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A model predictive control (MPC) method based on Q-learning algorithm, named QMPC, is proposed for weakly damped, nonlinear and open-loop unstable magnetic levitation platform (MLP) systems. In addition, the design of MPC controller for the MLP system, the state space of the MLP system airgap, the action space of the predictive horizon and control horizon, the reward and punishment function are also included in this research. Based on the Simscape and MATLAB/Simulink, the joint simulation of the MLP control system is realized. Compared with PID controller and traditional MPC controller, the simulation results show that QMPC controller has better disturbance rejection ability and tracking performance under six working conditions. [ABSTRACT FROM AUTHOR]

Nickel bicarbonate Ni(HCO3)2 has recently been demonstrated to be a highly attractive electrode material for lithium-ion batteries (LIBs) and supercapacitors (SCs), and its electrochemical performance could be further enhanced through rationally tuning the morphology. Herein, Ni(HCO3)2 spheres are successfully prepared via a facile, one-step hydrothermal route. The effects of the hydrothermal duration on the phase and morphology are investigated. XRD patterns indicate a phase conversion from NiCO3 into Ni(HCO3)2 that has never been previously reported. SEM images reveal that the reaction temperature and time play a key role in determining the phase and morphology of the resulting sample. The whole process includes, successively, nucleation, growth, self-assembly, dissolution, and recrystallization. As electrodes, the Ni(HCO3)2 spheres reacted for 15 h, delivering 602.4 mA h g−1 after 300 cycles at 0.2 A g−1 in LIBs and a specific capacitance of 450 F g−1 after 5000 cycles at 5 A g−1 in SCs. These results show strong potential applications in energy storage devices. [ABSTRACT FROM AUTHOR]

A rheological phase method has been successfully applied to synthesize a layered lithium nickel cobalt iron oxide Li(Co Ni)FeO (0 ≤ y ≤ 0.10) a promising cathode material of lithium-ion batteries. The impacts of Fe content and reaction conditions on the material structure are characterized by means of x-ray diffraction, scanning electron microscopy and transmission electron microscopy. Electrochemical properties are investigated in detail under different conditions as cathode materials of lithium-ion batteries. It is found that the average sizes of the prepared powders are about 100 nm. Compared to other samples, Li(CoNi)FeO shows the lowest cation mixing, the smallest impedance, the best reversible capacity and cycling performance. The initial discharge capacity is 146.9 mAhg in 3.0-4.3 V. The cyclability is better after several cycles, which shows great prospects for use in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Nickel bicarbonate Ni(HCO 3 ) 2 has recently been demonstrated to be a highly attractive electrode material for lithium-ion batteries (LIBs) and supercapacitors (SCs), and its electrochemical performance could be further enhanced through rationally tuning the morphology. Herein, Ni(HCO 3 ) 2 spheres are successfully prepared via a facile, one-step hydrothermal route. The effects of the hydrothermal duration on the phase and morphology are investigated. XRD patterns indicate a phase conversion from NiCO 3 into Ni(HCO 3 ) 2 that has never been previously reported. SEM images reveal that the reaction temperature and time play a key role in determining the phase and morphology of the resulting sample. The whole process includes, successively, nucleation, growth, self-assembly, dissolution, and recrystallization. As electrodes, the Ni(HCO 3 ) 2 spheres reacted for 15 h, delivering 602.4 mA h g -1 after 300 cycles at 0.2 A g -1 in LIBs and a specific capacitance of 450 F g -1 after 5000 cycles at 5 A g -1 in SCs. These results show strong potential applications in energy storage devices.