Porous structure and surface modification have been widely studied in applying metal oxide nanomaterials as Li-ion battery anodes for overcoming problems such as poor conductivity and large volume variation. Here, we demonstrate a direct triple-decomposition process for the in situ synthesis of C/Cu/ZnO porous hybrids. In a typical porous structure, 5-10 nm sized ZnO and Cu nanoparticles aggregate randomly and are modified with carbon layers in thickness of 1 nm. Moreover, the resulted hybrid nanostructures show a high and stable specific capacity of 818 mAh g(-1) at a current rate of 50 mA g(-1) with almost 100% capacity retention for up to 100 cycles when used an anode material for lithium ion batteries. By combination of the structural analyses and electrochemical behaviors, it could be speculated that the porous structure and the modifications of copper nanoparticles and carbon layers are mainly responsible for the dramatically improved electrochemical performance of ZnO anodes.
In this work, a novel and facile one-pot method has been developed for the synthesis of a hybrid consisting of Ni-Mn-Co ternary oxide and poly(3,4-ethylenedioxythiophene)-polystyrenesulfonate (PEDOT-PSS/NMCO) with a hierarchical three-dimensional net structure via a solvothermal-coprecipitation coupled with oxidative polymerization route. Apart from the achievement of polymerization, coprecipitation, and solvothermal in one pot, the hydroxyl (OH(-)) ions generated from the oxidative polymerization of organic monomer by neutral KMnO4 solution were skillfully employed as precipitants for metal ions. As compared with the PEDOT-PSS/Ni-Mn binary oxide, PEDOT-PSS/Co-Mn binary oxide, and PEDOT-PSS/MnO2, PEDOT-PSS1.5/NMCO exhibits overwhelmingly superior supercapacitive performance, more specifically, a high specific capacitance of 1234.5 F g(-1) at a current density of 1 A g(-1), a good capacitance retention of 83.7% at a high current density of 5 A g(-1) after 1000 cycles, an energy density of 51.9 W h kg(-1) at a power density of 275 W kg(-1), and an energy density of 21.4 W h kg(-1) at an extremely elevated power density of 5500 W kg(-1). Noticeably, the energy density and power density of PEDOT-PSS/NMCO are by far higher than those of the existing analogues recently reported. The exceptional performance of PEDOT-PSS/NMCO benefits from its unique mesoporous architecture, which could provide a larger reaction surface area, faster ion and electron transfer ability, and good structural stability. The desirable integrated performance enables the multicomponent composite to be a promising electrode material for energy storage applications.
Nickel-rich layered oxides are promising cathodes for
power batteries
owing to their high capacity and low cost. However, during the production,
storage, and application of nickel-rich cathodes, especially in case
the Ni content exceeds 70%, their surfaces almost inevitably react
with ambient air to form electrochemically inert Li2CO3 and LiOH, leading to significant capacity loss and therefore
imposing a significant hurdle to practical applications of nickel-rich
cathodes. Here, we reveal surface structures and electrochemical properties
of the exposed LiNi0.8Co0.15Al0.05O2 (NCA) cathodes and investigate systematically the impact
of exposure humidity, temperature, and time on NCA cathodes. We demonstrate
that introduction of a 3.0–4.5 V galvanostatic cycling operation
at initial cycles can remarkably regenerate the subsequent 3.0–4.3
V battery performances of the exposed cathode. This work represents
a facile method to regenerate the battery performance of surface-degraded
nickel-rich cathodes, opening up an avenue in fulfilling efficient
production, storage, and application of nickel-rich cathode materials.
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