Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0421—Methods of deposition of the material involving vapour deposition
  • H01M4/0423—Physical vapour deposition
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/134—Electrodes based on metals, Si or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
  • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/362—Composites
  • H01M4/366—Composites as layered products
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
  • H01M4/386—Silicon or alloys based on silicon
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/661—Metal or alloys, e.g. alloy coatings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/665—Composites
  • H01M4/667—Composites in the form of layers, e.g. coatings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/021—Physical characteristics, e.g. porosity, surface area
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the invention relates to a method for producing copper-rich silicon foams from at least binary mixed phases, in which a silicon layer structure is applied to a carrier substrate.
• the invention further relates to the use of the method according to the invention for the production of a high-capacity electrode material in a lithium-ion battery, in particular for a silicon anode and an anode material and its use in a battery cell and a lithium-ion battery.
• the aim of the invention is the formation of a porous silicon-rich layer which is electrically highly conductive and allows good diffusion for lithium.
• An intrinsic porosity of the layer would allow a permanent compensation of the volume expansion during lithium storage without losing the electrical contact to the carrier substrate.
• a stable and consistent surface would be advantageous when using such a layer as an electrode in a battery application to the electrolyte.
• Ni2Si shows a volume that is up to 200% larger than pure crystalline silicon.
• Batteries are electrochemical energy stores and are divided into primary and secondary batteries.
• Primary batteries are electrochemical power sources in which chemical energy is irreversibly converted into electrical energy. A primary battery is therefore not rechargeable. Secondary batteries, also called accumulators, on the other hand, are rechargeable electrochemical energy storage devices in which the chemical reaction taking place is reversible, so that multiple use is possible. Electrical energy is converted into chemical energy when charging, and from chemical energy to electrical energy when discharging.
• Battery is the generic term for interconnected cells.
• Cells are galvanic units consisting of two electrodes, electrolyte, separator and cell case.
• Figure 1 shows an exemplary structure and the function of a lithium-ion cell during the discharge process. The components of a cell are briefly explained below.
• Each Li-ion cell consists of two different electrodes, one negatively charged when charged and one positively charged when charged. Since ions migrate from the negatively charged electrode to the positively charged electrode when energy is released, i.e. during discharge, the positively charged electrode is called the cathode and the negatively charged electrode is called the anode.
• the electrodes each consist of one Current collector (also called collector) and an active material applied to it, the active layer. Between the electrodes are the ion-conducting electrolyte, which enables the necessary charge exchange, and the separator, which ensures the electrical separation of the electrodes.
• the cathode consists, for example, of mixed oxides applied to an aluminum collector.
• the anode of a Li-ion cell can consist of a copper foil as the collector and a layer of carbon or silicon as the active material. During the charging process, lithium ions are reduced and embedded in the graphite or silicon layers.
• the cathode In lithium-ion battery (LiB) designs, the cathode typically supplies the lithium atoms for charging and discharging in the anode, the battery capacity is therefore limited by the cathode capacity.
• Typical previously used cathode materials are z.
• the capacity of the battery is determined by the thickness of the active layer, more precisely the Si layer.
• the electrical conductivity of the active material in a battery should be set as high as possible.
• silicon is poorly conductive, in contrast to conductive graphite. Therefore, silicon requires high doping or structures that increase electrical conductivity.
• nanoscale silicon powders are surrounded by framework structures containing carbon and fixed to the current collector.
• Silicon-based nanoparticles and nanowires in particular have a smaller storage capacity of approx. 3400 mAh/g compared to the maximum possible storage capacity of silicon of 3579 mAh/g, but have more stable silicon structures with regard to the volume change of the silicon after the lithium has been stored to a specific Si structure size, as described in M. Green, E. Fielder, B. Scrosati, M. Wachtier and JS Moreno: Structured Silicon anodes for lithium battery applications, Electrochem. Solid-State Lett, 6, A75-A79 (2003). Ipm is considered to be the structural limit for amorphous and 100nm for crystalline silicon, so that a uniform volume change can take place.
• the volume expansion in the electrode material can on the one hand be absorbed by the free space between the nanostructures, and on the other hand the reduction in size of the structures facilitates the phase transitions during alloy formation, which leads to an increase in the performance of the electrode material.
• the Si nanostructures are fabricated by both physical and chemical methods, including ball milling, sputter deposition, PVD/CVD methods, chemical or electrochemical etching and reduction of SiC>2 (Feng, K. et al. Silicon -Based Anodes for Lithium-Ion Batteries: From Fundamentals to Practical Applications.Small 14, 1702737 (2016) ). Then, according to the state of the art, the nanostructures produced are conductive carbon and binder mixed and applied on a large scale to a copper current collector by calendering and drying for anode construction. The disadvantage of this method is that the nanostructures separate from one another during battery operation and the anode loses capacity as a result. Another disadvantage is the high surface area of the nanostructures, which leads to a large consumption of electrolyte and drying out of the battery.
• Si-Cu cavity structures for lithium-ion batteries could only be produced by complex furnace processes (He , Y . , Wang, Y . , Yu, X . , Li , H . & Huang, X . Si-Cu Thin Film Electrode with Kirkendall Voids Structure for Lithium-Ion Batteries J Electrochem Soc 159, A2076 (2012).
• the properties of the layers produced by the method should be varied in a targeted manner by adjusting the process parameters and adapted to the respective application, with the process being able to be carried out as simply, quickly and efficiently as possible.
• the object is solved by a method according to independent claim 1 .
• a Sili zium layer structure is applied to a carrier substrate, a layer of Silicon layer structure formed and applied from at least two layers and from at least two or more materials, the materials having different diffusion constants, and that the layer is subjected to short-term annealing with a targeted energy input, with cavity structures having different diameters being formed.
• Short-term tempering is understood to mean, in particular, flash lamp tempering and/or laser tempering.
• the flash lamp annealing takes place with a pulse duration or annealing time in the range from 0.3 to 20 ms and a pulse energy in the range from 0.3 to 100 J/cm 2 .
• the annealing time is adjusted from 0.01 to 100 ms by the scanning speed of the local heating site to produce an energy density of 0.1 to 100 J/cm 2 .
• the heating ramps achieved in the short-term tempering are in the range of 10 A 4-10 A 7 K/s required for the process. Flashlamp annealing uses a spectrum in the visible wavelength range for this, whereas laser annealing uses discrete wavelengths in the infrared (TR) to ultraviolet (UV) spectrum.
• TR infrared
• UV ultraviolet
• a layer is understood to be a stack of layers formed from at least two layers.
• a layer therefore comprises at least two layers.
• a layer is composed of at least two different materials, with a layer z. B. can be formed from two silicon layers and a copper layer, ie the layer comprises a Si-Cu-Si layer stack according to the example.
• the simple stacking of different layers to form a sheet of two or more materials produces cavities after a brief anneal that go beyond the effect described by Kirkendall.
• time-dependent processes can be controlled by short-time annealing with process parameters that can be set in a defined manner.
• the inventive method enables the formation of a porous sili cide-Sili zium matrix in which amorphous or nanoscale Sili zium together with cavities or. pores occurs.
• the layer made of at least copper and silicon, Cu—Si, is deposited.
• Cu and Si are deposited in layers, with Cu and Si then reacting to form a binary mixed phase by means of short-term annealing.
• the layer is made of copper, silicon and another Material, Cu-Si-X, deposited.
• the materials are deposited in layers, with the materials subsequently reacting to form a ternary mixed phase by means of a short-time anneal if three different materials are used.
• the further material is nickel (Ni), titanium (Ti), aluminum (Al), tin (Sn), germanium (Ge), lithium (Li), tungsten (W) and/or carbon ( C) .
• nickel is also deposited as a further material in addition to Cu and Si, a nickel silicide is first formed as a result of the short-term annealing, and this is then completely converted into a copper silicide.
• a foam-like silicide structure is produced that is suitable for use as an active layer in a lithium-ion battery in order to produce a stable anode for lithium-ion batteries.
• the size of the cavity structures formed can be controlled so that the mechanical contact of the active layer to the substrate is maintained despite the cavities formed. The cavities then mitigate the volume expansion of the silicon anode during lithium storage.
• the short-time annealing is a flash lamp annealing and the formation of the cavity structures is achieved by the flash lamp annealing using a pulse duration in the range from 0.3 to 20 ms and/or a pulse energy in the range of 0.3 to 100 J/cm 2 of flash lamp annealing and preheating or cooling of the carrier substrate in the range of 4°C to 200°C.
• the formation of the cavity structures is achieved by an annealing time in the range from 0.01 to 100 ms by setting a scanning speed of a local heating point and an energy density in the range from 0.1 to 100 J/cm 2 and a Preheating or cooling in the range of 4°C to 200°C of the laser annealing is controlled and thus partially reacted silicon is produced in every layer.
• any layer stack ie layers, made of metals with different diffusion constants can be deposited, for example by sputtering or evaporation processes.
• a layer stack forms a layer.
• a layer structure is made up of several layers.
• additional annealing processes can be carried out quickly and efficiently by varying the pulse energy of the
• Flashes/lasers the pulse time of the flashes/lasers and/or the preheating or cooling of the substrate.
• the silicon layer structure has stable cavity structures which are formed by removing previously introduced lithium or which develop during operation of a silicon anode consisting of an electrode material which is formed by the silicon layer structure form by lithium insertion and removal.
• the silicon layer structure has stable cavity structures which are formed in a self-regulating manner in terms of their size and number as a result of the rate of lithium diffusion.
• their number and size can be influenced by the charging speed, i.e. the type of application. i.e. in particular by the charging/discharging rate of a battery or generally by the operating mode or application of the battery.
• the charging speed i.e. the type of application. i.e. in particular by the charging/discharging rate of a battery or generally by the operating mode or application of the battery.
• the charging speed i.e. the type of application. i.e. in particular by the charging/discharging rate of a battery or generally by the operating mode or application of the battery.
• the charging speed i.e. the type of application. i.e. in particular by the charging/discharging rate of a battery or generally by the operating mode or application of the battery.
• the possible diffusion rates depend on the porosity of the silicon anode, which is self-regulating
• the void structures are formed in the mixed phase system.
• a stable cavity structure in each layer or in the overall layer structure is formed irreversibly when lithium is removed.
• Other mixed phases as an intermediate reaction are possible.
• a suitable layer stack of Cu-Si (-X) mixed phases expands with lithium Storage irreversible , but mechanically stable .
• the high adhesion of the overall layer structure to the carrier substrate and the use of mixed phases with a heterogeneous structure made of silicon embedded in silicide structures enable the formation of stable cavity structures.
• the introduction and removal of lithium can advantageously also take place during the first cycles (forming) in battery operation.
• the cavity structure can completely accommodate the volume expansion of silicon during lithiation and delithiation.
• the formed cavity structure of the entire active layer can be larger than the 300% volume formation (theor. even 400% for Li22Sis) by pure lithium silicide formation.
• the silicon expansion is always the same, depending on how much lithium is absorbed. Physically, the volumetric expansion is equal to the amount of storage.
• the cavity structure, which ultimately absorbs the expansion can thus be significantly larger than the pure expansion of silicon. It is important that the cavity structure must be stable. What is special about the method according to the invention is that the cavity structure is produced both during manufacture using the flash lamp method and during the "first" operation of a battery, and then remains stable. This is made possible according to the invention by providing a suitable conductive and stretchable framework of the mixed-phase system.
• the advantage of the method according to the invention for battery applications is that a variable stack structure for setting the cavity structures is possible without additional effort. Different material systems can be combined to adjust the amount of voids formed.
• a planar surface with minimal roughness is essential for the formation of a stable protective layer.
• the cavities, distributed in size on a nanoscale and microscale scale, ensure a stable layer both during production and during volume expansion due to lithium intercalation.
• each layer is subjected to an individual short-term tempering.
• the cavity structures can thus be set individually for each layer of the silicon layer structure.
• the energy input into the layer can be specifically controlled in the method according to the invention.
• the formation of the Kirkendall cavities is a diffusion-driven process that is set by the energy input per time.
• the inventive method allows temporary intermediate phases, d. H . reactions that do not run to completion and lattice structures that exist for a short time, and use any combination of materials with different diffusion constants to form cavities with different diameters.
• each layer can be built up individually and its properties can be specifically influenced in order to adjust the battery performance.
• This anode material can be used in a battery cell, which in turn can be installed in a battery with at least one battery cell.
• Fig. 1 Exemplary structure and function of a lithium-ion cell during the discharging process
• Fig. 2 Schematic representation of a layer formed from two materials and the formation of the copper-rich silicon foams as a function of the parameters used for the short-term annealing;
• FIG. 3 Schematic representation of the method according to the invention in an embodiment in which the cavity structures are formed by introducing and removing lithium;
• Fig. 4 SEM recording of cavity structures in a Si layer structure formed from a binary mixed system of Cu and Si;
• Fig. 5 SEM recording of a Si layer structure according to the invention during formation (first cycles and incorporation of Li in Si);
• the cavity structures can form because the diffusion rate of Cu in Si is significantly higher than that of Si in Cu, the following applies: D Cu in si >> D si in cu - In thermal equilibrium, the following applies approximately: D Cu in si ⁇ D voids + D si in cu -
• FIG. 5 shows the SEM image of a Si layer structure according to the invention during formation (first cycles and storage of Li in Si) and the structure of a stable cavity structure with microscopic cavities which absorbs the volume expansion of the silicon.
• the framework contains a large amount of copper, which ensures a consistently high level of electrical conductivity.

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• 2022
  • 2022-11-03 JP JP2024523896A patent/JP2024539917A/ja active Pending
  • 2022-11-03 KR KR1020247016782A patent/KR20240095257A/ko active Pending
  • 2022-11-03 WO PCT/EP2022/080662 patent/WO2023078988A1/de not_active Ceased
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