Moderate Temperature Sodium Cells: V . Discharge Reactions and Rechargeability of and Positive Electrodes in Molten

Abstract

NiS2 and normalNiS have been characterized as high energy density rechargeable positive electrodes for moderate‐temperature Na batteries of the configuration, Nafalse(1false)/β″‐Al2O3/NaAlCl4false(1false) , NiSx . The batteries operate in the temperature range 170°–190°C. Positive electrode reactions during discharge/charge cycles have been characterized. Excellent rechargeability of the batteries has been demonstrated by extended cell cycling. A normalNa/NiS2 cell, operating at 190°C, exceeded 600 deep discharge/charge cycles with practically no capacity deterioration. The feasibility of secondary normalNa/NiSx batteries with specific energies ≥ 50 Wh/lb and cycle lifes exceeding 1000 deep discharge/charge cycles has been demonstrated.

Mechanism of Reaction in NaAlCl4 Molten Salt Batteries with Nickel Felt Cathodes and Aluminum Anodes: II . Experimental Results and Comparison with Model Calculations

“…For small values of n, reasonable good agreement with experiment is obtained, with the sulfide species (n, n -1) = (7, 5), (8,6), (9, 7), (10,8), (11,9), (12,10), (13,10), (13,11)., (14,11), (14,12), (15, 12), (15, 13), and so on. Thus, in acidic melts sulfide seems to exist mainly as sulfide-chloride double bridges, as found above from fitting to the cathode potential-curves.…”

Rechargeable Sodium Batteries: VII . and as Positive Electrodes in Molten

“…We have found that NaFeO2 and FeOC1 behave as highly reversible positive electrodes in conjunction with molten NaA1C14 in Na cells operating at ~180~ We chose these materials anticipating that in molten NaA1C14 they would undergo insertion-type discharge/charge reactions as shown in Eq. [1] and [2] NaFeO2 ~ FeO2 + Na § + e [1] NaFeOC1 ~ FeOC1 + Na § + e- [2] Instead, our results seemed to indicate that they react with molten NaA1C14 during cell cycling at -180~ Conse-~0 quently, identical discharge/charge behavior was shown 4o by Na cells utilizing either the FeOC1/NaA1C14 or the ~, NaFeO2/NaA1C14 cathode. The same electrochemically ac-~ 2o tive material appeared to have been produced in situ in both cells.…”

“…In previous publications from this laboratory we have described the electrochemistry of a number of transition metal sulfides in molten NaA1C14, and have shown that many of those sulfides are highly desirable positive electrodes for rechargeable Na batteries operating in the 130 ~ 200~ range (1)(2)(3)(4)(5). We have extended our studies to include transition metal oxides which until now have received little attention in this context.…”

“…Basic NaA1C14 was obtained from Anderson Physics. The setup and operation of laboratory Na cells have already been described (1)(2)(3)(4)(5). The cathode material ~,_ 10 powder and about 10g NaA1C14 powder were loaded into the pores of a graphite felt sheet which served as the cur-~ 0 rent collector.…”

Controlled synthesis and morphology evolution of nickel sulfide micro/nanostructure

“…As a family member of the chalcogenide nanomaterial, nickel sulfide has shown excellent application in catalysts [10][11][12][13], photoconduction [14], rechargeable lithium ion battery cathode [15][16][17], and solar storage [18]. Up to now, three main approaches including solid-state reactions, vapor phase reactions and soft chemistry method have been developed successfully to fabricate nickel sulfide nanostructures [19][20][21][22], and different morphologies of nickel sulfide nanostructures such as nanoneedles [23], nanorods [24], nanotubes [25] and core-shell structures [26] have been synthesized successfully.…”