Patent Publication Number: US-2022223855-A1

Title: Method for producing silicon-based anodes for secondary batteries

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of and Applicant claims priority under 35 U.S.C. § 120 of U.S. patent application Ser. No. 16/077,963 filed on Aug. 14, 2018, which application is a national stage application under 35 U.S.C. § 371 of PCT Application No. PCT/EP2017/052956 filed on Feb. 10, 2017, which claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2016 001 949.2 filed on Feb. 15, 2016, the disclosures of each of which are hereby incorporated by reference. A certified copy of priority German Patent Application No. 10 2016 001 949.2 is contained in parent U.S. patent application Ser. No. 16/077,963. The International Application under PCT article 21(2) was not published in English. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a method for the manufacture of silicon-based anodes for secondary batteries. 
     2. Description of the Related Art 
     The electrochemical energy storage is an important cornerstone of an energy revolution being fought worldwide to temporarily store the fluctuating, regeneratively produced electricity as well as to supply it for stationary and mobile applications. In order to combat a shortage related to raw materials and thus an increase in the costs for secondary batteries in particular, not only the diversification of the energy-storage concepts but also new materials are needed. This should improve the technical performance of corresponding energy storage concepts on the one hand (including capacity, energy density, useful life) and also minimize the manufacturing costs on the other hand. The latter may be ensured in particular by the use of readily available chemical elements, such as silicon represents, for which a broad technological basis already exists. 
     The choice of silicon as a promising and resource-efficient anode material is based on an algorithm that was developed in the course of the CryPhysConcept Project (BMBF: 03EK3029A): Besides electrochemical characterizing variables, it encompasses the questions of resource availability, of recycling and of costs—i.e. the criticality—as well as of environmental compatibility and operating safety, and it permits a weighting corresponding to a desired storage application. 
     Secondary batteries may be secondary-storage lithium batteries, which have the highest development dynamic with respect to broad applications such as in hearing aids, smart phones, laptops and as buffers for the energy grid and also as traction batteries for electric vehicles. 
     For the increased use of regenerative energies for the electromobility, traction batteries with up to several tens of kWh are additionally necessary for electric vehicles. Modern secondary storage systems, e.g. on the basis of lithium ion technology, are very well suited for the area of electromobility. However, the current storage density greatly limits the range of such electric vehicles. A further aspect relates not only to safety but also to the price disadvantage of electric cars due to the battery cells, which continue to be expensive. This is where inexpensive battery materials, for example for Si-based lithium cells, may contribute to an outstanding extent. 
     Silicon as an anode material has a high storage capacity of approximately 4212 mAhg −1  at room temperature compared with the conventional carbon-type materials, such as graphite, for example, with a storage capacity of 372 mAhg −1 . However, challenges in the use of silicon as anode material arise with respect to the partly considerable volume change (volume contraction and expansion) of the host matrix during intercalation and deintercalation of the mobile ionic species during charging and discharging of corresponding energy storage systems. The volume change is approximately 10% for graphite but in contrast is approximately 400% for silicon. The volume change of the anode material during use of silicon leads to internal stresses, cracking, pulverization of the active material of the host matrix (silicon) and ultimately to complete destruction of the anode. 
     Selected scientific papers that can be associated with the method underlying the invention are indicated for silicon-based anodes in the following. 
     In the manufacture of batteries, carbon-based or silicon-based nanotubes and nanowires are already being used as anode materials in chargeable lithium batteries. The great advantage of such nanomaterials besides the increase of the speed of intercalation and deintercalation of the lithium is also the surface effect. A large surface increases the contact area for the electrolytes and the flow, associated therewith, of Li +  ions (vacancies) through the interface, as is described in the publication of M. R. Zamfir, H. T. Nguyen, E. Moyen, Y. H. Lee and D. Pribat: Silicon nanowires for Li-based battery anodes: a review, Journal of Materials Chemistry A (a review), 1, 9566 (2013). Investigations on the carbon-based nanotubes and nanowires, which are described in the publications of R. S. Morris, B. G. Dixon, T. Gennett, R. Raffaelle, M. J. Heben: High-energy, rechargeable Li-ion battery based on carbon nanotube technology, J. of Power Sources, 138, 277 (2004) and Z. Zhou, J. J. Zhao, X. P. Gao, Z. F. Chen, J. Yan, P. V. Schiever, M. Morinaga: Do composite single-walled nanotubes have enhanced capability for lithium storage?, Chem. Mater., 17, 992 (2005), indeed show a better energy density (approximately 600 Wh/kg) in comparison with graphite, but during a charging process (at potentials of &lt;100 mV vs. Li/Li + ) undergo the deposition of a reactive lithium layer, which is associated with a high safety risk. In contrast, silicon-based nanotubes and nanowires possess storage capacities of approximately 3400 mAhg −1  that are indeed smaller compared with the theoretical values of 4212 mAhg −1  of silicon, but exhibit more stable silicon structures in terms of the volume change of the silicon after the intercalation of the lithium up to a particular Si structure size, as is described in the publication of M. Green, E. Fielder, B. Scrosati, M. Wachtler and J. S. Moreno: Structured silicon anodes for lithium battery applications, Electrochem. Solid-State Lett, 6, A75-A79 (2003). 
     In general, the storage capacity depends on the discharge rate. For example, it follows from the publication: T. Song, J. Xia, J.-H. Lee, D. H. Lee, M.-S. Kwon, J.-M. Choi, J. Wu, S. K. Doo, H. Chang, W. I. Park, D. S. Zang, H. Kim, Y. Huang, K.-C. Hwang, J. A. Rogers and U. Paik: Arrays of sealed Silicon nanotubes as anode for lithium ion batteries, Nano Lett., 10, 1710-1716 (2010) that a reversible storage capacity of approximately 2600 mAhg −1  or 2100 mAhg −1  respectively with a cycling capability of more than 50 cycles has a discharge rate of C/20 or C/5 respectively as well as an improved axial or radial volume change of 35% or 120% respectively after the intercalation of the lithium. 
     Another example is likewise described in the publication of Song, Taeseup; Xia, Jianliang; Lee, Jin-Hyon; Lee, Dong Hyun; Kwon, Moon-Seok; Choi, Jae-Man et al.: Arrays of sealed silicon nanotubes as anode for lithium ion batteries, Nano Lett. 10 (5), S. 1710-1716 (2010), which shows that the densely packed Si-based nanotubes as arrays (30 nm-60 nm) are capable of drastically reducing the power losses of the anode material to less than 20% after 50 cycles at a discharge rate between C/20 and C/5. 
     Whereas the statements about capacity and volume change for the principle of the Si-based anodes differ, a consensus exists that the improvement of the power of the anode material as well as the reduction of the volume change are attributable to two kinds of reasons. 
     On the one hand, the free space between the nanostructures plays a key role in trapping the volume expansion in the material. 
     On the other hand, the shrinkage of the structures contributes to facilitation of the occurring phase changes during the alloy formation, as is described in the publication of A. S. Arico, P. Bruce, B. Scrosati, J.-M. Tarascon, W. Van Schalkwijk: Nanostructured materials for advanced energy conversion and storage devices, Nat. Mater., 4, 366 (2005). 
     Nanoalloys are likewise very topical. The focus of the research efforts is the principle of enlargement of the free space between the nanostructures for absorption of the volume contraction and volume expansion, as is described in the publication of M. Winter, J. O. Besenhard: Electrochemical lithiation of tin and tin-based intermetallics and composites, Electrochim. Acta, 45, 31 (1999). 
     Corresponding experiments show that a cell voltage of 4 V and up to 50 cycles are achieved on a tin nanoalloy that possesses a capacity of 550 mAhg −1 , as is described in the publication of J. Hassoun, S. Panero, B. Scrosati: Electrodeposited Ni—Sn intermetallic electrodes for advanced lithium ion batteries, J. of Power Sources, 160, 1336 (2006). The anode behavior of tin (with a theoretical storage capacity of 993 mAhg −1 ) is very similar to that of silicon in terms of the volume change. Even silicon nanocolumns exhibit an enormous decrease of the volume change with 80% of the total capacity after 100 cycles at a high discharge rate of 8 C, as is described in the publication of P. L. Taberna, S. Mitra, P. Piozot, P. Simon, J. M. Tarascon: High rate capabilities Fe 3 O 4 -based Cu nano-architectured electrodes for lithium-ion battery applications, Nat. Mater., 5, 567 (2006). 
     The publication WO 2015021368 A1 describes an Li-ion battery that consists not only of an intercalation cathode but also of a porous Si anode coated on both sides with aluminum oxide by means of an atomic layer deposition (the English term, ALD). The aluminum oxide layer functions both as a passivation layer at the electrolyte/anode interface and as a contact face of the anode. Here, the volume change of the silicon after the intercalation of the lithium is circumvented by the fact that a protective layer is applied at the electrolyte/anode interface. The disadvantage consists in the fact that the poor electrical conductivity at the interface to the current collector has to be tolerated. 
     The publication WO 2012158608 A1 describes a method for the manufacture of an anode, based on an SiO x /Si layer, for use in a Li ion battery. SiO x /Si microparticles obtained by a laborious mechanical comminution by milling are introduced for the manufacture of the SiO x /Si layer. 
     The publication US 2014/0370386 A1 describes a eutectic alloy of Si and at least one metallic element, e.g. Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr or Nb, which is used for the production of microstructured Si alloys (structures smaller than 4 μm) that permit stable discharging/charging processes and a long useful life. An additional current lead of copper is needed. 
     An important aspect with regard to market penetration is not only safety but also the manufacturing costs. The conventional methods, associated with the prior art, for preparation of the described Si nanostructures are mostly wet-chemical, such as the sol-gel method or the electrolytic deposition among others, and in most cases they need a catalyst. This makes the manufacture of such anode materials cost-intensive. 
     SUMMARY OF THE INVENTION 
     The task underlying the invention is therefore to specify a method for the manufacture of silicon-based anodes for secondary batteries, which is suitably designed in such a way that an improvement is achieved from the economic perspective and from the technical perspective. The capacity should also be increased. Moreover, resources and energy as well as manufacturing time and costs should be considerably reduced. Furthermore, internal stresses within the Si anode material should be absorbed and the anode material should be capable of being scaled in flat manner over several orders of magnitude and of being completely integrated into roll-to-roll technology. 
     The task is accomplished by the features according to the invention. According to the invention, the method for the manufacture of silicon-based anodes for secondary batteries, wherein the secondary batteries consist at least of the anode, of at least one electrolyte, a separator and a counter-electrode, has the following steps:
         depositing a silicon layer on a metal substrate,   heating the metal substrate to a temperature between 200° C. and 1000° C.,   tempering the interface region of the silicon layer turned away from the metal surface by means of an energy-intensive treatment while the metal substrate is being heated,   generating multiple phases in the region of the silicon layer and of the metal substrate, consisting of amorphous silicon and/or crystalline silicon of the silicon of the silicon layer and of crystalline metal of the metal substrate and of silicide.       

     An additional buffer layer or several additional buffer layers in the form of a metallic, oxidic, carbon-containing or polymer-containing layer may be introduced at one silicon-layer interface or at both Si-layer interfaces. 
     The tempering may be performed by means of an arrangement for rapid thermal treatment and annealing. 
     The metal substrate functions as an integrated current lead. 
     Nickel or copper, for example, may be used as the metal of the metal substrate. 
     The energy-intensive treatment and the process for annealing may be performed with an energy-intensive energy source, e.g. at least with a flash lamp that is capable of supplying a flash duration between 0.2 ms and 20 ms and an energy density of 0.6 J/cm 2  and 160 J/cm 2 . 
     The silicon-based anode, which according to the aforesaid method can be manufactured for secondary batteries, 
     comprises at least
         one metal substrate as carrier material and as current lead,   a silicon layer deposited on a metal substrate,   multiple phases of amorphous silicon, crystalline silicon and crystalline metal in the region of the metal substrate and of the Si layer and   crystalline metal of the metal substrate.       

     A buffer layer may be applied at least on the interface of the silicon layer turned away from the metal substrate. 
     A further buffer layer may be situated in the region of the second interface between metal substrate and the silicon layer. 
     An arrangement for rapid thermal treatment and annealing of the anode manufactured according to the method may at least comprise
         at least the high-energy source, e.g. at least one flash lamp, which is directed toward the silicon layer of the anode,   at least one reflector which is associated with the flash lamp, and which is directed toward the silicon layer of the anode and toward the flash lamp,   a heating unit, which is associated with the metal substrate and at least heats the metal substrate to a high temperature, preferably between 200° C. and 1000° C.,
 
wherein, during the heating, the flash-lamp light is directed toward the interface of the silicon layer turned away from the metal substrate for the transmission of short-time high energy.
       

     The tempering of the region of the second interface of the silicon layer turned away from the metal substrate is performed by means of energy-intensive irradiation, wherein the energy-intensive irradiation is realized on at least one partial area of the turned-away second interface. It is also possible, however, that the entire turned-away second interface of the silicon layer is irradiated and tempered over the entire surface in one irradiation process. 
     With the method according to the invention, silicon structures, for example, are generated directly on a metal foil and then tempered by means of a rapid thermal processing (the English term, RTP), e.g. flash lamp annealing (the English term, FLA). The improvement from the economic and technical perspective is achieved by the fact that the new invention permits substantially one Si anode material containing an integrated current lead in one material. RTP represents a rapid thermal processing in a high-temperature process, in which a very rapid heating of the silicon layer of the anode is achieved with halogen lamps. The case of a use of flash lamps is known as FLA. 
     The anode according to the invention, introduced into a process chamber, may be treated/irradiated with several flash lamps, wherein the flash lamps consist of gas discharge lamps, which emit a radiation in the wavelength region between the visible region and infrared region (400 nm-800 nm) and operate with an approximate total power of approximately 12 MW in shorter than 20 ms and are capable of being brought to a temperature of up to 2000° C. 
     The flash lamp annealing is used to favor the metal-induced layer-exchange process, also known as metal-induced crystallization. 
     In general, a crystallization of the silicon can first be brought about at approximately 700° C. After a flash lamp annealing, these Si atoms are free atoms and are able to diffuse even at lower temperatures along the grain boundaries of the metal substrate, since at the interface to a metal the covalent bonding of the Si atoms is weakened. This has already been shown and proved to be energetically favorable in several metal/semiconductor systems (e.g. Au/a-Si and Ag/a-Si), as is described in the publication of Z. M. Wang, J. Y. Wang, L. P. H. Jeurgens, E. J. Mittemeijer: Thermodynamics and mechanism of metal-induced crystallization in immiscible alloy systems: Experiments and calculations on Al/a-Ge and Al/a-Si bilayers, Physical Review B 77, 045424 (2008). Beyond this, a crystallization of the silicon can be achieved by the contacting with a metal at relatively low temperature. Very much simplified, the crystalline growth can begin after a drop below the melting temperature, and this can be used as the criterion for the phase transformation. Thus energy and manufacturing costs can be additionally considerably reduced by virtue of the lower processing temperatures. 
     The invention relates to a method for the manufacture of silicon-based anodes, which in combination with an intercalation cathode, a separator and a liquid/solid electrolyte can be used as anode in a secondary battery containing a mobile species (e.g. lithium, sodium). 
     The manufacture of the anode takes place by depositing, in a first step, an Si layer on a metal substrate containing grain boundaries. 
     An additional thin layer may be applied and further considered as a buffer layer, which may also be a metallic, an oxidic, a carbon-containing or a polymer-containing layer. 
     Then, in a second manufacturing step, a tempering by means of the RTP method, i.e. by means of a rapid thermal processing, e.g. a high-energy irradiation with flash-lamp light, takes place, wherein the lamp arrangement may consist at least of flash lamps and a reflector, wherein heating takes place at least during the tempering of the metal substrate. 
     Beyond this, manufactured multi-phase Si alloys make additional free spaces available for trapping of the volume change during lithiation and ensure the stabilization of the entire material composite. Since the metallic foils (substrates) being used also simultaneously form the faces of the current leads, the size of which is ultimately decisive for the power of the battery cell, the method according to the invention utilizes the great advantages of the Si nanostructures. 
     Whereas only a limited number of lithium ions can be stored by intercalation and deintercalation processes, alloys possess a higher storage capacity. One proof of this is the lithium battery development of the Sony Co. named Nexelion, which uses a composite material of cobalt, tin and graphite alloy and has a constant capacity of several hundred cycles. This means an increase of more than 50% is achieved in comparison with conventional graphite anodes. 
     The innovativeness of the method according to the invention for the manufacture of high-capacity silicon-based anodes for secondary batteries consists in depositing the Si structures directly on a metallic foil and then tempering them. In the process, multi-phase silicon-metal structures are formed, which absorb the volume change due to delithiation and lithiation and ensure the stabilization of the entire material composite. The method has good scalability and a complete integratability into roll-to-roll technology. In this respect, the method for manufacture of Si anodes with an integrated current lead from an electrically conductive material represents a special feature of the invention. This also permits a considerable reduction of the resources and energy used as well as of the manufacturing time and costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be explained in more detail by means of an exemplary embodiment on the basis of drawings, wherein: 
         FIGS. 1A-1B  show a schematic diagram of a metal-silicon anode according to the invention, wherein 
         FIG. 1A  shows the anode and 
         FIG. 1B  shows a treatment step of the energy-intensive irradiation of the anode according to  FIG. 1A  emitted by an energy source in the form of a flash-lamp arrangement and a step of heating of the metal substrate performed simultaneously during the treatment step, 
         FIG. 2  shows a cyclic voltammogram (CV) in the form of current (I)-voltage (V) curves in a half-cell/secondary battery consisting of an Ni/NiSi anode, of an electrolyte provided with a separator and of a counter electrode, 
         FIGS. 3A-3B  show a model description of the growth front after a flash lamp annealing from a longitudinal-section view and a surface overhead view: metal layer (metal foil)-deposited Si layer, wherein 
         FIG. 3A  shows the longitudinal section through the annealed anode with several multiple phases and crystalline metal 
         FIG. 3B  shows the overhead view of the annealed anode with several multiple phases and crystalline metal, 
         FIGS. 4A-4C  show the chemical composition, determined with a measurement, of the Ni—Si phases on the surface of the Ni—Si anode after a flash lamp annealing, wherein 
         FIG. 4A  shows a crystalline metal layer according to  FIG. 3 , characterized with energy-dispersive x-ray spectroscopy, 
         FIG. 4B  shows a crystalline silicon layer according to  FIG. 3 , characterized with energy-dispersive x-ray spectroscopy, 
         FIG. 4C  shows a crystalline combination of the crystalline metal layer and of the crystalline silicon layer according to  FIG. 3 , characterized with energy-dispersive x-ray spectroscopy, and 
         FIGS. 5A-5B  show a schematic longitudinal section through the main battery components of a secondary battery with anode according to the invention, wherein 
         FIG. 5A  schematically illustrates the secondary battery with the components present therein disposed in layers and 
         FIG. 5B  the schematically illustrated layered arrangement of the components: cathode, first electrolyte, separator, second electrolyte, anode with an insulation layer applied on the layered rim and with a metal housing jacket applied on the insulation layer, wherein a load is connected to anode and cathode. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, an exemplary embodiment of the method for the manufacture of a silicon-based anode  20  for secondary batteries by means of flash lamp annealing as a form of a short intensive energy transfer from an arrangement  21  of flash lamps onto the free interface of the anode  20  (second interface  15  of silicon layer  3 ) according to the invention is explained in more detail by joint consideration of  FIG. 1A  and  FIG. 1B  as well as  FIG. 3A  and  FIG. 3B . 
     The method for the manufacture of a silicon-based anode  20  for secondary batteries  30 , wherein the secondary batteries  30  consist at least of the anode  20 , of at least one electrolyte  31   a ,  31   b , a separator  32 , which is situated between the electrolytes  31   a  and  31   b , and a counter-electrode  33  according to  FIGS. 5A-5B , comprises, according to the invention, the following steps:
         depositing a silicon layer  3  on a metal substrate  1  containing grain boundaries  2 , wherein a first interface  14  is present between silicon layer  3  and the metal substrate  1 ,   heating the metal substrate  1  by means of a heating unit  22  to a temperature between 200° C. and 1000° C.,   tempering the region of the second interface  15  of the silicon layer  3  turned away from the metal substrate  1  by means of an energy-intensive irradiation while the metal substrate  1  is being heated,   generating multiple phases  10 ,  11  in the region of the silicon layer  3  and of the metal substrate  1 , consisting of amorphous silicon and/or crystalline silicon of the silicon of the silicon layer  3  and of crystalline metal of the metal substrate  1  and of silicide, and   generating crystalline metal  8  of the metal substrate  1 .       

     An additional buffer layer  4   a ,  4   b  in the form of a metallic, oxidic, carbon-containing or polymer-containing layer may be introduced at the first Si-layer interface  14  to the metal substrate  1  and/or at the second Si-layer interface  15  directed toward the electrolyte  31   b.    
     The tempering is performed by means of an arrangement  21  for rapid thermal treatment and annealing. 
     The metal substrate  1  also functions as an integrated current lead in the anode  20  according to the invention. 
     Nickel or copper is preferably used as the metal of the metal substrate  1 . 
     The energy-intensive irradiation for annealing may be performed at least with a flash lamp  6 , which is constructed as the energy source and which can have a flash duration between 0.2 ms and 20 ms and an energy density of 0.6 J/cm 2  and 160 J/cm 2 . 
     According to the invention, the silicon-based anode  20 , manufactured according to the aforesaid method, may at least comprise
         a metal substrate  1 , functioning as carrier material and as current lead,   a silicon layer  3  applied on the metal substrate  1 , wherein a first interface  14  is formed between the silicon layer  3  and the metal substrate  1 ,   at least one buffer layer  4   a  applied on the second interface  15  of the silicon layer  3  turned away from the metal substrate  1 ,   multiple phases  10 ,  11  of amorphous silicon, crystalline silicon and crystalline metal in the region of the metal substrate  1  and of the Si layer  3  and   crystalline metal  8  of the metal substrate  1 .       

     A further second buffer layer  4   b  may be situated in the region of the first interface  14  between metal substrate  1  and the silicon layer  3 . 
     For this purpose, an Si layer  3  (layer thickness 2.2 μm) according to  FIG. 1A  is deposited by means of CVD on a metal foil (Ni, layer thickness 100 μm) formed as metal substrate  1  and then tempered by means of a flash lamp annealing (with a flash duration between 0.2 ms and 20 ms) according to  FIG. 1B . Before and during the high-energy-intensive treatment of the silicon layer  3 , the metal substrate  1  is heated. 
       FIG. 1B  shows a schematic diagram of an arrangement  21  for rapid thermal treatment and annealing, wherein the arrangement  21  at least comprises
         at least the energy-intensive energy source  6 , which is directed toward the silicon layer  3  of the anode  20 ,   a heating unit  22 , which is associated with the metal substrate  1  and which heats the metal substrate  1  and the silicon layer  3  to a temperature between 200° C. and 1000° C.,
 
wherein, during the heating, the energy source  6  is directed toward the second interface  15  of the silicon layer  3  turned away from the metal substrate  1  for the transmission of short-time high energy.
       

     The energy-intensive energy source  6  in  FIG. 1B  may at least comprise
         at least the flash lamp, which is directed toward the second interface  15  of the silicon layer  3  of the anode  20 , as the energy-intensive energy source  6 , and   at least one reflector  5  associated with the flash lamp  6 , wherein the irradiating light  7  is directed toward the silicon layer  3 ,
 
wherein, during the heating, the irradiating light  7  is directed toward the second interface  15  of the silicon layer  3  turned away from the metal substrate  1  for the transmission of short-time high energy.
       

     An electrochemical characterization by means of cyclic voltammetry (the English term, CV) of a battery button cell from an amorphous nanostructured alloy with Si anode material and with the Ni/NiSi material system versus a liquid electrolyte, e.g. 1 mol LiTFSI in dimethoxyethane/dioxolane mixture (1:1 vol.) and a reference electrode, e.g. a lithium electrode, is shown in  FIG. 2 . 
       FIG. 2  shows a cyclic voltammogram (CV) in the form of current(I)-voltage(V) curves in a half-cell, formed as a secondary battery, from an Ni—NiSi anode, from a liquid electrolyte and the counter electrode at a constant charging/discharging voltage of 20 μv/s. The CV or IV measurement is performed at a constant charging/discharging voltage of 20 μv/s. It is evident that the silicon undergoes a lithiation in the first cycle and is then delithiated again during the charging. In total, ten cycles were performed at the same charging/discharging voltage of 20 μv/s in  FIG. 2 . Delithiation/lithiation is to be understood as deintercalation and intercalation respectively of the lithium ions in the host material, e.g. Si alloy. 
       FIG. 3A  shows a longitudinal section through the anode  20  according to the invention with a model description, derived from the morphological investigation, of the growth front after the flash lamp annealing of an Si layer  3  deposited on the Ni foil  1 . It leads to a diffusion of the Si atoms along the grain boundaries  2  occurring in the metal substrate  1  and to formation of a crystalline c-Si layer  9 . Further multiple phases  10  of a-Si+c-Ni (amorphous silicon and crystalline nickel) or multiple phases  11  of a-Si+c-Si+c-Ni crystalline (amorphous silicon and crystalline silicon and crystalline nickel) are formed in crystalline form.  FIG. 3B  shows an overhead view of the anode  20  manufactured with RTP, wherein not only the multiple phases  10  and multiple phases  11  but also ions I +  of the mobile species  12  and free electrons  13  e −  are present. 
       FIGS. 4A-4C  show, relative to  FIG. 3B , a model description, likewise obtained from the morphological investigations, of the generated structures on the Ni—NiSi surface after the flash lamp annealing and their chemical compositions by means of a method of energy-dispersive x-ray spectroscopy. The resulting Ni phases and Si phases of the structures described in  FIGS. 3A and 3B  are clearly indicated from the energy-dispersive x-ray spectroscopy. 
       FIG. 4A  shows the x-ray spectroscopic result of the crystalline nickel surface of the nickel layer  8  with nickel signal amplitudes  16  and  17 , 
       FIG. 4B  shows the x-ray spectroscopic result of the crystalline surface of the multiple phase  11  with silicon signal amplitudes  18 , and 
       FIG. 4C  shows the x-ray spectroscopic result of the crystalline surface of the multiple phase  10  with nickel signal amplitudes  16  and  17  and silicon signal amplitude  18 . 
       FIGS. 5A-5B  show a schematic diagram of a secondary battery  30 , consisting at least of the components
         a cathode  33 ,   a first electrolyte  31   b,      a separator  32 ,   a second electrolyte  31   a,      the anode  20  according to the invention,
 
wherein the anode  20  according to the invention is arranged after the second electrolyte  31   a , and
 
wherein the components  33 ,  31   b ,  32 ,  31   a ,  20  are combined in layered manner in the said order within the secondary battery  30 , as shown in  FIG. 5A  and in  FIG. 5B .
       

     In  FIG. 5A , the secondary battery  30  is illustrated together with the components  33 ,  31   b ,  32 ,  31   a ,  20  present therein disposed in layers. 
     In  FIG. 5B , the schematically illustrated layered arrangement of the components possesses: cathode  33 , first electrolyte  31   b , separator  32 , second electrolyte  31   a , anode  20  on the layered rim with an insulation layer  34  applied thereon and a metal housing jacket  35  applied on the insulation layer  34 . The anode  20  and the cathode  33  are respectively connected with load-current lines  36 , to which the at least one load  37  is connected. 
     The following advantages exist: 
     The Si layers  3 , on which the method according to the invention is based, are chemically stable, inexpensive as well as less time and energy consuming than the Si layers described in the publication WO 2012158608 A1. 
     The buffer layer  4   a , which is associated with the Si layer  3  and on which the Si layer  3  is deposited and which is disposed opposite the metal foil  1 , is not present on the current-lead side and therefore cannot impair the electrical conductivity, which determines the power of the anode  20 . 
     The Si layer  3 , on which the method according to the invention is based, is deposited directly on the metal substrate  1 . This process makes use of a metal-induced layer exchange process, due to the rapid thermal treatment according to  FIG. 1B , between the metal layer  1  and the silicon layer  3 . The metallic substrate  1  is considered to be an integrated current lead, in contrast to the current lead for the anode in the publication US 2014/0370386 A1. 
     By roll-to-roll technology, the following is understood: 
     By means of a roll-to-roll technology, both the deposition of the silicon layer  3  on the metal substrate  1  and the deposition of the buffer layers  4   a  and/or  4   b  as well as the thermal treatment and annealing can be performed on a metal substrate  1 , which is situated on a roll, unrolled, coated, heated and processed as well as finally rolled up once again. The needed anode  20  is then taken from the roll. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  Metal substrate 
           2  Grain boundary 
           3  Si layer 
           4   a  First metallic/oxidic/carbon-containing/polymer-containing buffer layer 
           4   b  Second metallic/oxidic/carbon-containing/polymer-containing buffer layer 
           5  Reflector 
           6  Energy-intensive energy source 
           7  Irradiating light 
           8  Crystalline metal layer (c-Me) 
           9  Crystalline Si layer (c-Si) 
           10  Multi-phase layer of c-Me, c-Si 
           11  Multi-phase layer of c-Me, c-Si and amorphous Si (a-Si) 
           12  Ion of the mobile species, e.g. Li +   
           13  Free electrons 
           14  First interface 
           15  Second interface 
           16  First nickel signal amplitude 
           17  Second nickel signal amplitude 
           18  Silicon signal amplitude 
           20  Anode according to the invention 
           21  Arrangement for energy-intensive treatment/lamp arrangement 
           22  Heating unit 
           30  Secondary battery of the anode according to the invention, two electrolytes, a separator situated between the two electrolytes and a cathode 
           31   a  Second electrolyte 
           31   b  First electrolyte 
           32  Separator 
           33  Cathode 
           34  Insulation layer 
           35  Metal housing jacket 
           36  Load current lines 
           37  Load