Battery module, method of fabricating the same, and vehicle having battery module

Abstract

Each of battery cells (12) that constitute a battery module includes a flat-shaped rolled electrode body (30) formed by rolling a sheet-like anode collector (32) and a sheet-like cathode collector (34) along with a sheet-like separator, and a trailing edge (32E) of the sheet-like anode collector (32) and a trailing edge (34E) of the sheet-like cathode collector (34) are located at a position (30B) outside a portion of the rolled electrode body (30) which substantially receives a restraining load. The battery module, in which the restraining load is applied to the cells, achieves long service life while maintaining good output characteristics.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The invention relates to a battery module in which a plurality of battery cells (secondary batteries) capable of charging and discharging are connected in series, a method of fabricating the battery module, and a vehicle having the battery module. More particularly, the invention is concerned with the construction of battery cells that constitute a battery module suitable for installation on a vehicle.[0003]2. Description of the Related Art[0004]Battery modules each constructed by connecting a plurality of battery cells in series are provided which use lightweight lithium-ion batteries having a high energy density or other secondary batteries or storage devices, such as capacitors, as the cells. It has been found increasingly important to use such battery modules as power supplies that can provide high power, more specifically, as power supplies to be installed on vehicles or power supplies for personal computers and po...

AI Technical Summary

Benefits of technology

[0009]The trailing edges of the anode and cathode collector sheets as described above may cause a step or steps to be formed on the outer surface of the rolled electrode body. If such steps are formed in a portion of the rolled electrode body which substantially receives the restraining load (typically, any portion contained in the flat outer surfaces of the rolled electrode body), the pressure (surface pressure) applied to the rolled electrode body due to the restraining load may differ between the stepped portion(s) (where the sheet trailing edges are located) and other portions surrounding the stepped portion(s). The unevenness in the load pressure (surface pressure) may cause unevenness in the degree of application of the pressure to the interior of the rolled electrode body, which in turn causes uneven or non-uniform distribution of battery components, such as an electrolyte, within the rolled electrode body, resulting in deterioration in the cycle life performance (a property concerning changes in the capacity as a result of repeated charging and discharging) of the cell. In the battery module according to the first aspect of the invention, both of the trailing edges of the anode and cathode collector sheets are positioned outside the portion of the rolled electrode body which substantially receives the restraining load. Therefore, the restraining load pressure (surface pressure) can be evenly or uniformly applied to the rolled electrode body. Accordingly, the battery module thus constructed is free from the problems as described above, and achieves excellent cycle life performance and long service life.

[0019]A third aspect of the invention relates to a vehicle having the battery module according to the first aspect of the invention or the battery module fabricated according to the second aspect of the invention. The battery module installed on the vehicle according to the third aspect of the invention achieves long service life while assuring excellent cycle life performance.

Problems solved by technology

The unevenness in the load pressure (surface pressure) may cause unevenness in the degree of application of the pressure to the interior of the rolled electrode body, which in turn causes uneven or non-uniform distribution of battery components, such as an electrolyte, within the rolled electrode body, resulting in deterioration in the cycle life performance (a property concerning changes in the capacity as a result of repeated charging and discharging) of the cell.

Images