WO2015024982A1 - Electrodes for energy storage devices comprising organic compounds with extended conjugated cores with electron withdrawing substituents - Google Patents

Abstract

Electrodes for energy storage devices comprising compounds of formula (1) or oligomers or polymers comprising units derived from compounds of formula (1) and/or (2) as repeating unit or as part of the repeating units.

Description

Electrodes for energy storage devices comprising organic compounds with extended conjugated cores with electron withdrawing substituents

[0001] This application claims priority to European application No. 13181576.3 filed on August 23, 2013, the whole content of this application being incorporated herein by reference for all purposes.

[0002] The present invention relates to electrodes for energy storage devices comprising organic compounds with extended conjugated cores with at least one electron withdrawing substituent in the core and to novel compounds of this type.

[0003] The development of sustainable systems for energy storage and supply is one of the great technological challenges in the foreseeable future. There is an increasing need of storing electrical energy obtained from renewable resources like sunlight and wind which are becoming important energy sources for the future.

[0004] A particularly important aspect in this regard is the development of new, low-cost and environmentally acceptable electro-active materials for electrodes in energy storage devices, in particular secondary batteries and capacitors.

[0005] Conventional positive electrodes (cathode) in secondary lithium-ion

batteries are usually lithium transition metal oxides or phosphates that can reversibly intercalate and de-intercalate lithium ions. The capacity of such batteries is usually limited by the cathode. Furthermore, these usual materials have to be obtained by energy demanding high temperature ceramic processes using rare and often toxic materials.

[0006] Replacement of lithium by sodium has been considered both for the non- toxicity and for the cost and also the natural abundance of sodium.

However, the insertion of sodium is generally handicapped by poor loading and slow kinetics of the larger sodium ion compared to the lithium ion.

[0007] Organic redox batteries could be a more sustainable approach based on synthetic versatility, solution processability and recyclability of functional organic compounds.

[0008] A prominent approach in this regard has been to use electro-active polymers showing reversible redox behavior, tunable potential, electric conduction, lightweight, flexibility, film forming and ease of wet processing.

[0009] In the early stage conjugated polymers have attracted the highest

attention (such as polyaniline, polypyrrole or polythiophene or the like) . However, their low doping limits and thus their low charge capacity as well as their slow doping-and de-doping process turned out to be serious drawbacks. Furthermore, these conjugated polymers in many cases are rather instable.

[0010] Efforts have thus been directed to amorphous, aliphatic organic polymers densely populated with pendant redox sites. In contrast to conjugated polymers, electrode-active sites in non-conjugated polymers can be fully doped and show constant potential during the redox process.

[001 1] In particular, stable nitroxide radicals such as tetramethylpiperidineoxyl derivatives (commonly referred to as TEMPO) or tetramethylpyridinyloxyl (PROXY) have been studied as suitable pendant groups in such polymers for positive electrodes.

[0012] Organic radical lithium batteries using such p-type nitroxyl-based positive electrodes have shown a remarkable cycling stability.

[0013] A further development increasing the capacity of secondary batteries

based on organic materials was the development of multi-electron redox- active materials incorporating carbonyl groups, namely quinones and polyketones, anhydrides and imides.

[0014] Coskun et al., RSC Adv. 2012, 2, 7968 describe the effect of N- substitution in naphthalenediimides on the electrochemical performance of organic rechargeable batteries.

[0015] Yang et al. J. Electroanal. Chem. 2012,

http:/dx.doi.org/10.1016/j.jelechem.2012.07.19, describe the reversible Li and Na storage behaviors of perylenetetracarboxylat.es as organic anodes for Li- and Na-ion batteries. Lithium and sodium perylene tetracarboxylates of chemical formulae LUC24H8O8 respectively Na₄C24H808 and having the structural formulae

[0016] and their reversible bonding properties of Li and Na ions with the

carboxylate group were investigated.

[0017] It is described that carboxylate groups conjugated with an aromatic core can allow the insertion and de-insertion of metal ions. The aromatic core with larger conjugated perylene system should increase chemical stability and decrease the solubility of the materials in the electrolytes used.

Dissolution of the electrode materials in the electrolyte is one of the major issues reducing cycling stability of organic redox batteries.

[0018] Sun et al., Electrochem. Comm. 25, 2012, 136-139 describe the synthesis and electrochemical performance of Li and Ni 1 ,4,5,8- naphthalenetetracarboxylat.es as anodes for Li-ion batteries.

[0019] US 2008/021220 describes compounds of formula

[0020]

[0021] wherein each of A-D and G-H can be independently selected from H, an electron withdrawing substituent and a moiety comprising such a substituent. The compounds are known as excellent electron-transporting (n-type) organic semiconductors in transistors.

[0022] WO 2005/076815 discloses perylene n-type organic semiconductors of the general formula

[0023]

[0024] with A-H and K-L being H, an electron withdrawing substituent or a moiety comprising such substituent and their use in devices, in particular transistors.

[0025] There is an ongoing need to provide improvements in the performance properties of energy storage devices in terms of storage capacity, energy density, power density and cycling performance.

[0026] Accordingly it was an object of the present invention to provide electrodes for energy storage devices with improved performance properties.

[0027] This object has been achieved with the electrodes for energy storage devices as defined in claim 1 .

[0028] Preferred embodiments of the present invention are set forth in the

dependent claims and in the detailed specification hereinafter.

[0029] In accordance with the present invention, electrodes for energy storage devices are provided which comprise compounds of formula (1 ) and/or (2) or oligomers or polymers comprising units derived from compounds of formula (1 ) or (2) as repeating unit or as part of the repeating units

[0030]

[0031]

[0032] wherein

Xi and X2, which may be the same or different, represent a covalent bond, O, S, NR or NM

Yi to Y₄, which may be the same or different, represent O or S or NR', Zi to Z₄, which may be the same or different, represent OM or SM, R and R' represent, independent of each other, a C1-C30 hydrocarbyl or C1-C30 heterohydrocarbyl group,

M, which may be the same or different at each occurrence, represents an alkali metal, an alkaline earth metal or a transition metal having an atomic number of at least 22,

[0033] Ri to Re, represent, independent of each other, hydrogen, a C1-C30

hydrocarbyl group, a C1-C30 heterohydrocarbyl group, halogen, NO2, (NR₉RioRii)⁺, CN, SO3M, SO2R12, SOR13, CORi₄, PORisRie with R₉ to R16, independent of each other, being a C1-C30 hydrocarbyl group or a Ci- C30 heterohydrocarbyl group, preferably OH, NR17R18, halogen, Ci-Cs- alkyl, Cs-C3o-aryl or OM with M having the meaning as defined above and Ri7 and R18 representing a C1-C18 alkyl or a C5-C30 aryl group, with the proviso that at least one of Ri to Re is a substituent selected from the group consisting of halogen, NO2, (NR9RioRn)⁺, d-Cs haloalkyl, C2-C8- haloalkenyl, C2-C8-haloalkynyl, Ci-Cs-haloheterohydrocarbyl, CN, SO3M, SO2R12, SOR13, CORi₄, POR15R16 with R₉ to Ri₆, independent of each other, being a C1-C30 hydrocarbyl or C1-C30 heterohydrocarbyl group, preferably OH, NR17R18, halogen, Ci-Cs-alkyl, Cs-C3o-aryl or OM with M having the meaning as defined above and R17 and R18 representing a Ci- C18 alkyl or a C5-C30 aryl group,

o is 0 or 1 and p is 0 or an integer of from 1 to 3, and wherein Ri and F¾, R3 and R₄, R5 and R6 and R₇ and Rs may form together a ring system.

[0034] For the purpose of the present invention the terms oligomer and polymer, respectively, represent homo-oligomers as well as co-oligomers and homopolymers and co-polymers. The prefix co- in those cases indicates that the co-oligomer respectively the co-polymer has at least two different repeating units whereas homo-oligomers and homo-polymers respectively do only contain one repeating unit.

[0035] Xi and X2, which may be the same or different, represent a covalent bond, O, S, NR or NM, preferably O, NR or NM and even more preferably O or NR.

[0036] Y1 to Y4, which may be the same or different, represent O, S or NR',

preferably O or S.

[0037] R and R', independent of one another, represent a C1-C30 hydrocarbyl or C1-C30 heterohydrocarbyl group.

[0038] The term "hydrocarbyl", for the purpose of this invention, is intended to denote a saturated or unsaturated, aliphatic or aromatic, cyclic or straight- or branched-chain hydrocarbon group.

[0039] Accordingly, the term hydrocarbyl includes alkyl, alkenyl, alkynyl,

cycloalkyl or aryl groups.

[0040] As used herein, "alkyl" refers to a straight-chain or branched saturated hydrocarbon group. In some preferred embodiments, an alkyl group can have from 1 to 20 carbon atoms, even more preferably from 1 to 8 carbon atoms). Examples of alkyl groups include methyl (Me), ethyl (Et), propyl (e.g., n-propyl and isopropyl), butyl (e.g., n-butyl, isobutyl, s-butyl, t-butyl), pentyl groups (e.g., n-pentyl, isopentyl, neopentyl), and the like. In some embodiments, alkyl groups can be substituted. A lower alkyl group typically has up to 6 carbon atoms, i.e., one to six carbon atoms.

Examples of lower alkyl groups include methyl, ethyl, propyl (e.g., n-propyl and isopropyl), and butyl groups (e.g., n-butyl, isobutyl, s-butyl, t-butyl.

[0041] As used herein, "alkenyl" refers to a straight-chain or branched alkyl group having one or more carbon-carbon double bonds. In some preferred embodiments, an alkenyl group can have from 2 to 20 carbon atoms in particular from 2 to 8 carbon atoms). Examples of alkenyl groups include ethenyl, propenyl, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl and hexadienyl groups. The one or more carbon-carbon double bonds can be internal (such as in 2-butene) or terminal (such as in 1 -butene). In some embodiments, alkenyl groups can be substituted.

[0042] As used herein, "alkynyl" refers to a straight-chain or branched alkyl group having one or more carbon-carbon triple bonds. In some preferred embodiments, an alkynyl group can have from 2 to 20 carbon atoms in particular from 2 to 8 carbon atoms). Examples of alkynyl groups include ethynyl, propynyl, butynyl, pentynyl, and the like. The one or more carbon- carbon triple bonds can be internal (such as in 2-butyne) or terminal (such as in 1 -butyne). In some embodiments, alkynyl groups can be substituted.

[0043] As used herein, "cycloalkyi" refers to a non-aromatic carbocyclic group including cyclized alkyl, alkenyl, and alkynyl groups. A cycloalkyi group can be monocyclic (e.g., cyclohexyl) or polycyclic (e.g. containing fused, bridged, and/or spiro ring systems), wherein the carbon atoms are located inside or outside of the ring system. A cycloalkyi group, as a whole, can preferably have from 3 to 14 ring atoms, in particular from 3 to 8 carbon atoms for a monocyclic cycloalkyi group and preferably from 7 to 14 carbon atoms for a polycyclic cycloalkyi group). Examples of cycloalkyi groups include cyclopropyl, cyclopropylmethyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclohexylmethyl, cyclohexylethyl, cycloheptyl, cyclopentenyl, cyclohexenyl, cyclohexadienyl, cyclo-heptatrienyl, norbornyl, norpinyl, norcaryl, adamantyl, and spiro[4,5]decanyl groups, as well as their homologs, isomers, and the like. In some embodiments, cycloalkyi groups can be substituted.

[0044] As used herein, "aryl" refers to an aromatic mono-cyclic hydrocarbon ring system or a polycyclic ring system in which two or more aromatic hydrocarbon rings are fused (i.e., having a bond in common with) together or at least one aromatic monocyclic hydrocarbon ring is fused to one or more cycloalkyi and/or cycloheteroalkyi rings. An aryl group can have from 6 to 14 carbon atoms in its ring system, which can include multiple fused rings. In some embodi-ments, a polycyclic aryl group can have from 8 to 14 carbon atoms. Examples of aryl groups having only aromatic

carbocyclic ring(s) include phenyl, 1 -naphthyl (bicyclic), 2-naphthyl (bicyclic), anthracenyl (tricyclic), phenanthrenyl (tricyclic) and like groups. Examples of polycyclic ring systems in which at least one aromatic carbocyclic ring is fused to one or more cycloalkyi and/or cycloheteroalkyl rings include, among others, benzo derivatives of cyclopentane (e.g., an indanyl group, which is a 5,6-bicyclic cycloalkyl/aromatic ring system), benzo derivatives of cyclohexane (e.g., a tetrahydronaphthyl group, which is a 6,6-bicyclic cycloalkyl/aromatic ring system).

[0045] Preferred hydrocarbyl groups for R and R' are alkyl and cycloalkyi groups, in particular C1 -C8-alkyl, cyclopentyl or cyclohexyl, which may all be substituted or unsubstituted.

[0046] The term "heterohydrocarbyl as used herein, denotes a structural skeleton as described above for hydrocarbyl groups with the difference that at least one of the carbon atoms and/or at least one of the hydrogen atoms of the hydrocarbyl group is replaced by a heteroatom.

[0047] As used herein, "heteroatom" refers to an atom of any element other than carbon or hydrogen and includes, for example, nitrogen, oxygen, sulfur, halogen, phosphorus, and selenium.

[0048] Thus, alkyl, alkenyl or alkynyl groups may bear at least one heteroatom as a substituent replacing a respective number of hydrogen atoms.

Particularly, hydrogen atoms may be replaced by halogen, such as fluoro and chloro atoms.

[0049] As used herein, "cycloheteroalkyl" refers to a non-aromatic cycloalkyi group that contains at least one ring heteroatom selected from O, N and S, which may be the same or different, and optionally contains one or more double or triple bonds. A cycloheteroalkyl group, as a whole, can have, for example, from 3 to 14 ring atoms and contain from 1 to 5 ring heteroatoms (e.g., from 3-7 ring atoms for a monocyclic cycloheteroalkyl group and from 7 to 14 ring atoms for a polycyclic cycloheteroalkyl group). In some embodiments, nitrogen atoms of cycloheteroalkyl groups can bear a substituent. Examples of cycloheteroalkyl groups include, among others, morpholine, thiomorpholine, pyran, imidazolidine, imidazoline, oxazoli- dine, pyrazolidine, pyrazoline, pyrrolidine, pyrroline, tetrahydrofuran, tetrahydrothiophene, piperidine, piperazine, and the like. In some embodiments, cycloheteroalkyl groups can be optionally substituted. As used herein, "heteroaryl" refers to an aromatic monocyclic ring system containing at least 1 ring heteroatom selected from oxygen (O), nitrogen (N) and sulfur (S) or a polycyclic ring system where at least one of the rings present in the ring system is aromatic and contains at least 1 ring heteroatom. When more than one ring heteroatoms are present they may be the same or different. Polycyclic heteroaryl groups include two or more heteroaryl rings fused together and monocyclic heteroaryl rings fused to one or more aromatic carbocyclic rings, non-aromatic carbocyclic rings, and/or non-aromatic cycloheteroalkyl rings. A heteroaryl group, as a whole, can have, for example, from 5 to 14 ring atoms and contain 1 -5 ring heteroatoms. The heteroaryl group can be attached to the defined chemical structure at any heteroatom or carbon atom that results in a stable structure. Generally, heteroaryl rings do not contain O-O, S-S, or S- O bonds. Examples of heteroaryl groups include, for example, the 5- and 6-membered monocyclic and 5-6 bicyclic ring systems shown below:

wherein T is O, S, or a substituted nitrogen atom (substituted with H or another substituent).

[0052] Examples of such heteroaryl rings include pyrrolyl, furyl, thienyl, pyridyl, pyrimidyl, pyridazinyl, pyrazinyl, triazolyl, tetrazolyl, pyrazolyl, imidazolyl, isothiazolyl, thiazolyl, thiadiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, indolyl, isoindolyl, benzofuryl, benzothienyl, quinolyl, 2-methylquinolyl, isoquinolyl, quinoxalyl. quinazolyl. benzotriazolyl, benzimidazolyl, benzothiazolyl, benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl, cinno- linyl, 1 H-indazolyl, 2H-indazolyl, indolizinyl, isobenzofuyl, naphthyridinyl, phthalazinyl, pteridinyl, purinyl, oxazolopyridinyl, thiazolopyridinyl, imidazopyridinyl, furopyridinyl, thienopyridinyl, pyridopyrimidinyl, pyridopyrazinyl, pyridopyridazinyl, thienothiazolyl, thienoxazolyl, thienoimidazolyl groups, pyridine, pyridazine, pyrazine, triazines or tetrazines. Further examples of heteroaryl groups include 4.5,6,7 - tetrahydroindolyl, tetrahydroquinolinyl, benzothienopyridinyl and benzofuropyridinyl groups. The heteroaryl groups can be substituted or unsubstituted.

[0053] Preferred substituents R and R' are straight chain or branched alkyl

groups, preferably with 1 to 12 carbon atoms, e.g. methyl, ethyl, propyl or butyl, cycloalkyl groups with 5 to 14 carbon atoms, preferably cyclopentyl or cyclohexyl and aryl groups, preferably phenyl or napthyl and heteroaryl groups, preferably pyridinyl. The nature of substituent R or R', however, is not particularly critical for the purpose of the present invention.

[0054] M represents an alkali metal such as Li, Na, K, Rb or Cs, preferably Li or Na, or an alkaline earth metal such as Ca or Mg or a transition metal having an atomic number of at least 22 like Ti, Cr, Mn, Fe, Co, Pt, Pd, Ni, Cu, Zn or Ir, to name only a few examples. The nature of the metal atom in the compounds of formula 2 determines the coordination chemistry and suitable selection can be used by the skilled person to build stable, well- organized metal-carboxylate organic frame-works with open architectures (C.N.R. Rao, Angew. Chem. Int. Ed. 2004, 43, 1466-1496). In case of metals having a valence exceeding 1 , the remaining valencies are saturated with other groups or the metal can coordinate more than one oxygen or sulfur atom. [0055] At least one of substituents Ri to Rs is a substituent selected from the group consisting of halogen, NO2, (NR9RioRn)⁺, Ci-Cs haloalkyl, C2-C8- haloalkenyl, C2-C8-haloalkynyl, d-Cs-haloheterohydrocarbyl, CN, SO3M, SO2R12, SOR13, CORi₄, POR15R16 with R₉ to Rie, independent of each other, being a C1-C30 hydrocarbyl or C1-C30 heterohydrocarbyl group, preferably OH, NR17R18, halogen, d-Cs-alkyl, C₅-C3o-aryl or OM with M having the meaning as defined above and R17 and R18 representing a Ci- C18 alkyl or a C5-C30 aryl group.

[0056] In accordance with a preferred embodiment, at last one of Ri to Rs is

selected from halogen, e.g. F, CI, Br or I, cyano, SO2R12, SOR13 or nitro, with R12 and R13 being as defined above.

[0057] In accordance with another preferred embodiment of the present

invention, in the compounds of formula (1 ) or (2) at least on of Yi to Y₄, preferably all of Yi to Y₄, are O and Xi and/or X2 are O or NR.

[0058] Compounds in which o is 1 represent another preferred embodiment of the present invention.

[0059] Another preferred embodiment is represented by compounds of formula (1 ) or (2) wherein p is 0.

[0060] A particularly preferred group of compounds of formulae (1 ) or (2) are represented by formulae (3), (3'), (4) and (4') :

[0061]

(3) (4)

(3') (4')

[0062] wherein Xi , X2, Yi to Y₄ , Zi to Z₄ and Ri to R6 have the meaning as defined in claim 1.

[0063] Preferred compounds of formula (3) or (4) are compounds wherein Yi to Y₄ are O, and/or at least one of Xi and X2 is NR or a covalent bond as shown below.

[0064] wherein Ri to R6 have the meaning as defined above.

[0065] I n accordance with another preferred embodiment of the present invention, the compounds of formula ( 1 ) or (2) are represented by the following formulae:

[0066] wherein Xi, X2, Yi to Y₄, Zi to Z₄ and Ri to Re have the meaning defined above and wherein Y5 to Ys, independent of Yi to Y₄, may have the same meaning as Yi to Y₄. L is an organic linker group, such as alkylene or heteroalkylene, or L is nil.

[0067] Particularly preferred are compounds wherein one or more, more

preferably all of Yi to Ye are oxygen.

[0068] The electrodes of the present invention, in accordance with another

preferred embodiment comprise oligomers or polymers comprising units derived from compounds of formula (1 ) and/or (2) as repeating unit or as part of the repeating units.

[0069] Oligomers or polymers derived from compounds of formulae (1) or (2) can be obtained in various ways which are in principle known to the skilled person.

[0070] As a first example, two of Ri to Rs are chosen from difunctional groups attached through one function to a carbon atom in formula (1 ) or (2) and providing one function for extending the chain of the oligomer or polymer. The respective substituents may be attached through any of the peripheral carbon atoms in formula (1) or (2) or through substituents Xi or X2 in case at least Xi and/or X₂ is NH or NR.

[0071] Thus, repeating units of suitable polymers or oligomers can be

represented by the following formulae

[0072] wherein the dotted lines represent the bonds for the chain extension ir the oligomer or polymer.

[0073] It is readily apparent to the skilled man that respective structures can a be derived from compounds of formula (2).

[0074] Preferred compounds according to claim 1 or oligomers or polymers according to claim 1 suitable for use in electrodes for energy storage devices are represented by formulae (5) and (5')

[0075] (⁵) (⁵')

[0076] wherein Xi, X2, Yi to Y₄, Ri to Re, o and p have the meaning as defined in claim 1 and Y5 to Ys can have the same meaning as Yi to Y₄ and n is 0 or an integer of from 1 to 10 000.

[0077] Compounds (5) and (5') are novel and constitute a still further embodiment of the present invention.

[0078] Furthermore, examples of repeating units of oligomers or polymers in the electrodes of the present invention are shown below

o: 0, 1

[0079] wherein L is alkylene or nil, and Ui and U₂ represent a bridging group selected from

O O

C— O— — O— C— O—

[0080] wherein R19, R20 and R21 are a C1-C30 hydrocarbyl or a C1-C30

heterohydrocarbyl group as defined herein above and wherein the dotted lines again represent the chain extending bonds .

[0081] If compounds of formula (1) or (2) with more than two functionalities are used, the oligomers or polymers may be crosslinked and thus form three- dimensional networks. Oligomers or polymers of formulae (6) to (8) are preferred in electrodes in accordance with the present invention. These oligomers or polymers are novel compositions of matter and thus these compounds as such form another embodiment of the present invention:

(6) (7)

o: 0, 1

o: 0, 1

wherein Xi , X2, Yi to Y₄ and Ri to R₇ have the meaning as defined in claim 1 ; Y5 toYs, independent of Yi to Y₄, may have the same meaning as Yi to Y_4; L is an organic linker group or nil, and Ui and U2 are selected from the group consisting of

o o

— c— o o— c— o—

[0083] with Rig, R20 and R21 being a C1-C30 hydrocarbyl or C1-C30

heterohydrocarbyl group as defined hereinabove.

[0084] Compounds of formula (1 ) or (2) or oligomers or polymers comprising units derived from compounds of formula (1 ) or (2) as defined in claim 1 as repeating unit or as part of the repeating units wherein each X represents a chemical bond are also novel and constitute a further embodiment of the present invention.

[0085] The compounds of formulae (1 ) to (8) described hereinabove have partly been described in the literature to the extent that these compounds are not novel. By way of example US 2008/081220 or WO2005/076815 may be mentioned here for further information on methods for the synthesis of the respective compounds.

[0086] Generally, a core substitution of fused conjugated ring systems derived from naphthylene or rylene conjugated cores can be achieved via bromo derivatives as intermediates or tin compounds as intermediates.

[0087] The bromination of naphthalene or rylene dianhydrides (NDA respectively RDA) is described in US 2008/0021220 starting in section 0071 to which reference is made herewith.

[0088] Tin compounds of naphthalene diimides (NDI) respectively rylene diimides (RDI) can be obtained in accordance with the method described in Org. Lett. 2012, 14(3), 918.

[0089] Core fluoroalkyl NDI respectively RDI can be obtained from bromo NDA respectively bromo RDA, which is transformed to an ester in the first step of the reaction, then reacted with a iodo-fluoroalkyl compound in the presence of copper, followed by anhydride formation and imidation following the method described in J. Org. Chem. 2010, 75, 3007. [0090] Core-halogenated compounds may be obtained by the copper mediated fluorination of iodides or bromides in accordance with J. Am.Chem.Soc.,

2012, 134, 107895, J.Am.Chem.Soc 2009, 131 , 6215, Org. Lett.2006, 8,

3765 and Adv. Mater. 2007, 19, 3692.

[0091] Cyanated compounds may be obtained through reaction of the respective bromo-intermediates with copper cyanide as described in J. Am. Chem.

Soc. 2007, 129, 15259 or Chem. Mater. 2007, 19, 2703.

[0092] Compounds with sulfone substituents in the core may be obtained by reaction respective bromine compounds with sulfides, followed by a mild oxidation, e.g. with hydrogen peroxide.

[0093] Bromo intermediates can also be subjected to nucleophilic substitution with amines, followed by the quaternization to form ammonium groups as substituents.

[0094] Compounds with acyl substituents in the core can be obtained via the stannyl intermediates as described in J. Org. Chem. 2012, 77, 5544.

[0095] In Angew. Chem. Int. Ed. 2013, 52, 5513 the synthesis of compounds of formula (4) is described, wherein at least one of Xi and X2 is a covalent bond:

[0098] The anhydride can be brominated as described above for NDA and RDA and thus intermediates for the other substitutions in the core may be obtained.

[0099] Ν,Ν-coupled compounds (e.g. of formula (5)) may be obtained by reacting the respective anhydrides with organic diamines or hydrazine hydrate (L is absent).

[00100] In accordance with a further preferred embodiment of the present

invention, the electrodes comprise the compound of formula (1 ) or (2) or oligomers comprising units derived from compounds of formula (1) or (2) as repeating unit or as part of the repeating units, as nano-sized crystalline particles.

[00101] The electrodes in accordance with the present invention can comprise, in addition to the compounds described hereinabove, a conductive carbon material and, optionally, other ingredients common in electrodes for respective energy storage devices. The skilled person will select the appropriate components based on his professional experience

[00102] The electrodes of the present invention are suitable for use in energy

storage devices like batteries or capacitors which can store electrical energy by a variety of methods.

[00103] Organic redox batteries, based on organic electrode materials known from the prior art show a good rate and cycling performance but are usually not satisfactory in terms of energy density and power density. This problem is often caused by low capacity values of the redox active compounds and/or a broad voltage range caused by multi-step redox reactions. Due to poor inherent electronic conducting capability, the practical capacity is further limited by the need to incorporate large quantities of conductive carbon additive.

[00104] Electrodes for such redox batteries based on the compounds as described hereinbefore through their extended planar cores allow to achieve favorable electronic transport and coupling to the carbon additive, which enables to greatly reduce the required quantity of the electrochemically inactive carbon additive. The electronic properties of the electrode can be easily tuned to adjust the redox potential, notably to obtain the required increase of the battery voltage to the desired level. The compounds can be designed to form crystalline structures and stable metal-carboxylate frameworks with open architecture, which are favourable for metal insertion and de-insertion at high rate and up to high levels in the course of operation of the device. A particular advantage is the replacement of Li ions by Na ions, both for its non-toxicity and its low cost due to its high natural abundance. [00105] Through the presence of multiple redox groups in the molecular structure, multi-electron transfer reactions may be achieved over a narrow potential range.

[00106] The core of the compounds can be modified by the substituents described to tune the redox potential of an electrode comprising such compounds. By introducing electron withdrawing groups (at least one of Ri to F¾ in the compounds described hereinbefore is preferably an electron withdrawing group, preferably selected from cyano, halogen, nitro, acyl or sulfonyl) this tunability can be achieved.

[00107] In a properly tuned system, excessive solvation of the redox active

material by the electrolyte may be avoided, and thus suppress dissolution of the redox material during the redox cycle which is detrimental for the cyclability.

[00108] The electrodes of the present invention, based on the compounds as described hereinbefore offer a good property spectrum which is advantageous compared to the electrodes known from the prior art.

[00109] Should the disclosure of any patents, patent applications, and publications which are incorporated herein by reference conflict with the description of the present application to the extent that it may render a term unclear, the present description shall take precedence.

Claims

Claims

1. Electrodes for energy storage devices comprising compounds of formula (1 ) and/or (2) or oligomers or polymers comprising units derived from compounds of formula (1 ) and/or (2) as repeating unit or as part of the repeating units

wherein

Xi and X2, which may be the same or different, represent a covalent bond, O, S, NR or NM

Yi to Y₄, which may be the same or different, represent O, S or NR',

Zi to Z₄, which may be the same or different, represent OM or SM,

R and R' represent, independent of each other, a C1-C30 hydrocarbyl or C1-C30 heterohydrocarbyl group,

M, which may be the same or different at each occurrence, represents an alkali metal, an alkaline earth metal or a transition metal having an atomic number of at least 22,

Ri to Re, represent, independent of each other, hydrogen, a C1-C30 hydrocarbyl group, a C1-C30 heterohydrocarbyl group, halogen, NO2,

(NR₉RioRi i)⁺, CN, SO3 , SO2R12, SOR13, COR14, PORisRie with R₉ to Rie, independent of each other, being a C1-C30 hydrocarbyl group or a C1-C30 heterohydrocarbyl group, preferably OH, NR17R18, halogen, Ci-Cs-alkyl, C5- C3o-aryl or OM with M having the meaning as defined above and R17 and R18 representing a C1-C18 alkyl or a C5-C30 aryl group, with the proviso that at least one of Ri to Rs is a substituent selected from the group consisting of halogen, NO2, (NR₉RioRii)⁺, Ci-C₈ haloalkyl, C₂-C₈-haloalkenyl, C2-C₈-haloalkynyl, Ci- Cs-haloheterohydrocarbyl, CN, SO3M, SO2R12, SOR13, CORi₄, PORisRie with R9 to R16, independent of each other, being a C1-C30 hydrocarbyl or C1-C30 heterohydrocarbyl group, preferably OH, NR17R18, halogen, Ci-Cs-alkyl, C5- C3o-aryl or OM with M having the meaning as defined above and R17 and R18 representing a C1-C18 alkyl or a C5-C30 aryl group,

0 is 0 or 1 and p is 0 or an integer of from 1 to 3, and

wherein Ri and R2, R3 and R₄, R5 and R6 and R7 and Rs may form together a ring system.

2. Electrodes in accordance with claim 1 wherein, in the compounds of formula (1) or (2), Yi to Y₄ are O and Xi and X2 are, independent of one another, O or NR.

3. Electrodes in accordance with claim 1 or 2 wherein , in the compounds of formula (1) or (2), o is 1.

4. Electrodes in accordance with any of claims 1 to 3 wherein, in the compounds of formula (1) or (2), p is 0.

5. Electrodes in accordance with any of claims 1 to 4 wherein, in the compounds of formula (1) or (2), at least one of Ri to Rs is selected from halogen, cyano, SO2R12, SOR13 or nitro wherein R12 and R13 have the meaning as defined in claim 1.

6. Electrodes in accordance with claim 5 wherein the compounds of formula (1 ) or (2) have the formulae (3), (3'), (4) or (4')

(3·) (4')

wherein Xi, X2, Yi to Y₄, Zi to Z₄ and Ri to R6 have the meaning as defined in claim 1.

7. Electrodes in accordance in accordance with any of claims 1 to 5 wherein the compounds of formula (1 ) or (2) are represented by formula (5) or (5')

(5) (5')

wherein Xi, X2, Yi to Y₄ , Zi to Z₄ and Ri to Rs, o and p have the meaning as defined in claim 1 and wherein Y5 to Y12 may have the same meaning as Yi to Y₄, n is 0 or an integer from 1 to 10 000 and L is an organic linker group or nil.

8. Use of the electrodes in accordance with any of claims 1 to 7 in batteries or capacitors.

9. Electrodes in accordance with claim 8, comprising the compound of formula (1 ) or (2) or oligomers comprising units derived from compounds of formula (1 ) or (2) as repeating unit or as part of the repeating units, as nano-sized crystalline particles.

10. Electrodes in accordance with any of claims 1 to 9 comprising, in addition to the compound of formula (1 ) or (2) or oligomers or polymers comprising units derived from compounds of formula (1 ) or (2) as repeating unit or as part of the repeating units, a conductive carbon material.

1 1 . Oligomers or polymers suitable for use in electrodes for energy storage

devices comprising repeating units of formulae (6), (7) or (8):

wherein Xi , X2, Yi to Y₄ and Ri to R₇ have the meaning as defined in claim 1 and wherein Y5 to Ys may have the same meaning as Yi to Y₄, L is an organic linker group or nil, and Ui and U2 are selected from the group consisting of Ri g O O O O

---N⁺-- -- — p. - - -S- - - — -s--- - - - C- - 20 R21 o

o

- -- c— 0 -— -— o— c— o—

with Rig, R20 and R21 represent, independent of each other, a C1-C30 hydrocarbyl or a C1-C30 heterohydrocarbyl group.

12. Compounds of formula (1) as defined in claim 1 or oligomers or polymers

comprising units derived from compounds of formula (1) as defined in claim 1 as repeating unit or as part of the repeating units suitable for use in electrodes for energy storage devices wherein each Xi and X2 represent a chemical bond.

13. Compounds of formula (1) or (2) as defined in claim 1 or oligomers or polymers comprising units derived from compounds of formula (1 ) or (2) as defined in claim 1 as repeating unit or as part of the repeating units suitable for use in electrodes for energy storage devices represented by the formulae (5) and (5')

(5) (5')

wherein Xi , X2, Yi to Y₄, Ri to Rs, o and p have the meaning as defined in claim 1 , Y5 to Y12 can have the same meaning as Yi to Y₄, n is 0 or an integer from 1 to 10 000 and L is an organic linker group or nil.

14. Battery or capacitor comprising at least one electrode in accordance with any of claims 1 to 10.