Search

Background: Owing to the excellent theoretical specific capacity and safety intercalation potential, Li3VO4 (LVO) has been proposed as an advanced anode material for lithium ions batteries (LIBs). However, the LVO suffers from low electronic conductivity that limits its commercialization. Objective: The reduced graphene oxide (rGO) is recommended to couple with micro-LVO particles aiming to enhance the conductivity of composite electrodes. Method: The LVO@rGO composite is synthesized by a facile hydrothermal method. The morphology, crystallinity, valance state and electrochemical behavior of LVO@rGO are characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and electrochemical workstation, respectively. Further, the LIBs’ performance is explored by making a coins-type half-cell LIBs battery via battery system. Results: The Li+ diffusion rate of the optimized LVO@rGO electrode is 7.67×10-23 cm2/s, which improves two orders of magnitudes of pure LVO electrode. As a result, the LVO@rGO anode delivers a reversible capacity of 190.1 mAh/g at 0.1 A/g after 100 cycles, which is even twice higher than that of pure LVO anode (90.6 mAh/g). Besides, it exhibits superior rate capability, i.e. a reversible capability of 285.0, 220.2, 158.7, 105.2 and 71.7 mAh/g at 0.05, 0.1, 0.2, 0.5 and 1.0 A/g, respectively. Conclusion: The high conductivity and flexible texture enable rGO an idea building block to enhance the Li ion diffusion of whole electrode. On the other hand, it is instrumental in alleviating the aggregation of host materials, leading to high specific surface and specific capacity.

Additional file 1. This file contains the questionnaire used in this study.

The use of retired batteries from electric vehicles as a second-life battery energy storage system has been recognized as a way to break the high investment cost limitation of battery energy storage systems with the associated cost reduction of a park-level integrated energy system. The battery degradation and replacements should be further considered in the planning period, especially compared with new battery energy storage systems. Additionally, there is a lack of discussion on utilizing thermal energy storage systems in coordination with second-life battery to reduce degradation. For this reason, an electric/thermal hybrid energy storage system planning method for park-level integrated energy systems with second-life battery utilization is proposed. A cumulative battery life loss calculation model is developed. A bi-level optimal planning model of electric/thermal hybrid energy storage system using second-life batteries, including an upper-level planning model and a lower-level operating model, is proposed. At the upper level, to maximize the net present value during the planning stage, the capacity of the hybrid energy storage system as well as when the second-life battery energy storage system needs to be replaced are optimized. At the lower level, the operation schemes are optimized to obtain the minimum annual operating cost, which are fed back to the upper level. The proposed method considers continuous capacity degradation of second-life batteries and mutually beneficial relationships between thermal energy storage and second-life batteries. Finally, a case study demonstrates the economic effectiveness and battery service life improvement of the proposed planning method.

Ship cranes will be shaken sharply due to the influence of additional loads such as wind, waves and current during operation. Due to the influence of additional loads such as wind, waves and flow, the marine crane in operation will cause the cargo to shake sharply, which reduces the efficiency of the work greatly. In order to solve this problem, a three-rope traction type anti-rolling device is designed. In this paper, a hydraulic speed control system of the crane anti-rolling device is designed, the boundary conditions of the traction cable load are analysed, The boundary conditions of the traction cable load are analyzed, and the parameter matching of the main components such as hydraulic motor and hydraulic pump in the speed control system is studied.

The hooks are prone to fatigue fracture due to the frequent impact loads on the hooks at sea. In order to further strengthen the structural strength of the hooks, the influence of the three parameters on the hooks is studied, such as the deflection angle of the hooks with large openings, the opening diameter of the hooks and the position of the maximum thickness of the hook walls.The main points are as follows: parameterized modeling of crane hooks, data simulation and analysis with ANSYS, and optimization analysis of hooks' strength, which provide basis for further enhancing reliability of hooks.