[0001] This application claims priority to European application No. 19172469.9 filed on May 3, 2019 and to European application No. 20155055.5 filed on February 3, 2020, the whole content of those applications being incorporated herein by reference for all purposes. Technical Field [0002] The present invention pertains to an electrode-forming composition, to use of said electrode-forming composition in a process for the manufacture of an electrode, to said electrode and to an electrochemical device comprising said electrode. Background Art [0003] To date, techniques for manufacturing either positive or negative electrodes involve the use of organic solvents such as N-methyl-2- pyrrolidone (also referred to as“NMP”) for dissolving fluoropolymer binders and homogenizing them with an electro-active material and all other suitable components to produce a paste to be applied to a metal collector. [0004] The role of the organic solvent is typically to dissolve the fluoropolymer in order to bind the electro-active material particles to each together and to the metal collector upon evaporation of the organic solvent. The polymer binder should properly bind the electro-active material particles together and to the metal collector so that these particles can chemically withstand large volume expansion and contraction during charging and discharging cycles. [0005] Although NMP is a solvent widely used for dissolving fluoropolymers, because of its costs and environmental concerns, this solvent is recycled. Flowever, the use of NMP is raising issues from both human health and environmental impact perspective. [0006] Therefore, recently the need was felt for alternative processes for the manufacture of electrodes in the absence of solvents. [0007] For example, WO 2018/050314 (in the name of Robert Bosch GmbH) discloses a method for producing an electrode film, wherein a particle mixture is produced from particles of a polymer binder and conductive carbon black by premixing, then agglomerates are produced by compacting said particles and, after addition of an electrochemical active material, the electrode film is manufactured by rolling or extrusion. Thus, this patent application described a process wherein solid particles are mixed, then compacted into agglomerates, which are then reduced in size and sieved, before rolling or extruding said solid mixture. While in the description a solvent is said that may be added, there is no example (nor reference in the accompanying figures) of a process wherein the mixture to be processed is liquid. Indeed, the entire description and the figures referred to a process wherein a solid mixture is used. Summary of invention [0008] The Applicant perceived that the need still exists for a process for the manufacture of electrodes, wherein no solvent (like NMP) is used to dissolve the fluoropolymer and hence no recycle is needed. [0009] The Applicant surprisingly found that the above technical problem can be solved by using the composition in the process according to the present invention. [0010] Indeed, the Applicant surprisingly found that by melt extruding the composition of the invention, it is possible to manufacture electrodes suitable for use in electrochemical devices. [0011] Thus, in a first aspect, the present invention relates to a composition [composition (C)] comprising: - from 0.5 wt.% to less than 20 wt.%, preferably to less than 15 wt.% of at least one semi-crystalline partially fluorinated polymer [polymer (F)] comprising recurring units derived from 1 ,1-difluoroethylene (VDF); - from 10 wt.% to less than 60 wt.%, preferably to less than 41 wt.%, of at least one liquid medium [medium (L)] characterized by a boiling point equal to or higher than 150 °C; and - at least 50 wt.% of at least one electro-active compound [compound (EA)]; wherein the above amounts are based on the total weight of said composition (C). [0012] In a second aspect, the present invention pertains to the use of said composition (C) in a process for the manufacture of an assembly, more preferably an electrode [electrode (E)]. [0013] In a third aspect, the present invention relates to a process for the manufacture of an assembly, said process comprising: (i) providing a substrate; (ii) providing composition (C) as defined above; (iii) heating said composition (C) at a temperature higher than 100°C; (iv) extruding the composition (C) provided in step (ii) onto the substrate provided in step (i), thereby providing an assembly comprising a substrate coated with at least one layer consisting of said composition (C). [0014] In a fourth aspect, the present invention relates to an assembly obtained with the above-mentioned process. [0015] Advantageously, said assembly comprises: - at least one substrate, and - directly adhered onto said substrate, at least one layer [layer (L1)] consisting of a composition [composition (C2)] comprising: - at least one polymer (F) as defined above, - at least one compound (EA) as defined above, - at least one liquid medium [medium (L)] as defined above. [0016] Advantageously, said assembly is an electrode [electrode (E)]. More preferably, said electrode (E) is a cathode or an anode. [0017] The electrode (E) of the invention is particularly suitable for use in electrochemical devices. [0018] Non-limiting examples of suitable electrochemical devices include secondary batteries, preferably an alkaline or an alkaline-earth secondary battery. More preferably, said secondary battery is a lithium-ion secondary battery. Description of embodiments [0019] As used within the present description and in the following claims: - the use of parentheses around symbols or numbers identifying the formulae, for example in expressions like“polymer (P)”, etc., has the mere purpose of better distinguishing the symbol or number from the rest of the text and, hence, said parenthesis can also be omitted; - the terms“1 ,1-difluoroethylene”,“1 ,1-difluoroethene” and“vinylidene fluoride” are used as synonyms; - the terms“poly-(1 ,1-difluoroethylene)” and“polyvinylidene fluoride” are used as synonyms; - the term“secondary battery” is intended to denote a rechargeable battery; - the term“electro-active compound [compound (EA)]” is intended to denote a compound which is able to incorporate or insert into its structure and substantially release therefrom alkaline or alkaline-earth metal ions during the charging phase and the discharging phase of an electrochemical device. The compound (EA) is preferably able to incorporate or insert and release lithium ions; - the expression“partially fluorinated polymer” is intended to denote a polymer comprising recurring units derived from at least one fluorinated monomer and, optionally, at least one hydrogenated monomer, wherein at least one of said fluorinated monomer and said hydrogenated monomer comprises at least one hydrogen atom; - the term“fluorinated monomer” is intended to denote an ethylenically unsaturated monomer comprising at least one fluorine atom; - the term“hydrogenated monomer” is intended to denote an ethylenically unsaturated monomer comprising at least one hydrogen atom and free from fluorine atoms; - the expression“at least one fluorinated monomer” is intended to indicate that the polymer may comprise recurring units derived from one or more than one fluorinated monomers; - the expression“fluorinated monomers” is intended both in the plural and the singular, that is to say that they denote both one or more than one fluorinated monomers as defined above; - the expression“at least one hydrogenated monomer” is intended to indicate recurring units derived from one or more than one hydrogenated monomers; - the expression“hydrogenated monomers” is intended both in the plural and the singular, that is to say that they denote both one or more than one hydrogenated monomers as defined above. [0020] The term“semi-crystalline” is hereby intended to denote a polymer (F) having a heat of fusion of from 5 to 90 J/g, preferably of from 30 to 60 J/g, as measured according to ASTM D3418-08. [0021] Advantageously, said polymer (F) is characterized by an intrinsic viscosity higher than 0.05 L/g, more preferably higher than 0.12 L/g and even more preferably higher than 0.25 L/g, the intrinsic viscosity being measured as the dropping time of a solution of said polymer (F1 ) at 25°C at a concentration of 0.2 g/dL in N.N-dimethylformamide using a Ubbelhode viscosimeter, as detailed in the Experimental Section. [0022] Preferably, said polymer (F) comprising recurring units derived from 1 ,1- difluoroethylene (VDF) and recurring units derived from at least one hydrogenated monomer comprising at least one carboxylic acid end group [monomer (MA)] and/or recurring units derived from at least one partially or fully fluorinated monomer [monomer (FFH)], said monomer (FFH) being different from VDF. [0023] According to a preferred embodiment, said polymer (F) comprises, more preferably consists of: (I) recurring units derived from VDF and (II) recurring units derived from at least one monomer (MA). [0024] Polymer (F) according to this embodiment will be herein after referred to as“polymer (F*)”. [0025] Preferably, said polymer (F*) comprises, more preferably consists of : - at least 90% by moles, preferably at least 95% by moles, more preferably at least 97% by moles of recurring units derived from VDF, - from 0.05% to 10% by moles, preferably from 0.1 % to 5% by moles, more preferably from 0.2 % to 3% by moles of recurring units derived from at least one monomer (MA). [0026] According to a preferred embodiment, said polymer (F) comprises, more preferably consists of : (I) recurring units derived from VDF, (II) recurring units derived from at least one monomer (MA) and (III) recurring units derived from at least one monomer (FFH). [0027] Polymer (F) according to this embodiment will be herein after referred to as“polymer (F**)”. [0028] Preferably, said polymer (F**) comprises, more preferably consists of : - at least 80% by moles, preferably at least 85% by moles, more preferably at least 90% by moles of recurring units derived from VDF, - from 0.01 % to 10% by moles, preferably from 0.05% to 5% by moles, more preferably from 0.1 % to 1.5% by moles of recurring units derived from at least one monomer (MA), and - from 0.1 % to 15% by moles, preferably from 0.5% to 12% by moles, more preferably from 1 % to 10% by moles of at least one monomer (FFH). [0029] In a particularly preferred embodiment of the present invention, said polymer (F**) is polymer (F**-1), which comprises, more preferably consists of: - at least 80% by moles, preferably at least 85% by moles, more preferably at least 90% by moles of recurring units derived from VDF, - from 0.01 % to 10% by moles, preferably from 0.05% to 5% by moles, more preferably from 0.1 % to 1.5% by moles of recurring units derived from at least one monomer (MA), and - from 5% to 12% by moles, more preferably from 6% to 10% by moles of at least one monomer (FFFI). [0030] The polymer (F**) may be obtained by polymerization of a VDF monomer, at least one monomer (MA) and at least one monomer (FFFI) according to the teaching, for example, of WO 2008/129041. [0031] Advantageously, said polymer (F*) and said polymer (F**) are characterized by an intrinsic viscosity higher than 0.25 L/g and lower than 0.60 L/g, the intrinsic viscosity being measured as the dropping time of a solution of said polymer (F*) or (F**) at 25°C at a concentration of 0.2 g/dL in N.N-dimethylformamide using a Ubbelhode viscosimeter, as detailed in the Experimental Section. [0032] According to a preferred embodiment, said polymer (F) comprises, preferably consists of: (I) recurring units derived from VDF, and (II) recurring units derived from at least one monomer (FFH). [0033] Polymer (F) according to this embodiment will be herein after referred to as“polymer (FA)”. [0034] More preferably, said polymer (FA) comprises : - at least 80% by moles, preferably at least 85% by moles, more preferably at least 90% by moles of recurring units derived from VDF, and - from 0.1 % to 15% by moles, preferably from 0.5% to 12% by moles, more preferably from 1 % to 10% by moles of at least one monomer (FFH). [0035] Advantageously, said polymer (FA) is characterized by an intrinsic viscosity higher than 0.05 L/g and lower than 0.60 L/g, more preferably lower than 0.25 L/g, the intrinsic viscosity being measured as the dropping time of a solution of said polymer (FA) at 25°C at a concentration of 0.2 g/dL in N.N-dimethylformamide using a Ubbelhode viscosimeter, as detailed in the Experimental Section. [0036] Determination of average mole percentage of recurring units derived from at least one monomer (MA) in the polymer (F) can be performed by any suitable method. Mention can be notably made of acid-base titration methods, well suited e.g. for the determination of the acrylic acid content, of NMR methods, adequate for the quantification of monomers (MA) comprising aliphatic hydrogen atoms in side chains, of weight balance based on total fed monomer (MA) and unreacted residual monomer (MA) during polymer (F) manufacture. [0037] Advantageously, said monomer (MA) complies with the following chemical formula: wherein: - R’i, R’2 and R’3 are hydrogen atoms, and - R’OH is a hydrogen atom or a C1-C5 hydrocarbon moiety comprising at least one hydroxyl group. [0038] Non-limiting examples of said monomer (MA) are, notably, acrylic acid, methacrylic acid, hydroxyethylmethacrylate, hydroxyethylacrylate, hydroxypropylmethacrylate, hydroxypropylacrylate, hydroxyethylhexyl methacrylate, hydroxyethylhexylacrylate, and mixtures thereof. [0039] Preferably, said monomer (MA) is selected from the group comprising, more preferably consisting of: - hydroxyethyl acrylate (HEA) of formula: - 2-hydroxypropyl acrylate (HPA) of either of formulae: - acrylic acid (AA) of formula: - and mixtures thereof. [0040] According to a preferred embodiment, said monomer (MA) is acrylic acid (AA). [0041] Preferably, said monomer (FFH) is selected in the group comprising, more preferably consisting of: C2-C8 perfluoroolefins, such as tetrafluoroethylene (TFE) and hexafluoropropylene (HFP); C2-C8 hydrogenated fluoroolefins different from VDF, such as vinyl fluoride, 1 ,2-difluoroethylene and trifluoroethylene; CFh=CFI-Rfo wherein Rm is a C1-C6 perfluoroalkyl; chloro- and/or bromo- and/or iodo-C2-C6 fluoroolefins, such as chlorotrifluoroethylene (CTFE); CF2=CFOXO wherein Xo is a C1-C6 fluoro- or perfluoroalkyl, e.g. CF3, C2F5, C3F7 ; a Ci- C12 alkyl group, a C1-C12 oxyalkyl group or a C1-C12 (per)fluorooxyalkyl group having one or more ether groups, such as perfluoro-2-propoxy- propyl group; group -CF20Rf2 wherein Rf2 is a C1-C6 fluoro- or perfluoroalkyl group, e.g. CF3, C2F5, C3F7 or a C1-C6 (per)fluorooxyalkyl group having one or more ether groups such as -C2F5-O-CF3; CF2=CFOYO wherein Yo is a C1-C12 alkyl group or (per)fluoroalkyl group, a C1-C12 oxyalkyl group or a C1-C12 (per)fluorooxyalkyl group having one or more ether groups and Yo comprising a carboxylic or sulfonic acid group, in its acid, acid halide or salt form; fluorodioxoles, preferably perfluorodioxoles. [0042] More preferably, said monomer (FFH) is selected in the group comprising, preferably consisting of: vinyl fluoride (VFi), chlorotrifluoroethylene (CTFE), hexafluoropropylene (HFP), tetrafluoroethylene (TFE), trifluoroethylene (TrFE) and perfluoromethylvinylether (PMVE). [0043] Polymer (F) is typically obtainable by emulsion polymerization or suspension polymerization according to the methods known to the skilled person in this field. [0044] The nature of the compound (EA) in composition (C) and as a consequence in layer (L1) of the assembly of the invention, depends on whether the final assembly thereby provided is a positive electrode [electrode (Ep)] or a negative electrode [electrode (En)]. [0045] In the case of forming a positive electrode for a lithium-ion secondary battery, said compound (EA) may comprise a composite metal chalcogenide of formula UMQ2, wherein M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr and V and Q is a chalcogen such as O or S. Among these, it is preferred to use a lithium- based composite metal oxide of formula UMO2, wherein M is the same as defined above. Preferred examples thereof may include UC0O2, LiNi02, LiNixCoi-x02 (0 < x < 1) and spinel-structured LiMn204. [0046] As an alternative, still in the case of forming a positive electrode for a lithium-ion secondary battery, the compound (EA) may comprise a lithiated or partially lithiated transition metal oxyanion-based electro-active material of formula MiM2(J04)fEi-f, wherein Mi is lithium, which may be partially substituted by another alkali metal representing less that 20% of the Mi metals, M2 is a transition metal at the oxidation level of +2 selected from Fe, Mn, Ni or mixtures thereof, which may be partially substituted by one or more additional metals at oxidation levels between +1 and +5 and representing less than 35% of the M2 metals, including 0, JO4 is any oxyanion wherein J is either P, S, V, Si, Nb, Mo or a combination thereof, E is a fluoride, hydroxide or chloride anion, f is the molar fraction of the JO4 oxyanion, generally comprised between 0.75 and 1. [0047] The MiM2(J04)fEi-f electro-active material as defined above is preferably phosphate-based and may have an ordered or modified olivine structure. [0048] More preferably, the compound (EA) has formula Li3-xM’yM”2-y(J04)3 wherein 0