Abstract
The initial charge/discharge behavior of LiNi0.5Mn0.5O2 for a Li-ion battery has been examined by XRD, in situ XAFS and electrochemical methods. The LiNi0.5Mn0.5O2(R¯3
m:a=0.28999(7)nm, c=1.4330(7)nm in a hexagonal setting) was observed to retain its initial structure after charging to 4.5 V (vs. Li/Li+). XAFS measurements have also revealed that the majority of the nickel and manganese, respectively, exists in a divalent and a tetravalent state. Upon charging LiNi0.5Mn0.5O2, Ni2+ ions were consequently oxidized to Ni4+. A Li-ion cell constructed with LiNi0.5Mn0.5O2/graphite shows only a 15% capacity loss after 500 cycles at 60°C.
