JP6425563B2 - Equipment for producing doped electrode body - Google Patents

Description

  The present invention relates to an apparatus for producing a doped electrode body for a storage device, and more particularly to pre-doping of lithium ions into an active material on the surface of an electrode body of a lithium ion storage device (eg, lithium ion capacitor).

  A lithium ion battery (LiB), an electric double layer capacitor (LiB), as a lithium ion storage device that performs charging and discharging through adsorption and desorption of lithium ions and the like at electrodes made of carbon-based materials and movement of lithium ions between positive and negative electrodes. EDLCs and lithium ion capacitors (LiC) are known. Among them, lithium ion capacitors are attracting attention as being able to expect output characteristics suitable for the on-vehicle power source of electric vehicles and hybrid electric vehicles.

  In a conventional lithium ion capacitor, an electrode body (electrode body for negative electrode and electrode body for positive electrode) formed by applying an active material on both sides of a foil-like current collector having pores, and a lithium metal thin plate as a lithium supply source And are arranged in the same device. Then, after the assembly of the device is completed, the current collector of each negative electrode and the lithium metal thin plate are short-circuited through an external circuit to allow lithium ions released from the lithium metal thin plate to reach each negative electrode It is manufactured through an operation (generally called "pre-doping") of loading or occluding to an active material.

However, there are drawbacks to conventional manufacturing methods where pre-doping is performed using a lithium source in the device after cell assembly is complete. If there are only three major drawbacks,
B) As the negative electrode moves away from the lithium source, not only the lithium ion transport resistance increases, but also the ohmic loss increases because the ions pass through the pores of the current collector. For this reason, the transport speed of lithium ions tends to decrease exponentially with the increase in the number of stacked layers of the electrode body, and the time required for pre-doping becomes excessive.
B) The doping speed of lithium ions varies depending on the distance from the lithium source to the negative electrode, and the amount of lithium ions supported on each negative electrode and SEI (Solid Electrolyte Interface) generated by reduction reaction on the negative electrode active material surface The quality of the film (thickness, density, etc.) will also vary.
C) It is necessary to form a current collector into a pore structure in order to pass lithium ions at the time of pre-doping after completion of cell assembly, but pore processing of this current collector is a major factor of high cost.

  Due to the above-mentioned drawbacks, the conventional manufacturing process of pre-doping after cell assembly is reconsidered, and establishment of a new manufacturing method of assembling cells after pre-doping lithium ion pre-doping on individual electrode bodies before cell assembly is required. It is done.

  For example, as a method of pre-doping lithium ions to the active material of the electrode body before cell assembly, the technology of Patent Document 1 (Japanese Patent No. 5003088) is known. This patent document 1 discloses a method and apparatus for occluding (predoping, supporting) lithium ions in a negative electrode body for a non-aqueous electrolyte secondary battery. The method is carried out by the apparatus shown in FIG. 3 of Patent Document 1 through the following steps. First, the long strip-shaped negative electrode body (negative electrode precursor 20) wound up on the supply roll (21) is drawn out (A step). The extracted negative electrode body (20) is sent out and inserted into a dope tank (electrolytic tank 24) holding a non-aqueous electrolytic solution (25) containing lithium ions (step B). Next, the negative electrode body (20) is stretched between the first support roll (33A) and the second support roll (33B) while continuously feeding the negative electrode body (20). And an electrode (27) inert to the lithium supply installed so as to face the active material layer of the negative electrode body (20) in the negative electrode body (20) and the non-aqueous electrolyte (25). And lithium ions are pre-doped into the active material layer (step C). Subsequently, the negative electrode body (20) pre-doped with lithium ions is wound up by a winding roll (22) (step D). Then, in order to keep the lithium ion concentration in the non-aqueous electrolyte (25) substantially constant, the non-aqueous electrolyte (25) having the same composition as the non-aqueous electrolyte (25) is supplied to the dope tank (24). The same amount of non-aqueous electrolyte as the supply amount is removed from the dope tank (24) (step E). Thereby, the method of patent document 1 pre-dopes lithium ion to the active material layer of a negative electrode body (20) continuously.

Patent No. 5003088 gazette

  The method and apparatus of Patent Document 1 adopt a so-called "roll-to-roll system", and while continuously feeding a long strip-like electrode body and continuously supplying an electrolytic solution to the electrode body Pre-doping treatment, and finally winding up and recovering a lithium ion pre-doped doped electrode body. However, the prior art such as Patent Document 1 has the following typical problems caused by the roll-to-roll method.

  Generally, it is known that the active material itself is cured when the active material of the electrode body is pre-doped with lithium ions. This hardening is due to the expansion of the graphite and does not exhibit extreme hardness. However, in the roll-to-roll manufacturing method, the doped electrode body after the lithium ion pre-doping treatment is bent vertically upward through the second support roll having a small diameter without considering hardening of the active material. It is drawn out of the dope tank, and then the dope electrode body is wound on a winding roll. That is, since the cured active material layer is forcibly curved along the radius of the second support roll and the winding roll, the active material layer may be cracked, or the active material layer may be an electrode body (precursor before pre-doping Or separated from the doped electrode (pre-doped product). That is, in the conventional manufacturing method, it has been a problem that the doped electrode body is easily damaged in the manufacturing process, and the product quality and the yield decrease. On the other hand, there is an approach of increasing the curvature of winding to avoid such damage. However, an increase in roll radius leads to a scale-up of the apparatus and an increase in the amount of consumption of the electrolyte, so it is realistic in terms of cost and productivity, and in terms of time lag in drying in the removal direction. Absent.

  The present invention has been made to solve the above problems, and its object is to provide an electrode body having a pattern of an active material on its surface, in order to produce a stable quality doped electrode body while maintaining productivity. It is an object of the present invention to provide an apparatus for producing a doped electrode body in which the active material of the above is doped with lithium.

The apparatus for producing a doped electrode body according to claim 1 is an apparatus for producing a doped electrode body in which lithium is doped to an active material of an electrode body having a pattern made of an active material on the surface,
A first holder which holds the electrode body and has conductivity ;
A second holder for holding the first holder together with the electrode body and having a lithium source;
A doping bath in which the electrode body and the second holder are both immersed in the electrolytic solution;
A doped circuit for connecting the electrode body and the lithium source via the first holder and through the external circuit, and doping the active material with lithium;
Tona is,
The electrode body is a horizontally long rectangle, and the first holder is configured to hold at least the upper long side of the electrode body over the entire longitudinal direction .

The apparatus for producing a doped electrode body according to claim 2 is characterized in that, in the apparatus for producing a doped electrode body according to claim 1 , the electrode body is held vertically.

The apparatus for producing a doped electrode body according to claim 3 is the apparatus for producing a doped electrode body according to claim 1 or 2 , wherein the first holding member has the upper long side and the upper long side of the electrode body. It is characterized by holding.

The apparatus for producing a doped electrode body according to claim 4 is the apparatus for producing a doped electrode body according to any one of claims 1 to 3 , wherein the first holder is in the shape of a rod, a frame or a lattice. It is characterized by

  According to one aspect of the present invention, in the dope tank, the electrode body held by the first holding member is held (held or held in a sandwiched state) by the second holding member including the lithium source. In the state of (d), the active material is doped. Then, the dope electrode body is opened (or released) from the second holding portion by the first holding tool, and the doped electrode body is released (or released) from the first holding tool. It is possible to recover as a product. That is, in the present invention, it is possible to introduce the electrode body (or the doped electrode body) into the dope tank, carry out the electrolytic treatment and recover it in a straight state without giving a curvature consistently in each process. The term "straight" means that the target member is not in a curved state whether it is totally or partially. As a result, it is possible to effectively prevent breakage of the active material coated surface (that is, the pattern of the active material), which is hardened along with lithium ion loading, due to bending of the doped electrode body. At the same time, it is possible to prevent the R from sticking to the electrode body and the electrode body product before and after the pre-doping treatment, and to suppress peeling of the active material. Furthermore, according to the present invention, it is only necessary that the dope tank can introduce at least a first holder, a second holder (lithium source) and an electrode body (a conventional roll-to-roll type device It is possible to reduce the scale-down of the device and the consumption of the electrolyte. Therefore, the present invention provides a device for producing a doped electrode body capable of producing a stable quality doped electrode body with higher productivity.

  According to another feature of the present invention, the first holder is electrically conductive and is connected to the external circuit through the first holder, whereby the first holder can hold the holding means and the current supply means. It is also used. Thereby, the manufacturing apparatus of the dope electrode body can be simplified, and the productivity can be improved.

  According to a further feature of the present invention, the electrode body plane is supported along the vertical direction (direction along gravity) in the dope tank, so that the area required for the opening surrounded by the upper edge of the dope tank is increased. Reduced. That is, as compared with the case where the electrode body plane is disposed horizontally or inclined from the vertical direction, the area in which the electrolyte contacts the vapor phase through the upward opening of the dope tank is relatively reduced, It is possible to significantly reduce the volatilization amount of the electrolyte. By reducing the volatilization amount of the electrolyte, it is possible to save the consumption of the electrolyte and to improve the productivity in terms of cost.

  According to a further feature of the present invention, the electrode body is oblong rectangular and the first holder having conductivity holds at least the upper long side of the electrode body to provide a first longitudinal holding from the external circuit. The current is more uniformly supplied to the upper side of the electrode body through the tool. As a result, it is possible to suppress the occurrence of a difference in current density between each position along the longitudinal direction of the electrode body. That is, it is possible to equalize the current density in the active material coated surface on the electrode body and to suppress the occurrence of the variation in the lithium ion doping amount in the active material coated surface.

The manufacturing apparatus of the dope electrode body of one Embodiment of this invention WHEREIN: The schematic perspective view which showed the arrangement | positioning relationship of an electrode body, a 1st holder, and a 2nd holder. The schematic block diagram in the dope stage of the manufacturing apparatus of FIG. The schematic plan view when the manufacturing apparatus of FIG. 2 is looked down on from the top (a 1st holder is abbreviate | omitted and shown). An example of each material of the manufacturing apparatus of FIG. 1 is shown, (A) is a front view and xx sectional drawing of an electrode body, (B) is a front view of a 2nd holding tool, and yy sectional view. The form which used the 1st holding fixture of another example is shown, (A) shows the rod-shaped 1st holding fixture holding an upper side and a lower side of an electrode body, (B) is frame shape holding four sides of an electrode body. (C) shows a grid-like first holder partially covering the surface of the electrode body together with the four sides of the electrode body. The manufacturing apparatus of the dope electrode body using the electrode body of another example is shown, and the disassembled perspective view which showed the arrangement | positioning relationship of an electrode body, a 1st holding fixture, and a 2nd holding fixture. In the manufacturing apparatus of FIG. 6, (A) is a front view and zz sectional view of an electrode body, (B) is a schematic plan view when looking down at the manufacturing apparatus from above. Each process in the manufacturing method of the dope electrode body of one Embodiment of this invention is shown, (A) is a schematic diagram for demonstrating a 1st clamping process, (B) is for demonstrating a 2nd clamping process. The schematic diagram, (C) is a schematic diagram for demonstrating an immersion step. The graph which shows an example of a time-dependent change of the electric potential ([V] vsLi / Li +) of the electrode body with respect to the lithium source in a dope step. Each step in the manufacturing method of the dope electrode body of one embodiment of the present invention is shown, (A) is a schematic diagram for explaining a taking-out step, (B) is a schematic diagram for explaining a second opening step, (C) is a schematic diagram for demonstrating a 1st open | release step. The schematic block diagram of the cell for lithium ion capacitors (cell for electrical storage devices). The experimental example (comparative example) of a feed terminal is shown, (A) is a front view of an electrode body, (B) is a figure which shows the current density in a collector, (C) is the current density in an active material coating area | region. Figure showing. The experimental example (Example) of a feed terminal is shown, (A) is a front view of an electrode body, (B) is a figure which shows the current density in a collector, (C) is the current density in an active material coating area | region. Figure showing. The experimental example (Example) of a feed terminal is shown, (A) is a front view of an electrode body, (B) is a figure which shows the current density in a collector, (C) is the current density in an active material coating area | region. Figure showing.

  The electricity storage device according to the present invention comprises a pre-assembly electrolytic treatment step of subjecting the electrode body to electrolytic treatment to pre-dope lithium ions in the electrode body, and a cell assembly step of assembling a cell using a doped electrode body manufactured by pre-doping lithium ions. And manufactured. In particular, the method of manufacturing the electricity storage device of the present invention is characterized by the pre-assembly electrolytic treatment step.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The respective drawings referred to in the following description are merely conceptual diagrams or schematic diagrams for explaining the preferred embodiments, and the present invention is not limited to the illustrated embodiments.

  In the pre-assembly electrolytic treatment step of the present invention, for example, a manufacturing apparatus 10 for a doped electrode body as shown in FIGS. 1 to 3 is used. FIG. 1 is a schematic perspective view showing the positional relationship of each component of the manufacturing apparatus 10 of the present embodiment (for convenience of explanation, the doping bath 11, the doping circuit 15, and the control unit 17 are not shown). FIG. 2 is a schematic block diagram (side cross section) of the doping step of the manufacturing apparatus 10. And FIG. 3 is a schematic plan view (when the first holder 13 is not shown for convenience of explanation) when the manufacturing apparatus 10 of FIG. 2 is viewed from above.

  The manufacturing apparatus 10 of the present embodiment is an apparatus for predoping lithium ions to the electrode body 20 in order to manufacture a doped electrode body (negative or positive doped electrode body) to be incorporated into a cell for lithium ion capacitors. However, it goes without saying that the present invention is widely applicable without being limited to the doped electrode body of the cell for lithium ion capacitors.

  As shown in FIGS. 1 to 3, the manufacturing apparatus 10 holds the first holder 12 holding the electrode assembly 20, and holds the first holder 12 together with the electrode assembly 20, and a lithium source (metallic lithium 13 b ), The doping bath 11 for immersing both the electrode body 20 and the second holding tool 13 in the electrolyte, the electrode body 20 and the lithium source (or lithium ion source) as an external circuit , And a control unit 17 for controlling the doped circuit 15. On the other hand, the electrode body 20 subjected to the electrolytic treatment in the manufacturing apparatus 10 includes a foil-like or plate-like current collector 21 and an active material 22 coated on the surface of the current collector 21. Hereinafter, each component of the manufacturing apparatus 10 and the electrode body 20 will be described in detail.

  In the manufacturing apparatus 10 of this embodiment, the dope tank 11 includes a bottom wall 11a, a side wall 11b erected substantially perpendicularly from the bottom wall 11a, and an opening 11c surrounded by the upper end edge of the side wall 11b. It is a rectangular parallelepiped case capable of holding the liquid 19. The dope tank 11 accommodates the second holder 13 having a lithium source, and has a size capable of introducing or accommodating the strip-like electrode body 20 kept straight. In addition, the doping tank 11 is configured to vertically support the electrode body 20 and the second holding tool 13, and it is determined that the area of the opening 11c is smaller than the area of each surface of the side wall 11a. preferable. In the said preferable embodiment, the area of the electrolyte solution 19 exposed to a gaseous phase can be reduced, and the volatilization amount of the electrolyte solution 19 can be reduced.

  The first holder 12 is formed of a pair of elongated rod-like metal pieces having conductivity. The pair of metal pieces of the first holder 12 can be detachably coupled by a plurality of connection members 12a (such as screws and scissors), and the entire upper side (long side) of the current collector 21 of the electrode body 20 can be held. Is configured. A lead wire is attached to the first holder 12, and is electrically connected to the doping circuit 15 and the control unit 17 (potential sensor 17a) (see FIG. 2). In the present embodiment, the first holder 12 is made of a copper plate, but another conductive metal material may be selected.

  It is preferable that the first holder 12 be configured to hold at least the upper long side of the electrode body 20. For example, in addition to the aspect of FIG. 1, it is preferable that the first holder 12 be configured to hold the entire upper side and the entire lower side as shown in FIG. Alternatively, as shown in FIG. 5 (B), the first holder 12 may be configured in a frame shape (frame shape) so as to hold the four sides of the electrode body 20. Furthermore, as shown in FIG. 5C, the first holding tool 12 holds the four sides of the electrode assembly 20 and surrounds the plurality of active material coated surfaces 22 (see FIGS. 6 and 7). It may be configured in a shape.

  The second holder 13 is prepared as a plate-like member (that is, a lithium supply electrode) containing metallic lithium which is a lithium source. FIG. 4B is a front view and a yy cross-sectional view of the second holder 13. As shown in FIG. 4B, the second holder 13 is a metal plate formed by supporting the metal lithium 13b on the entire surface on one side of a horizontally long rectangular metal terminal plate 13a (for example, a copper plate, copper foil). In the present embodiment, the metallic lithium 13b may be directly attached to the metallic terminal plate 13a, or a copper mesh sheet may be interposed between the metallic terminal plate 13a and the metallic lithium 13b. The metal lithium 13b supported on the metal terminal plate 13a may be in the form of a foil, a plate, or a block, and in some cases, the lithium lumps or pieces may be packed in a metal mesh It may be press-formed into a block shape.

  In the present manufacturing apparatus 10, as shown in FIG. 1 to FIG. 3, the surfaces are aligned along the vertical direction so that the metal lithiums 13b of the pair of second holders 13 face each other in parallel in the dope tank 11. . The pair of second holders 13 is disposed or immersed in the dope tank 11 so that the flat surface is parallel to one side wall 11 b. In the present embodiment, the long width of the second holder 13 is disposed along the horizontal direction, but the long width may be disposed along the vertical direction. In addition, the pair of opposing metal lithium 13b are separated by an interval that allows the electrode assembly 20 to be disposed in parallel and in a noncontact manner therebetween. And the metal terminal board 13a of the 2nd holding tool 13 and the doping circuit 15 are connected via the lead wire (refer FIG. 2).

  In addition, when the 2nd holding fixture 13 of this embodiment sets the electrode assembly 20 to the electrolytic treatment position, the said 2nd holding fixture 13 which opposes the active material coated surface 22 of the electrode assembly 20 (more specifically, It is preferable that the area of the lithium metal 13 b) be larger than the area of the active material coated surface 22. If the area of the second holding tool 13 is equal to or less than the area of the active material coated surface, it is likely to interfere with the uniform pre-doping of lithium ions to the entire active material coated surface.

  The doping circuit 15 is a so-called external circuit or an external power supply disposed outside the doping bath 11. The doping circuit 15 can supply a predetermined direct current through a lead wire connecting the first holder 12 (the current collector 21a of the electrode body 20) and the second holder 13 (metal terminal plate 13a). It is configured. In addition, a control unit 17 capable of controlling the on / off of the switch of the doping circuit 15 and the supply current is connected to the doping circuit 15. The control unit 17 is provided with a potential sensor 17 a that measures the potential of the electrode body 20 with respect to the second holder 13. That is, the control unit 17 displays or monitors the time change of the potential difference read by the potential sensor 17a, and controls the doping circuit 15 based on the value of the potential difference. As described later, it is possible to monitor the amount of lithium ions supported on the active material 22 based on this potential difference (see FIG. 9). In addition, current control may not always be necessary if short circuiting is used.

  Next, the electrode body 20 of the present embodiment will be described. The electrode body 20 is a strip-shaped member which constitutes the negative electrode (or positive electrode) of the electricity storage device. As shown to FIG. 4 (A), the electrode body 20 is equipped with the foil-like or plate-like collector 21 and the active material 22 coated by the coating area | region of the surface of the both sides. In the present embodiment, the active material 22 is applied in a predetermined pattern on the surface of the current collector 21 of a single long rectangular plate and the back surface of the current collector 21 in a single rectangular shape. The active material 22 extends in the longitudinal direction of the current collector 21. On the other hand, near the upper edge and the lower edge of the electrode body 20, the current collector 21 is exposed. Then, when the electrode assembly 20 is disposed at the electrolytic processing position, the lead wire extending from the doping circuit 17 is connected to the current collector 21 through the power supply terminal (first holder 12).

  The current collector 21 is made of, for example, a conductive metal of copper (Cu), and is preferably provided as a rectangular foil or plate. In the present invention, the current collector 21 does not need to have pores, but may have pores penetrating the front and back of the current collector 21.

  The active material 22 to be coated on the surface of the current collector 21 is not particularly limited as long as it can occlude and support lithium ions reversibly, but specific examples thereof include carbon materials such as graphite and amorphous carbon, Known active materials such as polyacene organic compounds can be mentioned. The active material 22 is prepared in the form of a slurry with a suitable dispersion medium (for example, water), applied to the surface (preferably both surfaces) of the current collector 21 and then dried by warm air drying and / or reduced pressure drying. It is fixed on the current collector. The form of the coating (the shape and arrangement of the active material coated surface, etc.) is not particularly limited. For example, the surface of the current collector 21 in the form of an oblong rectangle has the active material coated surface over the entire longitudinal direction. A plurality of substantially square active material coated surfaces 22 are formed on the surface of the horizontally long rectangular current collector 21 by coating 22 in a strip shape, or another example shown in FIG. 6 and FIG. It is preferable to coat so as to be arranged in series. In the present specification, a single active material coated surface 22 or an aggregate of the active material coated surface 22 composed of a plurality of frames is referred to as a “active material pattern”.

  In the pre-assembly electrolytic treatment process of the present embodiment, as shown in FIGS. 1 to 3, the first holding tool 12 is held together with the electrode assembly 20 by the pair of second holding tools 13 (that is, the pair of second holding tools). The active material coated surface 22 of the electrode body 20 and the metal lithium 13 b of the second holding tool 13 in a state where the first holding tool 12 is held or maintained together with the electrode body 20 in a state of being sandwiched between the holding tools 13 Are arranged substantially in parallel and opposite to each other. Then, in the preferred embodiment of the present invention, the electrode body 20 is supported in the doping tank 11 so that the plane is parallel to the vertical direction (gravity direction). That is, in the doping step of the present manufacturing apparatus 10, the electrolytic treatment position of the electrode body 20 is an intermediate position between the pair of second holders 13 and a position disposed parallel to the second holder 13 plane. It will be determined. The “electrolytic treatment position” indicates the position at which the electrolytic treatment is performed on the electrode body 20, and it does not matter whether the electrode body 20 is stationary with respect to the second holding tool 13.

  Further, in the present embodiment, the planes of the second holder 13 and the electrode body 20 are arranged in parallel in parallel to one surface of the side wall 11 b of the dope tank 11 and the side end surfaces of the second holder 13 and the electrode body 20 The upper surface faces the opening 11c vertically above. The opening 11 c of the doping tank 11 is formed to have a size (area) capable of accommodating the side end surfaces of the second holding tool 13 and the electrode assembly 20 on the horizontal plane. In the present embodiment, the long sides of the electrode body 20 are disposed along the horizontal direction, but the short sides of the electrode body 20 may be disposed along the horizontal direction. By arranging in this manner, the area of the opening 11 c of the doping tank 11 can be designed to be smaller.

  The electrode body 20 is held by the first holder 12 and vertically supported. The support means (not shown) of the first holder 12 can be appropriately selected by those skilled in the art. For example, the first holder 12 may be vertically suspended from above by an arm or the like. Alternatively, a separator may be interposed so as to fill the space between the first holding tool 12 (or the electrode assembly 20) and the second holding tool 13, and both may be held so as to hold the first holding tool 12 by the second holding tool 13. It may be fixed relatively. The separator may be a relatively thin liquid-absorbent insulating material (for example, paper, felt, resin fiber sheet, etc.) having a size corresponding to the size of the electrode body 20. By arranging the separator, direct contact (electrical short circuit) between the electrode assembly 20 and the second holder 20 can be prevented, and a safe and stable electrolytic treatment can be realized.

  The electrolytic solution 19 (electrolytic solution for electrolytic treatment) used in this electrolytic treatment step is an organic solvent (not capable of maintaining the liquid state by heating) which can promote the formation of the SEI film on the surface of the active material during electrolytic treatment. Lithium salt as a supporting electrolyte is dissolved in a low melting point organic substance).

  As organic solvents usable for the electrolytic solution for electrolytic treatment, cyclic esters such as ethylene carbonate (EC, ethylene carbonate, melting point: 34 to 37 ° C.), vinylene carbonate (VC), fluoroethylene carbonate (FEC), etc. And linear ester systems such as ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC) and the like.

Moreover, LiTFSI, LiFSI, LiPF ₆ , LiClO ₄ , LiBF ₄ can be exemplified as the supporting electrolyte in the electrolytic solution for electrolytic treatment. Here, TFSI refers to trifluoromethanesulfonyl Imide, and FSI refers to fluoromethanesulfonyl Imide.

  Next, with reference to FIGS. 8 to 10, a method of manufacturing a doped electrode body to be incorporated into a cell for a power storage device by pre-doping lithium ions on a strip-like electrode body using the manufacturing apparatus 10 of the present embodiment. Each step will be described in detail by reference. Specifically, the present invention relates to a method of manufacturing a negative electrode assembly to be incorporated into a lithium ion capacitor cell as shown in FIG.

  First, the strip-like electrode body 20 is pinched by the first holder 12 in the first pinching step. More specifically, as shown in FIG. 8A, the long side on the upper side of the current collector 21 on which the active material 22 of the electrode body 20 is not coated is held by the pair of holding pieces of the first holder 12 Do. The pair of holding pieces are approached and fixed by a connecting member 12a such as a screw. Then, in the first holding stage, the strip-like electrode body 20 is held straight by the first holder 12. At this time, the first holder 12 is connected to the doping circuit 15 through the lead wire, but may be connected by the lead wire immediately before the doping step.

  Next, in the second holding step, the first holder 12 is held together with the electrode body 20 in the (pair of) second holders 13 having the lithium source 13 b. More specifically, as shown in FIG. 8 (B), the first holding member 12 for holding the electrode assembly 20 in a state where the active material coated surfaces 22 on both sides are disposed opposite to each other with respect to the pair of metal lithium 13b. Are arranged relatively fixed between the second holding devices 13. Although a means for fixing (holding) the first holding tool 12 by the second holding tool 13 is not shown, a fixing member (frame or arm) disposed on the upper side or the back of the second holding tool 13 or the first holding tool It can be selected from the separators sandwiched between 12 and the second holder 13. As a result, in the second holding stage, the strip-like electrode body 20 is held straight by the second holder 12. At this time, the second holder 13 is connected to the doping circuit 15 through the lead wire, but may be connected by the lead wire immediately before the doping step. In addition, in the Y direction of FIG. 1, the form by which the 1st holding tool 12 was hold | maintained or fixed between a pair of 2nd holding tools 13 with "clamping" of the 1st holding tool 12 by the 2nd holding tool 13 is mentioned. means. That is, in the present invention, the first holder 12 may not be shifted in the X direction or the Z direction to face the second holder 13.

  Then, in the immersing stage, the electrode assembly 20 and the second holder 13 are both immersed in the dope tank 11 filled with the electrolyte solution 19. More specifically, as shown in FIG. 8C, the second holding tool 13 holding the first holding tool 12 together with the electrode assembly 20 is linearly linear in the vertically downward direction through the opening 11 c of the doping bath 11. The strip-like electrode body 20 which has been moved and kept straight is introduced into the dope tank 11. In this step, the strip-like electrode body 20 is inserted into the casing from the opening 11 c of the dope tank 11 while being held straight by the first and second holders 12 and 13 so as not to have a curvature. Do. At least the active material 22 and the metallic lithium 13b are immersed in the electrolytic solution 19 of the doping tank 11, and as a result, the electrode body 20 is vertically erected at the middle electrolytic treatment position of the opposing second holding tool 13. That is, from the first holding step to the immersion step, the strip-like electrode body 20 can be introduced into the electrolytic processing position while being held straight so as not to have a curvature. Although not shown, the first and second holders 12 and 13 may be handled manually using a jig or the like, or may be handled automatically by a robot arm or the like. In the main immersion step, the strip-like electrode body 20 may be immersed in the dope tank 11 holding the electrolytic solution 19 in advance, or the electrolytic solution 19 is injected after the electrode body 20 is disposed at the electrolytic treatment position. May be

  Then, in the doping step, the electrode body 20 and the metallic lithium 13b (lithium supply source) are electrically connected through the doping circuit 15 (external circuit), the active material 22 is doped with lithium, and the doped electrode body 20 'is obtain. That is, the active material coated surface 22 of the electrode body 20 and the second holder 13 including the lithium source are disposed opposite to each other with the electrolytic solution 19 interposed therebetween, and the current collector 21 and the lithium source 13 b Are electrically connected through the doping circuit 15, whereby the active material 22 is electrolytically treated to pre-dope lithium ions. In this doping step, the doping circuit 15 starts supply of direct current to the lithium source 13 b and the electrode assembly 20 according to an instruction from the control unit 17 (or by manual operation). In the present embodiment, the current supplied by the doping circuit 15 is a constant current, and the current value is about 2.3 mA.

  In this doping step, the electrolytic treatment is preferably performed in a state in which the electrode body 20 and the second holder 13 are relatively stationary. By performing the electrolytic treatment in such a state, it is possible to prevent the flow of the electrolyte solution 19 in the dope tank 11 or the occurrence of the time difference of the outside air exposure along the length direction of the electrode body 20. Thereby, electrolytic processing can be performed under a stable environment. Further, it is more preferable to maintain the electrolytic solution 19 so that the electrolytic solution 19 does not flow in the dope tank 11 during the electrolytic treatment. That is, in the present embodiment, by employing the metal lithium 13 b for the second holder 13, it is not necessary to keep flowing the electrolytic solution 19 during the electrolytic treatment. As a result, the amount of use of the electrolyte solution 19 can be suppressed, and pre-doping can be performed in a more stable environment.

  In the doping step, the electrolytic treatment is performed in a state in which the electrode assembly 20 and the second holder 13 are relatively stationary, and the loading amount of lithium ions on the active material 22 of the electrode assembly 20 is monitored. It is preferable to include.

  In the present embodiment, the potential sensor 17a can measure the potential ([V] vs Li / Li +) of the electrode body 20 (first holder 12) with respect to the lithium source 13b (second holder 13). By displaying or monitoring the time change of the potential via the control unit 17, it is possible to quantitatively determine the amount of lithium ions supported on the active material 22 of the electrode assembly 20. That is, by reading this potential, it is possible to accurately determine the point at which the lithium ion pre-doping is completed. For example, when the control unit 17 detects that the potential at the potential sensor 17a has reached a predetermined value, it determines that pre-doping of lithium ions is completed, and cuts off the power supply from the doping circuit 15. You may control. Generally, when the reference lithium electrode is placed at a place where an electric field is applied (during an electric field), the electric potential can not be accurately measured due to the influence of the IR drop. On the other hand, in the present embodiment, the lithium source 13b itself is a target of sensing as a reference (reference) lithium electrode, and the reference lithium electrode is disposed on the side surface of the negative electrode (electrode assembly 20). That is, in this embodiment, it is advantageous that the reference lithium electrode can be disposed at the side position of the negative electrode in the stationary state at the end (or outside) of the electric field. As a result, the influence of IR drop is suppressed and more accurate measurement values can be obtained.

  FIG. 9 is a graph illustrating the time change (minutes) of the potential ([V] vs Li / Li +) read by the potential sensor 17a. As shown in FIG. 9, the amount of lithium ions supported on the active material 22 increases with the passage of time of the electrolytic treatment, and the potential of the electrode body 20 with respect to the second holder 13 decreases exponentially. Finally, as the supported amount of lithium ions of the active material 22 reaches an equilibrium state, the potential converges to a predetermined value, and pre-doping is completed. For example, if the final potential indicating that pre-doping is completed is set to 72 mV in the main doping step, control unit 17 detects completion of pre-doping when the potential reaches 72 mV after 15.4 minutes from the start of electrolytic treatment Do. Then, the control unit 17 disconnects the feeding of the doping circuit 15, and ends the electrolytic treatment of the batch. That is, the manufacturing apparatus 10 of the present embodiment can manage the behavior of pre-doping almost accurately, and can control the SEI quality and the lithium ion loading amount.

  Subsequently, the lithium ion pre-doped doped electrode body 20 ′ is taken out, is subjected to the second open stage and the first open stage, and is recovered straight from the dope tank 11. In the removal step, at least the doped electrode body 20 ′ is removed from the doping bath 11. More specifically, as shown in FIG. 10A, the second holder 13 holding (holding) the first holder 12 together with the dope electrode body 20 ′ is pulled up vertically and taken out from the dope tank 11. In the second opening stage, the first holder 12 is released from the second holder 13 having the lithium source 13b together with the doped electrode body 20 '. More specifically, as shown in FIG. 10 (B), the fixing of the second holder 13 to the first holder 12 and the doped electrode body 20 ′ is released, and the pair of second holders 13 is moved outward. Let Then, in the first opening stage, the doped electrode body 20 ′ is released from the first holder 12. More specifically, as shown in FIG. 10C, the connection of the connecting member 12a in the first holder 12 is loosened to separate the first holder 12 from the dope electrode body 20 '. As a result, the doped electrode body 20 'in which lithium ions are pre-doped to the electrode body 20 can be recovered in a straight state.

  Through the above steps, the lithium ion can be pre-doped on the electrode assembly 20 in the pre-assembly electrolytic treatment process to manufacture the doped electrode assembly 20 '. It is also possible to control these series of steps by the control unit 17 and execute them automatically.

  The manufacturing method described here is merely an example, and the person skilled in the art can change the order of the steps, change or omit unnecessary steps depending on the situation, or add additional steps. Is also possible. For example, the soaking stage may be performed prior to the first clamping stage and the second clamping stage. That is, the electrode assembly 20, the first holding tool 12 and the second holding tool 13 are introduced into the dope tank 11, and the first holding tool 12 and the second holding tool 13 are operated in the dope tank 11 to You may hold it. Also, a second opening stage and a first opening stage may be performed prior to the removal stage. That is, the dope electrode body 20 ′ may be released by operating the first holder 12 and the second holder 13 in the dope tank 11, and only the dope electrode body 20 ′ may be taken out from the dope tank 11.

  Then, in the cell assembly process which is the next process of the pre-assembly electrolytic treatment process, the cell of the storage device (lithium ion capacitor) is assembled using the doped electrode body pre-doped with lithium ions in the above-described pre-assembly electrolytic treatment process. Be

  For example, FIG. 11 shows a lithium ion capacitor cell 30 in which a negative electrode body 31 (corresponding to a pre-doped doped electrode body 20 ') manufactured by the manufacturing apparatus 10 is incorporated. As shown in FIG. 11, in the lithium ion capacitor cell 30, the negative electrode active material 31b coated on the negative electrode current collector 31a is coated on the negative electrode body 31 in which lithium ions are predoped and the positive electrode current collector 32a. And a positive electrode body 32 having a positive electrode active material 32b such as activated carbon. That is, the doped electrode body 20 ′ corresponds to the negative electrode body 31, and the opposite electrode is the positive electrode body 32. In the lithium ion capacitor cell 30, the negative electrode body 31 and the positive electrode body 32 are alternately stacked. The negative electrode current collector 31 a of each negative electrode body 31 is electrically connected to a negative electrode terminal 35 as an external terminal by a lead 34. Similarly, the positive electrode current collector 32 a of each positive electrode body 32 is electrically connected to a positive electrode terminal 36 as an external terminal by a lead 34. Further, a separator 33 for preventing contact between the adjacent electrode bodies 31 and 32 is disposed. Then, the electrode stack with the leads is enclosed in a container (package) 37 together with the cell electrolyte 38. As the cell electrolyte, one to which the same electrolyte as that used in the electrolytic treatment electrolyte is added can be used. That is, in the assembly process, the doped electrode body 31 (20 ′) is laminated together with the counter electrode 32 and the separator 33 to obtain an electrode laminate, and then the electrode laminate and the electrolytic solution 38 are sealed in the container 37. And storage devices (lithium ion capacitors) can be manufactured.

  Hereafter, the effect in the manufacturing apparatus 10 of the dope electrode body of one Embodiment which concerns on this invention is demonstrated.

(1) According to the present embodiment, the strip-shaped electrode body 20 is introduced, electrolyzed, and recovered in a straight state without curvature consistently in each process. Thereby, it is possible to effectively prevent the active material coated surface 22 which has been hardened along with lithium ion support from being damaged by the bending of the electrode body 20. At the same time, it is possible to prevent the R from sticking to the electrode body 20 before and after the pre-doping treatment and the doped electrode body 20 '(the negative electrode body 31), and to suppress the subsequent peeling of the active material 22. Furthermore, in the present embodiment, the doping bath 11 may be capable of introducing or accommodating at least the second holding tool 13 and the strip-like electrode body 20, and a plurality of the doping baths 11 may be provided as compared with the conventional roll-to-roll system. It is possible to omit materials (supporting rolls, electrolytic rolls, etc.), and to reduce the scale of the apparatus and the consumption of the electrolyte solution 19. Therefore, the method and apparatus 10 for manufacturing a doped electrode body according to the present embodiment can manufacture a stable quality doped electrode body 20 'with higher productivity.

(2) According to the present embodiment, the electrolytic treatment is performed in a state where the electrode assembly 20 and the second holder 13 are relatively stationary, thereby making it possible to manufacture the doped electrode assembly 20 'of stable quality. It is a thing. Further, the electrolytic solution 19 is maintained without being continuously supplied so that the electrolytic solution 19 does not flow in the dope tank 11 during the electrolytic treatment. For example, in the conventional roll-to-roll method as disclosed in Patent Document 1, the electrode body is pre-doped while continuously supplying the electrolytic solution and continuously transporting the long strip-shaped electrode body at a constant speed. That is, since the electrode body is constantly moving, the flow of the electrolyte in the dope tank may occur, or the time difference of the external air exposure along the length direction of the electrode body may occur, etc. The pre-doping environment becomes unstable. In addition, since the electrolytic solution is continuously supplied to maintain the concentration of the electrolytic solution, a large amount of the electrolytic solution is required. Furthermore, in such a state where the strip-like electrode body is continuously moving, it is difficult to locally measure the potential of the electrode body to monitor the lithium ion loading amount of the active material during pre-doping treatment. There is no way to control the lithium ion loading properly. Therefore, in the conventional manufacturing method, a large amount of electrolytic solution is required, and moreover, the quality of the SEI film and the amount of lithium ion deactivation vary, and it is a problem that stable quality can not be obtained. The On the other hand, in the present embodiment, the electrolytic treatment is performed in a state where the electrode body 20 and the second holder 13 are relatively stationary, so that the electrolyte solution 19 flows in the dope tank 11, or the electrode It prevents the deterioration of the quality of the doped electrode body 20 'due to the occurrence of the time difference of the external air exposure along the length direction of the body 20. And since electrolysis processing is performed by a batch type (static state), accurate electric potential measurement and control of the amount of supported lithium are possible using the control part 17 and the electric potential sensor 17a for every electrolysis processing. Thereby, the amount of use of the electrolytic solution 19 can be suppressed, and the variation in SEI quality and the amount of Li carried can be significantly improved.

(3) According to the present embodiment, the strip electrode body 20 is supported along the vertical direction (the direction along the gravity) in the dope tank 11 so that it is surrounded by the upper edge of the dope tank 11. The area required for the opening 11c is reduced. That is, the opening 11 c of the doping tank 11 has an area (that is, plate thickness × length of side) capable of introducing or accommodating the side end surface (upper end surface) of the second holder 13 and the electrode body 20. Just do it. Therefore, the area required for the opening 11 c of the doping tank 11 is largely suppressed as compared with the case where the flat surfaces of the second holding tool 13 and the electrode body 20 are arranged horizontally or in a state where the plane is inclined from the vertical direction. As a result, it is possible to relatively reduce the area of the electrolyte solution 19 in contact with the gas phase through the upward opening 11 c of the dope tank 11 and to significantly reduce the volatilization amount of the electrolyte solution 19. By reducing the volatilization amount of the electrolytic solution 19, it is possible to save the consumption of the electrolytic solution 19 and improve the productivity in terms of cost. At the same time, it is possible to improve the safety in the manufacturing process by reducing the danger such as ignition and explosion due to the volatilization of the organic substance contained in the electrolytic solution 19. Furthermore, by arranging the electrode assembly 20 in the vertical direction, the reducing gas (e.g., CO ₂ , HF) generated during the electrolytic treatment in the doping step can be released upward and easily removed from the doping tank 11 . As a result, it is possible to suppress the possibility that the reducing gas will remain as air bubbles between the second holder 13 and the active material coated surface 22 of the electrode body 20 to affect the distribution of the amount of lithium ions supported. That is, the pre-doping quality of the doped electrode body 20 'can be improved.

(4) The present embodiment also solves the following problems. As a problem with conventional roll-to-roll equipment, a lithium source is supplied to a pre-doped electrode body stretched between a supply roll and a take-up roll so that the pre-doped electrode body can be used for cell assembly. And the process of taking it out of the dope tank and recovering it from the apparatus is not easy. That is, in the complicated recovery process of the roll-to-roll system, product handling errors and the like are likely to occur, and the quality deterioration such as peeling of the active material may be concerned. On the other hand, in the present embodiment, strip-shaped electrode bodies are adopted, and each of them is subjected to batch processing, which is free from the troublesome handling in the roll-to-roll manufacturing method.

(5) In the present embodiment, the electrode body 20 is a horizontally long rectangle, and the conductive first holder 12 holds at least the upper long side of the electrode body 20. That is, it can be considered that the feed terminal is provided over the entire upper side of the electrode body 20. Hereinafter, how the difference in the form of the power supply terminal (first holder 12) attached to the current collector 21 of the electrode body 20 affects the current density distribution on the current collector 21 and the active material coated surface 22 The analysis by computer simulation was performed. Specifically, three types of feed terminal models shown in FIGS. 12, 13 and 14 were examined. In the said analysis, the electrode body 20 shown in FIG. 6 was adopted.

  FIG. 12A is a two-contact power supply model. That is, round terminal-like power supply terminals 91 (shown by black circles) are set at two places near the upper side of the horizontally-long rectangular current collector (current collector foil) 21. The left round terminal 91 is located at the boundary between the first active material coated surface 22 and the second active material coated surface 22 from the left, and the right circular terminal 91 is the first active material from the right It is located at the boundary between the coated surface 22 and the active material coated surface 22 of the second frame.

  FIG. 12B schematically shows the distribution of the current density in the current collector 21 in the two-contact power supply model. In the actual computer simulation, the current density distribution is displayed on the display screen while being color-coded by about 20 natural color gradations, but FIGS. 12 (B) and (C), FIGS. 13 (B) and (C), and In FIG. 14 (B) and (C), it is simplified and displayed on three steps gradation for patent drawing (namely, H = high density, M = middle density, L = low density). As can be seen from FIG. 12B, the current density is high in the region near each of the round terminals 91, but the lower left corner, the lower right corner, and the central region of the current collector 21 far away from each of the round terminals 91. The current density is low.

  FIG.12 (C) shows typically the distribution condition of the current density in each coma of the active material coated surface 22 in a 2 contact electric power feeding model. As can be seen from FIG. 12C, concentration of current density is observed in the area near each of the round terminals 91.

  FIG. 13A shows an upper side feed model. That is, along the entire upper side of the horizontally long rectangular current collector (current collector foil) 21, a long strip-like feeding terminal 92 (shown by a blackened band) having the same length as the upper side is provided. ing. That is, the feed terminal 92 corresponds to the first holder 12 of the embodiment of FIG.

  FIG. 13 (B) schematically shows the distribution of the current density in the current collector 21 in the upper side power feeding model. As can be seen from FIG. 13B, the current density tends to gradually decrease from the upper side to the lower side of the current collector 21, but the difference in current density between the respective positions along the longitudinal direction of the current collector 21. Has not occurred.

  FIG. 13 (C) schematically shows the distribution of current density in each frame of the active material coated surface 22 in the upper side power feeding model. As can be seen from FIG. 13 (C), every piece of the active material coated surface 22 has a substantially even current density.

  FIG. 14A shows the upper and lower side power supply model. That is, along the entire upper and lower sides of the horizontally long rectangular current collector (current collector foil) 21, long strip-like feeding terminals 92 and 93 (black-painted bands) having the same length as the upper and lower sides. ) Are provided in pairs. That is, this form corresponds to the first holder 12 of the embodiment of FIG. 5 (A).

  FIG. 14 (B) schematically shows the distribution of current density in the current collector 21 in the upper and lower side power feeding model. As can be seen from FIG. 14B, the current density is highest near the upper and lower sides of the current collector 21 and tends to gradually decrease toward the middle of the current collector 21 in the height direction. There is no difference in current density between each position along the longitudinal direction of the current collector 21.

  FIG. 14C schematically shows the distribution of current density in each frame of the active material coated surface 22 in the upper and lower side power feeding model. As can be seen from FIG. 14 (C), every piece of the active material coated surface 22 has a substantially even current density.

  As can be seen from the comparison of FIGS. 12, 13 and 14, a long feed terminal 92 having substantially the same length as the long side of one side or two sides of the long side of the rectangular current collector 21. , 93, the current density at the active material coated surface 22 on the current collector 21 can be equalized. As a result, it is possible to suppress the occurrence of the variation in the lithium ion doping amount in the active material coated surface 22.

(Modification)
The apparatus for producing a doped electrode body of the present invention is not limited to the above embodiment, and can be modified, for example, as follows.

(1) In the above embodiment, the second holder is obtained by bonding metal lithium to a metal terminal plate, but it is sufficient if the active material can be doped with lithium ions, and the present invention is not limited to this. For example, the second holder may be a material inert to lithium ions, such as a carbonaceous material such as glassy carbon and a sintered graphite, or a noble metal such as platinum. Even in such a case, the second holder serves as a lithium supply source (lithium ion supply electrode), consumes lithium ions in the electrolytic solution, and can pre-dope the electrode body.

(2) In the above embodiment, the electrolytic treatment is performed with the electrode body and the second holder relatively stationary, but if the quality deterioration is not taken into consideration, the electrolytic treatment is performed with the relative movement. It may be executed. Furthermore, it is also possible to omit the step of monitoring the lithium ion loading amount without performing the pre-doping treatment in a stationary state.

  The present invention is not limited to the above-described embodiment and modifications, and may be embodied in various forms within the technical scope of the present invention.

DESCRIPTION OF REFERENCE NUMERALS 10 manufacturing apparatus 11 dope tank 11 c opening 12 first holder 13 second holder 13 a metal terminal plate 13 b lithium metal (lithium supply source)
15 Doped circuit (external circuit, external power supply)
Reference Signs List 17 control unit 17a potential sensor 19 electrolyte 20 electrode body 20 'doped electrode body 21 current collector 22 active material, active material coated surface 30 cell for lithium ion capacitor 31 negative electrode body (doped electrode body)
32 Positive electrode body (counter electrode)
33 separator 34 lead 35 negative terminal 36 positive terminal 37 package 38 electrolyte for cell

Claims (4)

It is a manufacturing apparatus of the dope electrode body which dopes lithium to the said active material of the electrode body which has a pattern which consists of an active material on the surface,
A conductive first holder holding the electrode body;
A second holder for holding the first holder together with the electrode body and having a lithium source;
A doping bath for immersing both the electrode body and the second holder in an electrolytic solution;
A doping circuit for connecting the electrode body and the lithium source via the first holder and through an external circuit, and doping the active material with lithium;
Tona is,
The electrode body is a horizontally long rectangle, and the first holder is configured to hold at least the upper long side of the electrode body over the entire longitudinal direction . manufacturing device. The apparatus according to claim 1 , wherein the electrode body is vertically held. The apparatus for manufacturing a doped electrode body according to claim 1 or 2 , wherein the first holding tool holds the lower long side together with the upper long side of the electrode body. The apparatus for producing a doped electrode body according to any one of claims 1 to 3 , wherein the first holder is in the shape of a rod, a frame, or a lattice.

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