Electrochemical stability of lithium bis(oxatlato) borate containing solid polymer electrolyte for lithium ion batteries

The electrochemical stability of lithium bis(oxatlato) borate (LiBOB) containing solid polymer electrolyte has been evaluated both by inert electrode and real cathodes. Enhanced intrinsic anodic stability and decreased interface impedance, are obtained by addition of nano-sized MgO to PEO20–LiBOB. It is also found that the LiBOB-containing SPEs exhibit prominent kinetic stability between 3.0 and 4.5 V. For cells using SPEs as the separators, good cycling performance is obtained for real 4 V class cathodes material LiNi1/3Co1/3Mn1/3O2 and LiCoO2. The Li|PEO20–LiBOB|LiNi1/3Co1/3Mn1/3O2 cell takes an initial capacity of 156.8 mAh g−1, with retention of 142.5 mAh g−1 after 20 cycles at 0.2C-rate. The cell also works well up to 1C-rate. The addition of nano-sized MgO into PEO20–LiBOB readily reduces the irreversible capacity per cycle, both for LiNi1/3Co1/3Mn1/3O2 and LiCoO2 cathodes. In addition, the critical role of LiBOB in obtaining kinetic stability and passivating ability towards cathodes are specially discussed.

► Nano-MgO enhances the intrinsic anodic stability and decreases the interface impendence for PEO20–LiBOB.
► Kinetic stability is obtained for LiBOB-containing PEO-based SPEs between 3.0 and 4.5 V.
► The SPEs supports the cycling of LiNi1/3Co1/3Mn1/3O2 and LiCoO2.
► Nano-MgO readily decreases the irreversible capacity per cycle.
► Total analysis indicates the effective application of LiBOB and nano-metal oxide in developing SPEs compatible with 4 V class cathodes.