MnO2 supercapacitor review

1、Recent developments of MnO2 Supercapacitor Huang Tao 2010 Pseudocapacitive reactions: MnO2 + C+ + e- MnOOC MnO2 as faradic materials Advantages: 1. Environmental friendliness 2. Low cost (natural abundance) 3. High theoretical specific capacitance (1370 F g-1) Disadvantages: 1. Poor electrical condu

2、ctivity (10-510-6 S cm-1) (low rate- capacity) 2. Electrochemical dissolution, lack of structural stability and long-term cyclability Enhance MnO2 materials electrical conductivity 1. Mixed with transition metal elements, such as Ni, Cu, Fe, V, Co, Mo and Ru (2003-2009, 7 articles) 2. Doping with sm

3、all amounts of other metallic elements such as Al, Sn and Pb (2003-2010, 3 articles; 2013 ,1 articles) 3. Deposit a thin MnO2 layer on the surface of a porous, high surface area, and electronically conducting structure (recently) 2013 Porous MnO2 films were electrodeposited Au atoms were doped in Mn

4、O2 by physical vapor deposition (PVD) using a sputtering coater SEM images of the top view of MnO2 (a) and Au doped MnO2 (b) 626 Fg-1 at a scan rate of 5 mVs-1 (compare to pure MnO2 film 380 Fg-1 at a scan rate of 5 mVs-1), 65% higher than that of pure MnO2 After 15000 cycles(1.35 um), a 7% incremen

5、t of the original capacitance (electrochemical cycling gives rise to a homogenization of the doped Au during the dissolutiondeposition process, result in an enhanced conductivity) 0.7 um 1.35 um To address electrochemical dissolution, a self-limited growth process based on co-electro-deposition of M

6、nO2 with polymer. The resulting polymer conformally coats the oxide nanoscale network, serving as an effective barrier to the electrolyte thereby protecting the underlying MnO2 nanoarchitecture from chemical dissolution. MnO2+PANi (2003-2008, 4 articles) MnO2+PEDOT (recently) Next article report a s

7、imple and highly efficient technology to fabricate a uniform MnO2PEDOT:PSS nanocomposite electrode in a one-step deposition process combined with both anode deposition and electrodeposition and electrophoretic deposition 2013 Preparation of the MnO2PEDOT:PSS nanostructured composite electrode: (0.1

8、M) of Mn(Ac)2 and 0.4 mL PEDOT:PSS aqueous solution (1 wt%) with a 10.0 V DC voltage ( 对照组只有草酸锰) (a) SEM and (b) TEM images of the anode-deposited pure MnO2 electrode material. (c) SEM and (d) TEM images of the co-electro-deposited MnO2PEDOT:PSS electrode material. The inset in (d) is the selected a

9、rea electron diffraction pattern of the same sample. 503 F g-1 at 1 mV s-1, 1670 mF cm-2 at 0.5 mA cm-2 1.8010-3 W h cm-3 and 0.38 W cm-3(3.6210-4 W h cm-3) 8.4 mg cm-2 within 20 minutes Deposited on Various Nanostructures Precursor Deposit a thin MnO2 layer on the surface of a porous, high surface

10、area, and electronically conducting structure, which can provide good electrochemical performance with high mass- loading of the MnO2 phase E = 1/2CV2 V: operating voltage C: device capacitance Nest two article focus on asymmetric supercapacitors with high voltage window. The first designed and fabr

11、icated a low-cost high-performance solid-state flexible asymmetric supercapacitors (ASC) with - MnO2 nanowires and amorphous Fe2O3 nanotubes grown on flexible carbon fabric. 2013 Preparation of MnO2 NWs: (hydrothermal approach) 2.5 mmol KMnO4 + 1 mL concentrated HCl + 45 mL deionized water, 140, 12h

12、 MnO2 150 mF cm-2 at 1 mA cm-2, 197.4 F g-1 at 1.3 A g-1 0.55 mWh cm-3, 0.32 mWh cm- 3 at 139.1 mW cm-3 (PVA/LiCl) 2014 They dipped the GCF fiber into the stirred 0.10 M KMnO4/0.10 M Na2SO4 solution at room temperature for 530 min, 2.36 mF cm1 (Mn), 2.37 mF cm1 (C),主要研究非对称电容器负极碳材料 Pillar nanoarrays

13、1. Fabrication of an inert polymer nanostructure by spin casting on a mold and transferring to a substrate 2. Deposition of current collector electrode material by sputtering 3. Electrochemical deposition of MnO2 on to the nanostructured electrode 2013 PAN nanostructuresCoated of AuPd Deposited MnO2

14、 nanoparticulates 603 F g1 at a scan rate of 5 mV s1 and 603 F g1 (or 6.13 mF cm2) at 10 A g-1 Compare PE (planar electrode) 237 F g1 (or 2.41 mF cm2) at 10 A g-1 Nanowires 2014 1.CuO NWs were grown uniformly on the Cu wire when heated at 500 for 4 hours. 2.Deposition of AuPd layer by sputter-coatin

15、g 3.MnO2 was then electrodeposited onto these NWs CuO NWs(10 m) AuPd sputter-coated(300nm) MnO2 deposited(200nm) 1,376 F g1 at 5 mV s-1 (mass loading of 0.04 mg cm2) 857 F g-1 at 1 mA cm2 0.55 mWh cm3 at 413 mW cm3 (0.8V) Nanowires 2014 1, Preparation of 3D Porous Ni Film by Electro-deposition Metho

16、d; 2, Growth of 3D Porous Ultrathin Graphite Foam by CVD Method; 3, Co3O4 nanowire arrays were prepared by hydrothermal synthesis method; 4, MnO2-PEDOT shells were synthesized by an anodic electro-deposition method 353 F g-1 at 5 A g-1 (single cell, commercial activated carbon in 3D porous graphite

17、foams as the negative electrode) 9.8 Wh kg-1 at a power density of 20 kW kg-1 Nanocone 2014 This article develop a simple and efficient method for fabricating ultrathin and flexible supercapacitor electrodes containing a manganese dioxide (MnO2) nanostructure deposited onto 3-D nickel nanocone array

18、s (NCAs). 1. The nickel nanocone arrays were fabricated by an electro- deposition method. ( NiCl ) 2. The electrodes were fabricated by the anode deposition method. ( Mn(Ac)2 , 3.0V DC) MNN is as thin as 3 mm, thinner than most commercial Cu and Al foil. The tensile strength of the film is measured

19、as high as 32.35 MPa, higher than those of commercial Cu foil (12 mm, 8.3 MPa) and Al foil (13 mm, 9.2 MPa) 632 F g-1 at 2 mV s-1, 31.6 mF cm-2 95.3% retention after 20 000 cycles 52.2 W h kg-1 at 2.0 kW kg-1, 12.73 Wh kg1 at 25.84kW kg1 1-ethyl- 3-methylimidazolium tetrafluoroborate (1-乙基-3甲基咪唑四 氟硼

20、酸盐) as the electrolyte( high voltage window 2.5 V ) Recently MnO2 pseudocapacitance materials research mainly focus on applying traditional MnO2 materials on emerging supercapacitors 2015 They report a simple route to synthesize aqueous MnO2 ink comprised of hexagonal MnO2 nanosheets. 1. Highly crys

21、talline carbon particles (HCCPs) were prepared by microwave hydrothermal treatment. 2. HCCPs+KMnO4(stirring at room temperature) MnO2 Plate supercapacitorLinear supercapacitor 1035 F g-1 (91.7 mF cm-2) at 2 mVs-1 25.3 W h kg-1 and 81 kW kg-1 (asymmetric supercapacitor) 17 W h kg-1 and 38 kW kg-1 (sy

22、mmetric supercapacitor) 2015 ACS NANO They fabricate asymmetric supercapacitor with MnO2/ CNT hybrid fiber as the positive electrode and pristine aerogel CNT fiber as the negative electrode, and KOH poly(vinylalcohol) (KOH-PVA) gel electrolyte. MnO2 Precipitation: KMnO4+CNT(stirring at room temperature) 157.53 F cm-1 at 50 mV s-1 142.22 F cm-1 at 1.1 mA cm-2 39.85 nWh cm-1, 15.03 W cm-1 CapacityMorphologyJournal nameAuthorSupercapacitor Energy density Power density 626 Fg-1（5 mVs-1）nanosheetAngewandte(2013)M