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JP-7856577-B2 - Polyamic acid derivative binder for lithium-ion batteries

JP7856577B2JP 7856577 B2JP7856577 B2JP 7856577B2JP-7856577-B2

Inventors

  • ビーソ， マウリツィオ
  • ピエリ， リカルド リノ
  • ソリアーノ， エドゥアルド
  • クワン， カーミット エス．
  • マウリ， ステファノ

Assignees

  • サイエンスコ スペシャルティ ポリマーズ イタリー エス．ピー．エー．

Dates

Publication Date
20260511
Application Date
20210324
Priority Date
20200505

Claims (12)

  1. A water-soluble aromatic polyamic acid derivative [polymer (P-A)], a) A repeating unit (L) comprising at least 50 mol% of repeating units (L) and at least one acidic moiety in the form of an ester, b) Repeating units (M) in 0 to 50 mol%, comprising at least one acid moiety either as is or in its imide form, c) A repeating unit (N) comprising 25 to 50 mol%, wherein the repeating unit (N) contains at least one acid moiety as a salt, The repeating unit (L) is given by the general formulas (L1) to (L4): [In the formula, - Ar is a trivalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated, or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms, independently of each other; - Ar' is a tetravalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated, or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms; - Each R1 is independently H or an alkyl, preferably H or an alkyl having 1 to 5 carbon atoms; - R is a divalent aromatic group; preferably, R has the following structure: and selected from the group consisting of the corresponding optionally substituted structures, where Y is selected from the group consisting of -O-, -S-, -SO2-, -CH2-, -C(O)-, -C(CF3)2- , - ( CF2 ) p- (where "p" is an integer from 0 to 5), More precisely, R is And, - Each Z is, • O-( CH2 ) k -O-CO-CH= CHR4 (where k is 1 to 20, preferably 1 to 8, more preferably 2 to 6, and even more preferably equal to 2 or 3, and R4 is H or alkyl, preferably an alkyl having 1 to 5 carbon atoms); • O-( CH2 ) p -Ar- CR5 = CHR6 or O-( CH2 ) p -OAr- CR5 = CHR6 (where p is 0 to 20, preferably 1 to 8; Ar comprises one or two aromatic rings or heteroaromatic rings; R5 and R6 are H, alkyl, preferably alkyl having 1 to 5 carbon atoms, phenyl, or COOR7 (where R7 is H or alkyl, preferably alkyl having 1 to 5 carbon atoms)); • O-( CH2 ) q -CH= CHR8 (where q is 0 to 20, preferably 1 to 8; and R8 is H or an alkyl, preferably an alkyl having 1 to 5 carbon atoms); • O-( CH2 ) r -O-CH= CHR9 (where r is 0 to 20, preferably 1 to 8; and R9 is H or an alkyl, preferably an alkyl having 1 to 5 carbon atoms) [ Selected independently from the group consisting of ] Selected from a group consisting of any of the following units, The repeating unit (M) is given by the general formulas (M1) to (M4): [In the formula, - Ar is a trivalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated, or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms, independently of each other; - Ar' is a tetravalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated, or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms; - Each R1 is independently H or an alkyl, preferably H or an alkyl having 1 to 5 carbon atoms; - R is a divalent aromatic group; preferably, R has the following structure: and selected from the group consisting of the corresponding optionally substituted structures, where Y is selected from the group consisting of -O-, -S-, -SO2-, -CH2-, -C(O)-, -C(CF3)2- , - ( CF2 ) p- (where "p" is an integer from 0 to 5), More precisely, R is is] Selected from a group consisting of any of the following units, The repeating unit (N) is given by the general formulas (N1) to (N4): [In the formula, - Ar is a trivalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated, or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms, independently of each other; - Ar' is a tetravalent aromatic moiety selected from the group consisting of substituted or unsubstituted, saturated, unsaturated, or aromatic monocyclic and polycyclic groups having 5 to 50 carbon atoms; - Each R1 is independently H or an alkyl, preferably H or an alkyl having 1 to 5 carbon atoms; - R is a divalent aromatic group; preferably, R has the following structure: and selected from the group consisting of the corresponding optionally substituted structures, where Y is selected from the group consisting of -O-, -S-, -SO2-, -CH2-, -C(O)-, -C(CF3)2- , - ( CF2 ) p- (where "p" is an integer from 0 to 5), More precisely, R is And, - Cat + is a monovalent cation, preferably selected from alkali metal cations, protonated primary, secondary, or tertiary ammonium cations, and quaternary ammonium cations , more preferably selected from Na + , K+, and Li + , and even more preferably Li + . A water-soluble aromatic polyamic acid derivative [polymer (P-A)] selected from the group consisting of any of the following units.
  2. A water-soluble aromatic polyamic acid derivative [polymer (P-A)] according to claim 1, a) At least 50 mol% of repeating units selected from the group consisting of units of either general formula (L2) or (L4); b) Repeating units selected from the group consisting of either the general formula (M2) or (M4), in an amount of 0 to 50 mol%; c) Repeating units selected from the group consisting of either the general formula (N2) or (N4), in an amount of 25 to 50 mol%, A water-soluble aromatic polyamic acid derivative [polymer (P-A)] containing [the specified substance].
  3. An aqueous binder composition (B) comprising the polymer (P-A) according to claim 1 or 2 and at least one aqueous solvent, wherein the aqueous solvent is preferably water .
  4. Electrode forming composition [Composition (C)], (i) The binder composition (B) according to claim 3, (ii) at least one electroactive material and (iii) Optionally, a thermal initiator and (iv) Optionally, a conductivity-imparting additive and A composition for electrode formation containing [Composition (C)].
  5. The electrode-forming composition [Composition (C)] according to claim 4 , wherein the electroactive material comprises one or more carbon-based materials and/or one or more silicon-based materials.
  6. The electrode-forming composition [Composition (C)] according to claim 5, wherein the thermal initiator is 1,2-bis(2-(4,5-dihydro-1H-imidazole-2-yl)-propan-2-yl)diazendihydrochloride.
  7. An electrode-forming composition [Composition (C)] according to any one of claims 4 to 6, (A) The binder composition (B) described in claim 3, (B) At least one electroactive material selected from one or more carbon-based materials and/or one or more silicon-based materials, (C) A thermal initiator which is 1,2-bis(2-(4,5-dihydro-1H-imidazole-2-yl)-propan-2-yl) diazendihydrochloride, (D) Optionally, an electrical conductivity-imparting additive and A composition for electrode formation containing [Composition (C)].
  8. Use of the electrode-forming composition (C) according to any one of claims 4 to 7 for the manufacture of an electrode [electrode (E)], wherein the manufacture is (i) Prepare a metal substrate having at least one surface, (ii) Prepare the electrode forming composition [composition (C)] according to any one of claims 4 to 7, (iii) Applying the composition (C) prepared in step (iii) onto the at least one surface of the metal substrate prepared in step (i), thereby preparing an assembly comprising the metal substrate coated with the composition (C) on the at least one surface, (iv) Drying the assembly prepared in step (iii), (v) Compressing the dried assembly obtained in step (iv) to obtain the electrode (E) of the present invention, The process includes, and includes, the use.
  9. An electrode [electrode (E)] obtainable by the process described in claim 8.
  10. An electrochemical device comprising at least one electrode (E) as described in claim 9.
  11. The electrochemical device according to claim 10, wherein the electrochemical device is - A secondary battery including a positive electrode and a negative electrode, An electrochemical device in which at least one of the positive electrode and the negative electrode is the electrode (E) described in claim 9.
  12. The electrochemical device according to claim 10, wherein the electrochemical device is - A secondary battery including a positive electrode and a negative electrode, The anode is the electrode (E) described in claim 9, an electrochemical device.

Description

Cross-reference of related applications This application claims priority to U.S. Provisional Patent Application No. 63/003253 filed March 3, 2020, and European Patent Application No. 20172958.9 filed May 5, 2020. The entire contents of this application are incorporated herein by reference for all purposes. This invention relates to lithium-ion polyamic acid derivatives and their use as binders in electrodes for lithium-ion batteries. Lithium-ion batteries (LIBs) are used in a variety of portable electronic devices and are being sought after as power sources for hybrid and electric vehicles. To meet the requirements of large-scale applications, LIBs with improved energy density and power capacity are desired. The recent trend in lithium batteries is to improve their energy capacity by increasing the amount of lithium stored in the anode. For this reason, conventional graphite anodes, which contain a large amount of silicon, are attracting considerable attention due to their significantly higher theoretical energy capacity. Silicon (Si) has a large capacity (at room temperature, Li 3.75 Si has a gravimetric capacity of 3572 mAhg⁻¹ and a volumetric capacity of 8322 mAhcm⁻³ ) and a low charge/discharge potential (delithiation voltage of approximately 0.4 V). Unfortunately, silicon also has the problem of very large volume changes (>400%) (anisotropic volume expansion) that occur when alloying with lithium ions. Changes in volume can lead to various disadvantages. For example, severe pulverization can occur, disrupting electrical contact between Si particles and the carbon conductive agent. Furthermore, (especially at high current densities) unstable solid electrolyte interfaces (SEIs) can form, resulting in electrode degradation and a rapid decrease in capacity. For the reasons mentioned above, electrode formulations for silicon anodes contain a maximum of 20% by weight of silicon compounds, with the remainder being graphite. In particular, electrode formulations containing graphite and silicon compounds ranging from 5% to 20% by weight are being studied. Traditionally, all graphite negative electrodes have used polyvinylidene fluoride (PVDF) as a binder. While PVDF interacts well with graphite particles, it does not adhere sufficiently to silicon particles. This makes the binder susceptible to damage from mechanical stress caused by the expansion and contraction of silicon during charging cycles. Recently, there has been a growing trend towards environmentally conscious approaches that generally avoid the use of organic solvents. As an example, aqueous slurries containing carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) are known in the art for use as binders. However, CMC/SBR binders are known to be brittle, and fracture points can form in the binder matrix itself. Furthermore, aqueous slurries containing CMC/SBR used as binders have high electrical resistance, resulting in a shorter lifespan (European Patent No. 2874212). Currently, lithium polyacrylate (LiPAA) exhibits the best properties among silicon active materials, but it is brittle and has low toughness. Therefore, when LiPAA is bent into a cylindrical shape, it breaks or cracks, making it suitable only for use in coin batteries. When polyimide is used as a binder for the negative electrode, interesting properties can be obtained. Polyimide has excellent mechanical properties, chemical resistance, and heat resistance, but it is insoluble in water and has low initial charge-discharge efficiency. Water-soluble polyamic acid may be used as a binder, in which case polyimide can be obtained through a post-treatment imidization process. However, when manufacturing electrodes in this manner, oxidation of the copper (Cu) substrate makes it difficult to raise the electrode plate temperature above 160°C, which is necessary for imidization, resulting in a low curing rate of the polyimide binder. A low curing rate leads to irreversible reactions as the carboxylic acid groups of the polyamic acid directly bond with lithium ions, resulting in poor initial efficiency. Furthermore, the presence of unstable amide bonds may negatively impact the battery's lifespan. Thus, although polyimide binders possess high adhesive strength and good mechanical and physical properties, they are unsuitable for actual industrial use due to reasons such as difficulty in low-temperature curing, resulting in unstable bonds and reduced long-term reliability, decreased initial efficiency due to irreversible lithium ion reactions, and insolubility in water. One objective of the present invention is to provide a polymer binder that can be efficiently used as a binder for silicon anodes. This invention provides a binder composition for lithium secondary batteries containing a water-soluble polyamic acid derivative. In a first embodiment, the present invention relates to a water-soluble aromatic polyamic acid derivative [polymer (P-A)], a) A repeating unit (L) comprising at leas