This paper reports part of the activities in progress in our laboratory in the investigation of electrode and electrolyte materials which may be of interest for the development of lithium-ion batteries with improved characteristics and performances. This investigation has been directed to both anode and cathode materials, with particular attention to convertible oxides and defect spinel-framework Li-insertion compounds in the anode area and layered mixed lithium–nickel–cobalt oxide and high voltage, metal type oxides in the cathode area. As for the electrolyte materials, we have concentrated the efforts on composite polymer electrolytes and gel-type membranes. In this work we report the physical, chemical and electrochemical properties of the defect spinel-framework Li-insertion anodes and of the high voltage, mixed metal type oxide cathodes, by describing their electrochemical properties in cells using either “standard” liquid electrolytes and “advanced” gel-type, polymer electrolytes. The results illustrated here demonstrate that the spinel-framework anodes of the Li[Li1/3Ti5/3]O4 type can be combined with high voltage cathodes of the Li2M x Mn(4−x)O8 family for the fabrication of new types of lithium-ion battery systems cycling around 3.5V. The development of this interesting concept is however still limited by the availability of highly stable electrolytes.