Herein, sulfur/bamboo charcoal (S/BC) composites with a sulfur content of 57.7 wt% were prepared by melt–diffusion method as cathode materials for Li–S batteries.
As the anode of sodium-ion batteries (SIBs), SnO 2 has been attracted considerable attention due to its high theoretical specific capacity. However, these shortcomings of SnO 2 anode seriously restrict its practical use for high-performance SIBs due to its poor conductivity, volume expansion and agglomeration of the active material during cycling. In this paper, carbon aerogel (CA) is a three-dimensional porous material with glucose as carbon source and freeze-dried hydrogel method is used to retain three-dimensional network structure by calcination. SnO 2 is prepared by hydrothermal method with nanoparticles and distributed on the CA homogeneously to prepare CA/SnO 2 . The CA/SnO 2 is prepared for SIB, in which CA can alleviate the problem of volume expansion and improve poor conductivity of SnO 2 as a good carrier. Moreover, the porous structure of CA is beneficial to increase the contact between the electrolyte and the electrode, and accelerates the transmission speed of ions and electrons. Nano-sized SnO 2 also contributes to cycle stability. The CA/SnO 2 exhibits superior electrochemical performance and maintains a reversible discharge specific capacity of 235[Formula: see text]mAh[Formula: see text]g[Formula: see text] at a current density of 50[Formula: see text]mA[Formula: see text]g[Formula: see text] after 100 cycles.
This paper proposes a novel scheme to solve the optimal control problem for unknown linear systems in a data driven manner. The method doesn't require any prior knowledge of the system, and only utilizes past input-output trajectories to describe the system features implicitly and realize the prediction on the basis of behavioral systems theory. Meanwhile, we adopt reinforcement learning to update the terminal cost function online to ensure the closed-loop stability. The merit of the proposed scheme is the avoiding of the system identification process and the complex design process of terminal cost, terminal set and terminal controller in the standard MPC. We verify the performance of the algorithm by simulation.
Abstract Unclear reaction mechanisms and unsatisfactory power performance hinder the further development of advanced lithium/fluorinated carbon (Li/CF x ) batteries. Herein, the mechano‐electrochemical coupling behavior of a CF x cathode is investigated by in situ monitoring strain/stress using digital image correlation (DIC) techniques, electrochemical methods, and theoretical equations. The DIC monitoring results present the distribution and dynamic evolution of the plane strain and indicate strong dependence toward the material structure and discharge rate. The average plane principal strain of fully discharged 2D fluorinated graphene nanosheets (FGNSs) at 0.5 C is 0.50%, which is only 38.5% that of conventional bulk‐structure CF x . Furthermore, the superior structural stability of the FGNSs is demonstrated by the microstructure and component characterization before and after discharge. The plane stress evolution is calculated based on theoretical equations, and the contributions of electrochemical and mechanical factors are examined and discussed. Subsequently, a structure‐dependent three‐region discharge mechanism for CF x electrodes is proposed from a mechanical perspective. Additionally, the surface deformation of Li/FGNSs pouch cells formed during the discharge process is monitored using in situ DIC. This study reveals the discharge mechanism of Li/CF x batteries and facilitates the design of advanced CF x materials.
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