Method and system for depositing a solid electrolyte onto electrode active material

Abstract

Method for depositing solid electrolyte material (4) onto electrode active material (2), comprising the steps: - Supply (20) of electrode active material (2) from a first storage unit (3) to a first dosing agent (8) while simultaneously supplying (20) of solid electrolyte material (4) from a second storage unit (3') to a second dosing agent (8'), - Supply (22) of inert gas to the first (8) and second metering device (8') by means of an inert gas supply device (10, 10'), - Feeding (24) the electrode active material (2) via the first metering device (8) into a reaction chamber (9) while simultaneously feeding (24) the solid electrolyte material (4) via the second metering device (8') into the reaction chamber (9), - wherein the electronic structure of the electrode active material (2) and the solid electrolyte material (4) is influenced during the supply (24) to the reaction chamber (9) by means of the first (8) and second dosing agent (8') such that the electrode active material (2) and the solid electrolyte material (4) bind at least partially to each other while maintaining the crystal structure of the solid electrolyte material (4) (28).

Description

[0001] The present invention relates to a method and a system for depositing solid electrolyte material onto electrode active material.

[0002] The document DE 10 2015 217 749 A1 relates to a coated cathode active material for a battery cell, wherein the coating is formed as a lithium-ion conductive solid electrolyte and a physical, mechanical or wet-chemical process is used as the coating method.

[0003] The document US 2017 / 0018760 A1 relates to a coated active cathode material for secondary lithium cells and batteries, wherein the coating is formed as a solid lithium-ion conductor with a layer thickness of 20 - 50 nm and a physical process, for example ALD, PECVD, or PLD, is used as the coating method.

[0004] The document WO 2016 / 196688 A1 relates to a method for coating anode and cathode material, wherein the coating is formed, for example, in the form of metal oxides, metal halides, metal oxyhalides, metal phosphates or the like, and ALD, MLD, CVD, PVD or the like are used as coating methods.

[0005] The document US 2011 / 0045348 A1 relates to a coated cathode active material with a resistance-reducing coating material and a lithium battery for using the cathode active material.

[0006] The document US 2014 / 0234715 A1 relates to a protective coating for cathode active materials, wherein the coating is formed in the form of aluminum oxide, aluminum phosphate or aluminum fluoride by immersion, spray coating or ALD.

[0007] Methods or systems for producing electrodes are also known from JP 2009 280 874 A, JP 2011 124 028 A, DE 10 2014 226 929 A1, US 2018 / 0138494 A1 and US 2017 / 0338522 A1.

[0008] A disadvantage of these processes is that many of the solid electrolytes used are not stable at high voltages and are therefore unsuitable as protective coatings. Synthesis of these materials using certain methods is also not feasible. Furthermore, many of the processes mentioned are very complex and expensive, making them difficult to apply on an industrial scale. Furthermore, some of the methods generally require additional purification steps, which can also be very complex depending on the process requirements.

[0009] It is therefore the object of the present invention to at least partially remedy the disadvantages described above, in particular it is the object of the present invention to provide a method and a system for the deposition of solid electrolyte material on electrode active material, which is versatile and can be carried out in a simple and cost-effective manner.

[0010] The above object is achieved by a method having the features of claim 1 and a system according to claim 10. Further features and details of the invention emerge from the subclaims, the description and the drawings.

[0011] Technical features disclosed for the method according to the invention also apply in connection with the system according to the invention, and vice versa, so that the disclosure of the individual aspects of the invention always refers to each other. Advantageous embodiments of the invention are listed in the dependent claims.

[0012] In the method according to the invention for depositing solid electrolyte material onto electrode active material, the electrode active material is first fed from a first storage unit to a first dosing means, while simultaneously feeding solid electrolyte material from a second storage unit to a second dosing means. The electrode active material can be formed either as an anode or cathode active material. The storage units can preferably be formed as reactors, reaction vessels, reaction containers, or the like.

[0013] After the electrode active material and the solid electrolyte material have been added, the method according to the invention involves supplying inert gas to the first and second dosing means by means of an inert gas supply means. The inert gas can preferably be a noble gas, in particular argon, but also another gas such as nitrogen or the like.

[0014] After the inert gas is supplied to the first and second dosing means according to the invention, the electrode active material is supplied to a reaction chamber via the first dosing means, while the solid electrolyte material is simultaneously supplied to the reaction chamber via the second dosing means. The materials can advantageously be atomized during supply to the reaction chamber in order to provide the largest possible reaction surface.

[0015] According to the present method, the electrode active material and the solid electrolyte material are fed into the reaction chamber in such a way that the electronic structure of the electrode active material and the solid electrolyte material is influenced during the feed to the reaction chamber such that the electrode active material and the solid electrolyte material at least partially bond to one another while maintaining the crystal structure of the solid electrolyte material. Bonding can occur, for example, via dipole interactions, via ionic interactions, via covalent interactions, or other types of interactions, with the solid electrolyte material preferably being arranged on the electrode active material, in particular being deposited on the electrode active material.

[0016] In the context of the invention, influencing the electronic structure means an alignment or spatial redistribution of charge carriers of the electrode active material and the solid electrolyte material up to the absorption or release of charge carriers.

[0017] In the context of the invention, maintaining the crystal structure of the solid electrolyte material means that the basic atomic arrangement or the basic atomic structure of the crystal structure of the solid electrolyte material is not changed during the process according to the invention. This means that although changes in bond lengths within crystallites of the solid electrolyte material may occur, the atomic bonding partners remain the same.

[0018] The solid electrolyte coating protects the electrode material by ensuring that it is no longer in direct contact with the liquid (in the case of a lithium-ion battery) or the solid catholyte (in the case of a solid-state battery) during operation of the electrode, thus ensuring a longer service life of the cells.

[0019] The present process makes it possible, in particular, to preserve the structure of the solid electrolyte during the coating process. This protects the electrode active material during the coating process because, on the one hand, high temperatures are not involved and, on the other hand, the electrode active material is not chemically attacked. In addition to protecting the electrode active material, the present process can be carried out with a variety of materials that can be produced in powder form and requires no post-treatment steps.

[0020] In order to ensure the most flexible and finely dosable supply of the solid electrolyte materials and electrode active materials when carrying out the method according to the invention, it can be provided in particular that the solid electrolyte material and the electrode active material are suspended separately in solvents before being fed to the dosing means. Separate storage and suspension of the materials enables, in particular, a flexible selection of a suitable solvent. Thus, in particular, highly volatile aprotic solvents such as THF, cyclohexane, methyl acetate, chloroform, NMP (n-methylpyrrolidone), NEP (n-ethylpyrrolidone), xylene, pentane, dichloromethane, diethyl ether, acetonitrile, or the like can be used to suspend the solid electrolyte material and the electrode active material.

[0021] In order to further enable the most flexible and, ideally, customized supply of the solid electrolyte material and the electrode active material, the invention further provides for the supply of the electrode active material to the first dosing means and the supply of the solid electrolyte material to the second dosing means to be carried out by means of two different supply means. The supply means can be designed, in particular, in the form of pumps or the like, for example, in the form of peristaltic pumps, rotary vane pumps, scroll pumps, oil diffusion pumps, turbomolecular pumps, water jet pumps, or the like.By using different feed devices, not only can a different vacuum be generated for feeding the respective materials to the dosing devices, but the feed devices can also be adapted to the solvents used, which is particularly advantageous since not all pumps are equally suitable for all solvents.

[0022] In order to further enable the most versatile and variably controllable and metered supply of the solid electrolyte materials to the reaction chamber, the invention can further provide for the inert gas to be heated during supply. The inert gas can preferably comprise at least partially noble gases, such as argon, helium, or the like. Nitrogen or another gas or specific gas mixtures can also be used. The aforementioned heating of the inert gases makes it possible, in particular, to create tailored supply conditions. It is also conceivable for the inert gas to be supplied to the first and second dosing units separately via a first and second inert gas supply means, which further improves the flexibility of the supply conditions to the reaction chamber.

[0023] To ensure a high bonding probability of the solid electrolyte materials on the electrode active material, the method according to the invention can further provide for the solid electrolyte material to be supplied with a size of 2-5 nm. In this case, the solid electrolyte materials can preferably be comminuted or otherwise processed before suspension. The solid electrolyte material can be comminuted in particular using mechanical-physical production processes such as milling processes or the like. Likewise, the solid electrolyte material can be produced using chemical-physical production processes in the liquid or gaseous phase, such as precipitation processes or spray pyrolysis or the like.With regard to the size of the solid electrolyte materials, these can preferably be comminuted or produced to a size of less than 10 nm, preferably to a size of less than 5 nm, in particular to a size of less than 3 nm.

[0024] In order to provide the widest possible electrochemical stability window for the coating materials used, the invention further provides for LLZO (garnet) and / or NASICON to be used as solid electrolyte materials. In addition to these two solid electrolyte materials, other materials can also be used that have a similar electrochemical stability window, for example, compared to Li / Li. + achieve an electrochemical stability of up to approx. 0.01 V (as solid electrolyte material for an anode material) or up to approx. 4.9 V (as solid electrolyte material for a cathode material).

[0025] To ensure the highest possible bonding probability or deposition probability of the solid electrolyte materials on the electrode active material, the method according to the invention can further provide for the electrode active material and the solid electrolyte material to be oppositely polarized during feeding to the reaction chamber. For example, a high voltage can be applied to the dosing means during feeding to the reaction chamber, so that the electrode active material and the solid electrolyte material are correspondingly polarized during feeding.

[0026] To ensure a higher bond strength or a stronger bond affinity, particularly between the solid electrolyte material and the electrode active material, it can further be provided that the electrode active material and the solid electrolyte material are ionized in opposite directions during feeding to the reaction chamber. This can be achieved, for example, by applying a high positive or negative voltage to the dosing means. Various ionization methods, such as electron impact ionization, chemical ionization, field ionization, electron spray ionization, and the like, can be used to oppositely ionize the solid electrolyte material and the electrode active material.

[0027] With a view to a simple and cost-effective method for separating the bonded particles of the electrode active material and the solid electrolyte material from the reaction chamber, the method according to the invention can further provide for the bonded particles of the electrode active material and the solid electrolyte material to be separated from the reaction chamber by means of a centrifugal separator. Within the scope of such a separation, for example, a practical and simple separation of the solvent-containing exhaust air can be achieved by means of a removal device, such as a pump or the like, while the bonded particles of the electrode active material and the solid electrolyte material are separated in a collecting container.

[0028] The invention also relates to a system for depositing a solid electrolyte onto electrode active material. The system comprises a first and a second storage unit for storing electrode active material and solid electrolyte material, at least one supply means for simultaneously supplying electrode active material and solid electrolyte material to a first and a second dosing means, and at least one inert gas supply means for supplying inert gas to the first and second dosing means.Furthermore, the system in question comprises a first dosing means for supplying an electrode active material to a reaction chamber and a second dosing means for simultaneously supplying a solid electrolyte material to the reaction chamber. The first and second dosing means are configured such that the electronic structure of the electrode active material and the solid electrolyte material can be influenced during supply to the reaction chamber such that the electrode active material and the solid electrolyte material at least partially bond to one another while maintaining the crystal structure of the solid electrolyte material. Thus, the system according to the invention offers the same advantages that have already been described in detail with regard to the method according to the invention.

[0029] To ensure effective communication and control of the individual system components, the individual system components can preferably be connected to one another via communication and control lines. Within the scope of a particularly flexible and easily integrated design of the system according to the invention, the individual system components can also communicate wirelessly or contactlessly via Bluetooth, WLAN, NFC, Zigbee, or the like.

[0030] The invention also relates to an electrode produced by the method described above, in particular a lithium-ion battery cell, comprising an electrode produced by the method described above.

[0031] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0032] They show: Fig. 1 a schematic representation of a system according to the invention for the deposition of solid electrolyte material on electrode active material, Fig. 2 a schematic representation of the individual steps of a method according to the invention for the deposition of solid electrolyte material on electrode active material.

[0033] In the figures, identical reference symbols are used for the same technical features.

[0034] Fig. 1 shows a schematic representation of a system 1 according to the invention for depositing solid electrolyte material 4 onto electrode active material 2. The electrode active material 2 is arranged in a first storage unit 3. The solid electrolyte material 4 is stored in a second storage unit 3'. The storage units 3, 3' can be designed, in particular, as reactors, reaction vessels, or other types of containers. The solid electrolyte material 4 and the electrode active material 2 can be stored, in particular, in the form of a suspension in the storage units 3, 3'. The electrode active material can be in the form of sulfides, oxides, halides, phosphides, nitrides, chalcogenides, oxysulfides, oxyfluorides, sulfur fluorides, or sulfur oxide fluorides, or the like.The solid electrolyte material is presently in the form of a lithium-ion conductive solid electrolyte, in particular LLZO and / or NASICON, but can also be in the form of aluminum oxide, aluminum phosphate or aluminum fluoride or the like.

[0035] The solid electrolyte material and the electrode active material are suspended in a suitable solvent. Suitable solvents include, in particular, aprotic solvents such as THF, cyclohexane, ethyl acetate, chloroform, or the like.

[0036] The suspended electrode active materials 2 and solid electrolyte materials 4 are conveyed to a first and second dosing means 8, 8' via a first and a second feed means 6, 6'. The feed means 6, 6' can be designed, in particular, as pumps, for example, as peristaltic pumps, rotary vane pumps, scroll pumps, turbomolecular pumps, or the like.

[0037] During the supply of the electrode active material 2 and the solid electrolyte material 4 via the supply means 6, 6' to the dosing means 8, 8', an inert gas, such as nitrogen or argon, is supplied via the inert gas supply means 10, 10'. The supplied inert gas can be heated to a desired supply temperature by the first and second heating means 7, 7'. The electrode active material 2 and the solid electrolyte material 4 are then supplied to the reaction chamber 9 via the first and second dosing means 8, 8'.

[0038] During the feeding, the materials 2, 4 are finely distributed, wherein the electronic structure of the electrode active material 2 and the solid electrolyte material 4 is additionally influenced during the feeding to the reaction chamber 9 in such a way that the electrode active material 2 and the solid electrolyte material 4 at least partially bond to one another while maintaining the crystal structure of the solid electrolyte material 4, in particular the solid electrolyte materials are deposited on the electrode active materials.

[0039] By preserving the structure of the solid electrolyte during the coating process, the electrode active material in particular is protected because, on the one hand, high temperatures are not present and, on the other hand, the electrode active material is not chemically attacked.

[0040] The electrical structure of the electrode active material 2 and the solid electrolyte material 4 is influenced in particular by polarization or ionization of the materials 2, 4. For polarization or ionization of the solid electrolyte material and the electrode active material, a high negative or positive voltage can be applied to the dosing means 8, 8', for example, so that the electronic structure of the electrode active materials 2 and solid electrolyte materials 4 supplied via the dosing means 8, 8' are polarized or ionized in opposite directions to one another in such a way that the oppositely polarized or ionized materials subsequently bond to one another within the reaction space 9. Such an influence can be achieved, for example, using a process such as electron spray ionization, electron impact ionization, or other suitable ionization methods.

[0041] After the bonding or deposition of portions of the solid electrolyte material onto the electrode active material 2, the bonded materials are transported via a transfer means 11 to a centrifugal separator 14, by which the bonded particles are separated. Transfer by means of the transfer means 11 can be achieved, for example, by utilizing electrostatic forces or, for example, by means of pumps. In this case, the solvent is removed from the system 1 via the discharge device 13, which can also be designed as a pump.

[0042] Fig.Figure 2 shows a schematic representation of a method according to the invention for depositing a solid electrolyte onto electrode active material. In a first step, electrode active material 2 is first supplied 20 from a first storage unit 3 to a first dosing agent 8, while simultaneously supplying 20 solid electrolyte material 4 from a second storage unit 3' to a second dosing agent 8'.

[0043] Subsequently, in one step, inert gas is supplied 22 to the first and second dosing means 8, 8' by means of an inert gas supply means 10, 10'. Optionally, the supplied inert gas can be heated to a desired supply temperature by means of a first and a second heating means 7, 7'.

[0044] In a subsequent step, the electrode active material 2 is fed 24 via the first dosing means 8 into a reaction chamber 9 while simultaneously feeding 24 the solid electrolyte material 4 via the second dosing means 8' into the reaction chamber 9.

[0045] After or during feeding 24 of the electrode active material 2 or the solid electrolyte material 4 into the reaction space 9, the electronic structure of the materials 2, 4 is influenced in a step 26 such that the materials 2, 4 are at least partially bonded to one another in a subsequent step 28 while maintaining the crystal structure of the solid electrolyte material 4, or the solid electrolyte materials 4 are deposited on the electrode active materials 2.

[0046] In this case, the materials 2, 4 can be polarized or ionized, in particular opposite to one another, during or after the feed, so that the materials 2, 4 form a bond during their further transport through the reaction chamber 9, or an attractive interaction exists between the different materials 2, 4. This can be achieved by applying a high positive or negative voltage to the dosing means 8, 8', so that the materials 2, 4 supplied via the dosing means 8, 8' are polarized or ionized. In addition, the materials 2, 4 can be finely atomized during their feed 24 to the reaction chamber 9, which further increases the probability of bonding between the materials.

[0047] In a final step 30, the particles of the electrode active material 2 and the solid electrolyte material 4 bound to one another are finally separated from the reaction chamber 9 by means of a transfer agent 11 and a centrifugal separator 14.

[0048] By means of the method according to the invention and the system according to the invention for depositing solid electrolyte material 4 onto electrode active material 2, it is possible, in particular, to use a wide variety of materials for deposition onto electrode active material and to deposit them onto the electrode active material in a simple and cost-effective manner. The deposition of solid electrolyte material onto electrode active material protects, in particular, the electrode active material, thus enabling the production of more stable and durable electrodes or cells comprising the electrodes. List of reference symbols 1 System for the deposition of solid electrolyte material on electrode active material 2 Electrode active material 3 first storage unit 3' second storage unit 4 Solid electrolyte material 6 first feeding means 6' second feeder 7 first heating agent 7' second heating medium 8 first dosing agent 8' second dosing agent 9 Reaction chamber 10 first inert gas supply means 10' second inert gas supply means 11 Transfer means 13 Discharge device 14 centrifugal separators 16 deposited electrode active material provided with solid electrolyte material 20 Supply of solid electrolyte material or electrode active material 22 Supply of inert gas 24 Feed to the reaction chamber 26 Influence of the electronic structure 28 Bonding between solid electrolyte material and electrode active material 30 Separation

Claims

[1] Method for the deposition of solid electrolyte material (4) on electrode active material (2), comprising the steps: - feeding (20) electrode active material (2) from a first storage unit (3) to a first dosing means (8) while simultaneously feeding (20) solid electrolyte material (4) from a second storage unit (3') to a second dosing means (8'), - supplying (22) inert gas to the first (8) and second dosing means (8') by means of an inert gas supply means (10, 10'), - feeding (24) the electrode active material (2) via the first dosing means (8) into a reaction chamber (9) while simultaneously feeding (24) the solid electrolyte material (4) via the second dosing means (8') into the reaction chamber (9), - wherein the electronic structure of the electrode active material (2) and the solid electrolyte material (4) is influenced during the supply (24) to the reaction space (9) by means of the first (8) and second dosing means (8') such that the electrode active material (2) and the solid electrolyte material (4) at least partially bond to one another (28) while maintaining the crystal structure of the solid electrolyte material (4). [2] Method according to claim 1, characterized by that the solid electrolyte material (4) and the electrode material (2) are each suspended separately from one another in solvents before being fed (20) to the dosing means (8, 8'). [3] Method according to claim 1 or 2, characterized by that the supply (20) of the electrode active material (2) to the first dosing means (8) and the supply (20) of the solid electrolyte material (8') to the second dosing means (8') takes place by means of two different supply means (6, 6'). [4] Method according to one of the preceding claims, characterized by that the inert gas is heated during the supply (22). [5] Method according to one of the preceding claims, characterized by that the solid electrolyte materials (4) are supplied with a size of 2 to 5 nm. [6] Method according to one of the preceding claims, characterized by that LLZO and / or NASICON are used as solid electrolyte materials (4). [7] Method according to one of the preceding claims, characterized by that the electrode active material (2) and the solid electrolyte material (4) are oppositely polarized during the supply (24) to the reaction space (9). [8] Method according to one of the preceding claims, characterized by that the electrode active material (2) and the solid electrolyte material (4) are ionized opposite to each other during the supply (24) to the reaction space (9). [9] Method according to one of the preceding claims, characterized by that the bonded particles of the electrode active material (2) and the solid electrolyte material (4) are separated (30) from the reaction chamber (9) by means of a centrifugal separator (14). [10] System (1) for depositing a solid electrolyte (4) on electrode active material (2), comprising: - a first (3) and a second storage unit (3') for storing electrode active material (2) and solid electrolyte material (4), - at least one supply means (6, 6') for the simultaneous supply (20) of electrode active material (2) and solid electrolyte material (4) to a first (8) and a second dosing means (8'), - at least one inert gas supply means (10, 10') for supplying (22) inert gas to the first (8) and second dosing means (8), - a first dosing means (8) for supplying (24) an electrode active material (2) to a reaction chamber (9), - a second dosing means (8') for simultaneously supplying (24) a solid electrolyte material (4) to the reaction chamber (9), - wherein the first (8) and second dosing means (8') are designed such that the electronic structure of the electrode active material (2) and the solid electrolyte material (4) can be influenced during the supply (24) to the reaction space (9) by means of the dosing means (8, 8') such that the electrode active material (2) and the solid electrolyte material (4) at least partially bond to one another while maintaining the crystal structure of the solid electrolyte material (4).

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