GB2574610A

GB2574610A - Polymer battery cell

Info

Publication number: GB2574610A
Application number: GB1809576.0A
Authority: GB
Inventors: Claire O'Sullivan Melanie; O'Regan Bryan; Blincow Jack; Kugler Thomas; Bourcet Florence
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 2018-06-11
Filing date: 2018-06-11
Publication date: 2019-12-18
Also published as: GB201809576D0

Abstract

A battery cell comprises an anode, a cathode, a separator between them, an anode current collector, and a cathode current collector, wherein the anode is an n-type polymer of formula (I) and the cathode comprises a p-type polymer with repeat unit (II), wherein R1 and R2 are each independently selected from H or a substituent; Ar1 and Ar2 are each independently an unsubstituted or substituted C6-20 arylene or heteroarylene group (preferably phenylene and naphthalene respectively); Ar3, Ar4 and Ar5 are each independently an unsubstituted or substituted C6-20 arylene or heteroarylene group (preferably phenyl); at least one aromatic ring atom of Ar3 is bound directly to an adjacent repeat unit or end group of the polymer; and at least one aromatic ring atom of Ar4 is bound directly to an adjacent repeat unit or end group of the polymer. A method of forming the battery includes depositing the relevant electrode material onto its associated current collector where the polymer is dissolved or dispersed in a solvent. Also claimed is a method of forming a battery cell electrode: providing a current collector with an insulating layer therein, wherein the insulator has a well which exposes the surface of the current collector; treating the insulkating surface and well with a surface treatment agent (preferably SF6 plasma); depositing an electroactive polymer into the well.

Description

Embodiments of the present disclosure relate to polymer battery cells and methods of forming the battery cells.

Background

Redox-active polymers have been used in the anode and cathode of so-called polymer-based battery cells. For example, polymer-based battery cells are disclosed in Journal of Power Sources, Volume 177, Issue 1, 15 February 2008, Pages 199-204, in Chem. Rev. 2016, 116, 9438-9484 and in Chemical Reviews, 1997, Vol. 97, No. 1 209.

Feng et al, Journal of Power Sources 177 (2008) 199-204 discloses use of polytriphenylamine as a cathode material in rechargeable lithium batteries.

CN 105261758 discloses Schiff base polymers of formula:

Bigoni et al, Journal of The Electrochemical Society, 164(1) A6171-A6177 (2017) discloses lithium ion batteries containing sodium alginate as a binder in the cathode of the batteries.

Summary of the Invention

In some embodiments of the present disclosure, a battery cell is provided comprising an anode, a cathode, a separator between the anode and the cathode, an anode current collector and a cathode current collector, wherein the anode comprises an n-type polymer comprising a repeat unit of formula (I) and the cathode comprises a p-type polymer comprising a repeat unit of formula (II):

(I) (II) wherein R and R are each independently selected from H or a substituent; Ar and Ar are each independently an unsubstituted or substituted C6-20 aromatic or heteroaromatic group; n, p and q are each independently 0, 1, 2, 3 or 4; and R³, R⁴ and R⁵ are each independently selected from Ci_2o-alkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci_2o-carboxyl, Ci-20-carbonyl, Ci-20-ester, and optionally substituted Cs-is-heteroaryl.

Battery cells as described anywhere herein are preferably rechargeable batteries.

Description of the Drawings

The disclosed technology and accompanying figures describe some implementations of the disclosed technology.

Figure 1 illustrates a polymer battery cell according to some embodiments of the present disclosure;

Figure 2 illustrates a method of forming a flexible polymer battery according to some embodiments of the present disclosure;

Figure 3 is a plot of discharge curves (voltage vs charge capacity) for a battery cell according to some embodiments of the present disclosure at current densities in the range of 0.33 - 5 mA/cm ; and

Figure 4 is a plot of discharge curves (voltage vs charge capacity) for a battery cell according to some embodiments of the present disclosure having thinner separator than the battery cell of Figure 3 at current densities in the range of 0.33 - 5 mA/cm .

Figure 5 is a plot of cyclic discharged capacity density vs. cycle number for battery cells according to some embodiments of the present disclosure, the anodes and cathodes of the battery cells having polymer : carbon black weight ratios of 1:0.8 or 1:0.4;

Figure 6 is a plot of cyclic midpoint voltage vs. cycle number for the battery cells described with respect to Figure 5;

Figure 7 is a plot of cyclic discharged capacity density vs. cycle number for battery cells according to some embodiments of the present disclosure including battery cells having an electroactive polymer : conductive carbon weight ratio of 1:0.3;

Figure 8 is a plot of cyclic midpoint voltage vs. cycle number for the battery cells described with respect to Figure 7;

Figure 9 is a plot of cyclic midpoint voltage vs. cycle number for a battery cell having an anode with an electroactive polymer : conductive carbon : electrolyte : binder ratio of 56.07:21.49:5.60:16.80; and

Figure 10 is a plot of cyclic discharged capacity density vs. cycle number for the battery cell of Figure 9.

The drawings are not drawn to scale and have various viewpoints and perspectives. The drawings are some implementations and examples. Additionally, some components and/or operations may be separated into different blocks or combined into a single block for the purposes of discussion of some of the embodiments of the disclosed technology. Moreover, while the technology is amenable to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and are described in detail below. The intention, however, is not to limit the technology to the particular implementations described. On the contrary, the technology is intended to cover all modifications, equivalents, and alternatives falling within the scope of the technology as defined by the appended claims.

Detailed Description

Unless the context clearly requires otherwise, throughout the description and the claims, the words comprise, comprising, and the like are to be construed in an inclusive sense, as opposed to an exclusive or exhaustive sense; that is to say, in the sense of including, but not limited to. As used herein, the terms connected, coupled, or any variant thereof means any connection or coupling, either direct or indirect, between two or more elements; the coupling or connection between the elements can be physical, logical, electromagnetic, or a combination thereof. Additionally, the words herein, above, below, and words of similar import, when used in this application, refer to this application as a whole and not to any particular portions of this application. Where the context permits, words in the Detailed Description using the singular or plural number may also include the plural or singular number respectively. The word or, in reference to a list of two or more items, covers all of the following interpretations of the word: any of the items in the list, all of the items in the list, and any combination of the items in the list.

The teachings of the technology provided herein can be applied to other systems, not necessarily the system described below. The elements and acts of the various examples described below can be combined to provide further implementations of the technology. Some alternative implementations of the technology may include not only additional elements to those implementations noted below, but also may include fewer elements.

These and other changes can be made to the technology in light of the following detailed description. While the description describes certain examples of the technology, and describes the best mode contemplated, no matter how detailed the description appears, the technology can be practiced in many ways. Details of the system may vary considerably in its specific implementation, while still being encompassed by the technology disclosed herein. As noted above, particular terminology used when describing certain features or aspects of the technology should not be taken to imply that the terminology is being redefined herein to be restricted to any specific characteristics, features, or aspects of the technology with which that terminology is associated. In general, the terms used in the following claims should not be construed to limit the technology to the specific examples disclosed in the specification, unless the Detailed Description section explicitly defines such terms. Accordingly, the actual scope of the technology encompasses not only the disclosed examples, but also all equivalent ways of practicing or implementing the technology under the claims.

To reduce the number of claims, certain aspects of the technology are presented below in certain claim forms, but the applicant contemplates the various aspects of the technology in any number of claim forms.

In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of implementations of the disclosed technology. It will be apparent, however, to one skilled in the art that embodiments of the disclosed technology may be practiced without some of these specific details.

Figure 1 illustrates a battery cell 100 according to an embodiment comprising an anode comprising an anode layer 101, a cathode comprising a cathode layer 105, a separator 103 between the anode and the cathode, an anode current collector 107 in contact with the anode and a cathode current collector 109 in contact with the cathode.

A plurality of devices may be linked to form a battery comprising a plurality of individual battery cells. In embodiments, a single current collector as described herein may be common to two adjacent battery cells, electrodes of the adjacent cells being formed on opposing surfaces of the current collector.

The anode comprises an n-type polymer of formula (I):

(I)

12 wherein R and R are each independently selected from H or a substituent; and Ar and Ar are each independently a C6-20 aromatic or heteroaromatic group, preferably a C6-20 arylene, optionally phenylene or napthylene.

Preferably, R and R are each independently selected from H Ci-20-alkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci_2o-carboxyl, Ci_2o-carbonyl, Ci_2o-ester, and optionally substituted Cs-is-heteroaryl. In a preferred embodiment, R and R are each H.

Preferably, Ar¹ is phenylene, more preferably meta- or para-linked phenylene which may be unsubstituted or substituted with one or more substituents selected from Ci-20-alkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci_2o-carboxyl, Ci_2o-carbonyl, Ci_2o-ester, and optionally substituted Cs-is-heteroaryl.

Preferably, Ar is naphthylene, more preferably a group of formula (III):

wherein R⁶ in each occurrence is independently a substituent selected from Ci-20-alkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci_2o-carboxyl, Ci_2o-carbonyl, Ci_2o-ester, and optionally substituted Cs-is-heteroaryl and t in each occurrence is independently 0, 1, 2 or

3.

Where present, substituents of a Ce-is-aryl, or a Cs-is-heteroaryl group as described anywhere herein are optionally selected from Ci_2o alkyl in which one or more non-adjacent, nonterminal C atoms may be replaced with O, C=O or COO.

Preferably, each t is 0.

The n-type polymer preferably has a LUMO level measured by square wave voltammetry of between -4.5 and -1.5 eV, more preferably between -3.5 and -2.0 eV

The cathode comprises a p-type polymer of formula (II):

Ar³^ Ar⁴

Δι-5 (Π) wherein Ar³, Ar⁴ and Ar⁵ are each independently an unsubstituted or substituted C6-20 arylene

Q or heteroarylene group; at least one aromatic ring atom of Ar is bound directly to an adjacent repeat unit or end group of the polymer; and at least one aromatic ring atom of Ar⁴ is bound directly to an adjacent repeat unit or end group of the polymer.

Optionally, at least one aromatic ring atom of Ar⁵ is bound directly to an adjacent repeat unit or end group of the polymer.

The repeat unit of formula (II) may be bound to adjacent repeat units or end groups through 2, 3 or 4 bonds on Ar³, Ar⁴ or Ar⁵.

Preferably, the repeat unit of formula (II) has formula (Ila):

(Ha) wherein n, p and q are each independently 0, 1, 2, 3 or 4 and wherein R³, R⁴ and R⁵ are each independently selected from Ci_2o-alkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci_2o-carboxyl, Ci_2o-carbonyl, Ci_2o-ester, and optionally substituted Cs-is-heteroaryl.

Preferably, n is 0.

Preferably, p is 0.

Preferably, q is 0.

The p-type polymer preferably has a HOMO level measured by square wave voltammetry of between -4.5 and -6.5 eV, more preferably between -4.8 and -6 eV.

At least one of, and preferably both of, the anode layer 101 and cathode layer 105 preferably further comprises a binder. The binder is preferably a water soluble polymer, more preferably alginic acid and salts thereof, preferably metal salts thereof, most preferably an alkali salt such as sodium or potassium alginate.

At least one of, and preferably both of, the anode layer 101 and cathode layer 105 preferably further comprises a conductive carbon material.

Conductive carbon materials may be selected from, without limitation, one or more of the group consisting of carbon black, ketjenblack, carbon fiber, graphite, and carbon nanotubes. .

Preferably, the BET specific surface area of the conductive carbon material is in the range of 10 m /g to 3000 m /g. Preferably, conductive carbon materials as described herein have an average diameter as measured by a scanning electron microscope of 50-100 nm. Preferably, carbon black is present in electrodes described herein, either alone or with one or more other forms of conductive carbon.

At least one of, and preferably both of, the anode layer 101 and cathode layer 105 preferably further comprises an electrolyte.

The electrolyte may be a dissolved salt or an ionic liquid.

The electrolyte may be a solution of a salt having an organic or metal cation, for example lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) or lithium hexafluorophosphate, in an organic solvent, optionally propylene carbonate.

Ionic liquids as described herein may be ionic compounds that are liquid at below 100 °C and at 1 atm pressure. Examples include, without limitation, compounds with an ammonium-, imidazolium-, phosphonium-, pyridinium-, pyrrolidinium- or sulfonium cation. The ionic liquid may have a sulfonimide anion, for example bis(trifluoromethane)sulfonimide (TFSI) or bis(fluorosulfonyl)imide (FSI) ionic liquids such as e.g. 1-methyl -1- propylpyrrolidinium bis(fluorosulfonyl)imide bis (trifluoromethane) sulfonimide bis (trifluoromethane) sulfonimide bis (trifluoromethane) sulfonimide bis(trifluoromethane)sulfonimide (BMP-TFSI), the latter being particularly preferable.

imidazolium (PMP-FSI), l-ethyl-3-methyl (EMI-TFSI), triethylmethoxyethyl (TEMEP-TFSI), triethyl (TES-TFSI) or 1 -butyl- 1-methy Ip yrrolidinium phosphonium sulfonium

The anode and cathode may be formed by depositing a formulation comprising the electroactive polymer of the electrode dissolved or suspended in a solvent onto the associated current collector followed by drying.

Formulation

The solvent of a formulation as described herein may be a single solvent material or a mixture of two or more solvent materials. The or each solvent material may be selected from organic solvents and water. Preferably, the solvent is an aqueous solvent which consists of water or comprises water as a major component (> 50 vol %) thereof.

The n-type polymer in the case of an anode formulation, and the p-type polymer in the case of a cathode formulation, is preferably suspended in particulate form in the formulation. Preferably, there is little or no dissolution of the polymer in the formulation. Optionally, following initial suspension of the polymer in the solvent, the solid polymer is separated from the solvent and suspended in fresh solvent to remove any dissolved polymer. This presence of little or no dissolved polymer in the formulation may limit swelling of the polymer in the formulation, and consequent contraction of the polymer when the solvent is evaporated.

Other electrode materials of the formulation may be dissolved or dispersed in the formulation. It will therefore be understood that a solvent as described herein does not necessarily dissolve all electrode materials of the formulation.

The formulation preferably comprises a dissolved binder polymer.

The electrolyte, if present, is preferably an ionic liquid which is dispersed in the aqueous solvent. In other embodiments, the electrolyte may be dissolved in the aqueous solvent.

Conductive carbon, if present, is preferably dispersed in the solvent.

Optionally, an aqueous formulation as described herein further comprises a wetting agent. Exemplary wetting agents are protic, water miscible, organic compounds, preferably alcohols. 2-butoxyethanol is particularly preferred. Some or all of the wetting agent may be removed when the deposited formulation is dried.

Optionally, the electroactive polymer : conductive carbon weight ratio is in the range of 1:0.3 -1:1, optionally 1:0.4 - 1:1.

Optionally, the electroactive polymer forms at least 30 wt %, optionally at least 40 wt %, of the mass of the electrode. Optionally, the electroactive polymer forms up to 65 wt % of the mass of the electrode.

Optionally, the conductive carbon forms at least 15 wt %, optionally at least 18 or 20 wt%, of the mass of the electrode.

Optionally, the binder forms at least 2.5 weight %, optionally at least 8 wt %, of the mass of the electrode. The binder may form 2.5 - 25 weight %, of the mass of the electrode.

Formulation deposition

The formulation may be deposited on a current collector by any suitable deposition method known to the skilled person including, without limitation, drop-casting, doctor blade coating, screen printing and dispense printing. In dispense printing, the aqueous formulation is deposited in a continuous flow from a nozzle.

An insulating structure comprising one or more layers and defining a well may be provided on a surface of the current collector. The surface of the current collector exposed by the well may have a lower contact angle with the formulation than the surface of the insulating structure. Optionally, the surface of the insulating structure and / or the surface of the current collector is treated with a surface treatment agent before the formulation is deposited.

The formulation may be deposited in the well area. The well may prevent or limit spreading of the formulation outside the well area exposed by the insulating structure.

In other embodiments, the formulation is deposited onto the current collector which does not have an insulating structure defining a well formed thereon.

In embodiments, the entire mass of an anode or cathode is deposited onto the current collector in a single formulation deposition step followed by drying of the formulation.

In embodiments, the entire mass of an anode or cathode is deposited onto the current collector in a plurality of formulation deposition and drying steps.

Preferably, the anode or cathode formed following deposition and drying of a formulation as described herein has a thickness in the range of about 100-500 microns, preferably about 400500 microns.

The formulation may be dried at ambient temperature (25°C) or it may be heated to remove the aqueous solvent. The heating temperature may be selected according to the boiling point of the solvent or solvents of the formulation. Optionally, heating is carried out at a temperature in the range of about 40 - 250°C, preferably about 100 - 200°C. Optionally, a first drying step is at a temperature in the range of 40-100°C and a second drying step is at a temperature in the range of 100-200°C.

The formulation may be dried, with or without heating, at atmospheric pressure or under reduced pressure.

The components of the electrode dissolved or dispersed in the formulation preferably make up at least 1 weight percent of the formulation, more preferably at least 3 weight % or at least 5 weight %. Optionally, the components of the electrode dissolved or dispersed in the formulation make up 1-85 or 1-50 weight % of the formulation. The formulation may be a paste.

Battery formation

According to an embodiment, formation of a battery cell as described herein may include the following steps:

(i) Deposition of an anode formulation onto an anode current collector.

(ii) Deposition of a cathode formulation onto a cathode current collector.

(iii) Lamination of a separator containing an electrolyte between the anode and cathode.

Steps (i) and (ii) may occur in either order, or simultaneously.

Following formation of an electrode, an electrolyte in liquid form may be applied to a surface of the electrode and / or to the surface of the separator before the electrode and separator are brought into contact with the separator. This may improve ionic conductivity within the electrode and / or across the separator and the electrode.

Figure 2, which is not drawn to any scale, illustrates a process of forming a battery.

A surface of anode current collector 107 of a metal foil is covered by an insulating structure 115 comprising one or more layers of insulating material, for example an adhesive insulating tape or a patterned layer of insulating polymer, for example a layer of photoresist, to define an exposed current collector area Al surrounded by the insulating material. The insulating structure may define a well configured to contain the formulation used to form the electrode in area AL The insulating structure may be a layer formed by depositing and patterning a photoresist; reel-to-reel lamination of a patterned film; and printing methods, e.g. screen printing or gravure printing. The formation of the insulating structure may or may not include one or more curing steps, e.g. thermal or UV treatment steps.

Optionally, the insulating structure has a thickness in the range of about 20-400 nm. Optionally, the base of the well defined by the insulating structure has a well area in the range of about 1-200 cm², optionally about 3-150 cm².

The whole of the surface of the metal foil may be covered except for battery area Al and a lead-out area A2. A lead out area A2 may be provided on the same surface of metal foil 107 as battery area Al if, for example, the opposing surface of the metal foil has an insulating backing such as PET-backed aluminium foil. In other embodiments, both surfaces of the current collector 107 are conductive and a connection may be made to the surface of the metal foil opposite battery area Al in which case area A2 on the same side of the current collector as area Al may or may not be covered.

An adhesive layer 117, for example a layer of pressure-sensitive adhesive, is provided on the insulating layer. Preferably, the adhesive layer does not extend to the perimeter of area Al defined by the insulating layer. In other embodiments, a single layer provides both adhesion and insulation; for example the insulating layer 115 as applied to the anode current collector 107 has an adhesive upper surface, for example an adhesive backing layer.

An anode formulation as described herein is deposited in the battery area Al by any suiable process, for example drop-casting, and dried to form anode 101 extending across at least some, preferably all, of area Al.

The insulating structure may be treated with a surface treatment agent before the formulation is deposited. The treatment may increase hydrophobicity of the insulating structure.

The area of the current collector exposed by the insulating structure may be treated with a surface treatment agent before the formulation is deposited. The treatment may increase adhesion between the formulation and the current collector. A mask may be provided over the adhesive layer to prevent the surface treatment agent from damaging this layer.

Preferably, a single surface treatment agent is used for both the insulating structure and the current collector, preferably in a single treatment step. Preferably, the surface treatment agent is a plasma, more preferably a SFe plasma. Surface treatment is particularly preferred when a photoresist is used as the insulating structure.

A p-type formulation as described herein is deposited onto a surface of a metal foil cathode current collector 109 to form a cathode (not shown). An insulating structure defining a well, as described with reference to the anode, is optionally provided for containment of the p-type formulation.

A separator 103 is sandwiched between the anode and cathode, and the cathode current collector is adhered to the adhesive layer 117 to form the battery cell.

The separator overlaps anode area Al, and preferably extends beyond the whole of the perimeter of anode area Al (illustrated as a dotted line in Figure 2).

The cathode current collector illustrated in Figure 2 has a lead out area A3. In other embodiments, connection may be made to the surface of the current collector opposite the surface carrying the cathode if that opposing surface is conductive, e.g. not covered with an insulating polymer in which case lead out area A3 may or may not be present.

Figure 2 illustrates an embodiment in which area Al is defined on the anode current collector and adhesive layer 117 is formed on the anode insulating structure, and the cathode current collector may also carry an insulating structure and / or an adhesive layer. In other embodiments, area Al may be defined on the cathode current collector only, and / or adhesive layer 117 may be formed over the cathode current collector only.

Both the anode and cathode may be formed from a formulation as described with reference to Figure 2. In other embodiments, only one of the anode and cathode is formed from a formulation as described herein, the other of the anode and cathode being formed according to a method known to a skilled person.

The completed battery may be sealed in a sealing structure 119, preferably vacuum sealed in a vacuum bag, or laminated between two laminating sheets. Adhesive tabs (not shown) may be applied to both sides of each lead out in the region where the lead -outs exit the sealing structure. Figure 2 illustrates sealing of a single battery cell. In other embodiments, a battery comprising a plurality of cells, preferably a battery including two or more cells having a common current collector, may be sealed in a sealing structure as described herein.

Vacuum sealing may compress the device, providing improved contact between the electrodes and their corresponding current collectors, and / or between the separator and one or both electrodes.

In embodiments, the anode formulation and / or the cathode formulation may be deposited onto a current collector by a printing process, for example screen printing, wherein the current collector may or may not have an insulating structure formed thereon.

Separator

The separator may be selected from separators known to the skilled person. The separator comprises an electrolyte. The electrolyte may be a liquid, for example a gel comprising an electrolyte solution or a liquid electrolye. The separator may be a solid polymer electrolyte.

The separator may comprise a mesh, for example a polymeric mesh, comprising electrolyte in the pores of the mesh.

Current collectors

The anode and cathode current collectors each independently comprise or consist of a layer of conductive material, for example a metal such as copper or aluminium; a conductive organic polymer such as poly(ethylene dioxythiophene) or polyaniline; or an inorganic conductive compound such as a conductive metal oxide, for example indium tin oxide. Each current collector may be supported on a suitable substrate, for example a glass or plastic substrate. The substrates may be flexible, particularly for applications in which flexibility of the battery is desirable, and / or to enable use of a roll-to-roll process in battery formation. An exemplary flexible current collector is a metal foil, for example aluminium foil.

Applications

A battery as described herein may be used as a power source for any device, preferably for a portable device such as a phone, tablet or laptop, or a wearable device. A battery as described herein may be provided on a card, for example a debit, credit, prepayment or business card comprising an electrical device including, without limitation, a display, a speaker, a transmitter or a receiver.

The battery cells described herein, and batteries comprising a plurality of these cells, may be flexible. Preferably, a battery cell as described herein is capable of bending to give a circular arc of at least 10°, optionally at least 20° or 40°.

Examples

Measurements

Square wave voltammetry measurements as described herein may be performed using a CHI660D Electrochemical workstation with software (U Cambria Scientific Ltd)), a CHI 104 3mm glassy carbon disk working electrode (IJ Cambria Scientific Ltd)); a platinum wire auxiliary electrode; an Ag/AgCl reference electrode (Havard Apparatus Ltd); acetonitrile as cell solution solvent (Hi-dry anhydrous grade-ROMIL); toluene as sample preparation solvent (Hi-dry anhydrous grade); ferrocene as reference standard (FLUKA); and tetrabutylammoniumhexafluorophosphate (FLUKA) as cell solution salt. For sample preparation, the polymer is spun as thin film (—20 nm) onto the working electrode. The measurement cell contains the electrolyte, a glassy carbon working electrode onto which the sample is coated as a thin film, a platinum counter electrode, and a Ag/AgCl reference glass electrode. Ferrocene is added into the cell at the end of the experiment as reference material (LUMO (ferrocene) = -4.8eV).

n-type Polymer 1

A 3-necked round-bottomed flask, equipped with a magnetic stirrer, Dean-stark apparatus, condenser, nitrogen inlet and exhaust was charged with naphthalene-1,5-diamine (15 g, 94.8 mmol) and toluene (75 mL). Then terephthalaldehyde (12.7 g, 94.8 mmol) was taken in toluene (75 mL) and it was added to the reaction flask. The reaction was refluxed under Dean-Stark condition for 24 h with azeotropic water removal. The orange solid formed was recovered by filtration of the warm solution and dried to get 16 g of crude material. The solid was triturated with THF (160 ml) for 4 h at 28 °C. The solid was filtered and dried in a vacuum oven at 50 °C to afford 13 g of n-type Polymer 1 as an orange solid. CHN analysis: C: 82.82, H: 4.829: 10.78 (expected: C: 84.35, H: 4.72, N: 10.93).

n-type Polymer 1 p-type Polymer 1

A 2 L 3-necked round-bottomed flask, equipped with a mechanical stirrer, nitrogen inlet and exhaust. Triphenylamine (40 g, 0.163 mol) and Iron trichloride (79.4 g, 0.489 mmol) were charged to reaction flask and purged with nitrogen. Then degassed 1,2-dichloroethane was added (1200 mL) to the reaction mixture and it was heated to 85 °C for 48 h. Once cooled the reaction mixture was poured into the acetone (2 L) stirred for 30 mins. The solid was filtered to afford 40 g of crude material which was triturated with THF (1200 mL) at 28 °C overnight, filtered and triturared again with methanol (1200 ml) at 70 °C for 16 hours. The solid was recovered by filtration and dried in a vacuum oven at 50 °C to afford 30 g of p-type Polymer

1. CHN analysis C: 83.69, H: 5.26, N: 5.40 ( expected C: 89.23; H: 4.99; N: 5.78).

p-type Polymer 1 n-type Formulation Example 1 n-type Polymer 1 (120 mg) was blended with with Super P® Conductive Carbon obtained from hnerys Graphite & Carbon (96 mg) and the dry materials were mixed using a pestle and mortar for 5 minutes. To this mixture was added 2.4 ml of a solution of sodium alginate (commercially available from Sigma-Aldrich) (1 wt.% in a water:2-butoxyethanol (95:5 V/V) mixture), water (1 ml) and 1 -butyl- 1-methyIpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-TFSI, 24 mg) obtained from Solvionic and the mixture was mixed until a smooth paste was obtained.

The paste composition by weight was n-type Polymer 1: Super P® Carbon Black: BMPTFSLSodium Alginate 46:36:9:9 (giving a Polymer : Carbon Black ratio of 1 : 0.8) with a total content of these electrode components of 7.7wt% .

p-type Formulation Example 1

A p-type formulation was prepared in the same way as for n-type Formulation Example 1 except that p-type Polymer 1 was used in place of n-type Polymer 1 and 2.4 ml of water was used rather than 1 ml as in n-type Formulation Example 1 give a paste having a p-type Polymer 1: Super P® Carbon Black: BMP-TFSI:Sodium Alginate weight ratio of 46:36:9:9 with a total cathode component content of 5.5 wt%.

Battery Cell Example 1

A battery cell was formed as described with reference to Figure 2.

n-type Formulation Example 1 and p-type Formulation Example 1 were each deposited on an aluminium current collector with a 25 micron thick polyethylene terephthalate backing obtained from “All Foils”, with each current collector having a layer of photoresist SU-8 patterned to define a 3 cm well into which the formulations were deposited.

A sulfur hexafluoride (SFe) plasma treatment was used to clean the aluminium surface and allow containment of the aqueous formulation pastes in the SU-8 defined wells.

A pressure sensitive adhesive film (PSA, 25 um from Adhesives Research Inc. product EE92734) was used as a frame around the active area defined by the wells on each current collector. The electrodes were stuck to a glass carrier substrate using a GelPak (X4) release film. An electronic pipette was used to dispense 0.35 ml and 0.49 ml of anode and cathode paste formulations into the wells defined on the anode and cathode current collectors respectively followed by drying on a hotplate at 70°C for 30 minutes resulting in an electrode loading around 9 mg/cm for each electrode. Electrode loading (in mg/cm ) was determined by weighing the substrate before and after formation of the electrode.

The coated substrates were transferred to a nitrogen filled glovebox and dried on a hotplate at 150°C for 30 minutes. 0.15 ml of BMP-TFSI electrolyte was dispensed on each electrode. The release liner of the pressure sensitive adhesive was removed from both electrodes and a filter paper separator (2x2.4 cm) was placed over the cathode substrate. The anode and cathode were aligned and manually laminated. The pressure sensitive adhesive films were pressed together to achieve a seal and a spring clamp (2 inches) was used to press the layers of the cell together.

Battery Cell Example 2

Battery Cell Example 2 was prepared as described for Battery Cell Example 1 except that an aramid-coated polyolefin separator (Pervio from Sumitomo Chemical Co., Ltd) was used in place of the filter paper. The Pervio separator was thinner than the filter paper of Battery Cell Example 1.

Battery Cell Example 3

Battery Cell Example 3 was prepared as described for Battery Cell Example 1 except that the paste composition weight ratio for both the anode and cathode pastes was Polymer: Super P® Carbon Black: BMP-TFSI:Sodium Alginate 59:23:9:9, giving a Polymer : Carbon Black ratio of 1 : 0.4 .

Battery Cell Example 4

Battery Cell Example 4 was prepared as described for Battery Cell Example 3 except that a thin aramid-coated polyolefin separator (Pervio from Sumitomo Chemical Co., Ltd) was used in place of the filter paper.

Battery Cell Example 5

Battery Cell Example 5 was prepared as described for Battery Cell Example 3 except that the electrode pastes were coated directly on aluminium foil (40 microns thick) without any insulating structure on the current collectors and without any adhesive to adhere the current collectors together. The surface of the current collectors were not exposed to SFe plasma before deposition of the electrode formulations. The dispensed volumes of electrode paste and ionic liquid were adjusted to keep the loading per area constant during fabrication and assembly.

The battery cell was sealed in a vacuum pouch. No clips were used to hold the vacuumsealed device together.

The battery cell was sealed in a pouch with a heat sealable aluminium laminate barrier foil. Pressure sensitive adhesive was used on both side of the electrode tab lead outs to provide sealing between the aluminium and the heat sealable pouch. Three sides of the pouch were heat sealed prior to using a vacuum heat sealer to seal the last side. The pouch cell fabricated by this method was not clamped for device testing.

Battery cells were placed in a sealed container under an inert atmosphere and connected to an Arbin battery tester (Model - BT2043).

For device testing, the battery was cycled with a constant current constant voltage charging

2 step (1 mA/cm to 3V, CV step until 0.2 mA/cm was reached) and constant current discharge at 1 mA/cm to IV. This sequence was repeated until the capacity degraded below 80% of maximum capacity. The nominal voltage and area capacity (mAh/cm ) were measured for each cycle.

Results are set out in Table 1 and in Figures 3 and 4, which are discharge curves for Battery Cell Examples 1 and 3, respectively.

Area capacity is the maximum measured discharge capacity normalised for area.

Specific capacity for each active polymer material is calculated by dividing the area capacity by the polymer loading.

Nominal voltage is the mid-point voltage of the discharge curve.

Capacity T80 is the number of cycles with more than 80% of the maximum capacity.

Battery thickness is the thickness the active area part of battery (all layers but the carrier substrate included), as measured using a micrometer.

□

Battery Volumetric Charge Density (mAh/cm ) is calculated by dividing the area capacity by the battery thickness (in cm)

Table 1

Specific capacity

Battery	Area	(mAh/g)
Cell		Capacity
exampl	Active	(mAh/cm
e	material: Carbon: Io	²⁾	n-type	p-type
	nic Liquid: Binder		Polym	Polym
	Weight Ratio		er 1	er 1

Battery

	Average			Volumetri
Nomin	Coulombi		Thickne	c Charge
al	C	Capacit	ss	Density
voltage	efficiency	yT80	(microns	(mAh/cm
(V)	(%)	(cycles)	)	³)

Battery Cell Examples 6-9

An anode formulation was prepared by blending 120 mg of Polymer n-type Polymer 1 and 48 mg Super P carbon and mixing using a pestle and mortar in the dry form for 5 minutes. 1.87 mL of a solution of sodium alginate (1 wt% in water:2-butoxyethanol (95:5 v/v)), water (0.86 mL) and 187 μΕ of a solution of BMP-TFSI (10 wt% in 2-butoxyethanol) were added, and the mixture was ground until a smooth paste was obtained.

A cathode formulation was prepared by blending 180 mg of p-type Polymer 1 and 144 mg Super P carbon and mixing using a pestle and mortar in the dry form for 5 minutes. 3.6 mL of a solution of sodium alginate (1 wt% in water:2-butoxyethanol (95:5 v/v)), water (3.6 mL) and 26 μΕ BMP-TFSI were added, and the mixture was ground until a smooth paste was obtained.

Further formulations were prepared using this method as set out in Table 2.

Battery Cell Examples 6-9 as set out in Table 3 were prepared using anode and cathode formulations as described in Table 2 by the method described in Battery Cell Example 1. Filter paper was used as the separator for Battery Cell Examples 6, 8 and 9. Pervio was used for Battery Cell Example 7

Table 2

Formulation	Polymer	Super	Na	BMP-	Water	All	Polymer
	(mg)	P	alginate	TFSI		components	•
		carbon	(ml)*	(ml)**		weight ratio	Carbon weight ratio

n-type Example 3	n-type, 120	48	1.87	0.187	0.86	59:23:9:9	1:0.4
p-type Example 3	p-type, 70	28	1.09	0.109	0.78	59:23:9:9	1:0.4
n-type Example 4	n-type, 120	96	2.4	0.017	1	46:36:9:9	1:0.8
p-type Example 4	p-type, 180	144	3.6	0.026	3.6	46:36:9:9	1:0.8

*1 wt% in water:2-butoxyethanol (95:5 v/v) **10 wt% in 2-butoxyethanol

Table 3

Batte ΐ Formulat	Ano de	Cath ode	Charge Capaci	Anode Discha	Catho de	Midp oint	Efficie ncy	Capa city
ry	ions
Exam		paste	paste	ty	rge	Discha	Voltag	(%)	Tso
pie	5	loadi ng /mg	loadi ng /mg	(mAh/c m²)	Specifi c Capaci ty (mAh/ g)	rge Specifi c Capaci ty (mAh/ , 8)	e (V)\M ax	\Avera ge	(Cycl es)

6	ΐ n-type ΐ Example ΐ 4, p-type : Example ί 4	19.7	19.9	0.286	75	76	2.11	98	134
?	ΐ n-type ΐ Example ; 4, p-type ; Example ί 4	18.9	19.2	0.286	78		2.16		173
8	s n-type ; Example ; 3, p-type ΐ Example 4	17.3	25.0	0.332	99	72	2.08	99	114
9	; n-type	29.5	21.1	0.354	79	86	2.14	99	184
	[ Example

( 4, p-type ( Example i 3

With reference to Figure 5, reduction of carbon content on the anode side (Battery Cell Example 8) resulted in an increased battery charge capacity as compared to Battery Cell Example 6. Furthermore, with reference to Figure 6, no voltage penalty was observed by reducing carbon content on either electrode.

Battery Cell Examples 10-13

Battery Cells were prepared as set out in Table 4, using the method described with reference to Battery Cell Example 1.

Table 4

Battery Exampl e	Electroacti ve Polymer : Carbon ratio	Anod e paste loadin g /mg	Cathod e paste loadin g /mg	Charge Capacity (mAh/cm ²)	Anode Dischar ge Specific Capacity (mAh/g)	Cathode Dischar ge Specific Capacity (mAh/g)	Midpoi nt Voltage (V)	Efficiency (%)\Avera ge	Capacit yT80 (Cycles )
ΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΧ	1:0.3	Χλλλλλλλλλλλλλλλλλχ	^ΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΧ	^ΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛ?	ΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΧ*	ΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΧ	Χλλλλλλλλλλλλλλλλλλλλχ*	\ΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΛΧ\	Χλλλλλλλ^λλλλλλλλλλλλλ.
10	(anode and	19.1	19.7	0.180	45	44	2.22	95	49
	cathode) .........1:0.3........
11	(anode and	22.8	22.7	0.250	52	52	2.21	96	35
	cathode) .........1:0.8........
12	(anode and	19.7	19.9	0.286	75	76	2.11	98	134
	cathode) .........1:0.4........
13	(anode) 1:08 (cathode)	17.3	25.0	0.332	99	72	2.08	99	114

Formation of Polymer : Carbon 1:0.4 and 1:0.8 formulations used in Battery Example 13 are described above.

The n-type Polymer : Carbon 1:0.3 weight ratio formulation was prepared by blending 150 mg of n-type Polymer 1 and 45 mg Super P carbon and mixing using a pestle and mortar in the dry form for 5 minutes. 2.17 mL of a solution of sodium alginate (1 wt% in water:2butoxyethanol (95:5 v/v)), water (0.20 mL) and 15 pF BMP-TFSI were added, and the mixture was ground until a smooth paste was obtained.

The p-type Polymer : Carbon 1:0.3 weight ratio formulation was prepared by blending 150 mg of p-type Polymer 1 and 45 mg Super P carbon and mixing using a pestle and mortar in the dry form for 5 minutes. 2.17 mL of a solution of sodium alginate (1 wt% in water:2butoxyethanol (95:5 v/v)), water (0.70 mL) and 15 pL BMP-TFSI were added, and the mixture was ground until a smooth paste was obtained.

Performance of these battery cells are shown in Figures 7 and 8 and Table 3.

As shown in Table 4, specific discharge capacities for Battery Examples 10-13, having a Polymer : Carbon 1:0.3 weight ratio, is lower than that of Battery Example 13 having higher carbon content in the anode and cathode.

Battery Examples 14 and 15

Prior to paste formulation, the redox polymer was ground together with Super P carbon in a ball mill.

Ball milling was carried out using a Retsch PM 100 planetary ball mill in a 50 mL zirconium oxide grinding jar with 5 mm diameter zirconium oxide grinding balls.

Anode 1.45 g of n-type Polymer 1, 0.55 g of Super P carbon and 60 g of zirconium oxide balls were weighed into a grinding jar.

Cathode 2.50 g of p-type Polymer 1, 1.00 g of Super P carbon and 60 g of zirconium oxide balls were weighed into a grinding jar.

The polymer and carbon were ground by running the programs detailed in Table 5 sequentially in the order:

Mix-Mill-Mix-Mill-Mix

Table 5

Milling Mixing program program

Time	5 min	2 min
Speed	200 rpm	100 rpm
Interval	1 min	15 s
Reversal	On
Break Time	2s	1 s

After the grinding program was complete, the polymer-carbon mix was sieved and transferred to ajar until required.

Electrode Paste Preparation

An anode formulation was prepared by blending 1.25 g of the n-type Polymer 1-Super P blend with 13.6 mL of a solution of sodium alginate (2 wt% in water:2-butoxyethanol (95:5 v/v)) and BMP-TFSI (64.7 qL) in a mortar and pestle until a smooth paste was obtained. In this preparation, the paste was not further diluted by addition of water. The paste composition by weight was [n-type Polymer 1: Super P® Carbon Black: BMP-TFSI:Sodium Alginate] weight ratio of {56.07:21.49:5.60:16.80} with a total anode component content of 11.9 wt%.

An cathode formulation was prepared by blending 1.01 g of the p-type Polymer 1-Super P blend with 21.6 mL of a solution of sodium alginate (2 wt% in water:2-butoxyethanol (95:5 v/v)) and BMP-TFSI (102.9 qL) in a mortar and pestle until a smooth paste was obtained. In this preparation, the paste was not further diluted by addition of water. The paste composition by weight was [p-type Polymer 1: Super P® Carbon Black: BMP-TFSLSodium Alginate] weight ratio of {45.45:36.36:9.09:9.09} with a total cathode component content of 7.3 wt%.

Electrode Preparation

Electrode design and battery cell formation was as described for Battery Cell Examples 1-4, except with a 25 cm active area.

Anode active material deposition·. An electronic pipette was used to dispense 1.9 mL of anode paste onto the anode current collector followed by drying on a hotplate at 70 °C for 30 minutes, resulting in an electrode loading of 5.0 mg/cm polymer per electrode. Electrode loading (in mg/cm ) was determined by weighing the substrate before and after deposition of the electrode.

Cathode active material deposition·. An electronic pipette was used to dispense 3.1 mL of cathode paste onto the cathode current collector followed by drying on a hotplate at 70 °C for 30 minutes, resulting in an electrode loading of 4.1 mg/cm polymer per electrode. Electrode loading (in mg/cm ) was determined by weighing the substrate before and after deposition of the electrode.

With reference to Table 6 and Figure 10, a long discharge capacity cycling lifetime was achieved compared to Battery Cell Example 15 having a different anode composition.

Batter yCell Exam pie

Anode Active material : Carbon : Ionic Liquid: Binder Weight Ratio 56.07:2

Discharge	Anode	Cathode
Capacity	Discharge	Discharge
Density	Specific	Specific
(mAh/cm^A2)/	Capacity	Capacity
Max	(mAh/g)\Max	(mAh/g)\Max

Midpoin t Voltage (V)\Max

Efficie ncy (%)\Av erage

Capaci ty T80 (Cycles

Voltag e T80 (Cycle

s)

14 1 ^L49:5· s 60:16.8 ί o	0.247	53 § 60	2.08	50	510	>1000
§ 45.45:3 15 § 6.36:9. § 09:9.09	0.286	75 ( 74	2.11	98	134	296

Although the present invention has been described in terms of specific exemplary embodiments, it will be appreciated that various modifications, alterations and/or combinations of features disclosed herein will be apparent to those skilled in the art without departing from the scope of the invention as set forth in the following claims.

Claims

1. A battery cell comprising an anode, a cathode, a separator between the anode and the cathode, an anode current collector and a cathode current collector, wherein the anode comprises an n-type polymer comprising a repeat unit of formula (I) and the cathode comprises a p-type polymer comprising a repeat unit of formula (II):

L J Ar⁵ (I) (Π)

12 1 wherein R and R are each independently selected from H or a substituent; Ar and Ar are each independently an unsubstituted or substituted C6-20 arylene or heteroarylene group; Ar³, Ar⁴ and Ar⁵ are each independently an unsubstituted or

Q substituted Ce-20 arylene or heteroarylene group; at least one aromatic ring atom of Ar is bound directly to an adjacent repeat unit or end group of the polymer; and at least one aromatic ring atom of Ar⁴ is bound directly to an adjacent repeat unit or end group of the polymer.

1 2

2. A battery cell according to claim 1 wherein R and R are H.

3. A battery cell according to claim 1 or 2 wherein Ar¹ is phenylene which is unsubstituted or substituted with one or more substituents selected from Ci_2o-alkyl, optionally substituted Ce-is-aryl, Ci-20-alkyl ether, Ci-20-carboxyl, Ci-20-carbonyl, Ci_ 20-ester, and optionally substituted Cs-ig-heteroaryl

4. A battery cell according to any one of the preceding claims wherein Ar is naphthylene.

5. A battery cell according to claim 4 wherein Ar is a group of formula (III):

(Ill)

6.

7.

8.

9.

10.

6.

7.

8.

9.

10.

wherein R⁶ in each occurrence is independently a substituent selected from Ccoalkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci-20-carboxyl, Ccocarbonyl, Ci-20-ester, and optionally substituted Cs-is-heteroaryl and t in each occurrence is independently 0, 1, 2 or 3.

A battery cell according to claim 5 wherein each t is 0.

A battery cell according to any one of the preceding claims wherein Ar³, Ar⁴ and Ar⁵are each phenyl which is independently unsubstituted or substituted with one or more substituents.

A battery cell according to any one of the preceding claims wherein Ar³, Ar⁴ and Ar⁵are each independently unsubstituted or substituted with one or more substituents selected from the group consisting of Ci_2o-alkyl, optionally substituted Ce-is-aryl, Ci_ 20-alkyl ether, Cco-carboxyl, Cco-carbonyl, Ci-20-ester, and optionally substituted C518-heteroaryl.

A battery cell according to any one of the preceding claims wherein an aromatic ring atom of Ar⁵ is bound directly to an adjacent repeat unit.

A battery cell according to claim 9 wherein the repeat unit of formula (II) has formula (Ila):

p (Ila) wherein n, p and q are each independently 0, 1, 2, 3 or 4; and R³, R⁴ and R⁵ are each independently selected from Ci_2o-alkyl, optionally substituted Ce-is-aryl, Ci_2o-alkyl ether, Ci-20-carboxyl, Ci-20-carbonyl, Ci-20-ester, and optionally substituted C5-18heteroaryl.

11. A battery cell according to claim 10 wherein n, p and q are each 0.

12. A battery cell according to any one of the preceding claims wherein at least one of ntype polymer and p-type polymer is in particulate form.

13. A battery cell according to any one of the preceding claims wherein at least one of the anode and cathode comprises a binder.

14. A battery cell according to any one of the preceding claims wherein at least one of the anode and cathode comprises a conductive carbon.

15. A battery cell according to any one of the preceding claims wherein at least one of the anode and cathode comprises an electrolyte.

16. A method of forming a battery cell according to any one of the preceding claims wherein the anode is formed by depositing an anode formulation comprising the ntype polymer dissolved or dispersed in a solvent onto a surface of the anode current collector and wherein the cathode is formed by depositing a cathode formulation comprising the p-type polymer dissolved or dispersed in a solvent onto a surface of the cathode current collector.

17. A method according to claim 16 wherein an insulating structure defining a well is provided on least one of the surface of the anode current collector and the surface of the cathode current collector; wherein the well exposes the surface of the current collector in the well area; and wherein the anode formulation or cathode formulation is deposited into the well.

18. A method according to claim 17 wherein a surface of the insulating structure and the surface of the current collector in the well area is treated by a surface treatment agent.

19. A method according to claim 18 wherein the surface treatment agent is SFe plasma.

20. A method of forming a battery cell electrode, the method comprising:

providing a structure comprising an insulating layer supported on a surface of the current collector, wherein the insulating layer defines a well exposing the surface of the current collector in a well area;

treating a surface of the insulating structure and the exposed surface of the current collector with a surface treatment agent; and following the surface treatment, depositing a formulation comprising an electroactive polymer dissolved or dispersed in a solvent into the well.

21. A method according to claim 20 wherein the surface treatment agent is SF₆ plasma.