Electrochemical cell

Abstract

The invention relates to a cell comprising: - An anode comprising a lithium metal layer, - An electrolyte comprising at least one lithium salt and at least one solvent, - A cathode comprising a porous composite layer which comprises at least one active material.

Description

[0001] ELECTROCHEMICAL CELL

[0002] The present invention relates to an electrochemical cell and to rechargeable lithium battery comprising at least one electrochemical cell.

[0003] Rapidly growing demand for batteries and technology are driven by increased electric vehicles (EV) sales throughout the world. Most of the price of a battery pack derives from cell price (up to 75 %). Cell prices in turn are primarily determined by the raw material inputs (between 40 and 50 %). As a result, the choice of battery cell chemistries i.e. raw material inputs used in battery cells, is critical in further cost reductions.

[0004] Only a handful of battery technology companies are focusing on new technologies and new chemistries in an attempt to find a winning formula with significant improvements.

[0005] Most technologies are based on ‘solid state’ batteries. However, the technology has experienced significant setbacks primarily due to low ionic conductivity (rate performance) and issues with interfaces. Unfortunately, too many technological challenges linked to solid-state batteries have delayed the go-to market of these types of cells.

[0006] Semi-solid technologies for EV batteries can reach commercialization in a shorter period of time, with the provision that the performances are sufficient to fulfil all technical requirements needed for the given final application - notably secondary batteries.

[0007] One of the main objectives is to promote the use of Li metal through semi-solid electrolyte (next-generation liquid electrolyte), while achieving higher energy density. Typically, a battery cell comprises 3 main active elements: an anode, a cathode and an electrolyte.

[0008] In Li ion batteries, an anode is the electrode where electrons are released during the chemical reaction, supplying the current to an external circuit. Most common anodes are made of graphite. The cathode of a battery is the negatively charged electrode (during charging) where reduction occurs during the electrochemical reaction, completing the circuit and balancing the flow of electrons. Examples of common cathodes include NMC (Nickel Manganese Cobalt), NCA (Lithium-Nickel Cobalt-Aluminium), LFP (Lithium-lron-Phosphate). An electrolyte is an ion conductive substance, typically a liquid or gel, that allows the movement of ions between the cathode and anode, enabling the flow of electrical current. Most common electrolyte can be LiPF6 in organic solvents.

[0009] WO 2022 170 363 relates to flame-retardant high-elasticity polymer for lithium metal protection in secondary batteries. Example 1 refers to a protective layer laminated between a Cu foil and a separator for use in an anode-less lithium battery (initially the anode being lithium- free) containing an NCM-532 cathode.

[0010] The use of graphite as anode has several drawbacks, it has low specific capacity when compared to other materials. As a result, more material is needed to store energy which requires more space and adds weight, limiting overall performance.

[0011] Pure silicon anodes have high theoretical capacity and increased energy density. It is an abundant and environmentally friendly material that has the potential to significantly improve battery performance. However, key challenges limit its use including poor cyclability due to large volume changes, during charging and discharging, leading to mechanical stress and degradation, and high manufacturing costs due to complex processes needed to mitigate volume expansion issues.

[0012] Pure lithium metal anodes are also selected for their high capacities. However, the main disadvantage relates to safety and flammability risks along with technological challenges, in particular with the growth of dendrites during cycling. Stability and cyclability cannot be guaranteed in all circumstances, which can result in capacity loss over repeated cycles. In addition, this anode type requires advanced electrolyte and separator technologies to address safety challenges.

[0013] There is therefore a need to provide an anode which can improve energy density and charging speed of the cell.

[0014] Regarding the commonly used cathodes, NCA cells have a high energy density of 200 to 260 Wh / kg and a decent lifespan of 2000 charge cycles. Although the high proportion of nickel in the cathode improves the energy density of the cell, NCA batteries can sustain a high charging current, thus enabling fast charging, but the limited availability of cobalt and nickel makes these batteries expensive.

[0015] NMC cells have a cathode made up of a combination of nickel, manganese, and cobalt - for example in the ratio of 60 %, 20 % and 20 % or 80%, 10% and 10% respectively. The properties of the cell can be altered by changing the proportion of each element to achieve either a higher specific energy density or a higher specific power. NMC has a high energy density of 150-260 Wh / kg, a low self-heating rate, which makes them highly popular. However, safety remains an issue with NMC, where high nickel NMC batteries also require more sophisticated thermal management systems which add to costs.

[0016] LFP have a moderate energy density of 90 to 160 Wh / kg and has a high operational life of 7000 to 12000 charge cycles. LFP cells have high thermal stability, low self-discharge rates, and low internal resistance, which make LFP cells suitable for power operations that can achieve high charge and discharge rates. LFP cells are one of the most affordable chemistries, considering their long operational life and initial investment cost.

[0017] In terms of volumetric energy density and gravimetric energy density, LFP is less efficient than NMC when considering energy density of the cell in battery technologies.

[0018] There is therefore a need to provide a robust electrochemical battery cell design with improved cycling stability, improved energy density, rate performance, enhanced safety, and improved sustainability at a competitive price, compared with available current solutions in the marketplace.

[0019] These technical issues are solved by the present invention which provides an improved robust electrochemical battery cell design in terms of cycling stability, energy density, rate performance, safety, sustainability at a competitive price.

[0020] The present invention is directed to an electrochemical cell for secondary batteries comprising:

[0021] An anode comprising: o A lithium metal layer, preferably pure lithium metal layer, o Eventually, a current collector A containing a metal foil, preferably copper, or a composite containing a metal film and a conductive non-metal material, preferably a conductive polymeric material, o Eventually a protective passivation coating A acting as an artificial Solid Electrolyte Interface (SEI), being conductive to Li+ions and being a (nano)coating, preferably applied by atmospheric plasma, Atomic Layer Deposition (ALD), CVD or PVD onto the surface of the lithium metal layer,

[0022] An electrolyte having high voltage stability, preferably nonflammable electrolyte, comprising: o At least one lithium salt, preferably selected from the group comprising LiPF6, LiFSI, LiTFSI, LiBF4, LiDFOB, LiBOB and any combinations thereof, o At least one solvent, preferably selected from the group comprising carbonate-based compounds, fluorinated compounds, ether-based compounds, sulfone containing compounds, nitrile-based compounds, ionic liquids, liquified gas and any combinations thereof,

[0023] A cathode comprising: o A porous composite layer which comprises at least one active material, preferably comprising a lithium transition metal oxide, configured to contain a part of the electrolyte within its pores, wherein the active material is a high-voltage (HV) intercalation cathode material having operating potential in part or entirely above 4.3 V, preferably selected from a Spinel-structured, for instance LMNO or LMNTO (Ti-substituted LiNio.5Mn1.2Tio.3O4), a Layered-structured, advantageously Li-rich layered oxides (LLO), such as manganese-rich layered oxides (LMLO) or Li-Rich Layered LifLio.2Nio.2Mno.6jO2 or LMR-NMC or Lithium-Manganese Rich Li1.2Mno.55Nio.15Coo.1O2, LOO or LiCoO2 and any combinations thereof, o Eventually, at least one cathode protective layer B located on the porous composite layer, preferably doped, o Eventually, a current collector B, preferably with a thickness comprised between 1 and 30 m, preferably between 5 and 30 pm, selected from a metal foil (Al), a composite comprising at least one metal film and at least one conductive non-metal material (polymer) and any combinations thereof.

[0024] The foundation of a battery cell relates to its energy density which is measured by volumetric energy density and gravimetric energy density. Volumetric energy density measures how much energy can be stored in a given volume of the material. Gravimetric energy density represents how much energy can be stored in a given mass of the material. In the context of the invention, greater volumetric energy and gravimetric energy is needed. A material with excellent gravimetric energy may have limitations in terms of volume, making it less suitable for certain applications where space is limited.

[0025] Preferably, the electrochemical cell of the present invention has an energy density between 350-500 Wh / kg and 800-1200 Wh / I.

[0026] It has been observed that the energy density of the electrochemical cell of the invention is high enough for secondary batteries. Present cell makes use of lithium metal anode, preferably pure lithium metal, for higher energy density. The electrolyte, preferably semisolid and / or liquid electrolyte enables enhancing safety, rate performance and stability, in particular with lithium metal and the cathode of the invention (LMNO I LNMO: Lithium Manganese Nickel Oxide with spinel structure). The cathode of the invention has a positive impact on the cost and enhanced sustainability. The electrolyte allows the battery to operate at higher voltages and reduces parasitic reactions on the cathode and the anode. The cell of the invention has a high voltage cathode, a higher nominal operating voltage and it offers rapid charging.

[0027] In a preferred embodiment, use is made of spinel LMNO, as a cathode material, combined with pure lithium metal.

[0028] Preferably, current collector B comprises a protective layer B having oxidative stability chosen from the group comprising carbonbased materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid (in)organic coatings.

[0029] More preferably, protective layer B of the current collector B is applied by atmospheric plasma, chemical solution deposition, chemical vapour deposition, atomic layer deposition or any combinations thereof.

[0030] According to an advantageous embodiment, the active material is in the form of particles having a mean diameter comprised between 50 nm and 90 m, preferably between 100 nm and 10 pm.

[0031] According to a more advantageous embodiment, the active material is in the form of particles having a particle size dso between 50 nm and 90 pm, preferably between 100 nm and 10 pm.

[0032] More advantageously, the particles of said active material have a core-shell structure, wherein the shell contains compounds selected from metal oxide, metal fluoride, LiXO, wherein X is P, Si or Nb, metal phosphate, carbon-based compounds, conductive polymer, solid- state electrolyte, hybrids and any combinations thereof.

[0033] Preferably, the electrochemical cell according to the invention comprises a separator chosen from be a polymer micro- or nanoporous membrane (e.g. PE, PI), a non-woven mat (fiber structure), e.g. PP or C-PET, potentially enhanced with a ceramic or polymer-coating, other fiber-based membranes (eg. PTFE, chitosan, silk glue, PVDF-HFP), covalent organic framework (COF), cellulose (eg. PE_HEC), a ceramic embedded in polymer matrix, crosslinked membrane (eg. PEGDE-DETA- PEGDME), a solid-state material.

[0034] More preferably, the current collector A comprises a protective layer A chosen from the group comprising carbon-based materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid in- / organic coatings, 3D structures or relief, polymers and any combinations thereof.

[0035] In a preferred embodiment, said protective layer A of said current collector A is applied by atmospheric plasma, chemical solution deposition, chemical vapour deposition, PVD, atomic layer deposition or electrochemical deposition

[0036] In a particularly preferred embodiment, said lithium salt is present in a concentration comprised between 0.1 and 10 mol / L per solvent.

[0037] Advantageously, said lithium metal layer has a thickness comprised between 1 and 100 m.

[0038] More advantageously, the protective passivation coating A comprises a compound selected from the group comprising fluorcontaining compounds, carbon-based compounds, nitrogen-containing compounds, sulfide-based compounds, lithium-based compounds, metal oxides, metal nitrides, metal carbides, polymer organic coatings, solid electrolytes, hybrids, covalent organic frameworks (COF) and any combinations thereof.

[0039] Even more advantageously, lithium-based compounds are selected from the group comprising lithium halides, lithium fluoride, lithium phosphate, lithium nitride, lithium nitrate, lithium carbonate and any combinations thereof. Preferably, protective passivation coating A is applied by ALD. Preferably, when ALD is used the protective passivation coating A comprises oxides.

[0040] Advantageously, protective passivation coating A is applied by CVD, PVD, chemical solution deposition or electrochemical deposition.

[0041] In a preferred embodiment, the protective passivation coating A comprises at least 60 mol %, preferably 70 mol %, more preferably 80 mol %, even more preferably 90 mol % of lithium nitrates, measured by XPS.

[0042] According to a particularly preferred embodiment, said porous composite layer further comprises at least one binder.

[0043] Preferably, said porous composite layer further comprises at least one conductive additive.

[0044] Even more preferably, said porous composite layer comprises a nanoscafold, acting as a binder and a conductive additive, can be used in the context of the present invention. This embodiment enables using one element having 2 functions - binder & additive.

[0045] According to a more preferred embodiment, the weight ratio between said active material, said at least one binder and said at least one conductive additive is respectively comprised between 80: 10: 10 and 99: 0.5: 0.5.

[0046] Even more preferably, said separator comprises a separator coating which comprises ceramic, polymer coating, zeolite, solid-state material, metal-organic framework or any combinations thereof.

[0047] The present invention also relates to a rechargeable lithium battery which comprises at least one electrochemical cell, preferably several electrochemical cells according to the present invention. The invention will be detailed hereinbelow with additional technical features which can be combined with each other, in particular with all aforementioned embodiments.

[0048] Anode

[0049] The anode comprises a lithium metal layer, preferably pure lithium metal layer. Said lithium metal layer has preferably a thickness comprised between 1 and 100 m, more preferably between 1 and 50 pm, even more preferably between 1 and 30 pm.

[0050] The anode can comprise, eventually, a current collector A containing a metal foil, preferably copper, or a composite containing a metal film and a conductive non-metal material, preferably a conductive polymeric material.

[0051] The main function of the current collector A is to transport electrons from the cell tabs to the active materials and conversely. The features referred to the current collector A enables the following: lower weight & cost, and safe shutdown of the cell in case of short circuiting due to fuse like properties. Preferably, this embodiment relates to the current collector A with a composite containing a metal film.

[0052] The current collector A has preferably a thickness between 1 and 30 microns, more preferably between 5 and 30 microns.

[0053] The current collector A preferably comprises a protective layer A chosen from the group comprising carbon-based materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid in- / organic coatings, polymers and any combinations thereof. It protects the current collector, preferably made of copper, and it creates a lithiophilic layer. With the protective layer A, the surface of the current collector A is treated which contribute to lithium metal anode stability in the form of lithiophilic layers that can reduce the nucleation overpotential and increase the current collector A surface area by adding a 3D structure or in increased roughness.

[0054] For instance, N2 plasma treatment of copper current collector A results in a layer capable of guiding uniform lithium nucleation and deposition, thus maximizing the spread of Li metal over the coated area.

[0055] The presence of protective layer A enables preventing corrosion and stabilizing lithium metal plating / stripping through uniform nucleation and deposition. It regulates Li metal deposition and increases nucleation sites, thus, maximizing the spread of Li metal over the coated area.

[0056] Protective layer A can advantageously be applied by atmospheric plasma, chemical solution deposition, PVD, chemical vapour deposition, atomic layer deposition.

[0057] Preferably, the protective layer A on the current collector A is chosen from the group comprising carbon-based materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid in- / organic coatings, polymers, and any combinations thereof.

[0058] Advantageously, the protective passivation coating A (SEI) on the lithium metal is selected from the group comprising : fluorcontaining compounds, carbon-based compounds, nitrogen-containing compounds, sulfide-based compounds, lithium-based compounds, metal oxides, metal nitrides, metal carbides, polymer organic coatings, solid electrolytes, hybrids, covalent organic frameworks (COF) and any combinations thereof.

[0059] More advantageously, lithium-based compounds are selected from the group comprising lithium halides, lithium fluoride, lithium phosphate, lithium nitride, lithium nitrate, lithium carbonate and any combinations thereof. The anode can eventually also comprise a protective passivation coating A acting as an artificial Solid Electrolyte Interface (SEI), being conductive to Li+ions and being a (nano)coating, preferably applied by atmospheric plasma, Atomic Layer Deposition (ALD), CVD ,PVD, chemical solution deposition or electrochemical deposition onto the surface of the lithium metal layer. The role of protective passivation coating A is to uniformly conduct lithium ions and having mechanical and electrochemical stability. It enables avoiding reaction of lithium metal with the electrolyte and formation of dendrites & high surface area lithium during stripping and depositing.

[0060] According to a particular embodiment of the present invention, the following structure with the successive layers is foreseen :

[0061] 1 ) Current collector A,

[0062] 2) Protective layer A onto the current collector A,

[0063] 3) Lithium metal layer onto the protective layer A,

[0064] 4) Protective passivation coating A onto the lithium metal layer,

[0065] Where the protective layer A is not essential and just preferred in the context of the invention.

[0066] Electrolyte

[0067] The function of the electrolyte is to allow lithium ions to flow between the electrodes. It is preferably combined with a separator. The separator provides the electrical insulation between the electrodes and is impregnated by the electrolyte to allow ion conductivity. The electrolyte also impregnates the porous composite layer of the cathode. The electrolyte is electrochemically stable within the cell operating voltage and in combination with the cathode and anode components. The electrolyte of the present invention has a low viscosity for improved wettability of both separator and porous composite layer of the cathode, and a good solvability towards lithium ions or lithium salts.

[0068] A high solvability and low viscosity result in lower internal resistance and uniform distribution of ion flux, which has a beneficial effect on cell ageing and performances.

[0069] The electrolyte of the invention is preferably non-flammable electrolyte and has a high voltage stability.

[0070] The electrolyte of the invention comprises: o At least one lithium salt, preferably selected from the group comprising LiPF6, LiFSI, LiTFSI, LiBF4, LiDFOB, LiBOB and any combinations thereof, o At least one solvent, preferably selected from the group comprising carbonate-based compounds, fluorinated compounds, ether-based compounds, sulfone containing compounds, ionic liquids, nitrile-based compounds, liquified gas and any combinations thereof.

[0071] Source of lithium ions, some salts are stable under high voltages and lead to stable interfaces.

[0072] The solvent is preferably carbonate based (e.g. ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diehtyl carbonate (DEC), propylene carbonate (PC), etc.), fluorinated (e.g. fluoro ethylene carbonate (EEC), methyl(2,2,2- trifluoroethyl) carbonate (FEMC), ether based (e.g. dimethoxyethane (DME), diethyl ether (DEE), sulfone based (e.g. TMS, EMS), nitrile-based compounds, ionic liquids. It provides anti-oxidation ability and flame retardancy. It can form a stable SEI (Solid Electrolyte Interface) and CEI (Cathode Electrolyte Interface). The electrolyte con also preferably comprise diluents or nonsolvating co-solvent selected from fluorinated compounds (e.g. fluorinated ethers, fluorinated borate, fluorinated orthoformate, fluorinated aromatic compounds, non-fluorinated compounds. It provides improved functionalities, in particular in terms of high voltage stability, stable SEI, lower viscosity and increased separator wettability or improved lithium nucleation. It also contributes to the reduction of the cost of the salt & solvent combination.

[0073] Preferably the ionic liquids of the electrolyte can be salts composed of organic cations (such as imidazolium or pyridinium ions) paired with inorganic or organic anions (e.g., Cl", Br", AICI4", PF6", BF4", NO3", (CF3SO2)2N"). These salts exhibit a unique property of remaining in a liquid state at or near room temperature, distinguishing them from conventional salts that are typically solid under similar conditions. This can be beneficial to the invention.

[0074] The electrolyte of the invention may preferably also contain additives selected from phosphorus-based compounds (e.g. TMP, TEP, DFP), nitride-based compounds, halogen-based compounds (F, Cl, Br, I), any composite of the elements above or any combinations thereof.

[0075] The additive can provide the following technical effect: flame retardant (catalytic removal of the highly reactive free radicals which originate from the combustion reactions - hydrogen-free radical capture mechanism, overcharge protection (redox shuttle, electrochemical polymerization), uniform Li nucleation, lower oxidation potential than EC (ethylene carbonate) solvent, lower reduction potential than the SEI (Solid Electrolyte Interface) film forming agent, strong coordination with transition metal ions, transition metal scavenging, which prevents deposition on the anode surface to further catalyse electrolyte decomposition, scavenge HF, H2O and other harmful substances produced in the aging process of electrolyte. The electrolyte of the present invention is preferably a semisolid electrolyte or liquid electrolyte.

[0076] Presence of some solid electrolyte can be possible, if combined with semi-solid, gel-polymer electrolyte or liquid electrolyte.

[0077] According to the preferred embodiment of the invention, solid electrolyte can be present in the at least cathode protective layer B, the separator or the protective passivation coating A of the lithium metal layer.

[0078] The electrolyte of the present invention is preferably a fluorinated solvent in order to enhance liquid electrolyte stability for high- voltage cathodes. Use is made of ethylene carbonate (EC) and a linear carbonate, preferably having a high boiling point, such as propylene carbonate (PC), in the presence of at least one strong electronwithdrawing group, preferably F (or CF3), in the electrolyte. These alterations can substantially improve the electrolyte's oxidative stability. In addition to offering increased thermal stability, PC combined with fluorinated solvents can improve the electrolyte's safety properties by reducing flammability. Yet, the application of pure PC-based electrolytes has its drawbacks. For instance, they show poor wetting behaviour on conventional polyolefin-based separators.

[0079] Fluorinated ether can also be part of the composition of the electrolyte of the present invention.

[0080] The electrolyte can preferably be a non-fluorinated nonsolvating co-solvent.

[0081] For instances:

[0082] I M LiPF6 in fluoroethylene carbonate and ethyl methyl carbonate (FEC: EMC) + LiDFOB • I M L1PF6 in fluoroethylene carbonate + methyl (2,2,2- trifluoroethyl) carbonate and hydro-fluoro-ethers (FEC: FEMC: HFE)

[0083] • Lithium Bis(fluorosulfonyl)imide + tetramethylene sulfone and 1 ,1 ,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, (LiFSI: TMS: TTE)

[0084] Cathode

[0085] A porous composite layer containing at least one cathode active material, preferably in the form of particles.

[0086] Advantageously, the cathode active material has particles with a diameter of 500 nm up to several tens of micrometres, which can be kept together with a binder. The active material (cathode active material) allows intercalation of lithium ions allowing the cell to charge and discharge. The pores are filled in situ with electrolyte to allow lithium ions to penetrate the electrode and reach the active material. The porous structure could also contain conductive additives to allow efficient transport of electrons from the active material to the current collector and vice versa.

[0087] The porous composite layer which comprises at least one active material, preferably comprising a lithium transition metal oxide, is configured to contain a part of the electrolyte within its pores. The active material is a high-voltage (HV) intercalation cathode material having operating potential in part or entirely above 4.3 V, preferably selected from a Spinel-structured, for instance LMNO or LMNTO, a Layered- structured, advantageously Li-rich layered oxides (LLO), such as LMLO or LMR-NMC, LCO and any combinations thereof.

[0088] More preferably, the porous composite layer is made of spinel LMNO (expression equal to LNMO). The active material in the form of particles preferably has a mean diameter comprised between 50 nm and 90 m, preferably between 100 nm and 10 pm.

[0089] Particles of said active material preferably have a core-shell structure, wherein the shell contains compounds selected from metal oxide, metal fluoride, LiXO, wherein X is P, Si or Nb, metal phosphate, carbon-based compounds, solid-state electrolyte, conductive polymer, hybrids and any combinations thereof.

[0090] Active material of the porous composite layer is preferably doped with Al, Ce, Co, Cr, Cu, Fe, Mg, Nd, P, Ru, Si, Ti, W, Zr or other elements (metals & non-metals) or any combinations thereof.

[0091] Active material of the porous composite layer is preferably doped with an amount of up to 10 wt. %.

[0092] Porous composite layer may further comprise at least one binder which ensures mechanical integrity of the porous composite layer of the cathode. Example of binders include PVDF, solid electrolyte, metal oxide, carbon-based nano-scaffold, covalent organic framework (COF) ...

[0093] Porous composite layer may further comprise at least one conductive additive, preferably selected from carbon-based compounds, e.g. carbon black, carbon nanotubes, graphene. Conductive additive increases electron conductivity.

[0094] The porous composite layer can comprise a nanoscafold, acting as a binder and a conductive additive, can be used in the context of the present invention. This embodiment enables using one element having 2 functions - binder & additive.

[0095] The cathode can be produced through several processes.

[0096] The cathode of the present invention can be manufactured by casting a slurry of active material particles, conductive additives, binders, and solvents on the current collector. The application of a drying step is then carried out.

[0097] Another possibility is spraying method which enables exposing a greater surface area to the atmosphere resulting in solvent evaporation in a quicker way.

[0098] An additional alternative can be to call for dry techniques, i.e. dry & solvent-free processes (roll milling of Maxwell type for example, extrusion, dry spraying deposition). With this alternative, one can get rid of solvent.

[0099] 3D printing can also be an alternative for manufacturing the cathode.

[0100] The cathode preferably contains at least one cathode protective layer B located on the porous composite layer and is preferably doped.

[0101] The eventual current collector B preferably has a thickness comprised between 1 and 30 m, preferably between 5 and 30 pm.

[0102] Eventual current collector B is preferably selected from a metal foil (Al), a composite comprising at least one metal film and at least one conductive non-metal material (polymer) and any combinations thereof.

[0103] Preferably, the active material forming the porous composite layer has particles which can be coated as explained above with the core-shell structure.

[0104] More preferably, the internal pores of the active material of the porous composite layer can also be coated, preferably by ALD, with the same composition as the one for the core-shell embodiment. Even more preferably, an additional coating can be deposited on the porous composite layer, for instance by being positioned between a separator and the porous composite layer.

[0105] All above embodiments regarding to which extent the active material I porous composite layer can be coated include combinations thereof.

[0106] In summary, there can be three coatings for the porous composite layer (cathode) that could be used individually or in combination:

[0107] - (i) core-shells that are perfectly coated particles before these are processed into composite cathodes,

[0108] - (ii) a composite cathode, preferably coated with ALD, inside the pores, and

[0109] - (iii) a layer on the composite cathode or separator.

[0110] Eventual current collector B comprises a protective layer B having oxidative stability chosen from the group comprising carbonbased materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid (in)organic coatings.

[0111] Aluminium can preferably be used in the cathode, and its electrochemical stability is attributed to a thin, nonporous native protective layer that forms rapidly in the air-atmosphere, approximately 5- 20 nm thick. Nevertheless, the protective oxide film becomes vulnerable to decomposition if the potential limit is exceeded, like in 5V class cathodes such as LNMO, or when exposed to chemically aggressive electrolytes. For this reason, a protective layer B is provided and guarantees excellent oxidative stability.

[0112] Protective layer B of the eventual current collector B may preferably be applied by atmospheric plasma, chemical solution deposition, chemical vapour deposition, atomic layer deposition, electrochemical deposition or any combinations thereof.

[0113] Separator

[0114] One of the main functions of the separator of the invention is to provide electrical isolation between the anode and the cathode and allow for the conduction of lithium ions.

[0115] The separator of the invention should advantageously be compatible with the anode, cathode and electrolyte. Be electrochemically stable with these materials. And it should also have sufficient tensile strength and hardness to resist against the formation of dendrites and being suited for high-speed roll to roll manufacturing.

[0116] The separator can preferably be a polymer micro- or nanoporous membrane (e.g. PE, PI), a non-woven mat (fiber structure), e.g. PP or C-PET, potentially enhanced with a ceramic or polymer-coating, other fiber-based membranes (eg. PTFE, chitosan, silk glue, PVDF-HFP), covalent organic framework (COF), cellulose (eg. PE_HEC), a ceramic embedded in polymer matrix, crosslinked membrane (eg. PEGDE-DETA- PEGDME), a solid-state material. In the context of the invention, solid-state material can be entirely or partly used in place of a porous separator, or certain materials or compounds of the separator could be a solid-state electrolyte (e.g. polymer or ceramic solid-state electrolyte) to increase the ion-conductivity , or it can be used to coat the surface of the separator.

[0117] Different architectures exist, such as single or multi-layer designs, which can be enhanced with ceramic or polymer coatings.

[0118] Examples of separators include, without being limited, fiber structures (PP fiber and C-PET separators), eventually with a ceramic coating, preferably coated with aluminum oxide, placed in the side of the cathode. Solid-state ion conductor, such as multilayer membrane can be used. Separator can be coated with lithium-ion exchange, where zeolite acts as an HF scavenger. Metal-organic framework and separator, like CU3(BTC)2, HKUST-1, can also be part of the separator. H2O & HF scavenging PE separator, coated with porous silica and (3- isocynatopropyl) triethoxysilane is also an option.

[0119] Description of the invention & definitions

[0120] The expression ‘pure lithium metal’ used in the context of the present invention should mean an electrode in a battery cell that is composed entirely of elemental lithium without any additional alloying elements or compounds. In the context of rechargeable lithium-ion batteries, the anode is typically made of a material that can intercalate lithium ions during the battery's charging process and release them during discharge. In the case of a pure lithium metal anode, the lithium ions are sourced directly from the metallic lithium.

[0121] The wording ‘semi-solid electrolyte’ refers to an electrolyte material that is in a state where liquid is the main component and solid part is the minor component of the material.

[0122] The phrase ‘liquid electrolyte’ means, in a battery cell, an electrolyte material which is in a liquid or fluid state.

[0123] The phrase ‘solid electrolyte’ means, in a battery cell, an electrolyte material which is in a solid state.

[0124] The wording gel-polymer electrolyte means an electrolyte where a polymer matrix is swollen with a liquid electrolyte, creating a gellike structure.

[0125] Use is made of a liquid electrolyte combined with either a porous separator or a gel-polymer, semi-solid or solid electrolyte that can fulfil the role of separator.

[0126] Advantageously, the electrolyte of the present invention is substantially free of any added amount of solid electrolyte, in particular it may contain less than 50 wt. % of solid electrolyte, preferably less than 30wt.%.

[0127] The expression ‘spinel LMNO’ in the context of the invention refers to spinel-structured cathodes, including spinel LMNO, which have a specific crystal structure known as spinel or inverse spinel.

[0128] All preceding embodiments, technical features can be combined with each other, even if not specifically mentioned. One aforementioned paragraph including technical features can be combined with any other paragraphs, except if disclosed otherwise.

[0129] Example 1

[0130] Electrochemical cell is provided and contains according to a first example of the invention the following elements.

[0131] Anode - lithium-on-copper anode:

[0132] - A pure lithium anode having a thickness less than 20 m,

[0133] - A current collector A made of copper foil and coated with protective layer A,

[0134] - A protective passivation layer A applied by atmospheric plasma (acting as SEI) or ALD with oxides.

[0135] N / P ratio less than 2.

[0136] Separator: PE / PP

[0137] Electrolyte: 1 M LiPF6 in FEC: FEMC: HFE 2:6:2 by weight or 1 M LiPF6in EC:DMC 1 :1 + 0.5% GT

[0138] Cathode:

[0139] - Spinel LMNO with particles having a core-shell structure,

[0140] - Cathode protective layer B, A current collector B mode of aluminium with its protective layer B.

[0141] Example 2

[0142] Electrochemical cell is provided and contains according to a second example of the invention the following elements.

[0143] Anode:

[0144] - A pure lithium anode having a thickness less than 20 m,

[0145] - A protective passivation layer A applied on the pure lithium anode by atmospheric plasma (acting as SEI) or ALD with oxides.

[0146] N / P ratio less than 2.

[0147] Separator: Covalent organic framework or polyimide (PI) porous separator with integrated metal oxides

[0148] Electrolyte: Ionic liquid or localized high concentration electrolyte (e.g. LiFSI:TMS:TTE (1 :3:3 molar ratio)

[0149] Cathode:

[0150] - Spinel LMNO

[0151] - A current collector B made of aluminium with its protective layer B.

[0152] The term ‘eventually’ used in the context of the present invention does not limit the scope of the given object or scope of protection and corresponds to the same meaning as the word ‘preferably’.

[0153] In the context of the present invention, any single article such as “a”, “the”, can be replaced by an article designating plural forms such as “a series of” or “plurality of” or “several” or “at least one” or “at least 2” or “at least 3”, etc.

[0154] The wording “comprising”, “contains” or any other equivalent terms can be replaced by “consisting of” in order to define a more restrictive list or possibilities and exclude thereby other non-cited elements from the expression used.

Claims

CLAIMS1 . Electrochemical cell for secondary batteries comprising:- An anode comprising: o A lithium metal layer, preferably pure lithium metal layer, o Eventually, a current collector A containing a metal foil, preferably copper, or a composite containing a metal film and a conductive non-metal material, preferably a conductive polymeric material, o Eventually a protective passivation coating A acting as an artificial Solid Electrolyte Interface (SEI), being conductive to Li+ions and being a (nano)coating, preferably applied by atmospheric plasma, Atomic Layer Deposition (ALD), CVD or PVD onto the surface of the lithium metal layer,- An electrolyte having high voltage stability, preferably nonflammable electrolyte, comprising: o At least one lithium salt, preferably selected from the group comprising LiPF6, LiFSI, LiTFSI, LiBF4, LiDFOB, LiBOB and any combinations thereof, o At least one solvent, preferably selected from the group comprising carbonate-based compounds, fluorinated compounds, ether-based compounds, sulfone containing compounds, nitrile-based compounds, ionic liquids, liquified gas and any combinations thereof,- A cathode comprising: o A porous composite layer which comprises at least one active material, preferably comprising a lithium transition metal oxide, configured to contain a part of the electrolyte within its pores, wherein the active material is a high-voltage (HV) intercalation cathode material having operatingpotential in part or entirely above 4.3 V, preferably selected from a Spinel-structured, for instance LMNO or LMNTO, a Layered-structured, advantageously Li-rich layered oxides (LLO), such as LMLO or LMR-NMC, LCO and any combinations thereof, o Eventually, at least one cathode protective layer B located on the porous composite layer, preferably doped, o Eventually, a current collector B, preferably with a thickness comprised between 1 and 30 m, preferably between 5 and 30 pm, selected from a metal foil (Al), a composite comprising at least one metal film and at least one conductive non- metal material (polymer) and any combinations thereof.

2. Electrochemical cell according to claim 1 , wherein the current collector B comprises a protective layer B having oxidative stability chosen from the group comprising carbon-based materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid (in)organic coatings.

3. Electrochemical cell according to claim 1 or 2, wherein the protective layer B of the current collector B is applied by atmospheric plasma, chemical solution deposition, chemical vapour deposition, atomic layer deposition, PVD, electrochemical deposition or any combinations thereof.

4. Electrochemical cell according to any one of the preceding claims, wherein the active material is in the form of particles having a mean diameter comprised between 50 nm and 90 pm, preferably between 100 nm and 10 pm.

5. Electrochemical cell according to any one of the preceding claims, wherein the particles of said active material have a core-shell structure, wherein the shell contains compounds selected from metal oxide, metal fluoride, LiXO, wherein X is P, Si or Nb, metal phosphate,carbon-based compounds, solid-state electrolytes, conductive polymer, hybrids and any combinations thereof.

6. Electrochemical cell according to any one of the preceding claims, comprising a separator which can be a polymer micro- or nanoporous membrane (e.g. PE, PI), a non-woven mat (fiber structure), e.g. PP or C-PET, potentially enhanced with a ceramic or polymer-coating, other fiber-based membranes (eg. PTFE, chitosan, silk glue, PVDF-HFP), covalent organic framework (COF), cellulose (eg. PE_HEC), a ceramic embedded in polymer matrix, crosslinked membrane (eg. PEGDE-DETA- PEGDME), a solid-state material.

7. Electrochemical cell according to any one of the preceding claims, wherein the current collector A comprises a protective layer A chosen from the group comprising carbon-based materials (graphite, graphene reduced graphene oxide), conducting polymers, hybrid in- / organic coatings, 3D structures or relief.

8. Electrochemical cell according to any one of the preceding claims, wherein said protective layer A of said current collector A is applied by atmospheric plasma, chemical solution deposition, chemical vapour deposition, PVD, atomic layer deposition.

9. Electrochemical cell according to any one of the preceding claims, wherein said lithium salt is present in a concentration comprised between 1 and 10 mol / L per solvent.

10. Electrochemical cell according to any one of the preceding claims, wherein said lithium metal layer has a thickness comprised between 1 and 100 m.1 1. Electrochemical cell according to any one of the preceding claims, wherein the protective passivation coating A comprises a compound selected from the group comprising fluor-containing compounds, carbon-based compounds, nitrogen-containing compounds, sulfide-based compounds, lithium-based compounds, metal oxides, metal nitrides, metal carbides, polymer organic coatings, solidelectrolytes, hybrids, covalent organic frameworks (COF) and any combinations thereof.

12. Electrochemical cell according to any one of the preceding claims, wherein said porous composite layer further comprises at least one binder.

13. Electrochemical cell according to any one of the preceding claims, wherein said porous composite layer further comprises at least one conductive additive.

14. Electrochemical cell according to any one of the preceding claims, wherein said separator comprises a separator coating which comprises ceramic, polymer coating, zeolite, solid-state material, metal-organic framework or any combinations thereof.

15. Rechargeable lithium battery comprising at least one electrochemical cell according to any one of the preceding claims.