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Contour tracking accuracy is the key performance index of multi-axis motion control system. In the previous design of contour error feedback controller, the independent design idea of tracking controller and contour controller of each logic axis is often adopted, which is not easy to realize the optimal control of tracking accuracy and contour accuracy. The coupling increment of each controller is inevitable in motion control compensation, which has an impact on the stability of the control system. Therefore, a predictive control method for contour error is proposed. At first, through the state space model of feed system, the system dynamics are judged to predict the contour accuracy in the future finite time domain. Besides, the linear quadratic performance index function of contour error is established, and the performance of the control objective is continuously optimized during the limited time domain with the form of rolling optimization. A closed-loop solution is obtained which is most suitable for the current motion situation and could add to the system, so as to realize the optimal control considering the trajectory contour and the tracking stability of each servo axis in the next few sampling cycles. Finally, by the means of comparative experiments on the three-axis motion control platform, it is verified that the proposed contour predictive control strategy not only effectively reduces the tracking error, but also significantly improves the contour accuracy, which is suitable for application in complex industrial environment.

Solid polymer electrolytes (SPEs), which are favorable to form intimate interfacial contacts with electrodes, are promising electrolyte of choice for long-cycling lithium metal batteries (LMBs). However, typical SPEs with easily oxidized oxygen-bearing polar groups exhibit narrow electrochemical stability window (ESW), making it impractical to increase specific capacity and energy density of SPE based LMBs with charging cut-off voltage of 4.5 V or higher. Here, a polyfluorinated crosslinker has been applied to enhance oxidation resistance of SPEs via inductive electron-withdrawing effect of polyfluorinated segments transmitted through crosslinked networks. As a result, polyfluorinated crosslinked SPE exhibits a wide ESW, and the Li|SPE|LiNi0.5Co0.2Mn0.3O2 cell with a cutoff voltage of 4.5 V delivers a high discharge specific capacity of ~ 164.19 mAh g− 1 at 0.5 C and capacity retention of ~ 90% after 200 cycles. This work opens a new direction in developing SPEs for long-cycling high-voltage LMBs by using polyfluorinated crosslinking strategy.

Guided by in situ synchrotron X-ray diffraction (SXRD) measurements and quantitative analysis, we identified and synthesized a new type of lithium nickel oxide as a cathode material for Li-ion batteries. This compound is a composition of two crystallographic components: a major stoichiometric layer-structured phase, LiNiO2, and a minor Li-containing disordered rock-salt phase, LiδNi1-δO, both embedded in the same cubic close-packed oxygen lattice. The LiNiO2|LiδNi1-δO composite, when used as the active material in a cathode, delivers high energy density, superior rate capability, and long-term cycling stability owing to its unique structural configuration.