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We present a comparative density functional theory study of Li, Na, and Mg storage energetics and diffusion in α-Sn, including the effects of temperature (vibrations). We study several concentrations corresponding to initial stages of insertion (number densities x= 1/64, 1/32, 1/16, and 1/8) as well as the final state of charge (Li17Sn4, Na15Sn4, and Mg2Sn). While final states of charge correspond to positive anode voltages for all three types of metal, insertion energetics is favorable for insertion for Li at all concentrations studied, for Na up to the concentration of x = 3/64, and Mg insertion is thermodynamically disfavored at all x. Diffusion barriers at dilute concentrations are computed to be 0.23, 0.51, and 0.44 eV for Li, Na, and Mg, respectively. Vibrations have a noticeable and temperature-, concentration-, and dopant-type dependent effect on voltages, of the order of 0.1 eV at room temperature.
Carbon nanotubes (CNTs) have been shown to be a viable conductive additive in Li-Ion batteries . By using CNTs battery life, energy, and power capability can all be improved over carbon black, the traditional conductive additive. A significantly smaller weight percentage (5% CNTs) is needed to get the same conductivity as 20% carbon black. Many of the previous efforts found that a combination of conductive additives was most advantageous . Unfortunately many of these efforts did not attend to the unique challenge that dispersing nanotubes presents and used non-optimal methods to disperse CNTs (e.g. ball milling) [3,4]. With poor dispersion a stable and resilient conductive network in the cathode is hard to form with CNTs alone. Here we investigate the formation of LiFePO₄ with CNTs using a polyol process synthesis.
The electrochemical effects of embedding Cu nanoparticles in carbonized wood supercapacitor electrodes have been investigated. The nanoparticles were embedded using a solution method. Subsequent X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that the Cu nanoparticles were anchored uniformly on the surface and deep within the pores of the electrode. Cyclic voltammetry measurements showed that the electrode has typical pseudocapacitive behavior, with two pairs of redox reaction peaks. The charge-discharge cycling also indicated that the redox charge transformation was a reversible process. An ultra-high specific capacitance of 888 F/g and an energy density of 123 Wh/kg were observed for the Cu loaded electrodes, as compared to the pure carbonized wood electrodes, which had a specific capacitance of 282 F/g and an energy density of 39 Wh/kg. Furthermore, both the carbonized wood and Cu loaded electrodes exhibited excellent long cycle abilities with at least 95% of the specific capacitance retained after 2000 cycles. These remarkable results demonstrate the potential for using Cu nanoparticle loaded carbonized wood as a high performance and environmentally friendly supercapacitor electrode material.
We present here performance of Li ion batteries with SiC nanoparticle-film anode, which is fabricated by a double multi-hollow discharge plasma chemical vapor deposition (CVD) method. The first cycle of charge/discharge property of the Li ion battery with the SiC nanoparticle-film anode shows a high capacity of over 4,000 mAh/g, which is 12 times higher than the Li ion battery with the conventional graphite anode. The discharge capacity shows high stability for first 10th cycle, and is 3750 mAh/g for the 10th cycle.