4 research outputs found
A Highly Reversible Low-Cost Aqueous Sulfur–Manganese Redox Flow Battery
Redox
flow batteries are promising energy storage technologies.
Low-cost electrolytes are the prerequisites for large-scale energy
storage applications. Herein, we describe an ultra-low-cost sulfur–manganese
(S–Mn) redox flow battery coupling a Mn2+/MnO2(s) posolyte and polysulfide negolyte. In addition to the
intrinsically low cost active materials, the polysulfide negolyte
removes the long-unresolved metal dendrite issue of metal–Mn
batteries (e.g., Zn–Mn2+/MnO2(s) batteries),
enabling substantially improved cycling stability at a high areal
capacity (50–100 mAh cm–2). Due to the low
cost of both sulfur and manganese species, this system promises an
ultralow electrolyte cost of $11.00 kWh–1 (based
on achieved capacity). This work broadens the horizons of aqueous
manganese-based batteries beyond metal–manganese chemistry
and offers a practical route for low-cost and long-duration energy
storage applications
Modified Separator Using Thin Carbon Layer Obtained from Its Cathode for Advanced Lithium Sulfur Batteries
The realization of a practical lithium
sulfur battery system, despite
its high theoretical specific capacity, is severely limited by fast
capacity decay, which is mainly attributed to polysulfide dissolution
and shuttle effect. To address this issue, we designed a thin cathode
inactive material interlayer modified separator to block polysulfides.
There are two advantages for this strategy. First, the coating material
totally comes from the cathode, thus avoids the additional weights
involved. Second, the cathode inactive material modified separator
improve the reversible capacity and cycle performance by combining
gelatin to chemically bond polysulfides and the carbon layer to physically
block polysulfides. The research results confirm that with the cathode
inactive material modified separator, the batteries retain a reversible
capacity of 644 mAh g<sup>–1</sup> after 150 cycles, showing
a low capacity decay of about 0.11% per circle at the rate of 0.5<i>C</i>
Mesopore- and Macropore-Dominant Nitrogen-Doped Hierarchically Porous Carbons for High-Energy and Ultrafast Supercapacitors in Non-Aqueous Electrolytes
Non-aqueous electrolytes
(e.g., organic and ionic liquid electrolytes) can undergo high working
voltage to improve the energy densities of supercapacitors. However,
the large ion sizes, high viscosities, and low ionic conductivities
of organic and ionic liquid electrolytes tend to cause the low specific
capacitances, poor rate, and cycling performance of supercapacitors
based on conventional micropore-dominant activated carbon electrodes,
limiting their practical applications. Herein, we propose an effective
strategy to simultaneously obtain high power and energy densities
in non-aqueous electrolytes via using a cattle bone-derived porous
carbon as an electrode material. Because of the unique co-activation
of KOH and hydroxyapatite (HA) within the cattle bone, nitrogen-doped
hierarchically porous carbon (referred to as NHPC–HA/KOH) is
obtained and possesses a mesopore- and macropore-dominant porosity
with an ultrahigh specific surface area (2203 m<sup>2</sup> g<sup>–1</sup>) of meso- and macropores. The NHPC–HA/KOH
electrodes exhibit superior performance with specific capacitances
of 224 and 240 F g<sup>–1</sup> at 5 A g<sup>–1</sup> in 1.0 M TEABF<sub>4</sub>/AN and neat EMIMBF<sub>4</sub> electrolyte,
respectively. The symmetric supercapacitor using NHPC–HA/KOH
electrodes can deliver integrated high energy and power properties
(48.6 W h kg<sup>–1</sup> at 3.13 kW kg<sup>–1</sup> in 1.0 M TEABF<sub>4</sub>/AN and 75 W h kg<sup>–1</sup> at
3.75 kW kg<sup>–1</sup> in neat EMIMBF<sub>4</sub>), as well
as superior cycling performance (over 89% of the initial capacitance
after 10 000 cycles at 10 A g<sup>–1</sup>)
Valence Change Ability and Geometrical Occupation of Substitution Cations Determine the Pseudocapacitance of Spinel Ferrite XFe<sub>2</sub>O<sub>4</sub> (X = Mn, Co, Ni, Fe)
Valence Change Ability and Geometrical Occupation
of Substitution Cations Determine the Pseudocapacitance of Spinel
Ferrite XFe<sub>2</sub>O<sub>4</sub> (X = Mn, Co, Ni, Fe