JP2008159314A - Lithium ion occlusion/release type organic electrolyte storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase productivity by smoothly conducting pre-occlusion of lithium ions in a negative electrode, and reducing processes or frequencies handling lithium metal in a production process in a lithium ion occlusion/release type storage battery using a laminated electrode formed by laminating rectangular sheet-like positive electrode and negative electrode through a separator. <P>SOLUTION: The lithium occlusion/release type organic electrolyte storage battery uses a laminated electrode body 20 formed by laminating the rectangular sheet-like positive electrode part 21 and negative electrode part 23 through the separator 22, and one side of a sheet-like negative current collector is protruded to the side of the laminated electrode body 20, and lithium metal 41 for pre-occluding lithium ions in the negative electrode is installed along a protruded part 232a in an electrically conductive state with a negative electrode 231. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lithium ion storage / release type organic electrolyte storage battery, and in particular, a positive electrode capable of reversibly carrying lithium ions or anions, a negative electrode capable of storing and releasing lithium ions, and a non-lithium containing a lithium salt. The present invention relates to a reversible charge / discharge operation using a water electrolyte.

  In recent years, electronic devices have dramatically increased the amount of data handled by small devices due to high performance. Along with this, the need for a small uninterruptible power supply is increasing in order to protect the data from a power failure.

  As the uninterruptible power supply, one using a lead storage battery has been conventionally provided. However, since lead is used, the use of the uninterruptible power supply is being reviewed due to problems such as environmental problems and heavy weight. In recent years, with the advent of lithium-ion secondary batteries with high energy density, uninterruptible power supplies that can be built into small devices such as portable data terminals have been commercialized.

  A lithium ion secondary battery includes a positive electrode using a composite oxide of lithium and a transition metal such as cobalt (for example, lithium cobaltate), a negative electrode capable of occluding and releasing lithium ions, and a lithium salt. A reversible operation of charge / discharge is performed by exchanging lithium ions between a positive electrode and a negative electrode, which is configured using a water electrolyte and performed via the electrolyte.

  However, the lithium ion secondary battery has a property that the characteristics deteriorate as it is repeatedly charged and discharged, and the number of cycles that can be charged and discharged is limited. That is, there is a problem that the charge / discharge cycle characteristics are not good. This is also a problem common to secondary batteries including lead-acid batteries, etc., but this makes it possible to perform maintenance such as inspection and replacement of secondary batteries in an uninterruptible power supply system using this type of secondary battery. It had to be done regularly (or frequently).

  There are two types of uninterruptible power systems: charging and discharging, and floating charging (floating charging) that performs charging and discharging in parallel. .

  In recent years, wind power generation and solar cells have attracted attention as a clean energy source with a small environmental load, but the power supplied from these sources is unstable depending on natural conditions such as wind and sunshine. As it is, the utility value as electric power is low.

  If this unstable electric power can be stored once and released at any time as needed, it is possible to obtain electric power with high utility value even with the same amount of energy. For this purpose, power storage means capable of storing electric power so that it can be released at any time is required.

  An electrical double layer capacitor that has good charge / discharge cycle characteristics and does not require maintenance is suitable for the power storage means, not the lithium ion secondary battery that places a heavy maintenance burden. However, the electric double layer capacitor can have a very large capacity (capacitance) as a capacitor, but the chargeable / dischargeable capacity is considerably inferior to that of the lithium ion secondary battery.

  Therefore, a lithium ion storage / release type organic electrolyte storage battery having a configuration in which an electric double layer capacitor and a lithium ion secondary battery are compromised has been proposed. This storage battery is configured using a positive electrode capable of occluding and releasing anions, a negative electrode capable of occluding and releasing lithium ions, and a non-aqueous electrolyte containing a lithium salt (see Patent Documents 1 and 2). ).

  In the lithium ion secondary battery, a composite oxide containing lithium is used for the positive electrode, but in the lithium ion storage / release organic electrolyte storage battery, a carbon material such as graphite or activated carbon is used for the positive electrode. The reversible operation of charging / discharging is performed by occlusion / release of anions at the positive electrode and occlusion / release of lithium ions at the negative electrode.

  This lithium ion storage / release type organic electrolyte storage battery has such properties that the lithium ion secondary battery and the electric double layer capacitor have the respective advantages. That is, the charge / discharge cycle characteristics are superior to each stage as compared with the lithium ion secondary battery, and the charge / discharge capacity (capacity capable of being charged / discharged) is greater than each stage of the electric double layer capacitor.

  This lithium ion storage / release type organic electrolyte storage battery can be suitably used as a high-performance secondary battery. A free uninterruptible power supply can be realized.

  In the lithium ion storage / release type organic electrolyte storage battery, it is possible to perform a reversible charge / discharge process in a region having high Coulomb efficiency by previously storing lithium ions in the negative electrode. That is, the capacity and efficiency of charge / discharge can be increased by preliminarily storing lithium ions in the negative electrode.

  In addition, in the lithium ion storage / release type organic electrolyte storage battery that has not been preliminarily stored, when the floating charge is performed at a high temperature (for example, 60 ° C.), the potential of the negative electrode and the positive electrode rises and the electrolytic solution decomposes. Is caused. When the electrolyte is decomposed and gas is generated, the internal pressure of the element rises abnormally, causing troubles such as liquid leakage and container deformation.

  However, by performing the pre-occlusion, the negative electrode potential can be fixed at substantially the same potential as the lithium potential, and an increase in the positive electrode potential can be suppressed. Thereby, the said decomposition reaction can be suppressed and the safety | security of a battery can be ensured.

This pre-occlusion can be performed by installing lithium metal in an element container in which an electrode body composed of a positive electrode, a negative electrode, and a separator is accommodated together with an electrolytic solution, and electrically connecting (short-circuiting) it to the negative electrode. it can. The lithium metal electrically connected to the negative electrode is eluted as lithium ions in the non-aqueous electrolyte and then moves to the negative electrode and is occluded.
JP-A-2005-19762 JP2002-305034

  In the lithium ion storage / release type organic electrolyte storage battery using a laminated electrode body in which a positive electrode part and a negative electrode part in a rectangular sheet shape are stacked with a separator interposed therebetween, the present inventors perform the above-described preliminary storage. We examined what to do.

In this type of lithium ion storage / release type organic electrolyte storage battery, as a configuration to install a pre-storage lithium metal,
(1) A lithium metal foil is laminated in advance on the sheet-like negative electrode before being assembled into the laminated electrode body.
(2) Open a hole in the negative electrode current collector, and paste lithium metal on the top and bottom of the hole.
Such a configuration has been proposed.

In the configuration of (1), a special measure is required so that all the subsequent processes do not react with the lithium metal, resulting in a problem that productivity is significantly hindered.
Lithium metal is highly reactive and requires special care when handling it. In particular, lithium metal in a thin foil-like state is easy to react and is likely to ignite during the process. For this reason, in the process after installing the lithium metal, large-scale and expensive apparatuses and facilities such as an atmosphere control system and a protection system are required.

  In the configuration of (2), in addition to the above problem, there is a problem that the current collector's original function of reducing the internal resistance is impaired by reducing the current collection efficiency by making a hole in the current collector. Arise.

  In addition, in both configurations (1) and (2), lithium metal is sandwiched between the layers of the laminated electrode body, and the lithium metal placed in this state does not necessarily elute smoothly into the electrolyte. In addition, it takes time to occlude, and the occlusion tends to be uneven.

  The present invention has been made in view of the above problems, and an object of the present invention is to use a laminated electrode body in which a rectangular sheet-like positive electrode portion and a negative electrode portion are laminated with a separator interposed therebetween. In lithium ion storage / release type organic electrolyte storage battery, it is possible to smoothly store lithium ions in the negative electrode, and to reduce the frequency or frequency of handling lithium metal in the production process. An object of the present invention is to provide a lithium ion storage / release type organic electrolyte storage battery having an improved battery.

  Other objects and configurations of the present invention will become apparent from the description of the present specification and the accompanying drawings.

The solution provided by the present invention is as follows.
(1) A rectangular sheet-like positive electrode part in which a positive electrode capable of reversibly carrying lithium ions or anions is formed on a sheet-like positive electrode current collector, and a negative electrode capable of occluding and releasing lithium ions are in a sheet form A rectangular sheet-shaped negative electrode portion formed on the negative electrode current collector is connected to each of the stacked electrode body alternately stacked with a separator interposed therebetween, and the positive electrode current collector and the negative electrode current collector. A lithium ion storage / release type organic electrolyte storage battery having an external terminal,
At least one side of the current collector for the negative electrode projects to the side of the laminated electrode body, and along this projecting portion, lithium metal for preliminarily occluding lithium ions in the negative electrode is in conduction with the negative electrode. Lithium ion storage / release type organic electrolyte storage battery characterized by being installed.

  (2) In the above means (1), the lithium metal is from at least one side of the negative electrode current collector located in the uppermost layer or the lowermost layer among the plurality of negative electrode current collectors forming the laminated electrode body. A lithium ion storage / release type organic electrolyte storage battery characterized by being installed along an overhanging portion.

  (3) In the above means (1), the lithium metal is inserted between the conductor portions connecting the plurality of negative electrode current collectors forming the laminated electrode body to the external terminals, and is in conduction with the negative electrode. Lithium ion storage / release type organic electrolyte storage battery characterized by being installed in

  (4) In any one of the above means (1) to (3), two separators located on both surfaces of each positive electrode part are bonded to each other at least on the installation side of the lithium metal, and the edge of the positive electrode part Lithium ion storage / release type organic electrolyte storage battery characterized by enclosing a part.

  Smooth pre-occlusion of lithium ions into the negative electrode in a lithium ion storage / release type organic electrolyte storage battery using a laminated electrode body in which a positive electrode part and a negative electrode part of a rectangular sheet are laminated with a separator interposed In addition, it is possible to reduce the frequency or frequency of handling lithium metal in the production process, thereby increasing productivity.

  Operations / effects other than those described above will be apparent from the description of the present specification and the accompanying drawings.

  FIG. 1 shows a first embodiment of a lithium ion storage / release organic electrolyte storage battery to which the technology of the present invention is applied. In the same figure, (a) is a plan view showing the main part of the element, (b) is a cross-sectional view taken along the line AA, and (c) is a cross-sectional view showing a part of the cross-sectional view with an exaggerated thickness.

The lithium ion storage / release type organic electrolyte storage battery shown in the figure is a storage battery that can also be used as a lithium ion secondary battery or a high-capacity capacitor. First, a laminated electrode body 20 formed in a rectangular flat shape is laminated with a laminated film. The element container 10 is configured to be accommodated together with a non-aqueous electrolyte (not shown).
As the element container 10, a soft container is used in which an airtight soft packaging material such as a laminate film is processed into a rectangular bag shape by fusion or the like. The element container 10 is hermetically sealed in the final process stage after the laminated electrode body 20 is accommodated together with the non-aqueous electrolyte.

  The laminated electrode body 20 is produced by alternately laminating a rectangular sheet-like positive electrode portion 21 and negative electrode portion 23 with a separator 22 interposed therebetween.

  In the positive electrode part 21, a positive electrode 211 using a carbon material capable of reversibly carrying lithium ions or anions is attached in layers to both surfaces of a sheet-like current collector 212 made of a metal foil (Al) by coating or the like. The whole is formed in a sheet shape. Similarly, the negative electrode part 23 has a negative electrode 231 capable of occluding and releasing lithium ions attached to both surfaces of a sheet-like current collector 232 made of a metal foil (Cu) by coating or the like, and is entirely sheet-like. Is formed.

  The current collectors 212 and 232 are not particularly limited as long as the current collectors 212 and 232 are good conductors that are inert to the non-aqueous electrolyte. For example, a metal net can be used. In consideration of the filling efficiency of substances (positive electrode and negative electrode), the use of metal foil is particularly preferable. As for the material, aluminum (Al) may be used for the positive electrode current collector 212 and copper (Cu) may be used for the negative electrode current collector 232.

  The positive electrode 211 occludes anions in the electrolyte during charging and releases them during discharging. The negative electrode 231 occludes lithium ions (cations) in the electrolyte during charging and releases them during discharging. The reversible operation of charging / discharging is performed by reversible occlusion / release of the anion and lithium ion.

  A carbon material is suitable as the material of the positive electrode 211 and the negative electrode 231. In particular, the positive electrode 211 is preferably a graphite material, and the negative electrode 231 is preferably a non-graphitizable carbonaceous material.

  The laminated electrode body 20 has a rectangular laminated surface, and external lead conductors, that is, external terminals 31 and 33 are arranged on both sides in the longitudinal direction.

  The external terminals 31 and 33 are made of a thin metal plate and are installed across the inner side and the outer side of the element container 10 to form external electrode terminals of a storage battery (lithium ion storage / release type organic electrolyte storage battery). In the illustrated example, the left external terminal 31 is a positive terminal, and the right external terminal 33 is a negative terminal. The external terminals 31 and 33 and the element container 10 are kept airtight by heat fusion or the like.

  A plurality of positive electrode portions 21 and negative electrode portions 23 are alternately stacked together with the separators 22 on the laminated electrode body 20, but the current collectors 212 of the respective positive electrode portions 21 are each one of the longitudinal sides of the laminated electrode body 20 (left side). The tip of the extended portion (longitudinal protruding portion) 212 b is connected to one external terminal (positive electrode terminal) 31 in the container 10.

  Similarly, the current collector 232 of each negative electrode portion 23 extends so as to protrude in the longitudinal direction of the other (right side) of the laminated electrode body 20, and the distal end portion of the extended portion (longitudinal extending portion) 232 b is the container. 10 is connected to the other external terminal (negative electrode terminal) 33.

  In addition to the above configuration, in the embodiment shown in FIG. 1, among the plurality of sheet-like negative electrode current collectors 232 forming the laminated electrode body 20, the sheet-like negative electrode current collector located in the lowermost layer (or the uppermost layer). One side which is the long side of the body 232 projects to the side of the laminated electrode body 20. Along the protruding portion 232a, lithium metal 41 for preliminarily occluding lithium ions in the negative electrode 231 is attached and installed. The lithium metal 41 has a band shape or a ribbon shape, and is electrically connected to the negative electrode 231 by being attached to the overhang portion 232a.

  What should be noted here is that the work place where the lithium metal 41 is stuck, that is, the overhanging portion 232a projects to the side of the laminated electrode body 20, so that the pasting work is performed after the laminated electrode body 20 is formed. It can be done easily and quickly.

  As a result, the lithium metal 41 may be handled at the end of the production process, and it is not necessary to handle lithium metal in the previous process. Therefore, the production of the laminated electrode body 20 can be performed at low cost and with high efficiency by avoiding problems derived from handling lithium metal.

  The laminated electrode body 20 can be accommodated in the element container 10 immediately after the lithium metal 41 is installed. Thereafter, the non-aqueous electrolyte is injected and the element container 10 is hermetically sealed. However, since these steps can be performed in a state where the lithium metal 41 is confined in the element container 10, the lithium metal is removed. It doesn't require much equipment or equipment to handle.

  Thus, in the embodiment of the present invention described above, productivity and productivity can be improved by reducing the frequency and frequency of handling lithium metal in the production process.

  On the other hand, the lithium metal 41 adhered to the protruding portion 232a of the negative electrode current collector 232 is eluted as lithium ions into the non-aqueous electrolyte, and the lithium ions are separated from the laminated end face of the laminated electrode body 20 to the separators 22 of each layer. Can reach each part of the negative electrode 231 in a short time. Thereby, it is possible to smoothly and uniformly preliminarily store lithium ions in each part of the negative electrode 231.

  In the illustrated embodiment, the two separators 22 located on both surfaces of each positive electrode portion 21 are bonded to each other on the installation side of the lithium metal 41. The bonding portion 221 is formed by heat fusion or the like. Thereby, the separator 22 wraps the edge part of the positive electrode part 21 on the installation side of the lithium metal 41.

  By providing such a configuration, it is possible to reliably avoid the lithium metal 41 electrically connected to the negative electrode 231 from being in conductive contact with the positive electrode side. Thereby, while being able to install lithium metal 41 safely, the workability | operativity of the installation can be improved significantly.

  This also allows the lithium metal 41 to be installed close to the end face of the laminated electrode body 20, so that the effect of further smoothing the occlusion of the lithium ions eluted from the lithium metal 41 into the negative electrode 231 is also obtained. It is done.

  The structure in which the separator 22 wraps around the edge of the positive electrode portion 21 can be formed by folding one separator, so-called bag binding, in addition to bonding the ends of the two separators. However, in order to increase the efficiency of the production process, it is more convenient to bond the end portions of the two separators by heat fusion or the like than to fold the separators back.

  Further, in the illustrated embodiment, the lithium metal 41 is disposed on the long side of the laminated electrode body 20, and thus, lithium ions eluted from the lithium metal 41 reach each part of the negative electrode 231. Therefore, the preliminary occlusion into the negative electrode 231 can be performed more smoothly and uniformly.

  FIG. 2 shows a second embodiment of a lithium ion storage / release organic electrolyte storage battery to which the technology of the present invention is applied. In the same figure, (a) is a plan view showing the main part of the element, and (b) is a cross-sectional view showing the BB cross section with exaggerated thickness.

  If it demonstrates paying attention to a difference with 1st Embodiment mentioned above, in 1st Embodiment, the lithium metal 41 will each current collector 212,232 of the positive electrode part 21 and the negative electrode part 23 to the external terminals 31 and 33, respectively. It was installed along a side other than the side to be connected. This installation position has an advantage that the workability of attaching the lithium metal 41 is good, but instead, there is only one overhanging portion 232a that can be easily attached.

  On the other hand, in the second embodiment shown in FIG. 2, the lithium metal 41 is inserted between the conductor portions that respectively connect the plurality of negative electrode current collectors 232 forming the laminated electrode body 20 to the external terminals 33. In this state, it is installed in conduction with the negative electrode 231.

  That is, as shown in the figure, the current collectors 212 and 232 of the positive electrode portion 21 and the negative electrode portion 23 are respectively extended to the side of the laminated electrode body 20, and the tip portions of the extended portions 212b and 232b are formed. Although connected to the external terminals 31 and 33, a lithium metal 41 for pre-occlusion is inserted between the extended portion 232b on the negative electrode side. The extended portion 232b is a conductor portion corresponding to the overhang portion 232a, and a plurality of spaces in which the lithium metal 41 can be inserted are formed between the conductor portions. The lithium metal 41 can be inserted into each of the plurality of spaces.

  In this embodiment, a plurality of lithium metals 41 can be installed between the extending portions 232b. Each lithium metal 41 elutes lithium ions, and the lithium ions are smoothly and uniformly diffused and stored from the end face of the laminated electrode body 20 to the negative electrode 231 of each layer.

  Furthermore, it should be noted that the lithium metal 41 can be installed even after the laminated electrode body 20 is accommodated in the element container 10 as shown in FIG. That is, with respect to the laminated electrode body 20 accommodated in the element container 10, the lithium metal 41 is laminated to the laminated electrode by inserting the linear or lead-like lithium metal 41 from the outside of the container 10 between the extended portions 232 b. It can be installed at a plurality of locations along the laminated end face of the body 20.

  Thereby, since the handling of lithium metal can be performed at a later stage of the production process, the productivity can be further improved.

  As described above, the present invention has been described based on the representative embodiments, but the present invention can have various modes other than those described above. For example, in the first embodiment, the lithium metal 41 may be disposed on two opposite sides of the laminated electrode body 20.

  Smooth pre-occlusion of lithium ions into the negative electrode in a lithium ion storage / release type organic electrolyte storage battery using a stacked electrode body in which a rectangular sheet-shaped positive electrode part and negative electrode part are stacked with a separator interposed therebetween In addition, it is possible to increase the productivity by allowing the process of handling lithium metal in the production process or the frequency thereof to be reduced.

It is the principal part top view and sectional drawing which show 1st Embodiment of the lithium ion occlusion / release organic electrolyte storage battery which concerns on this invention. It is the principal part top view and sectional drawing which show 2nd Embodiment of the lithium ion occlusion / release type organic electrolyte storage battery concerning this invention. It is a perspective view which shows the insertion method of the lithium metal in 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Element container 20 Stacked electrode body 21 Positive electrode part 211 Positive electrode 212 Positive electrode collector 212b Extension part of the positive electrode collector 22 Separator 221 Adhesion part 23 Negative electrode part 231 Negative electrode 232 Negative electrode collector 232a Negative electrode collector Overhang portion of electric body 232b Extension portion of current collector for negative electrode (corresponding to overhang portion)
31 External lead conductor (positive terminal)
33 External lead conductor (negative electrode terminal)
41 Lithium metal

Claims (4)

A rectangular sheet-like positive electrode portion in which a positive electrode capable of reversibly carrying lithium ions or anions is formed on a sheet-like positive electrode current collector, and a negative electrode electrode capable of occluding and releasing lithium ions are provided for the sheet-like negative electrode collector. A rectangular sheet-shaped negative electrode portion formed on the electric current body is alternately laminated with a separator interposed therebetween, and an external body connected to the positive electrode current collector and the negative electrode current collector, respectively. A lithium ion storage / release type organic electrolyte storage battery with a terminal,
At least one side of the negative electrode current collector extends to the side of the laminated electrode body, and along the protruding portion, lithium metal for preoccluding lithium ions in the negative electrode is in a conductive state with the negative electrode. Lithium ion storage / release type organic electrolyte storage battery characterized by being installed.   2. The lithium metal according to claim 1, wherein the lithium metal is along a protruding portion from at least one side of the current collector for negative electrode located in the uppermost layer or the lowermost layer among the plurality of current collectors for negative electrode forming the laminated electrode body. Lithium ion storage / release type organic electrolyte storage battery characterized by being installed.   2. The lithium metal according to claim 1, wherein the lithium metal is inserted between conductor portions respectively connecting the plurality of negative electrode current collectors forming the laminated electrode body to the external terminals, and is placed in conduction with the negative electrode. A lithium ion storage / release type organic electrolyte storage battery.   In any one of Claims 1-3, two separators located in both surfaces of each positive electrode part are mutually adhere | attached on the installation side of the said lithium metal, and envelop the edge part of the said positive electrode part. Lithium ion storage / release type organic electrolyte storage battery.

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