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Lots of lithium ion battery (LIB) products contain lithium metal oxide LiNi5Co2Mn3O2 (LNCM) as the positive electrode&rsquo, s active material. The stable surface of this oxide results in high resistivity in the battery. For this reason, conductive carbon-based materials, including acetylene black and carbon black, become necessary components in electrodes. Recently, carbon nano-tube (CNT) has appeared as a popular choice for the conductive carbon in LIB. However, a large quantity of the conductive carbon, which cannot provide capacity as the active material, will decrease the energy density of batteries. The ultra-high cost of CNT, compared to conventional carbon black, is also a problem. In this work, we are going to introduce long-length carbon nano-tube s(L-CNT) into electrodes in order to design a reduced-amount conductive carbon electrode. The whole experiment will be done in a 1Ah commercial type pouch LIB. By decreasing conductive carbon as well as increasing the active material in the positive electrode, the energy density of the LNCM-based 1Ah pouch type LIB, with only 0.16% of L-CNT inside the LNCM positive electrode, could reach 224 Wh/kg and 549 Wh/L, in weight and volume energy density, respectively. Further, this high energy density LIB with L-CNT offers stable cyclability, which may constitute valuable progress in portable devices and electric vehicle (EV) applications.

In this study, Si nanoparticles with interweaving carbon nanotubes are wrapped by graphitic sheets to achieve high conductivity and high dimensional stability of a composite anode (denoted as Si/CNT/G) for Li-ion batteries. In addition, an ionic liquid (IL) electrolyte that consists of ether-side-chain pyrrolidinium, asymmetric imide, and a high Li+ fraction is prepared. This electrolyte is for the first time employed for Si-based Li-ion batteries. Decomposition of the ether groups creates organic components in the solid electrolyte interphase (SEI). The high Li+ concentration promotes decomposition of the (fluorosulfonyl)(trifluoromethanesulfonyl)imide (FTFSI−) anions, leading to a LiF- and Li3N-rich SEI. The organic-inorganic balanced SEI is responsible for the excellent charge-discharge properties of the Si/CNT/G anode. The FTFSI− anions exhibit low corrosivity toward the Al current collector and high compatibility with the LiNi0.8Co0.1Mn0.1O2 (NCM-811) cathode. With a charging voltage of 4.5 V, remarkable reversible capacities and cycling stability of NCM-811 in the high-Li+-fraction N-methoxyethyl-N-methylpyrrolidinium/FTFSI IL electrolyte are observed. Differential scanning calorimetry is used to examine the interfacial exothermic reactions between the delithiated NCM-811 and various electrolytes. After 300 charge-discharge cycles, the capacity retention of a Si/CNT/G||NCM-811 full cell with the proposed IL electrolyte is 80% with a Coulombic efficiency of ∼99.9%. These values are significantly higher than those of the conventional carbonate electrolyte cell.

In this paper, we develop a bandpass filter using a stub-loaded stepped impedance resonator (SLSIR) and calculate the even and odd resonant modes of this type of resonator using the input impedance/admittance analysis. In this study, two impedance ratios and two length ratios are operated as the design parameters for controlling the resonant modes of the SLSIR. Several resonant mode variation curves operating three resonant modes with different impedance ratios and two length ratios are developed. By tuning the desired impedance ratios and length ratios of the SLSIRs, compact ultra-wideband (UWB) bandpass filters (BPFs) can be achieved. Two examples of the UWB BPFs are designed in this study. The first example is UWB filter with a wide stopband and the second one is dual UWB BPF, namely, with UWB performance and a notch band. The first filter is designed for a UWB response from 3.1 to 5.26 GHz having a stopband from 5.3 to 11 GHz, with an attenuation level better than 18 dB. The second filter example is a dual UWB BPF with the frequency range from 3.1 to 5 GHz and 6 to 10.1 GHz using two sets of the proposed SLSIR. The measured results have insertion loss of less than 1 dB, and return loss greater than 10 dB. Furthermore, the coupling structures and open stub of the SLSIR also provide several transmission zeros at the skirt of the passbands for improving the passband selectivity.

Electrolyte optimization plays a key role in deciding energy density (ED) and power density (PD) of supercapacitors. Increasing cell voltage is an effective way to improve ED and PD. Therefore, an electrolyte with a large potential window is highly desired. Ionic liquid (IL) electrolytes, characterized by wide potential windows, excellent thermal stability, intrinsic ionic conductivity, non-volatility, non-flammability, and low environmental concerns, are potential electrolytes and are used for micropore-and mesopore-rich activated carbon (ACmicro and ACmeso) supercapacitors. IL electrolytes consisting of various cations of EMI+ (1-ethyl-3-methyl imidazolium), PMP+ (N-propyl-N-methyl pyrrolidinium), and BMP+ (N-butyl-N-methyl pyrrolidinium) and various anions of TFSI– (bis(trifluoromethyl sulfonyl) imide), BF4 – (tetrafluoroborate), and FSI– (bis(fluorosulfonyl)imide) are explored. The electrolyte viscosity and conductivity and ion transport properties at the ACmicro and ACmeso electrodes are studied. Also, the capacitance, cycling stability, and rate capability of the ACmicro and ACmeso electrodes are systematically investigated, and post-mortem material analyses are conducted. This study shows the influence of IL composition on charge–discharge capacitances of the ACmicro electrodes is more pronounced than that for the ACmeso electrodes. The FSI-based IL electrolytes, whose electrochemical properties are dependent on cation, are found to be highly promising. Uniting EMI+ with FSI– results in low viscosity of electrolyte and high ion transport, optimizing the electrode capacitance and rate capability. Interchanging EMI+ with PMP+ enhances the cell voltage (to 3.5 V) and maximum ED (to 42 Wh kg−1) of the ACmicro cell at the cost of cycling stability.