Types Of Cell Configurations Research Articles

Electrodeposition behavior of lithium metal on carbon substrates with surface silvering

Li-ion batteries (LIBs), the widely used energy storage devices, have been intensively studied to further increase their energy density and working life. To this end, lithium metal is the most promising high-capacity anode material, but the unstable electrochemical performance and dendrites formation inhibit its development. Based on DFT calculation, the adsorption energy analysis shows that the preferential and uniform Li deposition may occur on Li–Ag surface comparing to bare carbon surface. Therefore, we adopt thermal evaporation to silver the carbon surface to change the electrodeposition behavior of lithium metal. Li metal preferentially deposits on the Ag surface with flat appearance, restraining the formation of Li dendrites. The lithium metal/carbon composite anodes are subsequently prepared by electrodepositing Li metal on the bare or the modified carbon substrates, and three types of cell configurations, namely, Ag (B), bare CP and Ag (F), are compared in terms of electrochemical performance. The results show that the Ag (B) cell can effectively prolong the short-circuit time, enhance the electrochemical stability in the Coulombic efficiency, and better retain the specific capacity in full-cell tests due to the suppression of “dead Li”. This research provides a basic guidance for the electrochemical preparation of lithium metal/carbon composite anodes.

Charging/discharging kinetics of poly(3,4-ethylenedioxythiophene) in 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide ionic liquid under galvanostatic conditions

The constant current charging/discharging experiments of poly(3,4-ethylenedioxythiophene) (PEDOT), modified electrodes in room temperature ionic liquid, for instance 1-ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)imide, were performed for two types of cell configurations, three and two-electrode cells. In each case, a linear variation of the voltage with respect to time was observed. The electrochemical responses were analyzed in term of a series combination of a resistance R and a capacitor C. Accordingly, the capacitance of the modified electrodes was determined. One observed a linear variation of the capacitance as a function of the amount of PEDOT. This capacitance described the chemical capacitance of PEDOT that reflected the capability of the system to accept or release additional charge carriers on a given variation of the chemical potential. Also, the electrochemical response during constant current charging/discharging experiments for two-electrode cell in which the same amount of PEDOT was deposited on each electrode showed a type I electrochemical supercapacitor response. This kind of an electrochemical chain allowed us to mimic and to analyze the electrical responses of an electrochemical actuator based on an interpenetrating polymer networks containing PEDOT that was able to work in air.

Preparation and characterization of thick-film Ni/MH battery

Using the porous polypropylene (PP) films sputtered with gold and the Ni as current collectors, the electroactive materials (Ni(OH) 2 and metal hydride (MH)) of positive and negative electrodes were prepared on the current collector using thick-film technology. Two types of cell configurations were prepared and the characteristics of these batteries were compared. The cycle number for the formation of batteries based on the porous PP film was found to be 2, which was significantly less than that of batteries based on the ceramic substrates. Using the porous PP film as substrate, the number of cycles for the formation of battery increased from 2 to 5 with the increase of the charge/discharge rate from 0.1 C/0.025 C to 2.0 C/0.5 C. The silver oxides dendrites formed by the oxidation of silver paste used to adhere the current collectors and the conducting wires in the charge/discharge process caused a short contact between the positive and negative electrodes, which then caused the battery failure. The cycle life of the battery based on the porous PP film was found to be greater than 400 when the charge/discharge rate was 2.0 C/0.5 C.