Current Collectors for Lithium‐Silicon Electrodes in Lithium/Iron Disulfide Cells

Abstract

Cold‐pressed lithium‐silicon pellet electrodes were fabricated using nickel foam (current collector) and were tested using counterelectrodes, lithium chloride‐potassium chloride electrolyte, and lithium‐aluminum reference electrodes. They were tested at current densities between 20 and 400 mA/cm2 and temperatures between 675 and 750 K. The effects of current collector content, porosity, electrolyte content, and starting material (, , or Si); on the lithium utilization were studied. The current collector (∼2 volume percent) was needed to utilize the lithium from the voltage plateau, and this utilization decreased with an increase in current density or a decrease in temperature. However, the lithium utilizations from the other voltage plateaus, were not influenced by the current collector, current density, or temperature variations. Furthermore, the composition of the starting material (, , or Si) did not influence the lithium utilizations from any of the plateaus. Utilizations of 89‐70% from the plateau, 100‐77% from the plateau, and 87‐66% from the total cycle ( to Si) were obtained over the ranges of current density and temperatures mentioned above. Alloying of the nickel current collector with the active material provided results comparable within 10% of those obtained from using the pressed foam pellet or vibration‐loaded electrodes. The iron, aluminum, and copper current collector alloying agents were found not to perform as well as the nickel additive. In the case of iron, performance apparently decreases due to the possible formation of the high‐melting compound, whereas in the case of aluminum and copper, performance apparently decreases due to loss of surface area caused by sintering of the powdered alloy.