The battery systems: A1/NaC1-A1C13-A12XJNi-felt (X = S, Se, Te) and the corresponding system without chalcogen have been studied experimentally at 175~ Charge/discharge experiments, performed on cells with NaC1 saturated melts, show that advantages with regard to rate capability and cyclability can be obtained with systems containing dissolved chalcogen compared with the chalcogen-free system. Exchange of chalcogen between cathode and electrolyte during cycling was confirmed by performing

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... etric analysis and Raman spectroscopy of the electrolytes. Cathode reactions were studied by coulometric titrations (performed on cells with slightly acidic NaC1-A1C13 melts and small amounts of chalcegen) and compared with model calculations. Cells containing chalcogen revealed at least three voltage plateaus during cycling. The lowest plateau is associated with formation/decomposition of essentially NiySz and Ni, Sez in the sulfide and selenide system, respectively. Cells containing selenide revealed extra capacity below the NL Sez-plateau, most probably associated with a AI~Ni, Se~ compound. On the second plateau of sulfide systems NiC12 or a Niy~z C12y_2z compound with y > (4.4 +-0.2) 9 z is formed during charging. Reduction of the formed compound to Ni takes place via consumption of sodium chloride. For 3380