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The second use of retired batteries can reduce energy storage system (ESS) costs, relieve the power supply pressure of the power grid during peak hours, peak cutting and valley filling and promote energy saving and emission reduction. Power users can allocate a certain amount of peak-shaving auxiliary service costs to guide users to cut peaks and fill valleys. This paper presented an optimal configuration method for a microgrid second-use battery energy storage system (BESS) considering the users allocate peak shaving auxiliary service costs. A second-use BESS optimization configuration model was established to configure the second-use BESS with the lowest cost and the lowest peak shaving service cost allocated by users. The optimization model was solved by the particle swarm algorithm (PSO). And compared with the configured conventional BESS of residential area micro-grid. Simulation is carried out on the MATLAB platform, and the results verify the model’s and algorithm’s rationality.

Based on high throughput (HTP) density functional theory calculations and topological characterization, we have identified four topologically nontrivial two dimensional (2D) materials out of 641 most stable systems in the 2D materials database. The HTP screening is carried out based on the automated construction of maximally localized Wannier functions followed by explicit calculations of the surface states, where the Wannier centers are evaluated as a further verification of the nontriviality. The electronic structure of such nontrivial materials is discussed in detail together with the features in the crystal structure and relevant orbitals.

Two-dimensional (2D) transition metal compound (TMC) monolayers, as well as their van der Waals heterostructures with unique properties, are fundamentally and technologically intriguing. Here, heterostructures consisting of a MoS2 monolayer and TM2CO2 (TM = Ti, Zr or Hf) monolayers are systematically researched by means of the density functional theory (DFT). Different from semiconductor/metal contacts, MoS2 and TM2CO2 monolayers are all semiconductors with band gaps ranging from 0.25-1.67 eV. According to rigorous screening of stacking patterns, MoS2/Zr2CO2 is shown to be an indirect type-II semiconductor with the maximum valence and minimum conduction bands spatially separated on opposite monolayers. Simultaneously, the interface charges transfer from Zr2CO2 to MoS2 results in a built-in field that separates the electrons and holes efficiently. Also, the smaller effective masses of electrons and the holes of band edges indicate the higher carrier mobility. Moreover, strain regulation can make the hetero-bilayer's character a semiconductor-semimetal-metal transition. The physical insights pave the way for the good performance of MoS2/TM2CO2 in next-generation electronic devices and photocatalysts.

Since the discovery of ferrocene, many one-dimensional metallic sandwich molecular wires have been identified. However, most of the known systems are assembled from organic molecules. Suffering from many drawbacks has, however, hampered their widespread applications. With the goal of breaking this logjam, we provide a blueprint for the designing of a variety of novel sandwich molecular wires ([(P)5TM]?, TM?=?Ti, V, Cr, Mn, Fe, and Co) assembled from ferrocene-like inorganic molecules (P)5TM, offering evidence of the existence of inorganic molecular wires in this class. We present first-principles calculations to investigate systematically the electronic and magnetic properties of such novel inorganic sandwich molecular wires. Compared with the organic molecular wires, all the inorganic [(P)5TM]? wires are of large magnetic moment. Among them, we find that [(P)5V]?, [(P)5Cr]? and [(P)5Mn]? display ferromagnetic character, while for [(P)5Ti]?, [(P)5Fe]? and [(P)5Co]?, the magnetic coupling is antiferromagnetic. More remarkably, the TM atoms distributed in these wires show regular docking and lead to structures with ordered spin signals, which is a long-term dream of spintronics. We propose that the difference in magnetic coupling for the studied systems is related to the competition between two exchange interactions of TM atoms. Specifically, we propound that the general mechanism for the formation of stable 1D [(P)5TM]? involves the transfer of one electron from the TM atom to the P5 ligand forming and TM+ alternating structure.