type KMn 8 O 16 was synthesized by a modified hydrothermal method (Poyraz et al, 2017). The typical preparation procedure is as follows, 6 mmol of MnSO 4 ·H 2 O and 12 mmol of (NH 4 ) 2 SO 4 and 12 mmol K 2 SO 4 were dissolved in 50 mL of 6 mmol (NH 4 ) 2 S 2 O 8 solution.…”

Section: Methodsmentioning

confidence: 99%

“…One dimensional (1D) tunnel structured cryptomelane type manganese dioxides, Mn 8 O 16 (α-MnO 2 ) as the cathode materials have been received extensive concerns, as they can reversibly host various cations including Li + and K + and so on, of which K x Mn 8 O 16 was previously reported in the fields of catalysis and lithium ion battery (Poyraz et al, 2017). Herein, this study aims to establish the aqueous hybrid battery based on cheap intercalated potassium compound KMn 8 O 16 as the cathode material and zinc as the anode.…”

Section: Introductionmentioning

confidence: 99%

Cryptomelane-Type KMn8O16 as Potential Cathode Material — for Aqueous Zinc Ion Battery

Cui

Yang

et al. 2018

Front. Chem.

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Aqueous battery has been gained much more interest for large-scale energy storage fields due to its excellent safety, high power density and low cost. Cryptomelane-type KMn8O16 confirmed by X-ray diffraction (XRD) was successfully synthesized by a modified hydrothermal method, followed by annealed at 400°C for 3 h. The morphology and microstructure of as-prepared KMn8O16 investigated by field-emission scanning electron microscopy (FE-SEM) with the energy spectrum analysis (EDS) and transmission electron microscopy (TEM) demonstrate that one-dimensional nano rods with the length of about 500 nm constitute the microspheres with the diameter about 0.5~2 μm. The cyclic voltammetry measurement displays that the abundant intercalation of zinc ions on the cathode takes place during the initial discharge process, indicating that cryptomelane-type KMn8O16 can be used as the potential cathode material for aqueous zinc ion batteries. The electrode shows a good cycling performance with a reversible capacity of up to 77.0 mAh/g even after 100 cycles and a small self-discharge phenomenon.

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Synthesis of cryptomelane type α-MnO₂(K_xMn₈O₁₆) cathode materials with tunable K⁺content: the role of tunnel cation concentration on electrochemistry

Abstract: Here, we synthesized a series of α-MnO2 samples with differing K+ content but similar physical properties allowing direct study of the role of tunnel K+ on the electrochemistry of α-MnO2 cathodes.

Cited by 101 publications

References 76 publications

Ordering Heterogeneity of [MnO6] Octahedra in Tunnel-Structured MnO2 and Its Influence on Ion Storage

Ordering Heterogeneity of [MnO6] Octahedra in Tunnel-Structured MnO2 and Its Influence on Ion Storage

Electrochemical performance of nanosized MnO2 synthesized by redox route using biological reducing agents

Cryptomelane-Type KMn8O16 as Potential Cathode Material — for Aqueous Zinc Ion Battery

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