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In order to solve the problem that the long cable variable voltage and variable frequency (VVVF) system does not adopt an effective capacitor voltage sharing control method, resulting in a poor effect of resonance overvoltage control, the resonance overvoltage control algorithm of the long cable VVVF system based on discrete mathematics is studied. First, the long cable frequency conversion drive system is established. In order to ensure voltage loss in the range of motor requirements, a frequency converter–cable–motor (ICM) system connection mode is used to maintain the system operation. Based on the research of the capacitor voltage balance control strategy of a long cable frequency conversion drive system, the discrete mathematical model of the AC side of the ICM system is established by using this control strategy. The improved constant active power controller is obtained by establishing the mathematical model, and the resonant overvoltage in a long cable frequency conversion drive is realized by using the constant active power controller. The experimental results show that the algorithm can effectively control the resonance overvoltage phenomenon in the long cable frequency control system, and the control accuracy is over 97%. It has good performance and can be applied in practice.

Electrolytes with high stability against both Li anode and high‐voltage cathode are critical for high‐energy and long‐cycling lithium metal batteries (LMBs). However, the free active solvents in common electrolytes are susceptible to decomposition at both Li anode and high‐voltage cathode. Although recently developed locally high‐concentration electrolytes (LHCEs) have largely restricted active solvents via Li+ coordination, the free molecules are still released upon the desolvation of Li+ at the surface of electrodes, causing continuous decomposition during long‐cycling processes. Here, a molecule competitive solvation electrolyte (MCE) is shown to stabilize high‐voltage LMBs by introducing a well‐designed and newly synthetic bipolar solvent molecule with one ion‐dissociative polar head and the other highly fluorinated nonpolar tail. The bipolar molecules competitively dissociate Li+ via weak coordination interactions, drastically reducing the ratio of active solvents in electrolytes and the detrimental decomposition at electrodes during the desolvation processes. Consequently, the MCE enables a 1.4‐Ah Li metal pouch cell with a stack energy density of 450 Wh kg−1 along with exceptional operation stability over 400 cycles (retention: 81%). Furthermore, the MCE also maintains the stable operation of a 2.5‐Ah Li‐S pouch cell with an excellent energy density of 417 Wh kg−1 for 70 cycles under practical conditions. [ABSTRACT FROM AUTHOR]

Monodisperse gold nanoparticles (AuNPs) are an important guarantee of their scientific value and technical reproducibility in applications. The tartrate has a similar molecule structure and physicochemical properties to citrate, bur is much less reducibility and is usually not favorable for the formation of monodisperse AuNPs. We have prepared monodisperse AuNPs with tartrate (potassium sodium tartrate) as reducing and capping agent. Various parameters affecting the monodisperse properties during the preparation of tartrate‐capped AuNPs were analyzed, such as reversing the order of reactant addition and ripening of seeds, while adjusting the synthesis parameters such as time, temperature, and pH value. The final results show that the addition of a trace amount of silver (Ag) ion into chloroauric acid, the monodispersed tartrate‐capped AuNPs can be obtained with the size range of 9–40 nm. The fabricated gold seeds and grown tartrate‐capped AuNPs have narrow size dispersions (or polydispersity, σ<10 %). The minimum size dispersion of AuNPs with twice growth steps was as low as 5.73 %. So, the weak reducing agent of tartrate is one of good candidates to synthesize the monodispersity of AuNPs. Additionally, tartrate‐capped AuNPs have good stability and can be easily modified and form a large two‐dimensional (2D) monolayer nanostructure film. [ABSTRACT FROM AUTHOR]

Flexible ultrathin copper films are desired for use as flexible electromagnetic shielding, smart clothing, and energy storage devices. The fabrication of such films can be realized through plasma assisted surface coating on flexible polymer thin films. Unfortunately, the use of plasma treatment leads to substantial damage to the polymer substrates, which is particularly serious for ultrathin films. Here, we report the fabrication of stretchable, ultrathin, yet ultrastrong hybrid copper films via simple nanoconfinement. The hybrid films are prepared by the conformal electroless deposition of copper nanoparticles on nanofibrils of ultrastrong ultrahigh molecular weight polyethylene (UHMWPE) membranes. These flyweight hybrid copper films (0.3 mg cm−2) possess a high mechanical strength of 390 MPa, 26% larger than pure copper foils; a low resistivity of 5 × 10−8 Ω m at a cyclic extensional strain of 1%; and macroscopic shape recovery after applying a biaxial extension strain of 10%. The shape recoverability and the high mechanical strength of the hybrid copper film were derived from the unique nanofibrous network of the ultrastrong UHMWPE substrate. As an application, we fabricated a lithium-ion battery using the CuPE as the current collector at the graphite anode and observed a near 100% and 10% increase in energy density concerning the total mass and total volume of the anode, respectively. [ABSTRACT FROM AUTHOR]