Lithium-rich
Li-ion battery cathode materials possess the virtues
of high specific capacities and high working potential, but the severe
decay of discharge potential and capacity during repeated cycling
hinders the practical applications. Herein, a Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO)
material is synthesized by a carbonate co-precipitation method, and
then three graphene quantum dots (GQDs)-coated LMNCO materials with
different contents of GQDs are fabricated by a solvent evaporation
method, in which the GQDs are prepared by a solvothermal method. The
GQDs-coated LMNCO material with 3 wt % GQDs demonstrates the best
electrochemical performance. For instance, the discharge specific
capacity at 0.2C rate is 270.3 mAh g–1. When the
charge/discharge current rate increases from 0.2C to 5C, the capacity
retention is 47.1%. After 150 cycles at 1C rate, the discharge capacity
decreases from 184.2 to 159.4 mAh g–1, with the
capacity retained at 86.5%. Surface coating with an appropriate amount
of highly conductive GQDs can effectively enhance the electrical conductivity
of the LMNCO material and promote the electron transport and charge
transfer process and thereby improve the specific capacity and rate
performance. Moreover, the GQDs coating layer can impede the side
reactions of the active material surface with the electrolyte as well
as the surface structure phase transition and therefore boost the
cycle stability.
This study analyzed the potential emission reductions associated with implementing the best management practices (BMPs) on the combined cycle and cogeneration power plants in Beijing. It determined that implementing the BMPs could potentially achieve up to 580 metric tonnes, or 0.6%, reductions of all NOx emissions in Beijing. Many other cities in China and Asia battling air quality issues may find the information useful in order to evaluate the emission reduction potential of their own gas turbine power plants.
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