Interaction Between the Cathode Active Material and the Carbon Conductive Agent in High-Voltage Cathode System that is Concerned with the Gas Evolution

Abstract

The interfacial reactions that contributed to the gas formation between carbon conductive agents and the electrolyte at the positive electrode in high-voltage batteries, potentials over 4.5 V, have been investigated. The amount of gas generated was quantified for various conductive agents: acetylene black (AB), furnace black (FB), specially customized AB, and graphite (GR). The experiments revealed that in the high-voltage system, the specific gas evolution was induced by both the cathode active material and the conductive agent. The high-voltage properties of the carbon conductive agents, such as the anion intercalation and self-discharging properties, were evaluated for each carbon electrode. The results implied the existence of a local battery composed of the conductive agent and LNi_0.5Mn_1.5O₄. This redox couple appears to play a key role in the gas evolution, which was sensitive to crystallinity, surface area and metallic impurities of conductive agents.