Abstract: The electrolyte includes one or more polysiloxanes, one or more alkali metal salts, and one or more silanes. At least one polysiloxane includes side chains having poly(alkylene oxide) moieties. At east one silane includes at least one moiety selected from a first group consisting of an alkyl group, a halogenated alkyl group, an aryl group, a halogenated aryl group, an alkoxy group and an oxyalkylene group and at least one moiety selected from a second group consisting of an alkoxy group, an oxyalkylene group and a carbonate group. In one example, the electrochemical device is a secondary battery.

Abstract: An inexpensive and durable polyelectrolyte composition includes both an aromatic polymer containing carbonyl linkages and/or sulfonyl linkages in the backbone chain and bearing cation-exchange groups and a fused salt exhibits a high ionic conductivity even in the absence of water or a solvent. The aromatic polymer is preferably an aromatic polyether sulfone comprising specific structural units and bearing cation-exchange groups, an aromatic polyether ketone comprising specific structural units and bearing cation-exchange groups, an aromatic polyether sulfone block copolymer consisting of at least one hydrophilic segment bearing cation-exchange groups and at least one hydrophobic segment free from cation-exchange groups, and/or an aromatic polyether ketone block copolymer consisting of at least one hydrophilic segment bearing cation-exchange groups and at least one hydrophobic segment free from cation-exchange groups.

Abstract: A non-aqueous electrolyte secondary battery has a positive electrode having a positive electrode collector, on which a positive electrode active material layer containing a positive electrode active material as a complex oxide of Li and transition metals are formed, and a negative electrode having a negative collector, on which a negative electrode active material layer is formed. The non-aqueous electrolyte secondary battery is a gel or solid non-aqueous electrolyte secondary battery having a battery device in which a positive electrode and a negative electrode are laminated with an electrolyte layer therebetween in a film-state packaging member constructed by metal foil laminated films, and containing a lithium salt, a non-aqueous solvent, and a polymer material. The concentration in mass ratio of a free acid in the electrolyte layer is 60 ppm and less.

Abstract: A solid polymer electrolyte is made up of a polymer compound having a hydrocarbon aromatic group in the backbone thereof and including a side chain expressed by FORMULA 1: wherein “n” is 1, 2, 3, 4, 5, or 6. The solid polymer electrolyte may be incorporated into a membrane and may be used in a solution for covering an electrode catalyst.

Abstract: The invention relates to a copolymer of ethylene oxide or propylene oxide and at least one substituted oxirane bearing an ionic group. The copolymer is characterized in that its chain comprises repeat units —O—CH2—CH(—CH2—O—SO3?Li+)—, repeat units —O—CH2—CHR— in which R is H or CH3, optionally, repeat units —O—CH2—CH(—CH2R?)— in which R? is a functional group.× Uses: electrolyte in electrochemical, selective-membrane and reference-membrane devices.

Abstract: An electrochemical cell comprises as an anode, a lithium transition metal oxide or sulphide compound which as a [B2]X4n? spinel-type framework structure of an A[B2]S4 spinel wherein A and B are metal cations selected from Li, Ti, V, Mn, Fe and Co, X is oxygen or sulphur, and n? refers to the overall charge of the structural unit [B2]X4 of the framework structure. The transition metal cation in the fully discharged state has a mean oxidation state greater than +3 for Ti, +3 for V, +3.5 for Mn, +2 for Fe and +2 for Co. The cell includes as a cathode, a lithium metal oxide or sulphide compound. An electrically insulative lithium containing liquid or polymeric electronically conductive electrolyte is provided between the anode and the cathode.

Abstract: A room temperature crosslinkable polymer system comprising an anhydride containing polymer and an oxyalkylene amine and a polymer electrolyte derived therefrom are prepared and employed as ion conducting materials for batteries such as lithium ion battery, solar cells and electrochromic devices is disclosed.

Abstract: An object of the present invention is to provide a highly durable solid polymer electrolyte that has a deterioration resistance equal to or higher than that of the fluorine-containing solid polymer electrolytes or a deterioration resistance sufficient for practical purposes, and can be produced at a low cost. According to the present invention, there is provided a solid polymer electrolyte comprising a polyether ether sulfone that is used as an electrolyte and has sulfoalkyl groups bonded to its aromatic rings and represented by the general formula —(CH2)n—SO3H.

Abstract: An alkali-metal-ion battery is disclosed in one embodiment of the invention as including an anode containing an alkali metal, a cathode, and an electrolyte separator for conducting alkali metal ions between the anode and the cathode. In selected embodiments, the electrolyte separator includes a first phase comprising poly(alkylene oxide) and an alkali-metal salt in a molar ratio of less than 10:1. The electrolyte separator may further include a second phase comprising ionically conductive particles that are conductive to the alkali metal ions. These ionically conductive particles may include ionically conductive ceramic particles, glass particles, glass-ceramic particles, or mixtures thereof.

Abstract: The present invention provides for a solid polymer electrolyte membrane having a fluorinated ionomer having imbibed therein a non-fluorinated, non-ionomeric polymer, wherein the fluorinated ionomer comprises at least 6 mole % of monomer units having a fluorinated pendant group with a terminal ionic group, and wherein the non-ionomeric polymer is selected from the group consisting of a polyamine, a polyvinyl amine, and derivatives thereof. The invention also provides a catalyst coated membrane and a fuel cell having this solid polymer electrolyte membrane.

Abstract: A reserve activated lithium ion battery is provided with a number of safety features designed to prevent a thermal run-away condition. The reserve activated battery may include a non-flammable electrolyte, a phosphate-based cathode, an anode with a non-fluorinated binder, and/or a solid electrolyte interface on the anode.

Abstract: The invention provides a novel lithium-ion battery electrolyte which is produced by adding an aluminate ester compound as a plasticizer in a solid polymer electrolyte. The lithium-ion battery solid polymer electrolyte of the present invention comprises a lithium ion source, an organic polymer compound, and one or more kinds of aluminate ester compounds represented by the general formula where R1, R2, and R3 each independently represent a straight-chain or branched-chain lower alkyl group having one to eight carbon atoms, an alkenyl group having three to six carbon atoms, acryloyl, or methacryloyl; OA1, OA2, and OA3 each independently represent an oxyalkylene group having two to four carbon atoms; l represents a number from 1 to 100; and m and n each independently represent a number from 0 to 100.

Abstract: The present invention provides a solid electrolyte with high ion-conductivity which is cheap and exhibits high conductivity in an alkaline form, and stably keeps high conductivity because of a small amount of the leak of a compound bearing conductivity even in a wet state. The invention is useful in an electrochemical system using the solid electrolyte, such as a fuel cell. The solid electrolyte with high ion-conductivity comprises a hybrid compound which contains at least polyvinyl alcohol and a zirconic acid compound, and also a nitrogen-containing organic compound having a structure of amine, quaternary ammonium compound and/or imine, obtained by hydrolyzing a zirconium salt or an oxyzirconium salt in a solution including water, polyvinyl alcohol, a zirconium salt or an oxyzirconium salt and a nitrogen-containing organic compound having a structure of amine, quaternary ammonium compound and/or imine coexist, removing a solvent and contacting with alkali.

Abstract: Disclosed is a rechargeable lithium battery comprising a negative electrode and a positive electrode capable of intercalating and deintercalating lithium, and an electrolyte, wherein the electrolyte comprises a polyacrylate compound having three or more acrylic groups.

Abstract: Disclosed is a nonaqueous and nonvolatile liquid type polymeric electrolyte comprising poly(siloxane-g-ethylene oxide). This electrolyte provides significant safety and stability. The present invention solves the problems of volatility, flammability and chemical reactivity of lithium ion type electrolytes. The disclosed electrolyte exhibits excellent stability, conductivity and low impedance characteristics. The electrolyte comprises a new class of structural siloxane polymers with one or more poly(ethylene oxide) side chains. The inorganic siloxanes comprising the main backbone of the copolymers are thermally very stable and resistant to decomposition by heat. Because the main chain of the disclosed class of electrolytes is an Si—O linkage, initiation of the combustion cycle is inhibited or prevented.

Abstract: An electrochemical cell comprises as an anode, a lithium transition metal oxide or sulphide compound which as a [B2]X4n- spinel-type framework structure of an A[B2]S4 spinel wherein A and B are metal cations selected from Li, Ti, V, Mn, Fe and Co, X is oxygen or sulphur, and n- refers to the overall charge of the structural unit [B2]X4 of the framework structure. The transition metal cation in the fully discharged state has a mean oxidation state greater than +3 for Ti, +3 for V, +3.5 for Mn, +2 for Fe and +2 for Co. The cell includes as a cathode, a lithium metal oxide or sulphide compound. An electrically insulative lithium containing liquid or polymeric electronically conductive electrolyte is provided between the anode and the cathode.

Abstract: The solid electrolyte of the present invention is composed of an organic/inorganic composite material having pores with a mean pore diameter of 1 to 30 nm and having a skeleton comprising a metal atom, an oxygen atom bonded to the metal atom, and an organic group having at least one carbon atom bonded to the metal atom or the oxygen atom, and a functional group having an ion exchange function and bonded to the organic group inside the pores. As a result, even if the relative pressure of the water vapor in the atmosphere is less than 1.0, it is still possible to achieve a solid electrolyte with a sufficiently high ion conductivity at a lower temperature than with a conventional solid electrolyte such as stabilized zirconia.

Abstract: The present invention generally relates to batteries or other electrochemical devices, and systems and materials for use in these, including novel electrode materials and designs. In some embodiments, the present invention relates to small-scale batteries or microbatteries. For example, in one aspect of the invention, a battery may have a volume of no more than about 5 mm3, while having an energy density of at least about 400 W h/l. In some cases, the battery may include a electrode comprising a porous electroactive compound. In some embodiments, the pores of the porous electrode may be at least partially filled with a liquid such as a liquid electrolyte. The electrode may be able to withstand repeated charging and discharging. In some cases, the electrode may have a plurality of protrusions and/or a wall (which may surround the protrusions, if present); however, in other cases, there may be no protrusions or walls. The electrode may be formed from a unitary material.

Abstract: The object of the present invention is to provide a lithium secondary battery of high output. According to the present invention, there is provided a lithium secondary battery having a positive electrode and a negative electrode which reversibly intercalate and deintercalate lithium and an electrolyte containing an ion conductive material and an electrolytic salt, where said electrolyte contains an electrolytic salt and a boron-containing compound represented by the following formula (1) or a polymer thereof, or a copolymer of the compounds of the following formulas (2) and (3).

Abstract: The invention relates to novel organic/inorganic hybrid membranes which have the following composition: a polymer acid containing —SO3H, —PO3H2, —COOH or B(OH)2 groups, a polymeric base (optional), which contains primary, secondary or tertiary amino groups, pyridine groups, imidazole, benzimidazole, triazole, benzotriazole, pyrazole or benzopyrazole groups, either in the side chain or in the main chain; an additional polymeric base (optional) containing the aforementioned basic groups; an element or metal oxide or hydroxide, which has been obtained by hydrolysis and/or sol-gel reaction of an elementalorganic and/or metalorganic compound during the membrane forming process and/or by a re-treatment of the membrane in aqueous acidic, alkaline or neutral electrolytes. The invention also relates to methods for producing said membranes and to various uses for membranes of this type.

Abstract: A solvent-free polymer electrolyte and a secondary battery employing the electrolyte are provided. The electrolyte includes: a porous film, including a first polymer and a second oligomer, the first polymer being at least one selected from the group consisting of poly (vinylidene fluoride-co-hexafluoropropylene) copolymers, polyvinylidenefluorides, polymethylmethacrylates, polyacrylonitriles, polyethyleneoxides, and celluloses having a polyether chain, and the second oligomer being at least one selected from the group consisting of poly(ethylene oxide-co-ethylene carbonate) copolymers with at least one terminal groups substituted by a halogen atom and polyethyleneglycols with at least one terminal group substituted by a halogen atom. An electrolyte comprising the second oligomer and a lithium salt is present in the pores of the porous film.

Abstract: An ion-conductive electrolyte which comprises a compound having in the molecule a structure represented by the following chemical formula and an electrolyte salt; and a cell employing the ion-conductive electrolyte. The ion-conductive electrolyte has a low vapor pressure, has a high ion conductivity even at room temperature, and has a high lithium ion transport number. With this ion-conductive electrolyte, a highly safe cell having excellent discharge characteristics can be provided.

Abstract: The invention is a material for a solid polyelectrolyte, comprising a multi-segmented fluoropolymer that comprises a block copolymer and/or a graft copolymer, wherein the copolymer contains one or more blocks essentially consisting of segment A and one or more blocks essentially consisting of segment B, the segment A combines with the segment B, wherein the segment A has a molecular weight of 5,000 to 1,000.

Abstract: Disclosed is a polymer electrolyte composition for a rechargeable lithium battery including a multifunctional monomer represented by formula 1, a polymer initiator, a non-aqueous organic solvent, and a lithium salt: where A is one represented by one of formulae 1a, 1b, or 1c; where n is an integer of 1 to 10; R1 to R7 are the same or are independently selected from H, C1 to C3 alkyls, and C?N; and X is a C1 to C20 aliphatic or aromatic carbon, or polyether.

Abstract: An electrochemical cell comprises as an anode, a lithium transition metal oxide or sulphide compound which has a [B2]X4n? spinel-type framework structure of an A[B2]X4 spinel wherein A and B are metal cations selected from Li, Ti, V, Mn, Fe and Co, X is oxygen or sulphur, and n? refers to the overall charge of the structural unit [B2]X4 of the framework structure. The transition metal cation in the fully discharged state has a mean oxidation state greater than +3 for Ti, +3 for V, +3,5 for Mn, +2 for Fe and +2 for Co. The cell includes as a cathode, a lithium metal oxide or sulphide compound. An electrically insulative lithium containing liquid or polymeric electronically conductive electrolyte is provided between the anode and the cathode.

Abstract: Disclosed is a rechargeable lithium battery comprising a negative electrode and a positive electrode capable of intercalating and deintercalating lithium, and an electrolyte, wherein the electrolyte comprises a polyacrylate compound having three or more acrylic groups.

Abstract: An ion conductor structural body having a high ion conductivity and excellent mechanical strength, principally comprising is provided. This ion conductor structural body includes (a) a polymer matrix; (b) a solvent capable of functioning as a plasticizer; and (c) an electrolyte. The polymer matrix (a) includes a polymer chain having at least a segment represented by the following general formula (1): wherein R1 and R2 are, respectively, H or an alkyl group of 2 or less carbon atoms, A is a group having at least a polyether group, and R3 is a group having at least an alkyl group of more than 6 carbon atoms. The main chain portion of the polymer chain and the side chain portion of the segment have an orientation property.

Abstract: The present invention provides a polymer electrolyte material comprising a polymer having a repeating unit based on an alicyclic fluoromonomer having a carbon-carbon double bond with radical polymerization reactivity, wherein either of carbon atoms at both ends of the double bond constitutes a ring structure; the repeating unit contains a strongly acidic group such as a sulfonic acid group; the polymer is preferably perfluorinated. This electrolyte material has a high softening temperature and a polymer electrolyte fuel cell using this electrolyte material can be operated at higher temperatures than before. Furthermore, when this electrolyte material is used for a catalyst layer of a cathode in a polymer electrolyte fuel cell, an output voltage of the cell can be increased.

Abstract: A single step, in situ curing method for making gel polymer lithium ion rechargeable cells and batteries is described. This method used a precursor solution consisting of monomers with multiple functionalities such as multiple acryloyl functionalities, a free-radical generating activator, nonaqueous solvents such as ethylene carbonate and propylene carbonate, and a lithium salt such as LiPF6. The electrodes are prepared by slurry-coating a carbonaceous material such as graphite onto an anode current collector and a lithium transition metal oxide such as LiCoO2 onto a cathode current collector, respectively. The electrodes, together with a highly porous separator, are then soaked with the polymer electrolyte precursor solution and sealed in a cell package under vacuum. The whole cell package is heated to in situ cure the polymer electrolyte precursor.

Abstract: An ethylene oxide copolymer of the present invention has a crystallization temperature of not more than 20° C. and a glass transition temperature of not more than ?64° C. This makes it possible to provide an ethylene oxide copolymer in which increase in the glass transition temperature is small even when metal salt is added, and a polymer composition including the ethylene oxide copolymer.

Abstract: A non-aqueous electrolyte cell that excels in the high-temperature cycle characteristics and that is without the possibility of solution leakage. The non-aqueous electrolyte cell includes a polymer electrolyte. This polymer electrolyte is a polymerization of a prepolymer included in a prepolymer electrolyte that includes a non-aqueous solvent, an electrolyte salt, and the prepolymer. The prepolymer includes a polyester-based monomer. The polymer electrolyte further includes a vinylene carbonate derivative and cyclic acid anhydride.

Abstract: An ion conductor structural body having a high ion conductivity and excellent mechanical strength, principally comprising is provided. This ion conductor structural body includes (a) a polymer matrix; (b) a solvent capable of functioning as a plasticizer; and (c) an electrolyte. The polymer matrix (a) includes a polymer chain having at least a segment represented by the following general formula (1): wherein R1 and R2 are, respectively, H or an alkyl group of 2 or less carbon atoms, A is a group having at least a polyether group, and R3 is a group having at least an alkyl group of more than 6 carbon atoms. The main chain portion of the polymer chain and the side chain portion of the segment have an orientation property. The polymer matrix has a cross-linked structure.

Abstract: A polymer including a block chain A which is formed from a random copolymer containing a repeating unit (I) represented by the formula (I) wherein R1 to R3 each independently represents hydrogen or C1-10 hydrocarbon and R1 and R3 may bond to form a ring; R4a and R4b each independently represents hydrogen or methyl; R5 represents hydrogen, hydrocarbon, acyl, or silyl; and m represents any integer of 1 to 100 and when m is 2 or more and each R4a may be the same or different from one another and each R4b may be the same or different from one another; and a repeating unit (II) represented by the formula (II) wherein R6 and R8 each independently represents hydrogen or C1-10 hydrocarbon and R6 and R8 may bond to form a ring; R7 represents hydrogen, C1-10 hydrocarbon, hydroxyl, hydrocarbonoxy, carboxyl, acid anhydride, amino, ester, or an organic group having at least one functional group selected from the group consisting of hydroxyl, carboxyl, epoxy, acid anhydride, and amino; and R9 represents an

Abstract: Provided is a polymer electrolyte containing a block copolymer comprising one or more blocks having sulfonic acid groups and one or more blocks having substantially no sulfonic acid group, and at least one block among all blocks is a block having aromatic rings in the main chain thereof, and a method for producing the same. The polymer electrolyte is suitable for a proton conductive film of a fuel cell due to excellent water resistance and heat resistance, and high proton conductivity.

Abstract: Provided is a polymer composition containing an oxocarbon and a polymer, further, a polymer composition that the oxocarbon are expressed by formula (1).

Abstract: A polymer electrolyte extends the cycle life, improves the safety, and reduces the swelling of a battery, compared with a polymer electrolyte containing a poly(alkylene oxide) polymer. Also, a lithium battery utilizes the polymer electrolyte. The polymer electrolyte contains a polymerized product from a polymer electrolyte forming composition containing a multifunctional isocyanurate monomer of a particular structure, a lithium salt, and a non-aqueous organic solvent.

Abstract: To provide a polymer electrolyte material for polymer electrolyte fuel cells, which is an electrolyte material having a high ion exchange capacity and a low resistance, and which has a higher softening temperature than a conventional electrolyte material.

Abstract: A do-it-yourself (DIY) thin film battery provides battery assembling components suitable for separate storage and easy fabrication. With through hole plating or sidewall plating, the current collectors of the anode and cathode, extend from one side of the substrates to the other to facilitate electric coupling with the electronic product outside. Through either soldering or direct contact with conductive tapes, the battery components mount with each other. Thus, the battery components can be combined to have batteries of various voltages and capacities via series or parallel connection means without extra circuits.

Abstract: This invention relates to a polysiloxane-based compound and a solid polymer electrolyte composition prepared using the same. More particularly, the present invention relates to a polysiloxane-based polymer, which promotes easy cross-linking and also enables to control the level of cross-linking according to the concentration of an acryl group by introducing a polyalkyleneoxide group and an acryl group are introduced as side chains to the backbone of methylsiloxane polymer.

Abstract: A composition for use as a polymer electrolyte, wherein said composition includes one or more polar materials and one or more polyesters of formula III, wherein each unit A may be identical or different and is of the structure IV, wherein each unit B may be identical or different and is of the structure V, wherein R and R1 are each, independently, hydrogen, optionally substituted hydrocarbyl or an inert functional group; a process for preparing said composition; the use of said composition as a polymer electrolyte in coulometers, displays, smart windows, cells or batteries; and a cell and/or battery having said composition.

Abstract: This invention relates to ion conducting random copolymers that are useful in forming polymer electrolyte membranes used in fuel cells.

Abstract: The invention provides a crosslinkable aromatic resin having a protonic acid group and a crosslinkable group, suitable for electrolytic membranes and binders used in fuel cells, etc., and electrolytic polymer membranes, binders and fuel cells using the resin. The crosslinkable aromatic resin has a crosslinkable group, which is not derived from the protonic acid group and can form a polymer network without any elimination component. This resin exhibits excellent ion conductivity, heat resistance, water resistance, adhesion property and low methanol permeability. Preferably, the crosslinkable group is composed of a C1 to C10 alkyl group directly bonded to the aromatic ring and/or an alkylene group having 1 to 3 carbon atoms in the main chain in which at least one carbon atom directly bonded to the aromatic ring bonds to hydrogen, and a carbonyl group, or a carbon-carbon double bond or triple bond.

Abstract: A method of forming an electrochemical cell is disclosed. The method comprises contacting a negative pole layer and a positive pole layer one with the other or with an optional layer interposed therebetween. The pole layers and the optional layer therebetween are selected so as to self-form an interfacial separator layer between the pole layers upon such contacting.

Abstract: A polymer battery which comprises a negative electrode comprising a carbon material as an active material, an electrolyte layer and a positive electrode comprising a chalcogenide containing lithium as an active material, characterized in that the electrolyte layer comprises an ion-conducting compound and a polymer fiber, and the carbon material comprises the graphite particles having amorphous carbon adhered on the surface thereof. The polymer battery is capable of preventing the decomposition of the ion-conductive material by graphite particles.

Abstract: An organic solid electrolyte comprises a polymer obtained by (co)polymerization of cyanoethyl acrylate and/or cyanoethyl methacrylate, the polymer being doped with an inorganic ion salt. The electrolyte has a high ionic conductivity and is based on a hydroxyl-free polymer so that it may be used to construct a secondary battery which eliminates the risk of gas evolution.

Abstract: A polymer gel electrolyte composition includes a crosslinked polymer network matrix having a three-dimensional crosslinked structure that includes a solution of an electrolyte in a non-aqueous solvent, and a non-crosslinked polymer included within the crosslinked polymer network matrix. The non-crosslinked polymer includes (a) an ethylene unit and/or propylene unit, and (b) an unsaturated carboxylic acid unit having a carboxyl group esterified by a polyalkylene glycol having one terminal hydroxyl group protected.

Abstract: In a lithium secondary cell having a negative electrode, a positive electrode and, arranged between the electrodes, a polymer electrolyte layer, the internal resistance of the cell and the interfacial resistance between the electrode and the polymer electrolyte can be reduced by incorporating into the electrode, in advance, a polymer electrolyte precursor solution in a manner such that the electrode has a higher content of the precursor monomer and/or an oligomer thereof than that in the polymer electrolyte layer formed on the electrode.

Abstract: A chemical battery, comprising a positive electrode, a negative electrode, and a gel electrolyte containing a crosslinked body and an electrolyte, the crosslinked body being obtained by crosslinking at least one compound selected from the group consisting of an epoxy compound having an alicyclic structure and at least one epoxy group in a single molecule and an alicyclic epoxy resin.

Abstract: A lithium polymer secondary battery comprising a negative electrode, a positive electrode and an electrolyte layer between both electrodes, wherein the negative electrode and the positive electrode each has a solid electrolyte prepared by incorporating an organic electrolytic solution into a polymer, the polymer is obtained by solidifying a precursor solution containing vinylene carbonate and a content of vinylene carbonate in the precursor solution for the positive electrode is smaller than that in the precursor solution for the negative electrode.

Abstract: Provided are a polymeric electrolyte or a nonaqueous electrolyte that can improve a transport rate of charge carrier ions by adding a compound having boron atoms in the structure, preferably one or more selected from the group consisting of compounds represented by the following general formulas (1) to (4), and an electric device such as a cell or the like using the same. wherein R11, R12, R13, R14, R15, R16, R21, R22, R23, R24, R25, R26, R27, R28, R31, R32, R33, R34, R35, R36, R37, R38, R39, R310, R41, R42, R43, R44, R45, R46, R47, R48, R49, R410, R411 and R412 each represent a hydrogen atom, a halogen atom or a monovalent group, or represent groups bound to each other to form a ring, and Ra, Rb, Rc and Rd each represent a group having a site capable of being bound to boron atoms which are the same or different.