Rechargeable Zn-ion batteries with high power and energy densities: a two-electron reaction pathway in birnessite MnO<sub>2</sub> cathode materials

Li, Guanzhou; Huang, Zongxiong; Chen, Jinbiao; Fu, Yao; Liu, Jianping; Li, Oi Lun; Sun, Shuhui; Shi, Zhicong

doi:10.1039/c9ta11985j

Cited by 118 publications

(70 citation statements)

References 56 publications

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“…It is worth to note that the overall shape of the voltage profile from first charge and onward matches very well with that of birnessite δ‐MnO 2 , [ 34 ] structurally similar to chalcophanite (Figure S10, Supporting Information). This indirectly supports that the dissolution of α‐MnO 2 possibly leads the “birnessite‐like” triclinic phase to dominate the cell electrochemistry of a Zn/α‐MnO 2 cell.…”

Section: Resultsmentioning

confidence: 57%

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO₂ Cathodes for Aqueous Zn‐Ion Batteries

Kim

Sadique

et al. 2020

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lithium-ion batteries due to their use of nonflammable aqueous electrolyte with high ionic conductivity [1,2] and safety. In this regard, aqueous zinc-ion batteries (ZIBs) are appealing owing to the water compatibility (i.e., low redox potential) and high natural abundance of Zn metal. Furthermore, Zn metal possesses high volumetric energy density by allowing multivalent charge transfer, making itself unparalleled as an anode material. [3] Recent studies on aqueous ZIBs using mildly acidic electrolyte have explored the candidate materials for the cathode, mostly focusing on Zn-ion insertion materials including Prussian blue analogues [4,5] and metal-inserted vanadates. [6,7] However, of those reported to date, a family of MnO 2 polymorphs, especially tunnel-type hollandite α-MnO 2 , is considered particularly promising owing to its low cost in synthesis and high energy density. Despite its appealing electrochemistry, however, the exact reaction mechanism of α-MnO 2 has remained controversial. The mechanisms reported so far include classical zincinsertion reaction, [8,9] chemical conversion reaction, [10] and combined reaction via coinsertion of H + and Zn 2+ ions. [11,12] While all of these claims are seemingly valid when considered in isolation, they are in some cases contradictory, as they largely rely on interpretation from bulk characterization. Data from routinely used X-ray diffraction (XRD) techniques may be ambiguous as the subsequent formation of various phases of low symmetry adds layers of complexity to indexing of peaks from a Zn/α-MnO 2 system upon cycling. X-ray adsorption spectroscopy measurements only reveal the change in oxidation state (i.e., manganese) of the entire system without any specific reference to the location within the cell and the important local changes. Hence, bulk measurements alone are not fully capable of determining the reaction mechanism of the electrodes and may require direct confirmation from nanoscale characterization through local scrutiny of the individual nanostructures upon electrochemical cycling. Here, we present a detailed picture of the Zn-redox reaction of an aqueous Zn/α-MnO 2 system from the microscopic viewpoint using K +-inserted α-MnO 2 nanorods as the cathode. The reaction mechanism was investigated by performing high-resolution scanning transmission electron microscopy (STEM) in conjunction with electron energy loss spectroscopy (EELS) for chemical composition analysis. Utilizing ex situ analysis on the cathode at various stages of the cycle, we Aqueous Zn/α-MnO 2 batteries have attracted immense interest owing to their high energy density, low cost, and safety, making them desirable for future large-scale energy application. Despite these merits, the comprehensive understanding of their reaction mechanism has been elusive due to the limitations of standard bulk characterization. Here, via transmission electron microscopy, the dissolution-mediated reaction mechanism of a Zn/α-MnO 2 system is discovered and explored in full scope to involve reversible forma...

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Section: Resultsmentioning

confidence: 57%

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO₂ Cathodes for Aqueous Zn‐Ion Batteries

Kim

Sadique

et al. 2020

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“…In order to further emphasize the importance of this work, Table 1 shows the comparison of the maximum specific capacity between this work and some recent reports. [ 53–59 ] It is obvious that the maximum discharge capacity and cycle life of the ZMBs in this work are better than that of most literatures published in the year of 2020.…”

Section: Resultsmentioning

confidence: 74%

Mn²⁺ Ions Confined by Electrode Microskin for Aqueous Battery beyond Intercalation Capacity

Liu

Zhi

Sedighi

et al. 2020

Advanced Energy Materials

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In aqueous rechargeable zinc–manganese dioxide batteries (ZMBs), some irreversible side reactions, such as Mn2+ dissolution, often lead to capacity fading over cycling. These side reactions play a crucial role in the capacity and cycle performance of the battery. The implementation of a bionic electrode microskin (EMS) composed of collagen hydrolysate to convert the irreversible side reactions into reversible reactions is reported. The proposed EMS effectively adsorbs and confines the Mn2+ ions around the cathode through van der Waals forces, hydrogen bonds, and/or ionic interactions, which makes the MnO2/Mn2+ reactions reversible during the charge/discharge process. Such Mn2+ dissolution reactions, with an ultrahigh theoretical capacity (617 mAh g‐1), contribute a large amount of capacity, ≈44% of the total specific capacity at a low scan rate. Based on these fundamental findings, the assembled ZMBs with an EMS display an unprecedented discharge capacity of 415 mAh g‐1 at 20 mA g‐1, which overcomes the theoretical capacity (308 mAh g‐1) limitation of the Zn2+ intercalation mechanism. More significantly, the EMS on all α‐, β‐, and γ‐MnO2 cathodes exhibits similar high capacity beyond the theoretical capacity of Zn intercalation and capacity retention enhancement after 3000 cycles.

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“…This strong interaction disassociates H 2 O, so the pH of 2 M ZnSO 4 solution is 4.57. When Co 2+ or Mn 2+ is added, disassociation of H 2 O becomes more apparent (Li G. et al, 2020 ). When 0.2 M CoSO 4 or MnSO 4 is mixed with 2 M ZnSO 4 , the solution pH value would decrease to 3.84 and 3.48, respectively.…”

Section: Resultsmentioning

confidence: 99%

Contribution of Cation Addition to MnO2 Nanosheets on Stable Co3O4 Nanowires for Aqueous Zinc-Ion Battery

et al. 2020

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Zinc-based electrochemistry attracts significant attention for practical energy storage owing to its uniqueness in terms of low cost and high safety. In this work, we propose a 2.0-V high-voltage Zn–MnO 2 battery with core@shell Co 3 O 4 @MnO 2 on carbon cloth as a cathode, an optimized aqueous ZnSO 4 electrolyte with Mn 2+ additive, and a Zn metal anode. Benefitting from the architecture engineering of growing Co 3 O 4 nanorods on carbon cloth and subsequently deposited MnO 2 on Co 3 O 4 with a two-step hydrothermal method, the binder-free zinc-ion battery delivers a high power of 2384.7 W kg −1 , a high capacity of 245.6 mAh g −1 at 0.5 A g −1 , and a high energy density of 212.8 Wh kg −1 . It is found that the Mn 2+ cations are in situ converted to Mn 3 O 4 during electrochemical operations followed by a phase transition into electroactive MnO 2 in our battery system. The charge-storage mechanism of the MnO 2 -based cathode is Zn 2+ /Zn and H + insertion/extraction. This work shines light on designing multivalent cation-based battery devices with high output voltage, safety, and remarkable electrochemical performances.

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Rechargeable Zn-ion batteries with high power and energy densities: a two-electron reaction pathway in birnessite MnO₂ cathode materials

Abstract: As one of the most promising next-generation safe and green energy storage technologies, aqueous Zn-ion batteries have attracted considerable attention in recent years.

Cited by 118 publications

References 56 publications

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO₂ Cathodes for Aqueous Zn‐Ion Batteries

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO₂ Cathodes for Aqueous Zn‐Ion Batteries

Mn²⁺ Ions Confined by Electrode Microskin for Aqueous Battery beyond Intercalation Capacity

Contribution of Cation Addition to MnO2 Nanosheets on Stable Co3O4 Nanowires for Aqueous Zinc-Ion Battery

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Rechargeable Zn-ion batteries with high power and energy densities: a two-electron reaction pathway in birnessite MnO2 cathode materials

Abstract: As one of the most promising next-generation safe and green energy storage technologies, aqueous Zn-ion batteries have attracted considerable attention in recent years.

Cited by 118 publications

References 56 publications

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO2 Cathodes for Aqueous Zn‐Ion Batteries

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO2 Cathodes for Aqueous Zn‐Ion Batteries

Mn2+ Ions Confined by Electrode Microskin for Aqueous Battery beyond Intercalation Capacity

Contribution of Cation Addition to MnO2 Nanosheets on Stable Co3O4 Nanowires for Aqueous Zinc-Ion Battery

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Rechargeable Zn-ion batteries with high power and energy densities: a two-electron reaction pathway in birnessite MnO₂ cathode materials

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO₂ Cathodes for Aqueous Zn‐Ion Batteries

Unraveling the Dissolution‐Mediated Reaction Mechanism of α‐MnO₂ Cathodes for Aqueous Zn‐Ion Batteries

Mn²⁺ Ions Confined by Electrode Microskin for Aqueous Battery beyond Intercalation Capacity