Enhanced High-Voltage Stability of LiNi0.6Co0.2Mn0.2O2 Cathode By Using Electrolyte Additive

Abstract

Demands for high-power and high-energy Li-ion batteries are rapidly increasing for their use in electric vehicles. Nickel-rich three-components oxides of Li(Ni1-x-yCoxMny)O2 (NCM, 1-x-y ≥ 0.5) are one of the promising cathode active materials of high-energy density Li-ion batteries because of higher capacity, operation to higher charge cut-off voltage, lower cost and less toxicity than LiCoO2. However, their high-voltage performance is difficult to achieve due to limited anodic stability of conventional electrolyte above 4.2 V vs. Li/Li+. At such an aggressive charge condition, cathode-electrolyte interfacial reactions often cause a degradation of cathode material and electrolyte consumption by oxidative decomposition, resulting in a rapid performance fade.1-3 To stabilize the high-voltage interface between cathode and electrolyte, efforts such as surface coating of cathode materials with inorganic materials have been made.4 Recently, the use of high-voltage electrolyte additives 1-3 is recognized as efficient and economic, because they form a surface protective layer on the cathode, improve the interfacial stability and prevent further electrolyte decomposition. Here we report the development of a new electrolyte additive for cycling the LiNi0.6Co0.2Mn0.2O2 cathode to the charge cut-off voltage of 4.6 V. ex-situ X-ray photoelectron spectroscopic and Infrared spectroscopic studies on cathode-electrolyte interfacial reaction phenomena would be discussed in the meeting. Acknowledgements This research was supported by the Korean Ministry of Trade, Industry & Energy (A0022-00725 & R0004645) and Nano Material Technology Development Program through the National Research Foundation funded by the Ministry of Science, ICT and Future Planning (2009-0082580).