γ-butyrolactone and glutaronitrile as 5 V electrolyte additive and its electrochemical performance for LiNi0.5Mn1.5O4

In this work, γ-butyrolactone (GBL) and glutaronitrile (GLN) are used as electrolyte additives for LiNi0.5Mn1.5O4 cathode of lithium ion battery. At 1 C rate, the capacity of LiNi0.5Mn1.5O4 is significantly improved by using 2% GBL as additive, its average capacity reaches 113 mA h g−1. In base electrolyte, the capacity is only 99.5 mA h g−1. However, utilizing 10% GLN just keeps the capacity around 110 mA h g−1 in first 50 cycles, and its final capacity is 32.3 mA h g−1. A series of tests indicate that GBL preferentially oxidized on LiNi0.5Mn1.5O4 forming a stable protective film, which prevents the subsequent oxidation decomposition of the electrolyte from taking place, on the contrary, although GLN has a wider electrochemical window, it can simply enable the cyclic stability at low current rate. When current is increased, the incompatibility of GLN with low voltage Li anode is enlarged.