Electricity: battery or capacitor charging or discharging – Cell or battery charger structure
Reexamination Certificate
2002-08-21
2003-03-18
Sherry, Michael (Department: 2838)
Electricity: battery or capacitor charging or discharging
Cell or battery charger structure
C429S048000, C029S623100
Reexamination Certificate
active
06534952
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates to a winding method for producing battery electrode groups by winding in a spiral shape both a battery anode (negative electrode) and a battery cathode (positive electrode) superimposed on each other with a separator disposed therebetween as used in lithium secondary batteries, nickel hydrogen batteries and the like, and also relates to a device employing the
2. Background Art
In constructing small and high capacity secondary batteries that are mass-produced, electrode groups formed of such electrode materials as belt-shaped anodes, cathodes, separators and the like superimposed one over another and wound in a spiral shape, respectively, have so far been employed in general. Respective anodes and cathodes are prepared by the steps of filling a paste with an active material serving as the main ingredient in a conductive substrate, drying the paste, performing roll pressing steps for a thickness adjustment of the electrode plates and making the active material layer high in density, cutting the electrode plates to a predetermined width with the used of a slitter to appear belt-shaped and further attaching a lead wire and the like to the respective electrode plates. Separators are formed of a belt-shaped porous polypropylene film and what is generally used are electrode groups, each produced by the steps of having both the foregoing anode and cathode plates superimposed one over another with a predetermined positional relationship maintained and with the separator disposed therebetween, and having the foregoing electrode and separator combination wound around a winding core in a spiral shape tightly without leaving any gaps left between the wound layers.
In producing secondary batteries by the use of electrode groups formed in the foregoing spirally wound body, it is a general practice to produce such spirally wound bodies by putting in place on four unreeling axes that are disposed in parallel with one another the electrode materials of an anode plate, a cathode plate, a first separator and a second separator, all being wound in a roll-shape, respectively. Further, winding cores are provided in parallel to the respective four unreeling axes and the respective tip ends of the electrode materials are tentatively fixed to the winding cores and the respective winding cores are rotated at a constant speed in a predetermined direction.
A tension unit is incorporated in the transportation route of the electrode materials to control a tension applied to thereto so that a tension suitable for winding the electrode groups is applied to each respective electrode material. As the winding core rotates, each respective belt-shaped material constituting the foregoing electrode groups is transported towards the winding core along with the rotation of the unreeling axis and wound around the winding core.
When electrode groups are produced by the use of a winding device as described above, respective anode and cathode plates wound in a roll-shape and fit to an unreeling axis are brought into contact with the periphery of each respective roller that is provided in a plurality for acting as a direction change unit, tension unit and the like and conveyed by running due to the rotation of the rollers. During the foregoing process, irregular end surfaces created on the respective anode and cathode plates in the working steps thereof variations in thickness from place to olace thereof, a localized unlevel condition created in the thickness thereof due to the attachment of lead wires, variations in machining of the electrode plate transporting rollers of the winding device, variations in mounting of the roller axes and the like gradually produce a velocity component perpendicular to the normal running direction thereof, thereby bringing the electrode plates into a meandering movement with the resulting great possibilities of causing a “staggered winding” of the electrode groups.
For reference, a description is given to the case where the width of an electrode material mainly used in a lithium secondary battery is involved. In general, a first separator and a second separator are of the same width and set to around 40 to 60 mm at the maximum of the electrode materials. The width of each respective anode (negative electrode) plate is large after that and the width of the cathode (positive electrode) plate is made the smallest among the electrode materials. Since the difference in width between the separator and the anode plate is about 2 mm and the difference between the anode plate and the cathode plate is about 1 mm, the process of electrode group winding has to be performed carefully so as to have the cathode plate remain within the width of the anode plate that is located opposite to the cathode plate with the separator sandwiched therebetween. In addition, the anode plate is not allowed to extend outside of the width of the separator. Even when the relative positional relationships among the three different electrode materials as described above are satisfied, the respective electrode materials are not allowed to be noticeably displaced in the axial direction of the winding axis as the winding turn to the respective electrode materials increases.
When the foregoing conditions are not satisfied, such defects as battery's internal short circuits and instability of battery capacity are caused. In the extreme case, it becomes difficult for the electrode groups to be housed in the battery case, resulting in problems not only in the battery's performance aspect but also the battery's safety and productivity aspects.
Therefore, a variety of meandering prevention units has been so far employed in the course of electrode materials transportation extending film the unreeling axis to the winding core. Here, some of the equipment is introduced. The most widely used meandering prevention unit is installed at the place where an unreeling axis fit with a roll of each respective electrode material is located. More specifically, the edge position of the electrode material released from the roll is compared with the predetermined reference position and a positional displacement is detected by the use of an optical sensor and the like. Based on the detection result, the unreeling axis fit with the electrode material roll is moved in the direction of the axis core, thereby allowing the edge position of the electrode material to be returned to the predetermined position with an accuracy of 0.1 mm max. This kind of unit is generally for a heavy weight electrode material roll and likely to become large in size and slow in response and, therefore, not suitable for a winding device requiring a high speed and a high degree of accuracy.
According to the Japanese Patent Application Laid-open Publication No. H11-40144, what is characterized by correcting automatically the edge positions of electrode plates is disclosed as
FIG. 6
shows. In
FIG. 6
, there are two axial cores
32
a
and
33
a
located perpendicularly to the running direction of respective cathode and anode plates
1
and
3
and the two axial cores are disposed in parallel with each other. An electrode plate is sandwiched between a pair of rollers
32
and
33
held by axial cores
32
a
and
33
a
in a rotatable manner, respectively, and the pair of rollers are prepared so as to be allowed to rotate without slippage when the electrode plate is transported. Edge detecting means
34
is disposed in the vicinity of the pair of rollers to detect the edge positions of the electrode plate and, based on the detection results of edge detecting means
34
, the pair of rollers are shifted in position in the roller's axial core direction, thereby correcting the edge positions of the electrode plate automatically.
According to the Japanese Patent Application Laid-open Publication No. H9-120822, a staggered winding prevention unit is disclosed as
FIG. 7
shows. In
FIG. 7
, electrode materials
1
and
3
are cut to a predetermined length to form a rectangular shape, respectively, and the win
Ishikawa Teruhisa
Nakanose Takeharu
Osawa Yoshiki
Tanaka Yasufumi
Sherry Michael
Wenderoth , Lind & Ponack, L.L.P.
LandOfFree
Spiral electrode group winding method and device and battery... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Spiral electrode group winding method and device and battery..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Spiral electrode group winding method and device and battery... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3047346