A nonaqueous-electrolyte battery, for instance, a lithium ion battery which uses a nonaqueous electrolyte and is a secondary battery has a high energy density as compared to other secondary batteries such as a nickel-hydrogen battery and a lead storage battery, and accordingly is widely used in household electrical appliances such as personal computers and mobile phones. In addition, in recent years, the nonaqueous-electrolyte battery is used also in electric power tools, and has been developed also as an in-vehicle power source of an electric vehicle (EV) and a hybrid electric vehicle (HEV). Furthermore, a plug-in hybrid electric vehicle (PHEV) which also provides both modes of EV travelling and HEV travelling has received attention, and the nonaqueous-electrolyte battery has been developed also as an in-vehicle power source for PHEV.
The in-vehicle power source for the PHEV is required to have not only an energy density which is important for the EV travelling but also a high output and input performance which is important for the HEV travelling, i.e. high charge/discharge performance. In other words, the battery for this application is required to have both performances of the high energy density and the high input/output density.
A graphite-based material is used for the most part of a negative electrode material of the lithium ion battery. It is considered that mainly an edge surface of graphite contributes largely to charge/discharge reactions of the lithium ion battery which uses the graphite-based material for a negative electrode material (for instance, refer to Non-Patent Literature 1).
In addition, as for examples of means of enhancing the input/output performance of the battery, a technology of using a non-graphitizable carbon material in place of the graphite-based material for the negative electrode material is disclosed in Patent Literature 1, and a technology of reducing a resistance component of an electrode is disclosed in Patent Literature 2.