High Rate Discharge Characteristics of Li / SOCl2 Cells

Abstract

The performance characteristics of the normalLi/SOCl2 cell have been determined as a function of discharge rate, electrolyte composition, cathode thickness, and cell temperature. Cells have been discharged at rates ranging from about 3 to nearly 300 mA/cm2. Cathodes with electrolyte solutions have contained either LiAlCl4 or AlCl3 , with the most efficient discharge characteristics being realized with 1.5MLiAlCl4 and 4.5MAlCl3 solutions. The use of pure AlCl3 dissolved in SOCl2 as the electrolyte results in substantially higher average discharge voltages and discharge capacities than can be achieved with cells containing the conventional LiAlCl4 electrolyte. With both electrolytes, however, the discharge capacity per unit cathode volume (the effective cathode utilization) decreases with increasing cathode thickness, the rate of decrease being greater the higher the discharge current density. Increasing cell temperature results in an improvement in cathode utilization and a decrease in overvoltage, again with both LiAlCl4 and AlCl3 electrolyte solutions.

Rechargeable Na/Cl2 and Li/Cl2 batteries

“…with the NaCl product depositing onto the positive electrode and passivating the electrode. Similar twoplateau discharge was observed in Li/SOCl 2 cells in initially acidic electrolytes 11,17 .…”

“…3a), consistent with passivation of the carbon electrode by deposited NaCl. The reduction chemistry of SOCl 2 to form S, SO 2 and Clwas similar to that in Li/SOCl 2 primary cells 17 . The proposed reactions (1) and (2) were supported by the fact that when an initially neutral electrolyte of 4 M NaCl + 4 M AlCl 3 in SOCl 2 was used, the higher plateau at ~ 3.47 V was not observed in the rst discharge and only the plateau at ~ 3.25 V appeared throughout the whole discharge (Extended Data Fig.…”

“…Prior to the invention of secondary LIBs, a primary Li-metal battery was developed in the 1970's using thionyl chloride (SOCl 2 ) as a catholyte, Li metal as anode and amorphous carbon as the positive electrode [10][11][12][13][14][15][16] . The Li-SOCl 2 battery was attractive due to its high energy density, but did not receive sustained interest due to the lack of rechargeability 17,18 . The battery discharges through Li anode oxidation and catholyte SOCl 2 reduction into sulfur (S), sulfur dioxide (SO 2 ), and chloride ion (Cl -) on the carbon electrode 19,20 .…”

A Rechargeable Na/Cl Battery

“…As discharge progressed in a neutralized electrolyte, a lower discharge plateau of ~ 3.27 V appeared, corresponding to 4 Na + 2 SOCl 2 4 NaCl + S + SO 2 (2) with the NaCl product depositing onto the positive electrode and passivating the electrode. Similar twoplateau discharge was observed in Li/SOCl 2 cells in initially acidic electrolytes 11,17 .…”

“…3a), consistent with passivation of the carbon electrode by deposited NaCl. The reduction chemistry of SOCl 2 to form S, SO 2 and Clwas similar to that in Li/SOCl 2 primary cells 17 . The proposed reactions (1) and (2) were supported by the fact that when an initially neutral electrolyte of 4 M NaCl + 4 M AlCl 3 in SOCl 2 was used, the higher plateau at ~ 3.47 V was not observed in the rst discharge and only the plateau at ~ 3.25 V appeared throughout the whole discharge (Extended Data Fig.…”