Electrochemical Behavior of Nonporous Ni/NiCl[sub 2] Electrodes in Chloroaluminate Melts

Abstract

The electrochemical behavior of nonporous Ni/NiCl 2 electrodes was studied using an Al/Na[AlCl 4 ]-NaCl/NiCl 2 /Ni cell in which the capacities of the cell were limited by the Ni/NiCl 2 electrode. The limiting mechanism of the electrode was found to be associated with formation of NiCl 2 on the surface of the nickel electrode. This phenomenon limits the mass-transfer processes of the nonporous electrode and thus its area capacity density. Based on the results of these investigations, an electrochemical model of the electrode reactions was developed which predicts the performance characteristics of porous Ni/NiCl 2 electrodes for various conditions of operation. Modifying the electrolyte with the NaBr, NaI, and sulfur additives was found to produce higher nickel utilization and lower impedance values due to doping effects, which is believed to open up the lattice for better mass transport. Solubility of the nickel chloride in sodium-chloroaluminate melts as a function of temperature and additives was also determined. The solubility measurements indicated that the solubility of nickel chloride in the chloroaluminate melt is strongly dependent on the operational temperature of the cell and the chemical additives present in the electrolyte. The results of this study clearly indicate the importance of the chemical additives, basicity of the melt, and the lower operating temperature of the Na/NiCl 2 cell for improved performance and cycle life.

Investigation of Al-Ni Alloys Deposition during Over-discharge Reaction of Na-NiCl2Battery

“…As a result, the modification of molten salt electrolytes with various additives may be advantageous to lower the NiCl 2 solubility and ultimately prevent over-discharge reactions. Since the Ni solubility is intensely related to Ni particle growth which causes rapid cell degradation of Zebra battery, 22,24) the long-term performance of the cells A, C, and D were compared at 12 mA/cm 2 (0.2C) in Fig. 5.…”

Li‐Ion Batteries and Beyond: Future Design Challenges

“…In order to enhance the stability of the ''-Al 2 O 3 electrolyte or the ionic conductivity of the cells, molten NaAlCl 4 and Na salts (NaBr and NaI) can be added between the electrolyte and the cathodes and into the electrode. [114] …”

Variable-temperature preparation and performance of NiCl2 as a cathode material for thermal batteries

“…Compared with FeS2 and CoS2 thermal batteries, nickel(II) chloride (NiCl2) as a cathode material has many advantages such as power and energy output capability, high open-circuit voltage, and thermal stability. The theoretical electromotive force of a single cell with the Li-Si alloy is 2.64 V, significantly higher than that of FeS2 and CoS2 sulfide cells [23][24][25]. With the Li-B alloy, the working temperature of NiCl2 thermal battery was 400-750°C, the power density was 1200 W kg −1 , and the capacity density was 120 W h kg −1 .…”