Patent Publication Number: US-2021167448-A1

Title: Secondary battery cell and solid-state storage having an actuator

Description:
BACKGROUND 
     One of the most promising future battery technologies is the lithium-air (or lithium-oxygen) battery, which theoretically could provide 100 times as much power for a given weight compared to the currently leading technology, lithium-ion batteries. This could have a significant impact on battery-powered vehicles, which nowadays rely on lithium-ion batteries. 
     When a lithium-air battery discharges, lithium ions are formed at the anode which then move through the electrolyte toward the anode. The cathode is typically made of a porous carbon sponge material. At the interface between the carbon cathode and the electrolyte, electrochemical oxygen reduction occurs so that oxygen molecules receive electrons from the carbon material and then undergo chemical reactions with the lithium ions. 
     However, it has been shown that lithium-air batteries generally suffer degradation mechanisms that limit their life-cycle. Specifically, for present state of the art batteries it is impossible to recharge them more than a few times. For lithium-air batteries having an aprotic electrolyte, this resides, inter alia, in the fact that the carbon positive electrode becomes degraded. The degradation mechanism is commonly attributed to discharge products, in particular LiO 2  and Li 2 O 2 . These discharge products are insoluble in aprotic electrolytes and thereby clog the pores of the carbon cathode which prevents new oxygen molecules from being reduced. Although in Lithium-air batteries which have an aqueous electrolyte, the issue of cathode clogging is avoided, these batteries suffer from the drawback that the lithium metal reacts violently with water. Therefore, the aqueous design requires a solid electrolyte interface between the lithium and electrolyte 
     It has further been shown that also porous membranes as well as porous electrolytes of solid-state batteries get clogged during operation of the battery, thereby leading to reduced life-cycles and increased maintenance costs. Moreover, similar problems occur in reversible solid-state storage systems. 
     Therefore, a need exists for providing an improved solid-state storage or an improved electrochemical cell, in particular an improved metal-air electrochemical cell, having an increased life-cycle and/or reduced maintenance costs. 
     SUMMARY 
     Embodiments provide an apparatus configured as an electrochemical battery cell. The apparatus includes an anode, a cathode, and an electrolyte which is configured to allow ions to travel between the anode and the cathode. The apparatus further comprises an actuator. The actuator is configured to adjust a parameter of an electrochemical reaction in which the actuator and/or an actuated portion of the battery cell is chemically involved. Additionally or alternatively, the actuator and/or the actuated portion is a permeable portion of the battery cell which is configured to allow the ions to permeate into the permeable portion, wherein the actuator is configured to adjust an ion permeability of the permeable portion to the ions. The actuated portion of the battery cell is in operative interaction with the actuator. 
     The electrochemical battery cell may be configured as an aqueous, aprotic, solid state or mixed aqueous/aprotic battery cell. The electrochemical battery cell may be rechargeable. For charging and/or discharging the electrochemical battery, the ions travel between the cathode and the anode. The ions may include cations and/or anions of one or more species. The electrochemical cell may be a metal-air electrochemical cell. Examples for metal-air electrochemical cells are lithium (Li)-air, sodium (Na)-air, potassium (K)-air, zinc (Zn)-air, magnesium (Mg)-air, and aluminum (Al)-air electrochemical cells. The actuator may be at least a portion of the anode, the cathode, the ion transport medium and/or the battery cell portion. The ion transport medium may be an electrolyte. The electrochemical reaction may be a reaction during the charging and/or the discharging cycle of the battery cell. The parameter of the electrochemical reaction may be a reaction rate of the electrochemical reaction. 
     According to an embodiment, the actuator is configured to desorb one or more adsorbed species. The adsorbed species may be adsorbed on the actuator and/or on the actuated portion. The parameter of the electrochemical reaction may be adjusted by causing the adsorbed species to desorb. 
     According to a further embodiment, the cathode, the anode, the ion transport medium and/or a separator membrane which is disposed in a flow path of the ions between the anode and the cathode comprise at least a portion of the actuated portion and/or the actuator. The anode may be a metal anode, in particular a lithium anode. The separator membrane may be an ion exchange membrane for the ions. At least one side of the separator membrane may be in contact with the electrolyte. Alternatively, the separator membrane may be configured to separate the anode or the cathode from the electrolyte. 
     According to an embodiment, the permeable portion comprises a porous material. The ion permeability of the permeable portion may be at least partially provided by pores of the porous material. The porous material may be, for example, porous carbon. The porosity of the cathode may store solid products generated from the reaction of the metal ions of the anode with  0   2 , such as metal superoxide or metal peroxide during the discharges cycle of the battery. Examples of such species are Li 2 O and an Li 2 O 2 . 
     According to an embodiment, the permeable portion is at least a portion of the cathode which is configured as a gas diffusion cathode, in particular as an air diffusion cathode. The gas diffusion cathode may include a substrate, such as carbon, in particular porous carbon. 
     According to a further embodiment, the ion permeable portion comprises a plurality of channels. A permeability of the channels determine the permeability of the permeable portion. 
     According to an embodiment, the actuator is configured to adjust the ion permeability by physically modifying at least a portion of the channels. 
     According to a further embodiment, the actuator is configured to interact with one or more adsorbed and/or entrapped species within the channels for adjusting a chemical reaction activity within the channels. By way of example, the actuator may be configured to generate an electric and/or magnetic field and/or to generate an electric current for performing the interaction with the one or more adsorbed and/or entrapped species. Additionally or alternatively, the actuator may be configured to couple acoustic energy into the permeable portion and/or to exert a mechanic, hydrodynamic and/or aerodynamic force for performing the interaction with the one or more adsorbed and/or entrapped species. 
     According to a further embodiment, the actuator and/or the actuated portion is at least a portion of the anode. The actuator may configured to desorb adsorbates from the anode and/or to prevent or reduce corrosion of the anode. By way of example, the anode is a lithium (Li) anode. The adsorbates may be physisorbed and/or chemisorbed. 
     According to a further embodiment, the apparatus further comprises a controller and a sensor system. The sensor system may be configured to measure an operational parameter of the battery cell. The actuator may be controlled by the controller depending on sensor output of the sensor system. The actuator may be controlled during charging and/or discharging cycles of the electrochemical battery cell. 
     According to an embodiment, the sensor is configured for measurement of a density of a species of charge carriers and/or a combined density of a plurality of species of charge carriers. Additionally or alternatively, the sensor may be configured for measurement of a flux density of a species of charge carriers and/or a combined density of a plurality of charge carriers. 
     According to a further embodiment, sensor system is configured for measurement of a charge density and/or a charge flux density within the electrolyte. 
     According to a further embodiment, the sensor system includes a resistive sensor, a capacitive sensor and/or a potentiometric sensor. The potentiometric sensor may include a surface which includes lead (Pb), zinc (Zn) and/or vanadium (V). 
     According to a further embodiment, the sensor is configured to measure one or a combination of a current of the battery cell, a voltage of the battery cell, a temperature, an internal resistance and/or a battery capacity of the battery cell. 
     According to a further embodiment, the actuator is configured to generate an electric field, a magnetic field and/or an electric current which adjust the parameter of the electrochemical reaction and/or the permeability. The actuator may include one or more electrodes and/or coils for generating the electric field, magnetic field and/or the electric current. The electric field, magnetic field and/or electric current may be configured to interact with adsorbates, in particular with adsorbates in channels or pores of the permeable portion. The interaction of the electric field, the magnetic field and/or electric current with the adsorbates may be configured so that the interaction causes the adsorbates to desorb. 
     According to a further embodiment, the electric and/or magnetic field is a constant, or time-varying electric and/or magnetic field. The time-varying electric and/or magnetic field may be a pulsed or oscillatory electric and/or magnetic field. At least a portion of the electric and/or magnetic field may pass through the actuated portion, in particular through the permeable portion. According to a further embodiment, the electric current is a constant or time-varying electric current. The time-varying electric current may be a pulsed or oscillating electric current. At least a portion of the electric current may pass through the actuated portion, in particular through the permeable portion. 
     According to a further embodiment, the actuator comprises one or more mechanical transducers for coupling acoustic energy into the actuated portion of the battery cell, such as the permeable portion. The mechanical transducer may be an electromechanical transducer. The electromagnetic transducer may include a piezo-active material. 
     According to a further embodiment, the actuator is configured to exert a mechanic, hydrodynamic and/or aerodynamic force on the actuated portion, in particular on the permeable portion. By way of example, the actuator includes one or more inlets for introducing gas or liquid into the battery cell, in particular into the cathode, the anode, the ion transport medium and/or the separator membrane which is disposed in at flow path of the ions between the cathode and the anode. 
     According to the embodiment, the permeable portion has micro-sized pores, meso-sized pores and/or macro-sized pores. Micro-sized pores may be defined as pores having a diameter of less than 2 nanometers. Meso-sized pores may be defined as pores having a diameter in the range of between 2 and 50 nanometers. Macro-sized pores may be defined as pores having a diameter of more than 50 nanometers. The micro-sized pores may have a diameter greater than 0.5 nanometer or greater than 1 nanometer. The macro-sized pores may have a diameter of less than 10 micrometers or less than 1 micrometer or less than 500 nanometers. 
     Embodiments provide an apparatus configured as a solid-state storage for a chemical species to be stored. The solid-state storage comprises a permeable portion which is configured to allow at least one storable chemical species to permeate into the permeable portion for storing or retrieving the storable chemical species in the solid-state storage. The solid-state storage further comprises an actuator which is in operative interaction with the permeable portion for adjusting an ion permeability of the permeable portion to the ions. 
     The solid-state storage may be a reversible stolid-state storage. The permeable portion may be at least a portion of a storage medium in which the storable chemical species is stored. The chemical species to be stored may be, for example, hydrogen. The chemical species to be stored may be in a gaseous, liquid or vapor state. 
     According to a further embodiment, the permeable portion includes porous material. A permeability of the permeable portion to the chemical species to be stored may be at least partially provided by pores of the porous material. 
     According to a further embodiment, the permeable portion comprises a plurality of channels. A permeability of the channels may at least partially determine the permeability of the permeable portion to the chemical species to be stored. 
     According to a further embodiment, the actuator is configured to adjust the permeability by physically modifying at least a portion of the channels for performing the adjustment of the permeability of the permeable portion to the chemical species to be stored. 
     According to a further embodiment, the actuator is configured to interact with one or more adsorbed and/or entrapped species within the channels for adjusting a permeability of the permeable portion to the chemical species to be stored. 
     According to a further embodiment, the apparatus further comprises a controller and a sensor system. The sensor system may be configured to measure an operational parameter of the solid-state storage. The actuator may be controlled by the controller depending on sensor output of the sensor system. 
     According to an embodiment, the sensor is configured for measurement of a density or a flux density of the species to be stored. 
     According to a further embodiment, the actuator is configured to generate an electric and/or magnetic field. The electric and/or magnetic field may penetrate into the permeable portion. 
     According to an embodiment, the actuator comprises one or more mechanical transducers for coupling acoustic energy into the permeable portion. 
     According to an embodiment, the actuator is configured to exert a mechanic, hydrodynamic and/or aerodynamic force on the permeable portion. 
     Embodiments of the present disclosure provide an electrochemical battery cell including an anode, a cathode and an electrolyte configured to allow ions to travel between the anode and the cathode. The electrochemical battery cell further includes an actuator which is in operative interaction with the electrolyte and configured to adjust a density distribution for each of one or more species contained in the electrolyte. 
     According to an embodiment, the actuator is configured to adjust the density distribution using an electric field, magnetic field and/or current. The electric field, magnetic field and/or current may be constant or time-varying. The time-varying electric field, magnetic field and/or current may be pulsed or oscillatory. 
     According to a further embodiment, the actuator is configured to adjust the density distribution using mechanical transducers which are configured to couple acoustic energy into the electrolyte. 
     According to a further embodiment, the actuator is configured to adjust the density distribution using a mechanic, hydrodynamic and/or aerodynamic force which is exerted on the electrolyte using the actuator. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The detailed description of some exemplary embodiments is made below with reference to the accompanying figures, wherein like numerals represent corresponding parts of the figures. 
         FIG. 1A  shows a schematic view of a battery cell according to a first exemplary embodiment; 
         FIGS. 1B  shows alternative configurations for the sensor electrodes in the battery cell of the first exemplary embodiment which is illustrated in  FIG. 1 ; 
         FIGS. 1C to 1F  show alternative configurations for the actuator and the sensor electrode arrangement in the first exemplary embodiment shown in  FIG. 1 ; 
         FIG. 1G to 1K  show further alternative configurations for the actuator in the first exemplary embodiment shown in  FIG. 1 ; 
         FIG. 2A  is a schematic view of a battery cell according to a second exemplary embodiment; 
         FIG. 2B  is a schematic view of a battery cell according to a third exemplary embodiment; 
         FIG. 2C  is a schematic view of a battery cell according to a fourth exemplary embodiment; 
         FIG. 3A  is a schematic view of the actuator interacting with the permeable portion in the battery cell according to the first to fourth exemplary embodiments, shown in  FIGS. 1 to 2   c ; 
         FIG. 3B  is a schematic view of an actuator of a battery cell according to a fifth exemplary embodiment; 
         FIG. 3C  is a schematic view of an actuator of a battery cell according to a sixth exemplary embodiment; 
         FIG. 3D  is a schematic view of an actuator of a battery cell according to a seventh exemplary embodiment; 
         FIG. 4A  is a schematic view of a battery cell according to a eighth exemplary embodiment; 
         FIG. 4B  is a schematic view of a battery cell according to a ninth exemplary embodiment; 
         FIGS. 4C  shows an exemplary configurations of an inlet member of the actuator in the battery cell according to the ninth exemplary embodiment, as shown in  FIG. 4B ; 
         FIG. 4D  shows a further exemplary configurations of an inlet member of the actuator in the battery cell according to the ninth exemplary embodiment, as shown in  FIG. 4B ; 
         FIG. 5A  is a schematic view of a battery cell according to a tenth exemplary embodiment; 
         FIG. 5B  shows an exemplary configuration of a transduction member of the actuator in the battery cell according to the tenth exemplary embodiment, as shown in  FIG. 5A ; 
         FIG. 6A  is a schematic illustration of a reversible solid-state storage according to an exemplary embodiment; and 
         FIG. 6B  is a further schematic illustration of the reversible solid-state storage according to the alternative exemplary embodiment. 
     
    
    
     Detailed description of exemplary embodiments 
       FIG. 1A  shows an electrochemical battery cell  1  according to a first exemplary embodiment. The electrochemical battery cell  1  is configured as a lithium (Li)-air battery cell. However, it is noted that it is also possible to obtain the technical effects and advantages described herein in connection with the embodiment of  FIG. 1A  in other battery systems, in particular in other metal-air battery sells, such as sodium (Na)-air, potassium (K)-air, zinc (Zn)-air, magnesium (Mg)-air, and aluminum (Al)-air electrochemical cells or in fuel cells. 
     The electrochemical battery cell  1  includes an anode  2 , a cathode  3  and an electrolyte  4 . During the discharging cycle of the electrochemical battery cell  1 , lithium ions travel from the anode  2  through the electrolyte  4  toward the cathode  3  and during the charging cycle, lithium ions travel from the cathode  3  through the electrolyte  4  toward the anode  2 . 
     In the exemplary embodiment, which is shown in  FIG. 1 , the cathode  3  is a gas diffusion cathode which is configured so as to allow air to diffuse into its interior. Thereby, during the battery&#39;s discharging cycle, oxygen reacts inside the gas diffusion cathode with lithium ions provided by the anode. Hence, the cathode  3  represents a permeable portion of the electrochemical battery cell  1  which is configured to allow the lithium ions and the oxygen to permeate into its interior. 
     The cathode  3  may include a catalyst. The catalyst may be provided no a reactive surface of the cathode, in particular within the pores of a porous cathode substrate. By way of example, the catalyst may include one or a combination of Pt, MnO 2 , and Au. Additionally or alternatively, the carbon substrate may be passivated by a passivation coating. The passivation coating may include Al 2 O 3  and/or FeO x . 
     For conventional aprotic metal-air electrochemical cells which rely on gas diffusion cathodes, it has been shown that the reactions inside the cathode lead to a degradation mechanism that limits the life cycle of the electrochemical battery cell  1 . This resides, inter-alia, in the fact that discharge products which are generated during the battery&#39;s discharge cycle such as LiO 2  and Li 2 O 2  clump inside the pores of the carbon electrode, thereby, obstructing the oxygen-diffusion pathways. 
     However, it has further been shown, that it is possible to improve the battery cell&#39;s life cycle by providing at least one actuator which is in operative interaction with the cathode and/or the adsorbates which clump together inside the pores of the cathode. The operative interaction is configured so as to cause the discharge products which are adsorbed inside the pores to desorb from the cathode. This increases the reaction rate of the electrochemical reaction between the lithium ions and oxygen. 
     Accordingly, in the exemplary embodiment of  FIG. 1A , two actuators  5  and  14  are provided so that the cathode  8  is disposed between the actuators  5  and  14 . The operative interaction of the actuators  5  and  14  with the cathode allows adjustment of the permeability of the permeable cathode  3  to the lithium ions and to the oxygen. The exemplary embodiment of  FIG. 1  is provided with two actuators  5  and  14 . However, it is also conceivable that the battery cell  1  only has a single actuator or has more than two actuators. 
     Each of the actuators  5  and  14  includes one or more electrodes for generating an electric field which penetrates into the pores of the cathode  3 . The electric field may be a continuous or time-varying electric field. The time-varying electric field may be a pulsed or an oscillating electric field. Exemplary configurations for the actuators  5  and  14  will be discussed further below. 
     The operation of the actuators  5  and  14  is controlled by a controller  7 , which is in signal communication with a sensor system  6 . The controller  7  is configured to control the actuators  5  and  6  depending on a sensor output generated by the sensor system  6 . It has been shown that this allows efficient interaction of the actuators  5 ,  14  with the cathode  3 . However, it is also conceivable that the battery cell&#39;s life cycle can be increased by using one or more actuators without relying on a sensor system and a controller. 
     In the exemplary embodiment of  FIG. 1 , the sensor system  6  is configured to measure a charge density within the electrolyte  4  using an electrode arrangement. As is illustrated in  FIG. 1A , the electrode arrangement includes a plurality of longitudinal electrodes  8 , each of which extending inclined relative to a flow direction of the lithium ions within the electrolyte  4 . Each of the electrodes  8  is connected at a first longitudinal end thereof to a first connecting portion of the electrode arrangement and at a second longitudinal end thereof to a second connecting portion of the electrode arrangement. Thereby, the electrode arrangement has two ends  29  and  30  which are connected by the electrodes  8 . Both ends  29  and  30  of the electrode arrangement are connected to a voltage source  9  of the battery cell  1 . The controller  7  is configured to measure a resistance and/or a change of the resistance between the ends  29  and  30 . 
     It has been shown that the resistance measured between the ends  29  and  30  of the electrode arrangement depends on the charge density of the electrolyte which is present between the longitudinal electrodes  8 . An increase in the measured resistance indicates a decrease in charge density, which, in turn, may indicate a clogged cathode. Upon detecting a high resistance and/or an increase in the resistance, the controller controls the actuators  5  and  14  to increase a level of interaction of the actuators  5  and  14  with the cathode  3  and/or the adsorbates within the cathode  3  to cause at least a portion of the adsorbates to desorb from within the cathode  3 . 
     Using the actuators  5  and  14  in conjunction with the battery cell  1  has several further technical advantages. Using the controllers  5  and  14 , it is possible to control the movement of the charge carriers in the electrolyte. Furthermore, the actuators  5  and  14  can be used to stop the battery&#39;s charging and/or discharging cycle. Thereby, it is possible to provide short circuit protection for the battery cell. Furthermore, it is possible to increase the battery&#39;s power for a short period of time. Thereby, it is possible to use batteries of smaller dimensions can be used which are lighter in weight. Moreover, using the actuators  5  and  6 , it is possible to provide a fast shutdown for the battery, which allows protection if the battery is under high load for a long period of time. Thereby, the battery is protected against overload and fire. 
       FIG. 1B  shows an alternative configuration for the electrode arrangement of the sensor system  6 . In the configuration of  FIG. 1B , the electrode arrangement is configured as a comb capacitor which includes a pair of comb electrodes  10  and  11 . The comb electrodes  10  and  11  are arranged so that their teeth are inter-meshed but not touching. Each longitudinal end of the comb electrodes  10  and  11  include transverse portions  12  and  13  which are oriented substantially perpendicular to a longitudinal axis of the respective tooth so that the transverse portions  12  and  13  of opposite longitudinal ends extend substantially parallel relative to each other. The transverse portions  12  and  13  may be configured as plates or as bars. It has been shown that the transverse portions  12  and  13  increase the sensitivity of the comb capacitor. 
     It has been shown that also for this configuration, a resistance measured between the comb electrodes  10  and  11  depends on the charge density of the electrolyte which is present between the comb electrodes  10  and  11 . 
     Both sensor systems which are described in connection with  FIGS. 1A and 1B  represent resistive sensors. Additionally or alternatively the sensor system may include one or more capacitive sensors and/or one or more potentiometric sensors. The potentiometric sensor may include a surface made of lead (Pb), zinc (Zn) and/or vanadium (V). The potentiometric sensor may include a working electrode, the potential of which depends on a concentration of a species to be measured, such as the concentration of the lithium ions. 
       FIGS. 1C to 1K  show various alternative configurations for the actuators  5  and  14 . It is to be noted that it is also conceivable that the configurations shown in  FIGS. 1A and 1B  for the electrode arrangement of the sensor system  6  can be used for the actuators  5  and  14 . It is further noted that the configurations for the actuator shown in  FIGS. 1C to 1F  also represent alternative configurations for the electrode arrangement of the sensor system  6 . Moreover, the actuators  5  and  14  may have configurations which are different from each other. Specifically, the actuator  5  may be configured to be partially transmissive for ions which pass from the anode  2  to the cathode  3 . This may be achieved by providing the actuator  5  with one or more openings. In contrast thereto, the actuator  14  may be configured as a solid plate or may be configured to be transmissive for air. 
     Additionally or alternatively, is also conceivable that one or more actuators are implemented in the cathode  3 , such as by coating the cathode, by doping the cathode and/or by forming the cathode by means of joining different materials or components. 
     The actuator which is shown in  FIG. 1C  has a plurality of holes  15 . The actuator includes one or more meshes  16  which span each of the holes.  FIG. 1D  shows an actuator which is configured as a mesh. The actuators shown in  FIGS. 1E and 1F  include a plurality of electrodes which are configured as stripes. As is illustrated by  FIGS. 1E and 1F , different orientations of individual portions of the actuator relative to the permeable portion may be chosen. The orientations may be chosen depending on the geometry of the permeable portion. By way of example, the orientation of the actuator portions may be adapted to a geometry or shape of the permeable portion. 
       FIG. 1G  shows an actuator which includes a plurality of coils  20  each of which being configured to generate a magnetic field within the pores of the permeable portion. The actuator which is shown in  FIG. 1H  includes a plurality of coils  22 , each of which spanning a circular hole  21  provided in the actuator. The actuators which are illustrated in  FIGS. 1J and 1K  include a plurality of permanent magnets  23 , which are arranged on a mounting structure. The mounting structure may include, for example, a plurality of parallel bars  24 , as shown in  FIG. 1J , and/or a grid  25 , as shown in  FIG. 1K . It is conceivable that the mounting structure is configured as an electrode arrangement for generating an electric field. 
       FIGS. 2A to 2C  illustrate electrochemical battery cells according to a second to fourth exemplary embodiment. Components, which correspond to components of the battery cell which is shown in  FIG. 1  with regard to their composition, their structure and/or function, are designated with the same reference numerals followed by a letter “a” “b” and “c”, respectively. 
     Each of the electrochemical battery cells  1   a ,  1   b  and  1   c  as shown in  FIGS. 2A to 2C , is a lithium (Li)-air battery cell. However, it is noted that it is also possible to obtain the technical effects and advantages described in connection with these embodiments in other battery systems, in particular in other metal-air battery cells, such as sodium (Na)-air, potassium (K)-air, zinc (Zn)-air, magnesium (Mg)-air, and aluminum (Al)-air electrochemical cells or in fuel cells. 
     The battery cell  1   a  which is shown in  FIG. 2A  includes a separator membrane  13   a , which is disposed in an ion flow path between the anode  2   a  and the cathode  3   a . The separator membrane  13   a  is permeable to the lithium ions, thereby forming a permeable portion. In order to prevent clogging of the ion channels within the membrane  13   a , two actuators  5   a  and  14   a  are provided, each of which being in operative interaction with the membrane  13   a  for adjusting an ion permeability of the membrane  13   a  to the ions. For the actuators  5   a  and  14   a , each of the configurations described herein in conjunction with the remaining embodiments, is conceivable. 
     Additionally or alternatively, is also conceivable that one or more actuators are implemented in the membrane  13   a , such as by coating the membrane  13   a , by doping the membrane  13   a  and/or by forming the membrane  13   a  by means of joining different materials or components. 
     The operative interaction of the actuators  5   a  and  14   a  with the membrane  13   a , allows extension of the battery&#39;s life-cycle. Although the battery cell  1   a  of  FIG. 2  includes two actuators  5   s  and  14   a , it is conceivable that the battery cell  1   a  includes one or more than two actuators. 
     In the battery cell  1   b  which is illustrated in  FIG. 2B , the actuators  5   b  and  14   b  are in operative interaction with the electrolyte and configured to adjust a density distribution for each of one or more species contained in the electrolyte. 
     The operative interaction of the actuators  5   b  and  14   b  with the electrolyte allows improvement of the homogeneity of the mixture of electrolyte, oxygen and reactive oxygen. It has been shown that thereby, the battery&#39;s life cycle can be increased. Moreover, it has been shown that there are synergistic effects between the carbon electrode and degradation mechanisms within the electrolyte. This can be prevented using the operative interaction of the actuator with the electrolyte. 
     In the battery cell  1   c  which is illustrated in  FIG. 2C , the actuators  5   c  and  14   c  are in operative interaction with the anode  2   c . It has been shown that this allows prevention of corrosion at the anode  2   c  which occurs when the anode  2   c  reacts with the electrolyte. This problem is particularly severe when lithium is used as anode material due to the highly reducing nature of lithium which leads to the decomposition of most known electrolytes. This leads to insoluble byproducts which further direct contact between the anode and the electrolyte. 
     Specifically, the operative interaction of the actuators  5   c  and  14   c  with the anode  2   c  and/or adsorbates on the anode  2   c  cause the adsorbates to be desorbed from the anode  2   c . Thereby, a corrosive layer may be removed from the anode  2   c . Additionally or alternatively, it has been shown that using the actuators  5   c  and  14   c , it is possible to suppress parasitic chemical reactions between lithium and other components of the battery cell, including O 2 , the electrolyte, and the products of the O 2  reduction and electrolyte decomposition. This allows prevention of corrosion of the anode. 
     Moreover, it has been shown that using one or more actuators in operative interaction with the anode  2   c , it is possible to suppress compositional and morphological changes in the solid-electrolyte interface (SEI) between the anode and the electrolyte. Such changes may lead to oxygen invasion to the anode and hence may lead to a decreased performance during charging and discharging cycles. 
     Additionally or alternatively, is also conceivable that one or more actuators are implemented in the anode  2   c , such as by coating the anode  2   c , by doping the anode  2   c  and/or by forming the anode  2   c  by means of joining different materials or components. 
       FIGS. 3A to 3D  schematically illustrate the actuators of different exemplary embodiments. Each of the actuators may, for example, be implemented in a lithium (Li)-air battery cell. However, it is noted that it is also possible to obtain the technical effects and advantages described in connection with these embodiments in other battery systems, in particular in other metal-air battery cells, such as sodium (Na)-air, potassium (K)-air, zinc (Zn)-air, magnesium (Mg)-air, and aluminum (Al)-air electrochemical cells or in fuel cells. 
     In the exemplary embodiment which shown in  FIG. 3A , the actuator is configured to generate an electric field within the actuated portion  15  as has been described in conjunction with the configurations of the first to fourth exemplary embodiments which are illustrated in  FIGS. 1 and 2 . The actuated portion  15  may be, for example, a membrane, a cathode, an anode and/or an electrolyte. The actuated portion  15  may be the permeable portion. The permeable portion may be permeable to the ions. 
     The electric field may be a static electric field or a time-varying electric field. The time-varying electric field may be a pulsed electric field or an oscillatory electric field. In the embodiment which is illustrated in  FIG. 3A , the electric field is generated using a first electrode and a second electrode. In the first to fourth exemplary embodiments, the first electrode was designated with reference numbers  5 ,  5   a ,  5   b  and  5   c  and the second electrode was designated with reference numbers  14 ,  14   a ,  14   b  and  14   c . However, it is also conceivable, that only one of the two electrodes or more than two electrodes are used for generating the electric field within the permeable portion  15 . 
     In the fifth exemplary embodiment, which is shown in  FIG. 3B , the actuators  5   d  and  14   d  are also configured as electrodes, wherein the actuator, is adapted so that an electric current passes through the actuated portion  15 . Using the electric current, the iron permeability of the actuated portion  15  to the ions is adjusted.  FIG. 3B  shows two electrodes  5   d ,  14   d . However, it is also conceivable, that only one of the two electrodes or more than two electrodes are used for passing the current through the actuated portion  15 . For the actuators  5   d  and  14   d , the same configurations can be used as has been disclosed in conjunction with the first to fourth exemplary embodiment. 
     In the sixth exemplary embodiment, which is shown in  FIG. 3C , the actuators  5   e  and  14   e  are configured to vary a pressure within the actuated portion  15 . By way of example, the pressure may be varied by varying the pressure of a liquid electrolyte in which the actuated portion  15  is disposed. The adapted pressure may be continuous or time-varying. The time-varying pressure may be a pulsed pressure variation or an oscillatory pressure variation. It is conceivable that only one or more than two actuators are provided for varying the pressure within the actuated portion  15 . 
     In the seventh exemplary embodiment, which is shown in  FIG. 3D , the actuator  5   f  is configured to generate a magnetic field within the permeable portion  15 . The magnetic field may be a constant, and/or a time-varying magnetic field. The time-varying magnetic field may be a pulsed magnetic field and/or an oscillatory magnetic field. The magnetic field may be generated using one or more coils and/or or one or more permanent magnets. 
       FIG. 4A  shows an electrochemical battery cell  1   g , according to a eighth exemplary embodiment. Components, which correspond to components of the battery cell, shown in any one of the remaining embodiments with regard to their composition, their structure and/or function are designated with the same reference number, followed by a suffix letter “g”. 
     The eighth exemplary embodiment is an implementation of the schematic embodiment discussed above with reference to  FIG. 3B . In the eighth exemplary embodiment, the actuator includes hydraulic actuators  19   g ,  20   g , each of which being connected to a hydraulic pump  23   g  for generating opposed compressional forces F 1  and F 2  which are directed from opposite sides toward the actuated portion represented by the porous cathode  3   g . Thereby, the pressure within the actuated portion is increased. The forces F 1  and F 2  are transmitted using force transmission plates  17   g  and  18   g , between which the cathode  3   g  is located. It is conceivable that the force transmission plates  17   g  and  18   g  are also configured as electrodes which are used for generating an electric field within the actuated portion or a current, which passes through the actuated portion. 
       FIG. 4B  shows a battery cell  1   h  according to a ninth exemplary embodiment. Components, which correspond to components of the battery cell of any one of the remaining embodiments with regard to their composition, their structure and/or their function, are designated with the same reference number, followed by a suffix letter “h”. 
     In the ninth exemplary embodiment, the actuator are configured to exert a hydrodynamic force to the actuated portion which is represented by the porous cathode  3   h . The actuator includes two inlet members  21   h  and  22   h . Each of the inlet members  21   h  and  22   h  is in fluid communication with a pump  23   h . Further, each of the inlet members  21   h  and  22   h  is provided with a plurality of inlet ports for injecting a liquid, such as water or a solvent in a direction toward the actuated portion which is represented by the cathode  3   h . It is also conceivable that additionally or alternatively, the actuator is configured to exert an aerodynamic force on the actuated portion. By way of example, the pump  23   h  may be configured to generate compressed air, which is injected into the battery cell  1   h  using the inlet ports provided in the inlet members  21   h  and  22   h.    
       FIGS. 4C and 4D  show exemplary configurations for the inlet member  21   h  and  22   h , of the actuator in the ninth exemplary embodiment illustrated in  FIG. 4B . Each of  FIGS. 4C and 4D  shows a side view of the respective inlet member, as seen from the cathode  3   h . Each of the inlet members  21   h  and  22   h  includes a plurality of inlet ports  24   h , through which a liquid and or a gas is injected into the battery cell  1   h . Furthermore, at least the member  21   h  has a plurality of opening  25   h , allowing the ions to pass through the inlet member  21   h  to reach the cathode  3   h.    
       FIG. 5A  is a schematic illustration of a battery cell according to a tenth exemplary embodiment. Components, which correspond to components of the battery cells of any one of the remaining embodiments with regard to their composition, their structure and/or their function, are designated with the same reference number, followed by a suffix letter “j”. 
     The actuator of the battery cell  1   j  according to the tenth exemplary embodiment is configured to couple acoustic energy into the actuated portion, which in the tenth exemplary embodiment is represented by the porous cathode  3   j . The actuator of the battery cell  1   j  includes mounting structure  26   j  and  27   j  on which and one or more mechanical transducers  28   j  are mounted. In the shown exemplary embodiment, the mechanical transducers  28   j  are configured as piezo-electric transducers. It is also conceivable that surface portions of the mounting structures  26   j  and  27   j  are coated using a piezo-active material. 
     The mechanical transducers  28   j  are configured so that application of a voltage to the mechanical transducers  28   j  cause the mechanical transducers  28   j  to extend toward the permeable portion, i.e porous cathode  3   j  so that acoustic energy is directed toward the permeable portion. 
       FIG. 5B  shows a view of a side of the mounting structure  26   j  of the battery cell  1   j , that faces the cathode  3   j . The mounting structure  26   j  has the plurality of mechanical transducers  28   j  mounted thereon. The mounting structure  26   j  further includes a plurality of openings  25   j  allowing the ions to pass through the mounting structure  26   j . The mounting structure  27   j  may have the same or a similar configuration as the mounting structure  26   j  or may be configured without openings  25   j.    
       FIG. 6A  shows an exemplary embodiment of a reversible solid-state storage  100  according to an exemplary embodiment. The exemplary solid-state storage  100  is configured to store hydrogen. However, alternatively or additionally, it is conceivable that the solid-state storage  100  is configured to store other species, such as oxygen. 
     The solid-state storage  100  includes a permeable portion, configured to allow the storable chemical species to permeate into the permeable portion. In the exemplary embodiment, the permeable portion represents at least a portion of the storage media in which the storable chemical species is stored. However, it is also conceivable that the permeable portion is a component of the solid-state storage  100  which does not function as a storage medium, such as a membrane. 
     Materials for the storage media include but are not limited to NaAlH 4 , LiAlH 4 , FeTiH 1,7 , LaNi 5 H 6 , Mg 2 (Ni 0.5 ,Cu 0.5 )H 4 , MgH 2 , LiBH 4 , Ca(BH 4 ) 2 , KBH 4 , NaBH 4  and graphene. 
     In the shown exemplary embodiment, the permeable portion is a porous material. The pore size of the permeable portion may be within the same range, as given above in connection with the electrochemical battery cell. 
     As is shown in  FIG. 6A , the solid-state storage  100  further comprises an actuator  103 , which is in operative interaction with the permeable portion and which is configured for adjusting a permeability of the permeable portion to the storable chemical species  100 . As is further shown in  FIG. 6A , the solid-state storage  100  further includes a sensor system  104 , which is configured to measure one or more operational parameters of the solid-state storage  100 . For the sensor system  104 , the same or basically the same configurations are conceivable as described above in conjunction with the exemplary embodiments of the electrochemical battery cell. 
     The solid-state storage  100  further comprises a controller which is not shown in  FIG. 6A  and which is configured to control the actuator  103  depending on sensor output generated by the sensor system  103 . 
       FIG. 6B  shows the arrangement of the actuators  103  and the sensors  104  in the exemplary solid-state storage  100  in greater detail. As can be seen from  FIG. 6B , the solid-state storage  100  includes a plurality of sensor systems  104  and a plurality of actuators  103 . The sensor systems  104  and the actuators  103  are arranged in an alternating fashion along an axis. It has been shown that this configuration allows for an improved control of the permeability of the permeable portion. 
     It has been shown that advantageous configurations of the actuator  103  correspond to the configurations which have been described above in connection with the embodiments of the electrochemical battery cell  1 . 
     Specifically, the actuator  103  may be configured to generate an electric and/or magnetic field which penetrates into the permeable portion. 
     The electric field may be a constant or time-varying electric field. The time-varying electric field may be a pulsed electric field or an oscillatory electric field. The magnetic field may be a constant or time-varying magnetic field. The time-varying magnetic field may be a pulsed magnetic field or an oscillatory magnetic field. The actuator  103  may include one or a plurality of electrodes and/or coils for generating the electric and/or magnetic field. 
     Additionally or alternatively, the actuator  103  may be configured to cause an electric current to pass through the permeable portion of the reversible solid-state storage  100 . The actuator  103  may be configured so that the electric current, adjusts the permeability of the permeable portion to the storable chemical species  100 . The electric current may be a constant or time-varying electric current. The time-varying electric current may be a pulsed electric current or an oscillatory electric current. 
     Additionally or alternatively, the actuator  103  may include one or more mechanical transducers for coupling an acoustic energy into the permeable portion. Additionally or alternatively, the actuator  103  may be configured to exert a mechanic, hydrogen and/or aerodynamic force on the permeable portion. The force may be a constant or time-varying force. The time-varying force may be a pulsed force or an oscillatory force. 
     Additionally or alternatively, the actuator  103  may be configured vary a pressure within the permeable portion. The adapted pressure may be constant or time-varying. The time-varying pressure may be a pulsed pressure variation or an oscillatory pressure variation. 
     It has been shown that thereby, a reversible solid-state storage  100  can be obtained which has an increased life-cycle and reduced maintenance costs.