JP6301657B2 - Recycling method of lithium ion secondary battery - Google Patents
Recycling method of lithium ion secondary battery Download PDFInfo
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- JP6301657B2 JP6301657B2 JP2014002276A JP2014002276A JP6301657B2 JP 6301657 B2 JP6301657 B2 JP 6301657B2 JP 2014002276 A JP2014002276 A JP 2014002276A JP 2014002276 A JP2014002276 A JP 2014002276A JP 6301657 B2 JP6301657 B2 JP 6301657B2
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- lithium ion
- ion secondary
- secondary battery
- aqueous electrolyte
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- 229910001416 lithium ion Inorganic materials 0.000 title claims description 153
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims description 152
- 238000000034 method Methods 0.000 title claims description 58
- 238000004064 recycling Methods 0.000 title description 2
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- 239000008151 electrolyte solution Substances 0.000 claims description 10
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- SBLRHMKNNHXPHG-UHFFFAOYSA-N 4-fluoro-1,3-dioxolan-2-one Chemical compound FC1COC(=O)O1 SBLRHMKNNHXPHG-UHFFFAOYSA-N 0.000 claims description 3
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/84—Recycling of batteries or fuel cells
Landscapes
- Secondary Cells (AREA)
Description
本発明は、リチウムイオン二次電池の充放電サイクル寿命を長期化し得る再生方法に関するものである。 The present invention relates to a regeneration method capable of extending the charge / discharge cycle life of a lithium ion secondary battery.
リチウムイオン二次電池は、使用によって容量が低下しても、充電することで再度使用可能になることから、携帯型電子機器の電源用途をはじめとして、多くの用途に利用されている。 Lithium ion secondary batteries can be used again by charging even if the capacity decreases due to use, and thus are used in many applications including power supply for portable electronic devices.
しかしながら、リチウムイオン二次電池は、充放電回数が進むにつれて、充電後の容量が初期（組み立て直後）よりも小さくなる。よって、リチウムイオン二次電池においては、充放電を繰り返しても、容量の低下を可及的に抑制し得るように、充放電サイクル特性を高める研究が数多くなされている。 However, in the lithium ion secondary battery, the capacity after charging becomes smaller than the initial (immediately after assembly) as the number of times of charging and discharging proceeds. Therefore, in lithium ion secondary batteries, many studies have been made to improve charge / discharge cycle characteristics so that a decrease in capacity can be suppressed as much as possible even after repeated charge / discharge.
充放電の繰り返しに伴うリチウムイオン二次電池の容量低下には、様々な原因が考えられるが、その一つとして、リチウムイオン二次電池の有する非水電解液が、充放電の繰り返しによって減量することが挙げられる。これは、リチウムイオン二次電池の充放電に伴って、負極や正極と非水電解液とが反応することで、非水電解液が分解してしまうために生じる。 Various causes can be considered for the capacity reduction of the lithium ion secondary battery due to repeated charge / discharge, and one of them is that the non-aqueous electrolyte of the lithium ion secondary battery is reduced by repeated charge / discharge. Can be mentioned. This occurs because the non-aqueous electrolyte is decomposed due to the reaction between the negative electrode and the positive electrode and the non-aqueous electrolyte accompanying charging and discharging of the lithium ion secondary battery.
そこで、リチウムイオン二次電池内での非水電解液の分解反応を抑制する技術も数多く提案されている。 Therefore, many techniques for suppressing the decomposition reaction of the nonaqueous electrolytic solution in the lithium ion secondary battery have been proposed.
他方、充放電を繰り返した後のリチウムイオン二次電池内に非水電解液を再注入することで、リチウムイオン二次電池を再生することも考えられる。特許文献１には、非水電解液を注入するための注射針を挿入可能な構造とした注液部を外装体に有することで、長期間の使用後にも非水電解液の再注入を可能としたリチウムイオン二次電池が提案されている。 On the other hand, it is also conceivable to regenerate the lithium ion secondary battery by reinjecting the non-aqueous electrolyte into the lithium ion secondary battery after repeated charging and discharging. In Patent Document 1, the exterior body has a liquid injection part having a structure in which an injection needle for injecting a non-aqueous electrolyte can be inserted, so that the non-aqueous electrolyte can be re-injected even after long-term use. A lithium ion secondary battery has been proposed.
ところで、使用の進んだリチウムイオン二次電池に非水電解液を再注入すると、膨れの問題が大きくなることが、本発明者の検討により明らかとなった。 By the way, the present inventors have clarified that the problem of swelling increases when the nonaqueous electrolyte is reinjected into a lithium ion secondary battery that has been used.
本発明は、前記事情に鑑みてなされたものであり、その目的は、リチウムイオン二次電池の充放電サイクル寿命を長期化でき、かつ膨れを抑制し得る再生方法を提供することにある。 This invention is made | formed in view of the said situation, The objective is to provide the reproduction | regenerating method which can prolong the charging / discharging cycle life of a lithium ion secondary battery, and can suppress a swelling.
前記目的を達成し得た本発明のリチウムイオン二次電池の再生方法は、有底筒形の外装缶と、前記外装缶の開口部を封口する蓋板とで形成された電池ケース内に、正極、負極、セパレータおよび非水電解液が収容されてなるリチウムイオン二次電池を再生する方法であって、前記リチウムイオン二次電池は、前記電池ケースに非水電解液注入口を有しており、かつ前記非水電解液注入口は、弾性体で構成された封止部材により封止されており、前記リチウムイオン二次電池の組み立てから充放電を繰り返して放電容量が初回の放電容量よりも小さくなった段階で、前記封止部材に管を突き刺し、前記管を通じて前記電池ケース内に非水電解液を補充し、その後に前記管を前記封止部材から抜く工程を有しており、前記リチウムイオン二次電池の組み立て時に使用する非水電解液（１）、および前記電池ケース内に補充する非水電解液（２）は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有しており、かつ負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の前記化合物の、前記非水電解液（２）における含有量が、前記非水電解液（１）における含有量よりも少ないか、または、前記リチウムイオン二次電池の組み立て時に使用する非水電解液（１）は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有しており、かつ前記電池ケース内に補充する非水電解液（２）は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の前記化合物を含有していないことを特徴とする。 The method for regenerating a lithium ion secondary battery of the present invention that has achieved the above object is a battery case formed of a bottomed cylindrical outer can and a lid plate that seals the opening of the outer can. A method for regenerating a lithium ion secondary battery containing a positive electrode, a negative electrode, a separator, and a nonaqueous electrolyte, wherein the lithium ion secondary battery has a nonaqueous electrolyte inlet in the battery case. And the non-aqueous electrolyte injection port is sealed by a sealing member made of an elastic body, and charge and discharge are repeated from the assembly of the lithium ion secondary battery, so that the discharge capacity is more than the initial discharge capacity. A step of piercing the sealing member with a tube, replenishing the battery case with a non-aqueous electrolyte through the tube, and subsequently removing the tube from the sealing member, Lithium ion secondary battery The non-aqueous electrolyte (1) used during assembly and the non-aqueous electrolyte (2) to be replenished in the battery case contain a compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential. And the content of the compound in which the reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential is higher than the content in the non-aqueous electrolyte (1). Or the non-aqueous electrolyte (1) used at the time of assembling the lithium ion secondary battery contains a compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential, And the nonaqueous electrolyte (2) replenished in the said battery case is characterized by not containing the said compound whose reduction potential in a negative electrode is 1.3 V or less with respect to metal Li potential.
本発明によれば、リチウムイオン二次電池の充放電サイクル寿命を長期化でき、かつ膨れを抑制し得る再生方法を提供することができる。 ADVANTAGE OF THE INVENTION According to this invention, the regeneration method which can prolong the charging / discharging cycle life of a lithium ion secondary battery, and can suppress a swelling can be provided.
本発明のリチウムイオン二次電池の再生方法は、充放電を繰り返すことによって放電容量が初回放電容量よりも低下してしまったリチウムイオン二次電池に対し、前記充放電に伴う分解などによって減量した非水電解液を補充することで、前記リチウムイオン二次電池の容量などの特性を、更に継続して使用可能な程度にまで回復させる方法である。 The method for regenerating a lithium ion secondary battery according to the present invention reduced the amount of the lithium ion secondary battery whose charge capacity had decreased from the initial discharge capacity due to repeated charge and discharge by decomposition associated with the charge and discharge. By replenishing the non-aqueous electrolyte, characteristics such as the capacity of the lithium ion secondary battery are further restored to a level where they can be used continuously.
本発明の再生方法は、リチウムイオン二次電池の組み立てから充放電を繰り返して放電容量が初回放電容量よりも小さくなった段階で、前記封止部材に管を突き刺し、前記管を通じて前記電池ケース内に非水電解液を補充し、その後に前記管を前記封止部材から抜く工程を有している。 In the regeneration method of the present invention, when the discharge capacity is smaller than the initial discharge capacity after repeated charging and discharging from the assembly of the lithium ion secondary battery, a tube is pierced into the sealing member, and the battery case is passed through the tube. And a step of replenishing the non-aqueous electrolyte, and then removing the tube from the sealing member.
本明細書でいう「リチウムイオン二次電池の初回放電容量」とは、リチウムイオン二次電池の完成後の初回充放電（所謂化成処理や予備充電と称される電池製造工程中の充電および放電ではなく、電池を使用するための充電および放電）によって求められる放電容量を意味している。なお、本発明の再生方法において、リチウムイオン二次電池の充放電を繰り返した後の放電容量が、初回放電容量よりも小さくなっていることは、各放電容量を測定する際の充放電条件を同一にして判断すればよく、その充放電条件については特に制限はないが、例えば、後述する実施例で採用している充放電条件で判断することができる。 As used herein, “initial discharge capacity of a lithium ion secondary battery” refers to initial charge / discharge after completion of a lithium ion secondary battery (charging and discharging during a battery manufacturing process called so-called chemical conversion treatment or pre-charging). Rather, it means the discharge capacity required by charging and discharging to use the battery. In the regeneration method of the present invention, the discharge capacity after repeating the charge / discharge of the lithium ion secondary battery is smaller than the initial discharge capacity. The charging / discharging conditions are not particularly limited, but can be determined, for example, based on the charging / discharging conditions employed in the examples described later.
本発明の再生方法では、有底筒形の外装缶と、前記外装缶の開口部を封口する蓋板とで形成された電池ケース内に、正極、負極、セパレータおよび非水電解液が収容されてなるリチウムイオン二次電池を使用する。なお、前記リチウムイオン二次電池は、電池ケースに非水電解液注入口を有しており、この非水電解液注入口を封止する封止部材は、弾性体で構成されていて注射針のような管を刺すことができ、この管を通じて電池ケース内に非水電解液を補充可能になっている。そして、電池ケース内に非水電解液を注入した後に前記管を前記封止部材から抜くと、封止部材が弾性体により構成されていることから、前記管を通した穴が塞がり、電池ケースの封止状態を保つことができる。よって、このようなリチウムイオン二次電池を使用する本発明の再生方法によれば、リチウムイオン二次電池に係る電池ケースの一部の取り外しや分解などを伴うことなく、リチウムイオン二次電池内に非水電解液を補充して特性を回復させることができる。 In the recycling method of the present invention, a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte are contained in a battery case formed by a bottomed cylindrical outer can and a lid plate that seals the opening of the outer can. Use a lithium ion secondary battery. The lithium ion secondary battery has a non-aqueous electrolyte inlet in the battery case, and a sealing member for sealing the non-aqueous electrolyte inlet is made of an elastic body and has a syringe needle. The tube can be stabbed, and the battery case can be replenished with the non-aqueous electrolyte through this tube. Then, after injecting the non-aqueous electrolyte into the battery case, when the tube is pulled out from the sealing member, the hole through the tube is closed because the sealing member is made of an elastic body. The sealed state can be maintained. Therefore, according to the regeneration method of the present invention using such a lithium ion secondary battery, the lithium ion secondary battery can be used without removing or disassembling part of the battery case according to the lithium ion secondary battery. The non-aqueous electrolyte can be supplemented to restore the characteristics.
本発明の再生方法において、電池ケース内に補充する非水電解液（２）には、リチウムイオン二次電池の組み立て時に用いた非水電解液（１）とは、特定の添加剤の含有量が異なるものを使用する。 In the regeneration method of the present invention, the non-aqueous electrolyte solution (2) to be replenished in the battery case is different from the non-aqueous electrolyte solution (1) used at the time of assembling the lithium ion secondary battery with a specific additive content. Use a different one.
リチウムイオン二次電池の非水電解液にはリチウム塩の有機溶媒溶液が使用されるが、通常、この非水電解液は、リチウム塩および有機溶媒の他に、リチウムイオン二次電池の特性を高めるなどの目的で各種の添加剤が添加されている。 An organic solvent solution of a lithium salt is used as a non-aqueous electrolyte for a lithium ion secondary battery. Normally, this non-aqueous electrolyte has characteristics of a lithium ion secondary battery in addition to a lithium salt and an organic solvent. Various additives are added for the purpose of enhancing the content.
このような添加剤の中に、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物がある。リチウムイオン二次電池では、充放電に伴って、例えば、負極表面に非水電解液が接触して非水電解液内の成分が分解し、非水電解液量が減少して容量が低下する問題が生じ得る。しかし、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有する非水電解液を用いたリチウムイオン二次電池では、充放電によって前記化合物が負極表面で反応して皮膜を形成し、この皮膜が負極と非水電解液との直接の接触を防止するため、電池の充放電に伴う負極表面での非水電解液の分解が抑制される。 Among such additives, there is a compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential. In a lithium ion secondary battery, with charge / discharge, for example, the nonaqueous electrolyte comes into contact with the negative electrode surface, the components in the nonaqueous electrolyte are decomposed, the amount of nonaqueous electrolyte is reduced, and the capacity is reduced. Problems can arise. However, in a lithium ion secondary battery using a non-aqueous electrolyte containing a compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential, the compound reacts on the surface of the negative electrode due to charge and discharge. This film prevents direct contact between the negative electrode and the non-aqueous electrolyte, so that the decomposition of the non-aqueous electrolyte on the negative electrode surface accompanying charge / discharge of the battery is suppressed.
ところが、電池ケース内に補充に使用する非水電解液と、リチウムイオン二次電池の組み立て時に使用する非水電解液とが、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を同じ量で含む場合には、非水電解液を補充して再生させたリチウムイオン二次電池を使用すると、その膨れ量（例えば、充電状態の電池を８５℃程度の高温下で貯蔵したときの膨れ量）が大きくなってしまう。 However, the nonaqueous electrolyte used for replenishing the battery case and the nonaqueous electrolyte used when assembling the lithium ion secondary battery have a reduction potential at the negative electrode of 1.3 V or less with respect to the metal Li potential. When the same amount of the compound is contained, when a lithium ion secondary battery replenished with a nonaqueous electrolyte is used, the amount of swelling (for example, a charged battery is stored at a high temperature of about 85 ° C.). The amount of swelling).
負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物は、正極側で酸化されることでガスを発生させる虞があるため、非水電解液中の量が多すぎると、リチウムイオン二次電池の膨れを引き起こす。 A compound having a reduction potential of 1.3 V or less with respect to the metal Li potential at the negative electrode may generate gas by being oxidized on the positive electrode side. Therefore, if the amount in the non-aqueous electrolyte is too large, Causes the ion secondary battery to swell.
リチウムイオン二次電池においては、組み立て時の化成処理時の充放電および実際の使用時に行う充放電によって、非水電解液中の前記化合物の分解による皮膜形成が行われるが、充放電回数がかなり経過しても、非水電解液中に未反応の前記化合物が残存しているのが通常である。非水電解液中に残存している前記化合物は、リチウムイオン二次電池の充放電回数が多くなることで、負極表面に形成された皮膜に欠陥が生じた場合に、この欠陥によって露出した負極表面と反応して、皮膜の欠陥部分を補修する役割を担っている。そのため、通常のリチウムイオン二次電池では、所定の充放電サイクル数を経ても、ある程度の前記化合物が残存するように、非水電解液中の前記化合物量が決定されている。 In a lithium ion secondary battery, a film is formed by the decomposition of the compound in the non-aqueous electrolyte by charge / discharge during chemical conversion treatment during assembly and charge / discharge during actual use. Even after the lapse of time, the unreacted compound usually remains in the nonaqueous electrolytic solution. The compound remaining in the non-aqueous electrolyte is a negative electrode exposed by a defect when a film is formed on the surface of the negative electrode due to an increase in the number of charge / discharge cycles of the lithium ion secondary battery. It reacts with the surface and plays a role in repairing defective parts of the film. Therefore, in an ordinary lithium ion secondary battery, the amount of the compound in the non-aqueous electrolyte is determined so that a certain amount of the compound remains even after a predetermined number of charge / discharge cycles.
よって、電池ケース内への補充に使用する非水電解液に、前記化合物の含有量が、リチウムイオン二次電池の組み立てに使用する非水電解液と同じものを使用すると、再生後のリチウムイオン二次電池の有する非水電解液中の前記化合物の量が多くなり過ぎて、満充電で高温環境に貯蔵された場合などに内部に発生するガス量が非常に多くなり、電池ケースが大きく膨れてしまうと考えられる。 Therefore, if the non-aqueous electrolyte used for refilling the battery case is the same as the non-aqueous electrolyte used for assembling the lithium ion secondary battery, the regenerated lithium ion When the amount of the compound in the non-aqueous electrolyte of the secondary battery is too large, the amount of gas generated inside becomes extremely large when stored in a high temperature environment with full charge, and the battery case expands greatly. It is thought that.
そこで、本発明の再生方法では、電池ケース内へ補充する非水電解液（２）として、リチウムイオン二次電池の組み立て時に使用する非水電解液（１）よりも、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の含有量が少ないものを使用するか、または、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有していないものを使用することにした。本発明の再生方法では、これにより、再生後のリチウムイオン二次電池内において、未反応の前記化合物の非水電解液中に過剰な量で残存することを防止して、貯蔵時のガス発生量を少なくし、膨れの発生を抑制している。 Therefore, in the regeneration method of the present invention, the nonaqueous electrolyte (2) to be replenished into the battery case has a reduction potential at the negative electrode as compared with the nonaqueous electrolyte (1) used when assembling the lithium ion secondary battery. A compound having a low content of a compound of 1.3 V or less with respect to the metal Li potential, or a compound having a reduction potential at the negative electrode that does not contain a compound of 1.3 V or less with respect to the metal Li potential. Decided to use. In the regeneration method of the present invention, this prevents generation of excess gas in the non-aqueous electrolyte solution of the unreacted compound in the regenerated lithium ion secondary battery, thereby generating gas during storage. The amount is reduced and the occurrence of swelling is suppressed.
本発明の再生方法に使用するリチウムイオン二次電池に係る非水電解液には、前記の通り、リチウム塩の有機溶媒溶液が用いられる。 As described above, an organic solvent solution of lithium salt is used for the non-aqueous electrolyte solution related to the lithium ion secondary battery used in the regeneration method of the present invention.
非水電解液に係るリチウム塩は、溶媒中で解離してＬｉ＋イオンを形成し、電池として使用される電圧範囲で分解などの副反応を起こしにくいものであれば特に制限はない。例えば、ＬｉＣｌＯ４、ＬｉＰＦ６、ＬｉＢＦ４、ＬｉＡｓＦ６、ＬｉＳｂＦ６などの無機リチウム塩、ＬｉＣＦ３ＳＯ３、ＬｉＣＦ３ＣＯ２、Ｌｉ２Ｃ２Ｆ４（ＳＯ３）２、ＬｉＮ（ＣＦ３ＳＯ２）２、ＬｉＣ（ＣＦ３ＳＯ２）３、ＬｉＣｎＦ２ｎ＋１ＳＯ３（ｎ≧２）、ＬｉＮ（ＲｆＯＳＯ２）２〔ここでＲｆはフルオロアルキル基〕などの有機リチウム塩などを用いることができる。 The lithium salt related to the non-aqueous electrolyte is not particularly limited as long as it dissociates in a solvent to form Li + ions and hardly causes a side reaction such as decomposition in a voltage range used as a battery. For example, LiClO 4 , LiPF 6 , LiBF 4 , LiAsF 6 , LiSbF 6 and other inorganic lithium salts, LiCF 3 SO 3 , LiCF 3 CO 2 , Li 2 C 2 F 4 (SO 3 ) 2 , LiN (CF 3 SO 2 ) 2 , LiC (CF 3 SO 2 ) 3 , LiC n F 2n + 1 SO 3 (n ≧ 2), LiN (RfOSO 2 ) 2 [where Rf is a fluoroalkyl group] and the like can be used. .
非水電解液に係る有機溶媒は、前記のリチウム塩を溶解し、電池として使用される電圧範囲で分解などの副反応を起こさないものであれば特に限定されない。例えば、エチレンカーボネート、プロピレンカーボネート、ブチレンカーボネートなどの環状カーボネート；ジメチルカーボネート、ジエチルカーボネート、メチルエチルカーボネートなどの鎖状カーボネート；プロピオン酸メチルなどの鎖状エステル；γ−ブチロラクトンなどの環状エステル；ジメトキシエタン、ジエチルエーテル、１，３−ジオキソラン、ジグライム、トリグライム、テトラグライムなどの鎖状エーテル；ジオキサン、テトラヒドロフラン、２−メチルテトラヒドロフランなどの環状エーテル；アセトニトリル、プロピオニトリル、メトキシプロピオニトリルなどのニトリル類；エチレングリコールサルファイトなどの亜硫酸エステル類；などが挙げられ、これらは２種以上混合して用いることもできる。なお、より良好な特性の電池とするためには、エチレンカーボネートと鎖状カーボネートの混合溶媒など、高い導電率を得ることができる組み合わせで用いることが望ましい。 The organic solvent related to the non-aqueous electrolyte is not particularly limited as long as it dissolves the lithium salt and does not cause a side reaction such as decomposition in a voltage range used as a battery. For example, cyclic carbonates such as ethylene carbonate, propylene carbonate, and butylene carbonate; chain carbonates such as dimethyl carbonate, diethyl carbonate, and methyl ethyl carbonate; chain esters such as methyl propionate; cyclic esters such as γ-butyrolactone; dimethoxyethane; Chain ethers such as diethyl ether, 1,3-dioxolane, diglyme, triglyme and tetraglyme; cyclic ethers such as dioxane, tetrahydrofuran and 2-methyltetrahydrofuran; nitriles such as acetonitrile, propionitrile and methoxypropionitrile; ethylene Sulfites such as glycol sulfite; and the like. These may be used in combination of two or more. In order to obtain a battery with better characteristics, it is desirable to use a combination that can obtain high conductivity, such as a mixed solvent of ethylene carbonate and chain carbonate.
リチウム塩の非水電解液中の濃度は、０．５〜１．５ｍｏｌ／ｌとすることが好ましく、０．９〜１．２５ｍｏｌ／ｌとすることがより好ましい。 The concentration of the lithium salt in the non-aqueous electrolyte is preferably 0.5 to 1.5 mol / l, and more preferably 0.9 to 1.25 mol / l.
そして、リチウムイオン二次電池に用いる非水電解液は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有している。２−プロピニルジエチルホスホノアセテート（ＰＤＥＡ）、４−フルオロ−１，３−ジオキソラン−２−オン（ＦＥＣ）、ビニレンカーボネート（ＶＣ）、ビニルエチレンカーボネート（ＶＥＣ）などが挙げられ、これらのうちの１種のみを用いてもよく、２種以上を併用してもよい。 And the non-aqueous electrolyte used for a lithium ion secondary battery contains the compound whose reduction potential in a negative electrode is 1.3V or less with respect to metal Li potential. 2-propynyldiethylphosphonoacetate (PDEA), 4-fluoro-1,3-dioxolan-2-one (FEC), vinylene carbonate (VC), vinylethylene carbonate (VEC), etc. Only seeds may be used, or two or more kinds may be used in combination.
リチウムイオン二次電池に使用する非水電解液において、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の含有率は、前記化合物の使用による効果を良好に確保する観点から、２質量％以上であることが好ましく、３．５質量％以上であることがより好ましい。また、前記化合物によって引き起こされ得る電池の膨れをより良好に抑制する観点から、リチウムイオン二次電池に使用する非水電解液において、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の含有率は、７質量％以下であることが好ましく、５質量％以下であることがより好ましい。ただし、リチウムイオン二次電池にかかる電池ケース内への補充に使用する非水電解液（２）においては、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の含有率は、０質量％であってもよい。 In the non-aqueous electrolyte used for the lithium ion secondary battery, the content of the compound having a reduction potential at the negative electrode of 1.3 V or less with respect to the metal Li potential is from the viewpoint of ensuring a good effect by using the compound. The content is preferably 2% by mass or more, and more preferably 3.5% by mass or more. In addition, from the viewpoint of better suppressing the battery swelling that can be caused by the compound, in the non-aqueous electrolyte used for the lithium ion secondary battery, the reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential. The content of the compound is preferably 7% by mass or less, and more preferably 5% by mass or less. However, in the non-aqueous electrolyte (2) used for replenishing the battery case of the lithium ion secondary battery, the content of the compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential is , 0% by mass.
そして、前記の通り、リチウムイオン二次電池に係る電池ケース内への補充に使用する非水電解液（２）は、リチウムイオン二次電池の組み立てに使用する非水電解液（１）よりも、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の含有量が少ないか、または、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有していないものを使用する。 And as above-mentioned, the non-aqueous electrolyte (2) used for the replenishment in the battery case concerning a lithium ion secondary battery is more than the non-aqueous electrolyte (1) used for the assembly of a lithium ion secondary battery. The content of the compound having a reduction potential at the negative electrode of 1.3 V or less with respect to the metal Li potential is low, or the compound has a reduction potential at the negative electrode of 1.3 V or less with respect to the metal Li potential. Use something that doesn't exist.
負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の、非水電解液（２）における含有量は、前記化合物の非水電解液（１）における含有量と、非水電解液（２）の補充を行う時点でのリチウムイオン二次電池の状態とから決定することが好ましい。 The content of the compound in which the reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential in the nonaqueous electrolytic solution (2) is the same as the content of the compound in the nonaqueous electrolytic solution (1) and nonaqueous electrolysis. It is preferable to determine from the state of the lithium ion secondary battery at the time of replenishment of the liquid (2).
リチウムイオン二次電池は、初回放電容量から、充放電を繰り返すことで低下する放電容量の程度に応じて、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の、電池内の非水電解液中に残存している量が変動する。よって、リチウムイオン二次電池の組み立てに使用した非水電解液（１）中の前記化合物の含有量と、充放電を繰り返した後の放電容量の、初回放電容量からの低下の程度に応じて、リチウムイオン二次電池の非水電解液中に残存している前記化合物の大凡の量が把握できるため、非水電解液（２）における前記化合物の好適な含有量を見積もることができる。 Lithium ion secondary batteries have a compound in which the reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential, depending on the degree of discharge capacity that is reduced by repeated charge and discharge from the initial discharge capacity. The amount remaining in the non-aqueous electrolyte varies. Therefore, depending on the content of the compound in the non-aqueous electrolyte (1) used for the assembly of the lithium ion secondary battery and the degree of decrease in the discharge capacity after repeated charge and discharge from the initial discharge capacity Since the approximate amount of the compound remaining in the non-aqueous electrolyte solution of the lithium ion secondary battery can be grasped, a suitable content of the compound in the non-aqueous electrolyte solution (2) can be estimated.
具体的には、非水電解液（２）を補充した後のリチウムイオン二次電池内における非水電解液中の、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の含有量が、組み立ての時点でリチウムイオン二次電池が有していた非水電解液（１）中の含有量の５０質量％を超えない量となるように、非水電解液（２）中の前記化合物の含有量を設定することが好ましい。 Specifically, a compound in which the reduction potential at the negative electrode in the non-aqueous electrolyte in the lithium ion secondary battery after replenishing the non-aqueous electrolyte (2) is 1.3 V or less with respect to the metal Li potential is used. In the non-aqueous electrolyte (2) so that the content does not exceed 50% by mass of the content in the non-aqueous electrolyte (1) that the lithium ion secondary battery had at the time of assembly. It is preferable to set the content of the compound.
例えば、リチウムイオン二次電池の放電容量が、充放電の繰り返しによって組み立て直後の８０％程度に低下した段階では、そのリチウムイオン二次電池内の非水電解液中に残存している前記化合物の量は、リチウムイオン二次電池の組み立てに使用した非水電解液（１）の１０質量％程度になることが、経験的に判明している。 For example, when the discharge capacity of a lithium ion secondary battery is reduced to about 80% immediately after assembly due to repeated charge and discharge, the compound remaining in the non-aqueous electrolyte in the lithium ion secondary battery It has been empirically found that the amount is about 10% by mass of the non-aqueous electrolyte (1) used for assembling the lithium ion secondary battery.
よって、電池ケース内への非水電解液（２）の補充を、リチウムイオン二次電池の放電容量が、組み立て直後の初回放電容量の８０％±３％となった段階で実施する場合には、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の非水電解液（１）の含有量をａ（ｍｇ）としたとき、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を０．４×ａ（ｍｇ）以下で含有する非水電解液（２）を使用するか、または前記化合物を含有していない非水電解液（２）を使用することが好ましい。なお、非水電解液（２）に前記化合物を含有させて補充することによって、負極表面に形成されていた前記化合物由来の皮膜に欠陥部分が生じた場合に、これを修復する作用をより良好に確保する観点からは、電池ケース内への非水電解液（２）の補充を、リチウムイオン二次電池の放電容量が、組み立て直後の初回放電容量の８０％±３％となった段階で実施する場合には、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の非水電解液（１）の含有量をａ（ｍｇ）としたとき、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を、０．２×ａ（ｍｇ）以上で含有する非水電解液（２）を使用することが好ましい。 Therefore, when replenishing the non-aqueous electrolyte (2) into the battery case when the discharge capacity of the lithium ion secondary battery is 80% ± 3% of the initial discharge capacity immediately after assembly. When the content of the non-aqueous electrolyte (1) of the compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential is a (mg), the reduction potential at the negative electrode is relative to the metal Li potential. Use a non-aqueous electrolyte (2) containing a compound of 1.3 V or less at 0.4 × a (mg) or less, or use a non-aqueous electrolyte (2) not containing the compound. It is preferable. In addition, when the non-aqueous electrolyte (2) contains the compound and replenishes, when a defect portion is generated in the film derived from the compound formed on the negative electrode surface, the effect of repairing the defect portion is improved. From the viewpoint of ensuring the rechargeability of the non-aqueous electrolyte (2) in the battery case, the discharge capacity of the lithium ion secondary battery becomes 80% ± 3% of the initial discharge capacity immediately after assembly. In the case of carrying out, when the content of the non-aqueous electrolyte (1) of the compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential is a (mg), the reduction potential at the negative electrode is It is preferable to use a nonaqueous electrolytic solution (2) containing a compound of 1.3 V or less with respect to the metal Li potential in an amount of 0.2 × a (mg) or more.
また、リチウムイオン二次電池の放電容量が、充放電の繰り返しによって組み立て直後の６０％程度に低下した段階では、そのリチウムイオン二次電池内の非水電解液中に残存している前記化合物の量は、リチウムイオン二次電池の組み立てに使用した非水電解液（１）の５質量％程度になることが、経験的に判明している。 In addition, when the discharge capacity of the lithium ion secondary battery is reduced to about 60% immediately after assembly due to repeated charge and discharge, the compound remaining in the non-aqueous electrolyte in the lithium ion secondary battery It has been empirically found that the amount is about 5% by mass of the non-aqueous electrolyte (1) used for assembling the lithium ion secondary battery.
よって、電池ケース内への非水電解液（２）の補充を、リチウムイオン二次電池の放電容量が、組み立て直後の初回放電容量の６０％±３％となった段階で実施する場合には、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の非水電解液（１）の含有量をｂ（ｍｇ）としたとき、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を０．４５×ｂ（ｍｇ）以下で含有する非水電解液（２）を使用するか、または前記化合物を含有していない非水電解液（２）を使用することが好ましい。なお、非水電解液（２）に前記化合物を含有させて補充することによって、負極表面に形成されていた前記化合物由来の皮膜に欠陥部分が生じた場合に、これを修復する作用をより良好に確保する観点からは、電池ケース内への非水電解液（２）の補充を、リチウムイオン二次電池の放電容量が、組み立て直後の初回放電容量の６０％±３％となった段階で実施する場合には、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物の非水電解液（１）の含有量をｂ（ｍｇ）としたとき、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を、０．２５×ｂ（ｍｇ）以上で含有する非水電解液（２）を使用することが好ましい。 Therefore, when replenishing the non-aqueous electrolyte (2) into the battery case when the discharge capacity of the lithium ion secondary battery is 60% ± 3% of the initial discharge capacity immediately after assembly. When the content of the nonaqueous electrolyte (1) of the compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential is b (mg), the reduction potential at the negative electrode is relative to the metal Li potential. The non-aqueous electrolyte (2) containing a compound of 1.3 V or less at 0.45 × b (mg) or less is used, or the non-aqueous electrolyte (2) not containing the compound is used. It is preferable. In addition, when the non-aqueous electrolyte (2) contains the compound and replenishes, when a defect portion is generated in the film derived from the compound formed on the negative electrode surface, the effect of repairing the defect portion is improved. From the viewpoint of ensuring the rechargeability of the non-aqueous electrolyte (2) into the battery case, the discharge capacity of the lithium ion secondary battery becomes 60% ± 3% of the initial discharge capacity immediately after assembly. In the case of carrying out, when the content of the non-aqueous electrolyte (1) of the compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential is b (mg), the reduction potential at the negative electrode is It is preferable to use a nonaqueous electrolytic solution (2) containing a compound of 1.3 V or less with respect to the metal Li potential at 0.25 × b (mg) or more.
リチウムイオン二次電池の組み立てに使用する非水電解液（１）および電池ケース内に補充する非水電解液（２）には、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物以外にも、リチウムイオン二次電池の特性を高め得る作用を有する添加剤を含有させることができる。このような添加剤としては、例えば、１，３−プロパンスルトン、１，３−ジオキサン、ニトリル化合物（スクシノニトリル、グルタロニトリル、アジポニトリルなど）などが挙げられる。 In the non-aqueous electrolyte (1) used for assembling the lithium ion secondary battery and the non-aqueous electrolyte (2) supplemented in the battery case, the reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential. In addition to the compound, an additive having an action capable of improving the characteristics of the lithium ion secondary battery can be contained. Examples of such additives include 1,3-propane sultone, 1,3-dioxane, nitrile compounds (succinonitrile, glutaronitrile, adiponitrile, etc.) and the like.
リチウムイオン二次電池の組み立てに使用する非水電解液（１）と、電池ケース内に補充する非水電解液（２）とは、リチウム塩および有機溶媒の種類やリチウム塩の濃度については同じであってもよく、電池特性を損なわない範囲であれば異なっていてもよい。 The nonaqueous electrolytic solution (1) used for assembling the lithium ion secondary battery and the nonaqueous electrolytic solution (2) to be replenished in the battery case are the same in terms of the types of lithium salt and organic solvent and the concentration of the lithium salt. It may be different as long as the battery characteristics are not impaired.
本発明法においては、リチウムイオン二次電池の使用後における再生処理〔リチウムイオン二次電池の充放電を繰り返して容量が初回容量よりも低下した後の非水電解液（２）の補充〕は、１回のみ行うのであってもよいが、リチウムイオン二次電池の非水電解液以外の構成要素（電極、セパレータなど）の劣化の状態が、電池の更なる使用を妨げない程度である場合には、前記再生処理を２回以上行ってもよい。 In the method of the present invention, regeneration treatment after use of the lithium ion secondary battery [replenishment of the non-aqueous electrolyte (2) after the capacity is reduced from the initial capacity through repeated charge and discharge of the lithium ion secondary battery] It may be performed only once, but the deterioration of components (electrodes, separators, etc.) other than the non-aqueous electrolyte of the lithium ion secondary battery is such that it does not prevent further use of the battery. Alternatively, the reproduction process may be performed twice or more.
本発明の再生方法に使用されるリチウムイオン二次電池に係る正極には、例えば、正極活物質、導電助剤およびバインダを含有する正極合剤層を、集電体の片面または両面に有する構造のものが用いられる。 The positive electrode according to the lithium ion secondary battery used in the regeneration method of the present invention has, for example, a structure having a positive electrode mixture layer containing a positive electrode active material, a conductive additive and a binder on one side or both sides of a current collector Is used.
正極活物質には、従来から知られているリチウムイオン二次電池用の正極活物質として使用されているもの、例えば、リチウムイオンを吸蔵・放出できる活物質が使用される。このような正極活物質の具体例としては、例えば、Ｌｉ１＋ｘＭＯ２（−０．１＜ｘ＜０．１、Ｍ：Ｃｏ、Ｎｉ、Ｍｎ、Ａｌ、Ｍｇなど）で表される層状構造のリチウム含有遷移金属酸化物、ＬｉＭｎ２Ｏ４やその元素の一部を他元素で置換したスピネル構造のリチウムマンガン酸化物、ＬｉＭＰＯ４（Ｍ：Ｃｏ、Ｎｉ、Ｍｎ、Ｆｅなど）で表されるオリビン型化合物などが挙げられる。前記層状構造のリチウム含有遷移金属酸化物の具体例としては、ＬｉＣｏＯ２やＬｉＮｉ１−ｘＣｏｘ−ｙＡｌｙＯ２（０．１≦ｘ≦０．３、０．０１≦ｙ≦０．２）などの他、少なくともＣｏ、ＮｉおよびＭｎを含む酸化物（ＬｉＭｎ１／３Ｎｉ１／３Ｃｏ１／３Ｏ２、ＬｉＭｎ５／１２Ｎｉ５／１２Ｃｏ１／６Ｏ２、ＬｉＮｉ３／５Ｍｎ１／５Ｃｏ１／５Ｏ２など）などを例示することができる。 As the positive electrode active material, a conventionally known positive electrode active material for a lithium ion secondary battery, for example, an active material capable of inserting and extracting lithium ions is used. As a specific example of such a positive electrode active material, for example, a layered structure represented by Li 1 + x MO 2 (−0.1 <x <0.1, M: Co, Ni, Mn, Al, Mg, etc.) Lithium-containing transition metal oxide, LiMn 2 O 4 and spinel-structured lithium manganese oxide obtained by substituting some of its elements with other elements, LiMPO 4 (M: Co, Ni, Mn, Fe, etc.) Type compounds. Specific examples of the lithium-containing transition metal oxide having a layered structure include LiCoO 2 and LiNi 1-x Co xy Al y O 2 (0.1 ≦ x ≦ 0.3, 0.01 ≦ y ≦ 0. 2) and other oxides containing at least Co, Ni and Mn (LiMn 1/3 Ni 1/3 Co 1/3 O 2 , LiMn 5/12 Ni 5/12 Co 1/6 O 2 , LiNi 3 / 5 Mn 1/5 Co 1/5 O 2 etc.).
正極合剤層に係る導電助剤としては、例えば、天然黒鉛（鱗片状黒鉛など）、人造黒鉛などの黒鉛（黒鉛質炭素材料）；アセチレンブラック、ケッチェンブラック、チャンネルブラック、ファーネスブラック、ランプブラック、サーマルブラックなどのカ−ボンブラック；炭素繊維；などの炭素材料などが挙げられる。また、正極合剤層に係るバインダには、例えば、ポリフッ化ビニリデン（ＰＶＤＦ）、ポリテトラフルオロエチレン（ＰＴＦＥ）、スチレンブタジエンゴム（ＳＢＲ）、カルボキシメチルセルロース（ＣＭＣ）などを用いることができる。 Examples of the conductive additive related to the positive electrode mixture layer include graphite (graphite carbon material) such as natural graphite (flaky graphite, etc.) and artificial graphite; acetylene black, ketjen black, channel black, furnace black, lamp black. And carbon materials such as carbon black, carbon black, and the like. In addition, for example, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), or the like can be used for the binder related to the positive electrode mixture layer.
正極は、例えば、正極活物質、導電助剤およびバインダなどを、Ｎ−メチル−２−ピロリドン（ＮＭＰ）などの溶剤に分散させたペースト状やスラリー状の正極合剤含有組成物を調製し（ただし、バインダは溶剤に溶解していてもよい）、これを集電体の片面または両面に塗布し、乾燥した後に、必要に応じてカレンダー処理を施す工程を経て製造される。ただし、正極は、前記の製造方法で製造されたものに限定される訳ではなく、他の方法で製造したものであってもよい。 For the positive electrode, for example, a positive electrode mixture-containing composition in the form of a paste or slurry in which a positive electrode active material, a conductive additive and a binder are dispersed in a solvent such as N-methyl-2-pyrrolidone (NMP) is prepared ( However, the binder may be dissolved in a solvent), and this is applied to one or both sides of the current collector, dried, and then subjected to a calendering process as necessary. However, the positive electrode is not limited to those manufactured by the above manufacturing method, and may be manufactured by other methods.
また、正極には、必要に応じて、リチウムイオン二次電池内の他の部材と電気的に接続するためのリード体を、常法に従って形成してもよい。 Moreover, you may form the lead body for electrically connecting with the other member in a lithium ion secondary battery according to a conventional method to a positive electrode as needed.
正極合剤層の厚みは、例えば、集電体の片面あたり１０〜１００μｍであることが好ましい。また、正極合剤層の組成としては、例えば、正極活物質の量が６０〜９５質量％であることが好ましく、バインダの量が１〜１５質量％であることが好ましく、導電助剤の量が３〜２０質量％であることが好ましい。 The thickness of the positive electrode mixture layer is preferably, for example, 10 to 100 μm per one side of the current collector. Moreover, as a composition of a positive mix layer, it is preferable that the quantity of a positive electrode active material is 60-95 mass%, for example, it is preferable that the quantity of a binder is 1-15 mass%, and the quantity of a conductive support agent. Is preferably 3 to 20% by mass.
正極の集電体は、従来から知られている非水電解質二次電池の正極に使用されているものと同様のものが使用でき、例えば、厚みが１０〜３０μｍのアルミニウム箔が好ましい。 As the current collector for the positive electrode, the same one as used for the positive electrode of a conventionally known non-aqueous electrolyte secondary battery can be used. For example, an aluminum foil having a thickness of 10 to 30 μm is preferable.
本発明の再生方法に使用されるリチウムイオン二次電池に係る負極には、例えば、負極活物質およびバインダ、更には必要に応じて導電助剤などを含有する負極合剤層を、集電体の片面または両面に有する構造のものが用いられる。 The negative electrode for the lithium ion secondary battery used in the regeneration method of the present invention includes, for example, a negative electrode active material and a binder, and further, a negative electrode mixture layer containing a conductive auxiliary agent if necessary, a current collector The thing of the structure which has in one side or both sides of this is used.
負極活物質には、例えば、天然黒鉛（鱗片状黒鉛）、人造黒鉛、膨張黒鉛などの黒鉛材料；ピッチをか焼して得られるコークスなどの易黒鉛化性炭素質材料；フルフリルアルコール樹脂（ＰＦＡ）やポリパラフェニレン（ＰＰＰ）およびフェノール樹脂を低温焼成して得られる非晶質炭素などの難黒鉛化性炭素質材料；などの炭素材料が挙げられる。また、炭素材料の他に、リチウムやリチウム含有化合物も負極活物質として用いることができる。リチウム含有化合物としては、Ｌｉ−Ａｌなどのリチウム合金や、Ｓｉ、Ｓｎなどのリチウムとの合金化が可能な元素を含む合金が挙げられる。更にＳｎ酸化物やＳｉ酸化物などの酸化物系材料も用いることができる。 Examples of the negative electrode active material include graphite materials such as natural graphite (flaky graphite), artificial graphite, and expanded graphite; graphitizable carbonaceous materials such as coke obtained by calcining pitch; furfuryl alcohol resin ( Carbon materials such as non-graphitizable carbonaceous materials such as amorphous carbon obtained by low-temperature firing of PFA), polyparaphenylene (PPP), and phenol resins. In addition to the carbon material, lithium or a lithium-containing compound can also be used as the negative electrode active material. Examples of the lithium-containing compound include lithium alloys such as Li—Al, and alloys containing elements that can be alloyed with lithium such as Si and Sn. Furthermore, oxide-based materials such as Sn oxide and Si oxide can also be used.
負極合剤層に係るバインダおよび導電助剤には、正極合剤層に係るバインダおよび導電助剤として先に例示したものと同じものを用いることができる。 As the binder and the conductive auxiliary agent related to the negative electrode mixture layer, the same materials as those exemplified above as the binder and the conductive auxiliary agent related to the positive electrode mixture layer can be used.
負極は、例えば、負極活物質およびバインダ、更には必要に応じて導電助剤などを、ＮＭＰや水などの溶剤に分散させたペースト状やスラリー状の負極合剤含有組成物を調製し（ただし、バインダは溶剤に溶解していてもよい）、これを集電体の片面または両面に塗布し、乾燥した後に、必要に応じてカレンダー処理を施す工程を経て製造される。ただし、負極は、前記の製造方法で製造されたものに限定される訳ではなく、他の方法で製造したものであってもよい。 The negative electrode is prepared, for example, by preparing a paste-like or slurry-like negative electrode mixture-containing composition in which a negative electrode active material and a binder and, if necessary, a conductive additive are dispersed in a solvent such as NMP or water (however, The binder may be dissolved in a solvent), and this is applied to one or both sides of the current collector, dried, and then subjected to a calendering process as necessary. However, the negative electrode is not limited to those manufactured by the above manufacturing method, and may be manufactured by other methods.
また、負極には、必要に応じて、リチウムイオン二次電池内の他の部材と電気的に接続するためのリード体を、常法に従って形成してもよい。 Moreover, you may form the lead body for electrically connecting with the other member in a lithium ion secondary battery according to a conventional method to a negative electrode as needed.
負極合剤層の厚みは、集電体の片面あたり、集電体の片面あたり１０〜１００μｍであることが好ましい。また、負極合剤層の組成としては、例えば、負極活物質の量が８０〜９５質量％であることが好ましく、バインダの量が１〜２０質量％であることが好ましく、導電助剤を使用する場合には、その量が１〜１０質量％であることが好ましい。 The thickness of the negative electrode mixture layer is preferably 10 to 100 μm per side of the current collector per side of the current collector. Moreover, as a composition of a negative mix layer, it is preferable that the quantity of a negative electrode active material is 80-95 mass%, for example, it is preferable that the quantity of a binder is 1-20 mass%, and uses a conductive support agent. When it does, it is preferable that the quantity is 1-10 mass%.
負極の集電体としては、銅製やニッケル製の箔、パンチングメタル、網、エキスパンドメタルなどを用い得るが、通常、銅箔が用いられる。この負極集電体は、高エネルギー密度の電池を得るために負極全体の厚みを薄くする場合、厚みの上限は３０μｍであることが好ましく、下限は５μｍであることが望ましい。 As the current collector for the negative electrode, a foil made of copper or nickel, a punching metal, a net, an expanded metal, or the like can be used, but a copper foil is usually used. In the negative electrode current collector, when the thickness of the entire negative electrode is reduced in order to obtain a battery having a high energy density, the upper limit of the thickness is preferably 30 μm, and the lower limit is preferably 5 μm.
本発明の再生方法に使用されるリチウムイオン二次電池に係るセパレータは、８０℃以上（より好ましくは１００℃以上）１７０℃以下（より好ましくは１５０℃以下）において、その孔が閉塞する性質（すなわちシャットダウン機能）を有していることが好ましく、通常のリチウムイオン二次電池などで使用されているセパレータ、例えば、ポリエチレン（ＰＥ）やポリプロピレン（ＰＰ）などのポリオレフィン製の微多孔膜を用いることができる。セパレータを構成する微多孔膜は、例えば、ＰＥのみを使用したものやＰＰのみを使用したものであってもよく、また、ＰＥ製の微多孔膜とＰＰ製の微多孔膜との積層体であってもよい。セパレータの厚みは、例えば、１０〜３０μｍであることが好ましい。 The separator according to the lithium ion secondary battery used in the regeneration method of the present invention has a property that the pores are closed at 80 ° C. or higher (more preferably 100 ° C. or higher) and 170 ° C. or lower (more preferably 150 ° C. or lower). That is, it is preferable to have a shutdown function, and a separator used in a normal lithium ion secondary battery, for example, a microporous membrane made of polyolefin such as polyethylene (PE) or polypropylene (PP) is used. Can do. The microporous film constituting the separator may be, for example, one using only PE or one using PP, or a laminate of a PE microporous film and a PP microporous film. There may be. The thickness of the separator is preferably 10 to 30 μm, for example.
前記の正極と前記の負極とは、前記のセパレータを介して重ねて構成した積層体（積層電極体）や、この積層体を更に渦巻状に巻回して構成した巻回体（巻回電極体）の形態で、リチウムイオン二次電池に使用される。 The positive electrode and the negative electrode are a laminated body (laminated electrode body) configured by being stacked with the separator interposed therebetween, or a wound body (wound electrode body) formed by further winding the laminated body in a spiral shape. ) In the form of lithium ion secondary batteries.
図１および図２に、本発明の再生方法に使用されるリチウムイオン二次電池の一例を示す。図１は、リチウムイオン二次電池を模式的に表す部分縦断面図であり、図２は図１に示すリチウムイオン二次電池の斜視図である。 1 and 2 show an example of a lithium ion secondary battery used in the regeneration method of the present invention. FIG. 1 is a partial longitudinal sectional view schematically showing a lithium ion secondary battery, and FIG. 2 is a perspective view of the lithium ion secondary battery shown in FIG.
図１および図２に示すリチウムイオン二次電池は、有底円筒（角筒形）の外装缶４と、外装缶４の開口部を封口する蓋板９とで形成された電池ケース内に、正極１と負極２とがセパレータ３を介して積層され渦巻状に巻回された後、横断面が扁平状になるように加圧成形された扁平状巻回電極体と、非水電解液とを収容している。なお、図１では、煩雑化を避けるため、正極１および負極２の各層を区別して示しておらず、また、非水電解液も図示していない。更に、図１では、扁平状巻回電極体６の内周部を断面にしていない。 The lithium ion secondary battery shown in FIGS. 1 and 2 is in a battery case formed by a bottomed cylindrical (square tube) outer can 4 and a lid plate 9 that seals the opening of the outer can 4. After the positive electrode 1 and the negative electrode 2 are laminated via the separator 3 and wound in a spiral shape, a flat wound electrode body that is pressure-molded so as to have a flat cross section, a non-aqueous electrolyte, Is housed. In FIG. 1, in order to avoid complication, the layers of the positive electrode 1 and the negative electrode 2 are not shown separately, and the non-aqueous electrolyte is not shown. Further, in FIG. 1, the inner peripheral portion of the flat wound electrode body 6 is not shown in cross section.
外装缶４はアルミニウム合金などで構成されており、図１に示すリチウムイオン二次電池では、この外装缶４は正極端子を兼ねている。そして、外装缶４の底部にはＰＥシートからなる絶縁体５が配置されている。正極１、負極２およびセパレータ３からなる扁平状巻回電極体６からは、正極１および負極２のそれぞれ一端に接続された正極リード体７と負極リード体８が引き出されている。また、蓋板９はアルミニウム合金などで構成されており、この蓋板９にはＰＰなどで構成された絶縁パッキング１０を介してステンレス鋼などで構成された端子１１が取り付けられ、この端子１１には絶縁体１２を介してステンレス鋼などで構成されたリード板１３が取り付けられている。 The outer can 4 is made of an aluminum alloy or the like. In the lithium ion secondary battery shown in FIG. 1, the outer can 4 also serves as a positive electrode terminal. An insulator 5 made of a PE sheet is disposed at the bottom of the outer can 4. From the flat wound electrode body 6 including the positive electrode 1, the negative electrode 2 and the separator 3, a positive electrode lead body 7 and a negative electrode lead body 8 connected to one ends of the positive electrode 1 and the negative electrode 2 are drawn out. The cover plate 9 is made of an aluminum alloy or the like, and a terminal 11 made of stainless steel or the like is attached to the cover plate 9 via an insulating packing 10 made of PP or the like. A lead plate 13 made of stainless steel or the like is attached via an insulator 12.
そして、この蓋板９は外装缶４の開口部に挿入され、両者の接合部を溶接することによって、外装缶４の開口部が封口され、電池（電池ケース）内部が密閉されている。蓋板９には、電池の温度が上昇した際に内部のガスを外部に排出する機構として、開裂ベント１５が設けられている。 And this cover plate 9 is inserted in the opening part of the armored can 4, and the opening part of the armored can 4 is sealed by welding the junction part of both, and the inside of a battery (battery case) is sealed. The lid plate 9 is provided with a cleavage vent 15 as a mechanism for discharging the internal gas to the outside when the temperature of the battery rises.
また、図１のリチウムイオン二次電池では、蓋板９に非水電解液注入口が設けられており、この非水電解液注入口には、封止部材１４が挿入され、電池の密閉性が確保されている。封止部材１４は、前記の通り、リチウムイオン二次電池の充放電を繰り返して容量が低下した段階で非水電解液（２）を補充するための注射針などの管を突き刺すことが可能であり、かつ前記管を引き抜いた後にも電池の密閉性が維持できるように、弾性体で構成されている。 Further, in the lithium ion secondary battery of FIG. 1, the lid plate 9 is provided with a non-aqueous electrolyte inlet, and a sealing member 14 is inserted into the non-aqueous electrolyte inlet, thereby sealing the battery. Is secured. As described above, the sealing member 14 can pierce a tube such as an injection needle for replenishing the non-aqueous electrolyte (2) at a stage where the capacity is reduced by repeatedly charging and discharging the lithium ion secondary battery. In addition, the battery is made of an elastic body so that the airtightness of the battery can be maintained even after the tube is pulled out.
封止部材を構成し得る弾性体としては、例えば、ブチルゴムなどが挙げられる。 Examples of the elastic body that can constitute the sealing member include butyl rubber.
図１および図２に示すリチウムイオン二次電池では、正極リード体７を蓋板９に直接溶接することによって外装缶５と蓋板９とが正極端子として機能し、負極リード体８をリード板１３に溶接し、そのリード板１３を介して負極リード体８と端子１１とを導通させることによって端子１１が負極端子として機能するようになっているが、外装缶４の材質などによっては、その正負が逆になる場合もある。 In the lithium ion secondary battery shown in FIGS. 1 and 2, the outer can 5 and the cover plate 9 function as a positive electrode terminal by directly welding the positive electrode lead body 7 to the cover plate 9, and the negative electrode lead body 8 is used as the lead plate. 13 is connected to the negative electrode lead body 8 and the terminal 11 through the lead plate 13 so that the terminal 11 functions as a negative electrode terminal. However, depending on the material of the outer can 4, The sign may be reversed.
本発明の再生方法は、車載用や産業用の電池のような大型のリチウムイオン二次電池や、携帯機器用に使用されている小型のリチウムイオン二次電池など、各種のリチウムイオン二次電池の再生に有用な方法である。 The regeneration method of the present invention is applied to various lithium ion secondary batteries such as large lithium ion secondary batteries such as in-vehicle and industrial batteries and small lithium ion secondary batteries used for portable devices. This is a useful method for reproduction.
以下、実施例に基づいて本発明を詳細に述べる。ただし、下記実施例は、本発明を制限するものではない。 Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.
実施例１
＜正極の作製＞
正極活物質であるＬｉＣｏＯ２：１００質量部と、バインダであるＰＶＤＦを１０質量％の濃度で含むＮＭＰ溶液：２０質量部と、導電助剤である人造黒鉛：１質量部およびケッチェンブラック：１質量部とを、プラネタリーミキサーを用いて混練し、更にＮＭＰを加えて粘度を調節して、正極合剤含有スラリーを調製した。
Example 1
<Preparation of positive electrode>
LiCoO 2 as positive electrode active material: 100 parts by mass, NMP solution containing PVDF as binder at a concentration of 10% by mass: 20 parts by mass, artificial graphite as conductive aid: 1 part by mass and Ketjen Black: 1 The slurry was mixed with a mass part using a planetary mixer, and NMP was added to adjust the viscosity to prepare a positive electrode mixture-containing slurry.
前記の正極合剤含有スラリーを、厚みが１５μｍのアルミニウム箔（正極集電体）の両面に塗布した後、１２０℃で１２時間の真空乾燥を行って、アルミニウム箔の両面に正極合剤層を形成した。その後、カレンダー処理を行って、正極合剤層の厚みおよび密度を調節し、アルミニウム箔の露出部にニッケル製のリード体を溶接して、長さ３７５ｍｍ、幅４３ｍｍの帯状の正極を作製した。得られた正極における正極合剤層は、片面あたりの厚みが５５μｍであった。 The positive electrode mixture-containing slurry is applied to both surfaces of an aluminum foil (positive electrode current collector) having a thickness of 15 μm, and then vacuum-dried at 120 ° C. for 12 hours to form a positive electrode mixture layer on both surfaces of the aluminum foil. Formed. Thereafter, calendar treatment was performed to adjust the thickness and density of the positive electrode mixture layer, and a nickel lead body was welded to the exposed portion of the aluminum foil to produce a strip-like positive electrode having a length of 375 mm and a width of 43 mm. The positive electrode mixture layer in the obtained positive electrode had a thickness of 55 μm per one side.
＜負極の作製＞
負極活物質である数平均粒子径が１０μｍの天然黒鉛：９７．５質量部と、バインダであるＳＢＲ：１．５質量部と、増粘剤であるＣＭＣ：１質量部とに、水を加えて混合し、負極合剤含有ペーストを調製した。この負極合剤含有ペーストを厚みが８μｍの銅箔の両面に塗布した後、１２０℃で１２時間の真空乾燥を行って、銅箔の両面に負極合剤層を形成した。その後、カレンダー処理を行って、負極合剤層の厚みおよび密度を調節し、銅箔の露出部にニッケル製のリード体を溶接して、長さ３８０ｍｍ、幅４４ｍｍの帯状の負極を作製した。得られた負極における負極合剤層は、片面あたりの厚みが６５μｍであった。
<Production of negative electrode>
Water is added to 97.5 parts by mass of natural graphite having a number average particle diameter of 10 μm as a negative electrode active material, 1.5 parts by mass of SBR as a binder, and 1 part by mass of CMC as a thickener. And mixed to prepare a negative electrode mixture-containing paste. This negative electrode mixture-containing paste was applied to both sides of a copper foil having a thickness of 8 μm, and then vacuum-dried at 120 ° C. for 12 hours to form negative electrode mixture layers on both sides of the copper foil. Thereafter, calendar treatment was performed to adjust the thickness and density of the negative electrode mixture layer, and a nickel lead body was welded to the exposed portion of the copper foil to produce a strip-shaped negative electrode having a length of 380 mm and a width of 44 mm. The negative electrode mixture layer in the obtained negative electrode had a thickness of 65 μm per one surface.
＜非水電解液の調製＞
エチレンカーボネートとメチルエチルカーボネートとジエチルカーボネートとの容積比２：３：１の混合溶媒に、ＬｉＰＦ６を１ｍｏｌ／Ｌの濃度で溶解させ、更にＦＥＣを２質量％となる量で、およびＶＣを２質量％となる量で、それぞれ溶解させて、リチウムイオン二次電池の組み立てに使用する非水電解液（１）を調製した。
<Preparation of non-aqueous electrolyte>
LiPF 6 was dissolved at a concentration of 1 mol / L in a mixed solvent of ethylene carbonate, methyl ethyl carbonate and diethyl carbonate in a volume ratio of 2: 3: 1, and FEC was added in an amount of 2% by mass, and VC was 2%. A non-aqueous electrolyte solution (1) used for assembling a lithium ion secondary battery was prepared by dissolving each in an amount of mass%.
また、ＦＥＣを１．０５質量％となる量で、およびＶＣを１．０５質量％となる量で、それぞれ溶解させた以外は前記非水電解液（１）と同様にして、リチウムイオン二次電池の電池ケースに補充するための非水電解液（２ａ）を調製した。 Further, in the same manner as in the non-aqueous electrolyte (1) except that FEC was dissolved in an amount of 1.05% by mass and VC was dissolved in an amount of 1.05% by mass, respectively, a lithium ion secondary solution was obtained. A non-aqueous electrolyte (2a) for replenishing the battery case of the battery was prepared.
＜リチウムイオン二次電池の組み立て＞
前記帯状の正極と前記帯状の負極とを、厚みが１６μｍの微孔性ポリエチレンセパレータ（空孔率：４１％）を介して重ね、渦巻状に巻回した後、扁平状になるように加圧して扁平状巻回電極体とした。この扁平状巻回電極体を厚み５ｍｍ、幅４２ｍｍ、高さ６１ｍｍのアルミニウム合金製外装缶に入れ、外装缶の開口部にアルミニウム合金製の蓋板を被せて溶接して電池ケースを構成した。続いて、蓋板に設けた非水電解液注入口から、前記非水電解液（１）：４ｇを電池内に注入し、化成処理〔８００ｍＡの電流値で４．２Ｖまで定電流充電し、続いて４．２Ｖの定電圧充電を行い（定電流充電および定電圧充電の総充電時間が２．５時間）、その後に１６０ｍＡで３Ｖになるまで放電を行う処理〕を行った後に、非水電解液注入口にブチルゴム製の封止部材を挿入することで電池ケースを封止して、リチウムイオン二次電池を得た。このリチウムイオン二次電池は、前記の量の非水電解液（１）を注入することで、８０ｍｇのＦＥＣと８０ｍｇのＶＣ（両者の合計が１６０ｍｇ）を有していることになる。
<Assembly of lithium ion secondary battery>
The strip-shaped positive electrode and the strip-shaped negative electrode are stacked with a microporous polyethylene separator (porosity: 41%) having a thickness of 16 μm, wound in a spiral shape, and then pressed so as to be flat. Thus, a flat wound electrode body was obtained. The flat wound electrode body was placed in an aluminum alloy outer can having a thickness of 5 mm, a width of 42 mm, and a height of 61 mm, and an aluminum alloy lid plate was placed on the opening of the outer can and welded to form a battery case. Subsequently, 4 g of the non-aqueous electrolyte (1): 4 g was injected into the battery from the non-aqueous electrolyte injection port provided on the cover plate, and a chemical conversion treatment [constant current charging to 4.2 V at a current value of 800 mA, Subsequently, a constant voltage charge of 4.2 V is performed (total charge time of constant current charge and constant voltage charge is 2.5 hours, and then a discharge is performed until the voltage reaches 3 V at 160 mA). A battery case was sealed by inserting a sealing member made of butyl rubber into the electrolyte inlet, and a lithium ion secondary battery was obtained. This lithium ion secondary battery has 80 mg of FEC and 80 mg of VC (the total of both is 160 mg) by injecting the above-mentioned amount of the non-aqueous electrolyte (1).
＜リチウムイオン二次電池の充放電処理＞
前記のリチウムイオン二次電池について、８００ｍＡの電流値で４．２Ｖになるまで定電流充電し、続いて４．２Ｖの定電流充電を行い（定電流充電および定電圧充電の総充電時間が２．５時間）、その後に１６０ｍＡで３Ｖになるまで放電を行う一連の操作を１サイクルとして、この充放電サイクルを繰り返した。そして、放電容量が１サイクル目の放電容量の８０％を下回った時点（具体的には７８％であり、そのときのサイクル数は６１２回であった）で充放電を止めた。なお、この充放電処理を施したリチウムイオン二次電池の一部について、内部に残存しているＦＥＣとＶＣとの合計量を調べたところ、１６ｍｇであった。
<Charge / discharge treatment of lithium ion secondary battery>
About the said lithium ion secondary battery, constant current charge was carried out until it became 4.2V with the electric current value of 800 mA, and then 4.2V constant current charge was performed (the total charge time of constant current charge and constant voltage charge is 2). .5 hours), and thereafter, a series of operations for discharging until 160 V at 3 V was taken as one cycle, and this charge / discharge cycle was repeated. Then, charging and discharging were stopped when the discharge capacity fell below 80% of the discharge capacity at the first cycle (specifically, 78%, and the number of cycles at that time was 612). In addition, about the part of lithium ion secondary battery which performed this charging / discharging process, when the total amount of FEC and VC which remain | survived inside was investigated, it was 16 mg.
＜非水電解液の補充＞
次に、充放電サイクル処理後のリチウムイオン二次電池に、前記の非水電解液（２ａ）：３ｇを補充して、再生処理を行った。非水電解液（２）の補充は、先に注射針を有しているシリンジに非水電解液（２ａ）を入れ、この蓋板を封止している封止部材にシリンジの注射針を刺し電池ケース内部に非水電解液（２ａ）を注入することにより行った。そして、非水電解液（２ａ）を補充が終了した時点で注射針を封止部材から引き抜き、封止部材から非水電解液（２ａ）が漏出しないことを確認した。なお、この非水電解液（２ａ）の補充によって、３１．５ｍｇのＦＥＣと３１．５ｍｇのＶＣ（両者の合計が６３ｍｇ）を、電池ケース内に新たに導入したことになる。
<Replenishment of non-aqueous electrolyte>
Next, the lithium ion secondary battery after the charge / discharge cycle treatment was supplemented with 3 g of the non-aqueous electrolyte (2a), and a regeneration treatment was performed. The replenishment of the non-aqueous electrolyte (2) is performed by putting the non-aqueous electrolyte (2a) into a syringe having an injection needle first, and inserting the syringe needle into the sealing member sealing the lid plate. This was performed by injecting a non-aqueous electrolyte (2a) into the stab battery case. And when replenishment of the non-aqueous electrolyte (2a) was completed, the injection needle was pulled out from the sealing member, and it was confirmed that the non-aqueous electrolyte (2a) did not leak from the sealing member. By replenishing this non-aqueous electrolyte (2a), 31.5 mg of FEC and 31.5 mg of VC (a total of 63 mg of both) were newly introduced into the battery case.
＜再生処理後のリチウムイオン二次電池の高温貯蔵特性評価＞
再生処理後のリチウムイオン二次電池について、前記の充放電処理時と同じ条件で定電流充電および定電圧充電を行った。次に、充電後のリチウムイオン二次電池を８５℃に設定した恒温槽内に入れて２４時間貯蔵し、取り出した後の電池の厚みを測定した。そして、求めた厚みから、下記式に従って膨れ量を算出した。
<High temperature storage characteristics evaluation of regenerated lithium ion secondary battery>
About the lithium ion secondary battery after a regeneration process, the constant current charge and the constant voltage charge were performed on the same conditions as the time of the said charging / discharging process. Next, the charged lithium ion secondary battery was placed in a thermostat set at 85 ° C., stored for 24 hours, and the thickness of the battery after removal was measured. And the amount of swelling was computed from the calculated | required thickness according to a following formula.
電池の膨れ量 ＝ １００×（ｔ１−ｔ０）／ｔ０
ここで、前記式中、ｔ１は再生処理を行い定電流−定電圧充電を行ってから、８５℃で２４時間貯蔵した後の電池の厚み（ｍｍ）であり、ｔ０は組み立て直後の電池の厚み（すなわち、電池の組み立てに使用した外装缶の厚み。ｍｍ。）である。
Battery swell amount = 100 × (t 1 −t 0 ) / t 0
Here, in the above formula, t 1 is the thickness (mm) of the battery after regenerating and performing constant current-constant voltage charging and storing at 85 ° C. for 24 hours, and t 0 is the battery immediately after assembly. (That is, the thickness of the outer can used for assembling the battery, mm.).
また、再生処理を行ったものとは別の電池について、再生処理前の前記条件での充放電処理を、再生処理を行った電池に施したときと同じサイクル数行い、その後に、再生処理を行った電池と同じ条件で高温貯蔵後の膨れ量を求めた。 In addition, for a battery different from the battery that has undergone the regeneration process, the charge / discharge process under the above conditions before the regeneration process is performed for the same number of cycles as the battery that has undergone the regeneration process, and then the regeneration process is performed. The amount of swelling after high-temperature storage was determined under the same conditions as the battery used.
＜再生処理前後でのリチウムイオン二次電池の充放電サイクル特性評価＞
再生処理後のリチウムイオン二次電池（前記の高温貯蔵特性評価に供したものとは別の電池）について、前記の充放電処理時と同じ条件で充放電サイクルを行い、リチウムイオン二次電池の組み立て後の初回放電容量の８０％の容量を維持し得るサイクル数を求めた。そして、このサイクル数と、再生処理前の充放電処理時にリチウムイオン二次電池に施した充放電のサイクル数とを合計して、再生処理前後でのリチウムイオン二次電池における、初回放電容量の８０％の容量を維持し得るサイクル数を算出した。
<Evaluation of charge / discharge cycle characteristics of lithium ion secondary battery before and after regeneration treatment>
About the lithium ion secondary battery (battery different from what was used for the said high temperature storage characteristic evaluation) after a regeneration process, a charge / discharge cycle is performed on the same conditions as the time of the said charge / discharge process, The number of cycles capable of maintaining 80% of the initial discharge capacity after assembly was determined. Then, the total number of cycles and the number of charge / discharge cycles applied to the lithium ion secondary battery during the charge / discharge process before the regeneration process are combined to determine the initial discharge capacity of the lithium ion secondary battery before and after the regeneration process. The number of cycles capable of maintaining 80% capacity was calculated.
比較例１
再生処理時にリチウムイオン二次電池に補充する非水電解液に、実施例１で作製したものと同じ非水電解液（１）を使用した以外は、実施例１と同様にしてリチウムイオン二次電池の充放電処理および再生処理を行った。なお、再生処理時の非水電解液（１）の補充によって、６０ｍｇのＦＥＣと６０ｍｇのＶＣ（両者の合計が１２０ｍｇ）を、電池ケース内に新たに導入したことになる。
Comparative Example 1
The lithium ion secondary was the same as in Example 1, except that the same nonaqueous electrolyte (1) as that prepared in Example 1 was used as the nonaqueous electrolyte to replenish the lithium ion secondary battery during the regeneration process. The battery was charged / discharged and regenerated. Note that 60 mg of FEC and 60 mg of VC (total of both 120 mg) were newly introduced into the battery case by replenishment of the non-aqueous electrolyte (1) during the regeneration process.
そして、再生処理後のリチウムイオン二次電池について、実施例１と同じ方法で高温貯蔵特性評価（電池の膨れ量の測定）と、充放電サイクル特性評価とを行った。 And about the lithium ion secondary battery after a regeneration process, high temperature storage characteristic evaluation (measurement of the swelling amount of a battery) and charge / discharge cycle characteristic evaluation were performed by the same method as Example 1. FIG.
実施例１および比較例１に係るリチウムイオン二次電池における前記の高温貯蔵特性評価および充放電サイクル特性評価の結果を表１に示す。 Table 1 shows the results of the high-temperature storage characteristic evaluation and the charge / discharge cycle characteristic evaluation in the lithium ion secondary batteries according to Example 1 and Comparative Example 1.
表１に示す通り、実施例１に係るリチウムイオン二次電池は、再生処理前後での充放電サイクル特性評価時において、組み立て直後の初回放電容量の８０％を維持し得るサイクル数が、比較例１の電池よりはやや少ないものの、非常に多かった。よって、実施例１に係るリチウムイオン二次電池に施した再生処理によって、リチウムイオン二次電池の充放電サイクル寿命を長期化できていた。また、実施例１に係るリチウムイオン二次電池は、再生処理後の再生処理後の高温貯蔵特性評価時における膨れ量が、比較例１に係る電池に比べて小さく、再生処理前の高温貯蔵特性評価時における膨れ量と同等であり、再生処理に伴って生じ得る膨れを良好に抑制できていた。 As shown in Table 1, in the lithium ion secondary battery according to Example 1, the number of cycles that can maintain 80% of the initial discharge capacity immediately after assembly in the charge / discharge cycle characteristics evaluation before and after the regeneration treatment is a comparative example. Although it was slightly less than the battery of 1, it was very much. Therefore, the regeneration treatment applied to the lithium ion secondary battery according to Example 1 can prolong the charge / discharge cycle life of the lithium ion secondary battery. Further, the lithium ion secondary battery according to Example 1 has a small amount of swelling at the time of high temperature storage characteristic evaluation after the regeneration process after the regeneration process, compared with the battery according to Comparative Example 1, and the high temperature storage characteristic before the regeneration process. It was equivalent to the amount of swelling at the time of evaluation, and it was possible to satisfactorily suppress the swelling that could occur with the regeneration process.
実施例２
ＦＥＣを１．２質量％となる量で、およびＶＣを１．２質量％となる量で、それぞれ溶解させた以外は、実施例１における非水電解液（１）と同様にして、リチウムイオン二次電池の電池ケースに補充するための非水電解液（２ｂ）を調製した。
Example 2
Lithium ions were obtained in the same manner as the non-aqueous electrolyte (1) in Example 1 except that FEC was dissolved in an amount of 1.2% by mass and VC was dissolved in an amount of 1.2% by mass. A non-aqueous electrolyte (2b) for replenishing the battery case of the secondary battery was prepared.
実施例１で作製したものと同様に作製したリチウムイオン二次電池について、実施例１と同じ条件で充放電処理を繰り返し、放電容量が１サイクル目の放電容量の６０％を下回った時点（具体的には５９％であり、そのときのサイクル数は７１５回であった）で充放電を止めた。なお、この充放電処理を施したリチウムイオン二次電池の一部について、内部に残存しているＦＥＣとＶＣとの合計量を調べたところ、８ｍｇであった。 For a lithium ion secondary battery produced in the same manner as that produced in Example 1, the charge / discharge treatment was repeated under the same conditions as in Example 1, and the discharge capacity fell below 60% of the discharge capacity in the first cycle (specifically 59%, and the number of cycles at that time was 715). In addition, about the part of lithium ion secondary battery which performed this charging / discharging process, when the total amount of FEC and VC which remain | survived inside was investigated, it was 8 mg.
充放電処理後のリチウムイオン二次電池に、前記の非水電解液（２ｂ）を実施例１と同じ方法で補充して、再生処理を行った。なお、この非水電解液（２ｂ）の補充によって、３６ｍｇのＦＥＣと３６ｍｇのＶＣ（両者の合計が７２ｍｇ）を、電池ケース内に新たに導入したことになる。 The lithium ion secondary battery after the charge / discharge treatment was supplemented with the nonaqueous electrolyte solution (2b) in the same manner as in Example 1 to perform a regeneration treatment. By replenishing this non-aqueous electrolyte (2b), 36 mg of FEC and 36 mg of VC (total of both 72 mg) are newly introduced into the battery case.
再生処理後のリチウムイオン二次電池について、実施例１と同じ方法で高温貯蔵特性評価（電池の膨れ量の測定）を行った。 The lithium ion secondary battery after the regeneration treatment was evaluated for high-temperature storage characteristics (measurement of battery swelling) by the same method as in Example 1.
また、再生処理後のリチウムイオン二次電池（前記の高温貯蔵特性評価に供したものとは別の電池）について、前記の充放電処理時と同じ条件で充放電サイクルを行い、リチウムイオン二次電池の組み立て後の初回放電容量の６０％の容量を維持し得るサイクル数を求めた。そして、このサイクル数と、再生処理前の充放電処理時にリチウムイオン二次電池に施した充放電のサイクル数とを合計して、再生処理前後でのリチウムイオン二次電池における、初回放電容量の６０％の容量を維持し得るサイクル数を算出した。 Moreover, about the lithium ion secondary battery (Battery different from what was used for the said high temperature storage characteristic evaluation) after a reproduction | regeneration process, a charge / discharge cycle is performed on the same conditions as the time of the said charge / discharge process, and a lithium ion secondary The number of cycles capable of maintaining 60% of the initial discharge capacity after battery assembly was determined. Then, the total number of cycles and the number of charge / discharge cycles applied to the lithium ion secondary battery during the charge / discharge process before the regeneration process are combined to determine the initial discharge capacity of the lithium ion secondary battery before and after the regeneration process. The number of cycles that can maintain a capacity of 60% was calculated.
比較例２
再生処理時にリチウムイオン二次電池に補充する非水電解液に、実施例１で作製したものと同じ非水電解液（１）を使用した以外は、実施例２と同様にしてリチウムイオン二次電池の充放電処理および再生処理を行った。なお、再生処理時の非水電解液（１）の補充によって、６０ｍｇのＦＥＣと６０ｍｇのＶＣ（両者の合計が１２０ｍｇ）を、電池ケース内に新たに導入したことになる。
Comparative Example 2
The lithium ion secondary was the same as in Example 2, except that the same nonaqueous electrolyte (1) as that prepared in Example 1 was used as the nonaqueous electrolyte to replenish the lithium ion secondary battery during the regeneration process. The battery was charged / discharged and regenerated. Note that 60 mg of FEC and 60 mg of VC (total of both 120 mg) were newly introduced into the battery case by replenishment of the non-aqueous electrolyte (1) during the regeneration process.
そして、再生処理後のリチウムイオン二次電池について、実施例１と同じ方法で高温貯蔵特性評価（電池の膨れ量の測定）と、充放電サイクル特性評価とを行った。 And about the lithium ion secondary battery after a regeneration process, high temperature storage characteristic evaluation (measurement of the swelling amount of a battery) and charge / discharge cycle characteristic evaluation were performed by the same method as Example 1. FIG.
実施例２および比較例２に係るリチウムイオン二次電池における前記の高温貯蔵特性評価および充放電サイクル特性評価の結果を表２に示す。 Table 2 shows the results of the high-temperature storage characteristic evaluation and the charge / discharge cycle characteristic evaluation in the lithium ion secondary batteries according to Example 2 and Comparative Example 2.
表２に示す通り、実施例２に係るリチウムイオン二次電池は、再生処理前後での充放電サイクル特性評価時において、組み立て直後の初回放電容量の６０％を維持し得るサイクル数が、比較例２の電池よりはやや少ないものの、非常に多かった。よって、実施例２に係るリチウムイオン二次電池に施した再生処理によって、リチウムイオン二次電池の充放電サイクル寿命を長期化できていた。また、実施例２に係るリチウムイオン二次電池は、再生処理後の再生処理後の高温貯蔵特性評価時における膨れ量が、比較例２に係る電池に比べて小さく、再生処理前の高温貯蔵特性評価時における膨れ量と同等であり、再生処理に伴って生じ得る膨れを良好に抑制できていた。 As shown in Table 2, the lithium ion secondary battery according to Example 2 has a comparative example in which the number of cycles capable of maintaining 60% of the initial discharge capacity immediately after assembly is evaluated at the time of charge / discharge cycle characteristics evaluation before and after the regeneration process. Although it was slightly less than the battery of 2, it was very much. Therefore, the regeneration treatment applied to the lithium ion secondary battery according to Example 2 can extend the charge / discharge cycle life of the lithium ion secondary battery. Further, the lithium ion secondary battery according to Example 2 has a small swelling amount at the time of high temperature storage characteristic evaluation after the regeneration process after the regeneration process, compared with the battery according to Comparative Example 2, and the high temperature storage characteristic before the regeneration process. It was equivalent to the amount of swelling at the time of evaluation, and it was possible to satisfactorily suppress the swelling that could occur with the regeneration process.
１ 正極
２ 負極
３ セパレータ
1 Positive electrode 2 Negative electrode 3 Separator
Claims (5)
前記リチウムイオン二次電池は、前記電池ケースに非水電解液注入口を有しており、かつ前記非水電解液注入口は、弾性体で構成された封止部材により封止されており、
前記リチウムイオン二次電池の組み立てから充放電を繰り返して放電容量が初回の放電容量よりも小さくなった段階で、前記封止部材に管を突き刺し、前記管を通じて前記電池ケース内に非水電解液を補充し、その後に前記管を前記封止部材から抜く工程を有しており、
前記リチウムイオン二次電池の組み立て時に使用する非水電解液（１）、および前記電池ケース内に補充する非水電解液（２）は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有しており、かつ負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の前記化合物の、前記非水電解液（２）における含有量が、前記非水電解液（１）における含有量よりも少ないか、または、
前記リチウムイオン二次電池の組み立て時に使用する非水電解液（１）は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の化合物を含有しており、かつ前記電池ケース内に補充する非水電解液（２）は、負極での還元電位が金属Ｌｉ電位に対して１．３Ｖ以下の前記化合物を含有していないことを特徴とするリチウムイオン二次電池の再生方法。 A lithium ion secondary battery in which a positive electrode, a negative electrode, a separator, and a non-aqueous electrolyte are accommodated in a battery case formed by a bottomed cylindrical outer can and a lid plate that seals the opening of the outer can. Is a method of playing
The lithium ion secondary battery has a non-aqueous electrolyte inlet in the battery case, and the non-aqueous electrolyte inlet is sealed by a sealing member made of an elastic body,
In the stage where the discharge capacity is smaller than the initial discharge capacity by repeating charge and discharge from the assembly of the lithium ion secondary battery, a tube is pierced into the sealing member, and the non-aqueous electrolyte is inserted into the battery case through the tube And then removing the tube from the sealing member,
The non-aqueous electrolyte (1) used when assembling the lithium ion secondary battery and the non-aqueous electrolyte (2) to be replenished in the battery case have a reduction potential at the negative electrode of 1. The content of the compound containing 3 V or less and the reduction potential at the negative electrode of 1.3 V or less with respect to the metal Li potential in the non-aqueous electrolyte (2) is the non-aqueous electrolyte. Less than the content in (1), or
The non-aqueous electrolyte (1) used at the time of assembling the lithium ion secondary battery contains a compound whose reduction potential at the negative electrode is 1.3 V or less with respect to the metal Li potential, and in the battery case The method of regenerating a lithium ion secondary battery, wherein the nonaqueous electrolyte solution (2) to be replenished does not contain the compound having a reduction potential at the negative electrode of 1.3 V or less with respect to the metal Li potential.
前記化合物（Ａ）の、前記非水電解液（１）における含有量をａ（ｍｇ）としたとき、前記非水電解液（２）には、前記化合物（Ａ）の含有量が０．４×ａ（ｍｇ）以下であるか、または前記化合物（Ａ）を含有していないものを使用する請求項２に記載のリチウムイオン二次電池の再生方法。 The replenishment of the non-aqueous electrolyte (2) into the battery case is performed when the discharge capacity of the lithium ion secondary battery is 80% ± 3% of the initial discharge capacity immediately after assembly,
When the content of the compound (A) in the nonaqueous electrolytic solution (1) is a (mg), the nonaqueous electrolytic solution (2) has a content of the compound (A) of 0.4. The method for regenerating a lithium ion secondary battery according to claim 2, wherein the lithium ion secondary battery is not more than × a (mg) or does not contain the compound (A).
前記化合物（Ａ）の、前記非水電解液（１）における含有量をｂ（ｍｇ）としたとき、前記非水電解液（２）には、前記化合物の含有量（Ａ）が、０．４５×ｂ（ｍｇ）以下であるか、または前記化合物（Ａ）を含有していないものを使用する請求項２に記載のリチウムイオン二次電池の再生方法。 The replenishment of the non-aqueous electrolyte (2) into the battery case is performed when the discharge capacity of the lithium ion secondary battery is 60% ± 3% of the initial discharge capacity immediately after assembly,
When the content of the compound (A) in the non-aqueous electrolyte solution (1) is b (mg), the non-aqueous electrolyte solution (2) has a content (A) of 0. The method for regenerating a lithium ion secondary battery according to claim 2, which is 45 × b (mg) or less or does not contain the compound (A).
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| KR102261711B1 (en) * | 2016-07-21 | 2021-06-08 | 주식회사 엘지에너지솔루션 | Cylindrical Battery Having Electrolyte Injection-hole |
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| JP2003036892A (en) * | 2001-07-23 | 2003-02-07 | Japan Storage Battery Co Ltd | Battery control unit and battery |
| JP2008041548A (en) * | 2006-08-09 | 2008-02-21 | Sanyo Electric Co Ltd | Nonaqueous electrolyte secondary battery |
| JP2013149451A (en) * | 2012-01-19 | 2013-08-01 | Hitachi Maxell Ltd | Lithium secondary battery |
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