Activation of electrical unit cell

Abstract

To provide: a method for compensating loss of carrier ions caused by formation of a solid electrolyte intermediate phase during a charging cycle of a secondary battery; and a secondary battery.SOLUTION: A method is provided for activating a secondary battery having: a negative electrode including anodically active silicon or an alloy thereof; a positive electrode; and a microporous separator impregnated with a carrier ion-containing electrolyte. The method includes the steps of: transporting carrier ions from the positive electrode to the negative electrode to at least partially charge the secondary battery; and transporting the carrier ions from an auxiliary electrode to the positive electrode to provide a positive end-of-discharge voltage Vpos,eod and a negative end-of-discharge voltage Vneg,eod to the secondary battery when a cell is at a predetermined Vcell,eod value. A value of the Vpos,eod corresponds to a voltage at which a charging state of the positive electrode is at least 95% of a coulombic capacity of the positive electrode. The Vneg,eod is at least 0.4 V (v.s. Li) and less than 0.9 V.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure generally relates to methods for replenishing energy storage devices and to replenished energy storage devices such as secondary batteries.

Background Art

[0002] In a rocking chair type battery cell, both the positive electrode and the negative electrode have a material into which carrier ions such as lithium are inserted and withdrawn. When the cell is discharged, the carrier ions are withdrawn from the negative electrode and inserted into the positive electrode. When the cell is charged, the reverse process occurs. That is, the carrier ions are withdrawn from the positive electrode and inserted into the negative electrode.

[0003] Silicon is a promising candidate to replace carbonaceous materials as an anode for high-capacity secondary batteries. In bulk silicon, a large volume increase of more than 300% upon insertion of carrier ions (e.g., lithium ions) has been observed. Along with cracking and pulverization associated with charge-discharge cycles, this volume increase has effectively limited the use of bulk silicon anodes.

[0004] When an energy storage device such as a secondary battery is assembled, the cathode active material such as lithium cobaltate is relatively stable in ambient air (e.g., against oxidation) compared to the lithiated anode material such as lithiated graphite. Thus, the amount of carrier ions available for circulation between the anode and the cathode is often first given to the cathode. When the secondary battery is charged for the first time, carrier ions are extracted from the cathode and introduced into the anode. As a result, the anode potential is significantly decreased (towards the potential of the metallic carrier ions), and the cathode potential is further increased (becomes more positive). These potential changes can cause parasitic reactions on both electrodes, but sometimes can cause more significant reactions on the anode. For example, decomposition products containing lithium (or other carrier ions) and electrolyte components, known as solid electrolyte interphase (SEI), are easily formed on the surface of the carbon anode. These surface layers or coating layers are carrier ion conductors that establish an ionic bond between the anode and the electrolyte and prevent the reaction from proceeding further.

[0005] The formation of the SEI layer is necessary for the stability of the half-cell system including the anode and the electrolyte. However, a portion of the carrier ions introduced into the cell through the cathode is irreversibly bound and thus removed from the capacity available to the user during periodic operation. As a result, during the first discharge, fewer carrier ions are returned from the anode to the cathode than were initially given by the cathode during the first charge operation, resulting in an irreversible capacity loss. During each subsequent charge-discharge cycle, the capacity loss due to mechanical and / or electrical degradation of the anode and / or cathode tends to be much less per cycle. However, even when the loss of carrier ions per cycle is relatively small, the energy density and cycle life decrease significantly as the battery ages. Furthermore, chemical and electrochemical degradation can occur on the electrodes, causing capacity loss.

[0006] Among various aspects of the present disclosure, there is provided an energy storage device such as a secondary battery, a fuel cell, and an electrochemical capacitor, in which the capacity lost as a result of SEI formation and / or mechanical or electrical degradation of the negative electrode and / or the positive electrode can be recovered. Advantageously, the energy storage device of the present disclosure provides an extended cycle life, an increased energy density, and / or an increased discharge rate.

Summary of the Invention

[0007] Therefore, briefly, one aspect of the present disclosure relates to a method of compensating for the loss of carrier ions caused by the formation of a solid electrolyte interphase in the secondary battery during the first or subsequent charge cycle of the secondary battery. The secondary battery includes a negative electrode, a positive electrode, a microporous separator impregnated with a carrier ion-containing electrolyte in ionic contact with the negative electrode and the positive electrode between the negative electrode and the positive electrode, and a control unit programmed to perform a charge-discharge cycle between a predetermined cell charge end voltage Vcell,eoc value and a predetermined cell discharge end voltage Vcell,eod value. The negative electrode includes an anodically active silicon or an alloy of the anodically active silicon and has a Coulombic capacity for the carrier ions. The positive electrode includes a cathodic active material and has a Coulombic capacity for the carrier ions. The Coulombic capacity of the negative electrode exceeds the Coulombic capacity of the positive electrode. The method includes Step (i) of transporting carrier ions from the positive electrode to the negative electrode during the first or subsequent charge cycle to at least partially charge the secondary battery, and forming a solid electrolyte interphase on the surface of the negative electrode during the transport. Transporting carrier ions from an auxiliary electrode including a source of carrier ions and electrolytically coupled to the negative electrode and / or the positive electrode via the separator, when the cell is at the predetermined Vcell,eod value, assuming that the positive electrode has a discharge cut-off voltage Vpos,eod and the negative electrode has a discharge cut-off voltage Vneg,eod, where the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of the Coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li) (step (ii)).

[0008] Another aspect of the present disclosure is a method of activating a secondary battery. The secondary battery has a negative electrode, a positive electrode, a microporous separator impregnated with a carrier ion-containing electrolyte in ionic contact with the negative electrode and the positive electrode, and a control unit. The positive electrode includes a cathode active material and has a reversible Coulombic capacity for the carrier ions. The negative electrode includes an anodic active silicon or an alloy of this anodic active silicon and has a reversible Coulombic capacity exceeding the Coulombic capacity of the positive electrode for the carrier ions. The method includes: (i) Transporting carrier ions from the positive electrode to the negative electrode to at least partially charge the secondary battery, and forming a solid electrolyte interphase on the surface of the negative electrode during the transport. (ii) After step (i), transporting carrier ions from the auxiliary electrode to the positive electrode. (iii) After step (ii), transporting carrier ions from the positive electrode to the negative electrode to charge the secondary battery, and (iv) Programming the control unit to set a cell discharge cut-off voltage Vcell,eod. When the cell is at Vcell,eod, the activated secondary battery has a positive electrode discharge cut-off voltage Vpos,eod and a negative electrode discharge cut-off voltage Vneg,eod. The value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0009] Another aspect of the present disclosure is a method of charging a secondary battery. The secondary battery has a negative electrode, a positive electrode, and a microporous separator impregnated with a carrier ion-containing electrolyte that is in ionic contact with the negative electrode and the positive electrode between the negative electrode and the positive electrode. The negative electrode contains anodically active silicon or an alloy of this anodically active silicon. The positive electrode contains a cathode active material. The ratio of the Coulomb capacity of the negative electrode to the Coulomb capacity of the positive electrode is at least 1.2:1 in this order. The method is (i) transporting carrier ions from an auxiliary electrode to the positive electrode, and (ii) charging the negative electrode with the carrier ions transported from the auxiliary electrode to the positive electrode, thereby charging the secondary battery. The charged secondary battery has a discharge cut-off voltage Vcell,eod and a negative electrode discharge cut-off voltage Vneg,eod. When Vcell,eod is reached, Vneg,eod is less than 0.9 V (vs. Li) and at least 0.4 V (vs. Li).

[0010] Another aspect of the present disclosure is a secondary battery having a negative electrode, a positive electrode, a microporous separator impregnated with a carrier ion-containing electrolyte that is in ionic contact with the negative electrode and the positive electrode between the negative electrode and the positive electrode, and a control unit. The positive electrode contains a cathode active material and has a Coulomb capacity for the carrier ions. The negative electrode includes anodically active silicon or an alloy of this anodically active silicon, and has a Coulomb capacity for the carrier ions that exceeds the Coulomb capacity of the positive electrode. The control unit includes a controller and a sensor electrically coupled to the controller, The sensor is configured to measure the cell voltage of the secondary battery during operation of the secondary battery, and to measure the voltage of the positive electrode or the negative electrode with respect to a removable auxiliary electrode that includes a source of carrier ions and is electrolytically coupled to the negative electrode and / or the positive electrode via the separator. The controller is programmed to perform a charge / discharge cycle between a predetermined cell charge termination voltage Vcell,eoc value and a predetermined cell discharge termination voltage Vcell,eod value, that is, to end the charging operation of the secondary battery when the cell charge termination voltage Vcell,eoc is detected, and to end the discharging operation of the secondary battery when the cell discharge termination voltage Vcell,eod is detected. Furthermore, During the first or subsequent charge cycle, when carrier ions are transported from the positive electrode to the negative electrode and the secondary battery is at least partially charged, a solid electrolyte interphase is formed on the surface of the negative electrode during that transport, and When carrier ions are transported from the removable auxiliary electrode, and when the cell is at the predetermined Vcell,eod value, assuming that the positive electrode has a discharge termination voltage Vpos,eod and the negative electrode has a discharge termination voltage Vneg,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0011] Other objectives and features will be partially revealed and partially pointed out hereinafter.

Brief Description of the Drawings

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[0028] Throughout the drawings, corresponding reference numerals indicate corresponding parts. [Definitions]

[0029] As used herein, "a", "an", and "the" (i.e., the singular forms) refer to plural referents unless the context clearly indicates otherwise. For example, in one instance, a reference to "an electrode" includes both a single electrode and multiple similar electrodes. The terms "comprising", "including", and "having" are inclusive and mean that additional elements other than the recited elements may exist.

[0030] As used herein, "About" and "approximately" mean ±10%, 5%, or 1% of the stated value. For example, in one instance, about 250 μm includes 225 μm to 275 μm. As a further example, in one instance, about 1000 μm includes 900 μm to 1100 μm. Unless otherwise indicated, all numbers expressing quantities (e.g., measured values, etc.) used in this specification and the claims, etc., should be understood to be modified in all instances by the term "about". Thus, unless the contrary is indicated, the numerical parameters set forth in the following specification and the appended claims are approximations. Each numerical parameter should be construed in light of at least the number of significant digits reported and by applying ordinary rounding techniques.

[0031] As used herein in the context of the state of a secondary battery, "state of charge" refers to a state in which the secondary battery is charged to at least 75% of its rated capacity. For example, the battery can be charged to at least 80% of its rated capacity, at least 90% of its rated capacity, at least 95% of its rated capacity, up to 100% of its rated capacity.

[0032] As used herein in relation to the negative electrode, the term "discharge capacity" means the amount of carrier ions available for extraction from the negative electrode and insertion into the positive electrode between the limits of a predetermined set of cell charge cut-off voltage and discharge cut-off voltage during the discharge operation of the battery.

[0033] As used herein in the context of the state of a secondary battery, "state of discharge" refers to a state in which the secondary battery is discharged to less than 25% of its rated capacity. For example, the battery can be discharged to less than 20% of its rated capacity, less than 10% of its rated capacity, less than 5% of its rated capacity, down to 0% of its rated capacity.

[0034] As used herein in the context of secondary batteries, the "rated capacity" refers to the ability of a secondary battery to deliver current over a certain period of time measured under standard temperature conditions (25°C). For example, the rated capacity can be measured in units of ampere-hours (Ah) by determining the current output for a specified time, or by determining the time for which a specified current can be output, and by taking the product of the current and the time. For example, in the case of a battery with a rated capacity of 20 ampere-hours, when the current is specified as 2 amperes for the rating, it can be understood that the battery provides its current output for 10 hours. Conversely, if the time is specified as 10 hours for the rating, it can be understood that the battery outputs 2 amperes for 10 hours.

[0035] As used herein in connection with an electrode (i.e., a positive electrode, a negative electrode, or an auxiliary electrode), the term "reversible Coulombic capacity" means the total capacity of the electrode for carrier ions available for reversible exchange with a counter electrode.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Among the various aspects of the present disclosure, the method for designing and forming cells for secondary batteries may be noted to provide various advantages including, for example, improved cycle life, greater energy density, greater charging rate, and / or greater discharging rate. Generally, a secondary battery has cell voltage limits for the charge / discharge cycles of the secondary battery, the positive electrode, and the negative electrode, and the reversible Coulombic capacity of the positive electrode is matched to the discharge capacity of the negative electrode after the formation of the battery (i.e., after the first charge / discharge cycle).

[0037] As described above, the formation of the solid electrolyte interphase (SEI) during the first charge / discharge cycle reduces the amount of carrier ions available for reversible cycles. Mechanical and / or electrical degradation during the cycling of the battery can further reduce the amount of carrier ions available for reversible cycles. Thus, additional or supplementary carrier ions can be provided from an auxiliary electrode after formation of the battery to compensate for the formation of SEI (or other carrier ion consumption mechanisms such as mechanical and / or electrical degradation of the negative electrode).

[0038] Generally, the voltage limits of a secondary battery and its positive and negative electrodes are related as follows. Vcell,eoc = Vpos,eoc - Vneg,eoc [1] Vcell,eod = Vpos,eod - Vneg,eod [2] Here, Vcell,eoc is the end-of-charge voltage for the cell, Vpos,eoc is the end-of-charge voltage for the positive electrode, Vneg,eoc is the end-of-charge voltage for the negative electrode, Vcell,eod is the end-of-discharge voltage for the cell, Vpos,eod is the end-of-discharge voltage for the positive electrode, and Vneg,eod is the end-of-discharge voltage for the negative electrode.

[0039] Generally, Vcell,eoc is a maximum value in that the cell voltage should ideally always be below this value, while Vcell,eod is a minimum value in that the cell voltage should ideally always be above this value. By design, the voltage limits of the cell, Vcell,eoc and Vcell,eod, are fixed during the life of the battery, while the voltage limits of the individual electrodes can vary. Thus, as used herein, it should be understood that the specification of the voltage limits of the positive and negative electrodes at the end of charge or at the end of discharge refers to the charge or discharge cycles after formation of the battery, i.e., after the first charge-discharge cycle.

[0040] The end-of-charge voltage Vpos,eoc for the positive electrode active material used in a secondary battery is at most 5 V (versus Li), typically in the range of about 4.3 V to 4.5 V (versus Li). The end-of-discharge voltage Vpos,eod for the positive electrode active material typically used in a secondary battery is typically at least 2.5 V (versus Li). In the case of a silicon-containing negative electrode, the end-of-charge voltage Vneg,eoc is typically 0.1 V (versus Li), and the end-of-discharge voltage is a design choice programmed and controlled by the battery's control unit. Therefore, according to equations [1] and [2], the cell end-of-charge voltage Vcell,eoc for a cell containing such a material is typically at least about 4.2 V, at least about 4.4 V (versus Li), or a larger value. The cell end-of-discharge voltage Vcell,eod for such a material typically has a value determined by the difference between 2.5 V and Vneg,eod (versus Li) (i.e., Vcell,eod = 2.5 V - Vneg,eod).

[0041] In one embodiment of the present disclosure, when the secondary battery reaches the cell end-of-discharge voltage Vcell,eod during the discharge cycle of the secondary battery (after the initial charge-discharge cycle in which SEI is formed), the negative electrode end-of-discharge voltage Vneg,eod is less than 0.9 V (versus Li) and greater than 0.4 V (versus Li). Thus, for example, in such an embodiment, when the secondary battery reaches the cell end-of-discharge voltage Vcell,eod during the discharge cycle of the secondary battery (i.e., when the battery is under a discharge load), the negative electrode end-of-discharge voltage Vneg,eod is in the range of about 0.5 V (versus Li) to about 0.8 V (versus Li). As a further example, in such an embodiment, when the secondary battery reaches the cell end-of-discharge voltage Vcell,eod during the discharge cycle of the secondary battery (i.e., when the battery is under a discharge load), the negative electrode end-of-discharge voltage Vneg,eod is in the range of about 0.6 V (versus Li) to about 0.8 V (versus Li). In such an embodiment, when the secondary battery reaches the cell end-of-discharge voltage Vcell,eod during the discharge cycle of the secondary battery (i.e., when the battery is under a discharge load), the negative electrode end-of-discharge voltage Vneg,eod is in the range of about 0.6 V (versus Li) to about 0.7 V (versus Li).

[0042] Figures 1 to 4 show exemplary charge / discharge cycles for a silicon-containing negative electrode. The silicon-containing negative electrode has a charge termination voltage Vneg,eoc of 0.1 V (versus Li) and a discharge termination voltage Vneg,eod of 0.9 V (Figure 1), 0.8 V (Figure 2), 0.7 V (Figure 3), or 0.6 V (Figure 4) (versus Li). The discharge capacities of the silicon-containing electrodes having these charge-discharge limits are given by Ca (Figure 1), Cb (Figure 2), Cc (Figure 3), and Cd (Figure 4). When comparing the discharge capacities of the silicon-containing electrodes illustrated in each of Figures 1 to 4, it can be observed that the discharge capacity of the electrode decreases as the value of the discharge termination voltage Vneg,eod decreases (when the reversible Coulombic capacity is constant).

[0043] As shown in Figures 1-4, values of the discharge termination voltage less than 0.4 V (versus Li) reduce the energy density of the entire cell and are not very desirable. Values of Vneg,eod of at least 0.9 V (versus Li) significantly improve the energy density of the entire cell but tend to reduce the cycle life and are generally not very desirable. According to one aspect of the present disclosure, the discharge termination voltage Vneg,eod for a lithium-ion battery including a silicon-containing electrode is less than 0.9 V (versus Li). For example, in one such embodiment, Vneg,eod does not exceed 0.8 V (versus Li). As a further example, in one such embodiment, Vneg,eod does not exceed 0.7 V (versus Li). As a further example, in one such embodiment, Vneg,eod does not exceed 0.6 V (versus Li). As a further example, in one such embodiment, Vneg,eod does not exceed 0.5 V (versus Li). In such an exemplary embodiment, Vneg,eod exceeds 0.4 V but is less than 0.9 V (versus Li). As a further example, in one such embodiment, Vneg,eod is in the range of about 0.5 V to about 0.8 V (versus Li). As a further example, in one such embodiment, Vneg,eod is in the range of about 0.6 V to about 0.8 V (versus Li). In such an exemplary embodiment, Vneg,eod is in the range of about 0.6 V to about 0.7 V (versus Li).

[0044] Generally, the positive electrode of the secondary battery of the present disclosure preferably has a reversible Coulombic capacity that matches the discharge capacity of the negative electrode. In other words, the cathode is sized to have a reversible Coulombic capacity corresponding to the discharge capacity of the negative electrode, and in turn, is a function of the negative electrode discharge cut-off voltage Vneg,eod (see FIGS. 1 to 4). For example, referring to FIGS. 1A to 4A, the reversible Coulombic capacities of the positive electrodes sized to match the discharge capacities of the negative electrodes having the discharge cut-off voltage limits of FIGS. 1 to 4 are given by Ce (FIG. 1A), Cf (FIG. 2A), Cg (FIG. 3A), and Ch (FIG. 4A). Comparing FIGS. 1A to 4A, the reversible Coulombic capacity of the positive electrode that matches the discharge capacity of the negative electrode decreases as the value of the discharge cut-off voltage Vneg,eod for the negative electrode (having a constant reversible Coulombic capacity) decreases.

[0045] In one embodiment, the reversible capacity of the positive electrode is matched to the discharge capacity of the negative electrode. As a result, when Vcell,eod is reached, the positive electrode has a Vpos,eod value corresponding to a voltage at which the state of charge of the positive electrode is at least 95% of its reversible Coulombic capacity, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li). For example, in one such embodiment, when Vcell,eod is reached, the positive electrode has a Vpos,eod value corresponding to a voltage at which the state of charge of the positive electrode is at least 96% of its reversible Coulombic capacity, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li). As a further example, in such an embodiment, when Vcell,eod is reached, the positive electrode has a Vpos,eod value corresponding to a voltage at which the state of charge of the positive electrode is at least 97% of its reversible Coulombic capacity, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li). As a further example, in such an embodiment, when Vcell,eod is reached, the positive electrode has a Vpos,eod value corresponding to a voltage at which the state of charge of the positive electrode is at least 98% of its reversible Coulombic capacity, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li). As a further example, in such an embodiment, when Vcell,eod is reached, the positive electrode has a Vpos,eod value corresponding to a voltage at which the state of charge of the positive electrode is at least 99% of its reversible Coulombic capacity, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li).

[0046] According to one aspect of the present disclosure, the negative electrode is designed to have a reversible Coulombic capacity that significantly exceeds the reversible Coulombic capacity of the positive electrode. For example, in one embodiment, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is, in this order, at least 1.2:1. As a further example, in one embodiment, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is, in this order, at least 1.3:1. As a further example, in one embodiment, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is, in this order, at least 2:1. As a further example, in one embodiment, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is, in this order, at least 3:1. As a further example, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is, in this order, at least 4:1. As a further example, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is, in this order, at least 5:1. Advantageously, the excess Coulombic capacity of the negative electrode provides a source of anode active material, enabling the battery to operate reversibly within a specific voltage that inhibits the formation of a crystalline phase (including carrier ions) on the negative electrode. The crystalline phase on the negative electrode reduces the cycle life of the negative electrode (and thus the battery) as a result of the cyclic use of the battery. Further, the excess anode Coulombic capacity and the reduction of the voltage of the negative electrode during discharge provide a battery with a higher energy density (as a result of a higher average voltage).

[0047] Generally, the carrier ions can be any carrier ions suitable for use in a secondary battery. In one preferred exemplary embodiment, the secondary battery utilizes carrier ions that circulate between members of a group of an electrode and a counter electrode as the secondary battery is charged and discharged, for example, carrier ions selected from lithium ions, sodium ions, potassium ions, calcium ions, magnesium ions, and aluminum ions. For example, in one such embodiment, the carrier ions are lithium ions. As a further example, in another such embodiment, the carrier ions may be magnesium ions. As a further example, in another such embodiment, the carrier ions may be aluminum ions.

[0048] Now, referring to FIG. 5, an embodiment of the two-dimensional battery of the present disclosure, generally indicated at 10, is illustrated. The battery 10 includes at least one positive electrode structure 20, at least one negative electrode structure 22, an auxiliary electrode 24 that can be selectively electrically connected or coupled (e.g., by a switch 32) to the positive electrode structure 20, and a control unit (not shown) within a battery enclosure 11. The auxiliary electrode 24 is shown in the headspace of the battery 10, but may be provided elsewhere as desired. Tabs 26, 28, 30 enable connection of the positive electrode, negative electrode, and auxiliary electrode to battery terminals (not shown) for connection to an energy source or a consumer, and the switch 32 enables an electrical connection between the positive electrode structure 20 and the auxiliary electrode 24. The control unit includes sensors for detecting the cell voltage (i.e., the voltage between the positive electrode and the negative electrode) and for detecting the voltage of the positive electrode, negative electrode, or both the positive electrode and the negative electrode with respect to the auxiliary electrode. Further, the control unit includes a controller for controlling the charging and discharging cycles of the battery in response to the voltages detected by the sensors.

[0049] The battery enclosure 11 can be composed of any material within the range of materials conventionally used for secondary batteries. For example, in one embodiment, the battery enclosure 11 may be made of a plastic material or a plastic foil laminate material (e.g., an aluminum foil provided between a polyolefin layer and a polyester layer). Alternatively, the battery enclosure 11 may be made of stainless steel, titanium, aluminum, or other metals or their alloys.

[0050] In one embodiment, the positive electrode structure 20 includes any of a range of cathode active materials capable of storing lithium or other carrier ions. For example, the positive electrode can selectively use a cathode active material selected from transition metal oxides, transition metal sulfides, transition metal nitrides, lithium transition metal oxides, lithium transition metal sulfides, and lithium transition metal nitrides. The transition metal elements of these transition metal oxides, transition metal sulfides, and transition metal nitrides can include metal elements having a d-shell or f-shell. Specific examples of such metal elements are Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Tc, Re, Fe, Ru, Os, Co, Rh, Ir, Ni, Pb, Pt, Cu, Ag, and Au. Further, the cathode active material is LiCoO 2 , LiNi 0.5 Mn 1.5 O 4 , Li(Ni x Co y Al 2 )O 2 , LiFePO 4 , Li 2 MnO 4 , V 2 O 5 , molybdenum oxysulfide, phosphates, silicates, and vanadates, and combinations thereof. The cathode active material can be deposited to form the positive electrode structure by any range of techniques including, for example, electrophoretic deposition, electroplating, co-deposition, or slurry deposition. In an exemplary embodiment, one or a combination of the aforementioned cathode active materials is electrophoretically deposited in particulate form. In another exemplary embodiment, V 2 O 5A cathode active material such as that is electrodeposited. In another exemplary embodiment, one or a combination of the aforementioned cathode active materials is co-deposited in particulate form in a conductive matrix such as polyaniline. In another exemplary embodiment, one of the above cathode active materials, or a combination thereof, is deposited as a slurry in particulate form.

[0051] The anode structure 22 includes a silicon-containing anode active material. In one embodiment, the anode structure 22 includes silicon, a silicon alloy, a mixture of silicon and other anode active materials, a mixture of silicon and an electrochemically inert material, or a combination thereof. For example, in one exemplary embodiment, the anode structure 22 includes silicon, or a combination of silicon and carbon, germanium, selenium, nickel copper, tin, manganese, bismuth, silver, gold, zinc, lead and / or lead. As a further example, in such an exemplary embodiment, the anode structure 22 includes silicon, silicon and germanium, silicon and carbon, silicon and selenium, silicon, selenium and carbon, a mixture of silicon and nickel and / or copper, or a combination thereof. In one exemplary embodiment, the anode structure 22 includes silicon or an oxide or nitride thereof, a fluoride thereof, or other alloy. In another exemplary embodiment, the anode structure 22 includes silicon or an alloy thereof. In each of the embodiments and sub - embodiments described in this paragraph, the anode structure 22 may be a granular aggregate electrode or a monolithic electrode. The anode structure 22 can be formed or otherwise assembled using methods such as electrodeposition, electrophoretic deposition, vapor deposition, catalyst - based growth such as vapor - liquid - solid method, gel casting, tape casting, patterning and slurry deposition. Subsequently, it is densified by methods such as sintering, bonding, etc.

[0052] In one embodiment, the negative electrode structure 22 includes a microstructured silicon-containing active material having a significant void volume fraction to accommodate volume expansion and contraction associated with the incorporation or release of carrier ions into or from the negative electrode structure 22 during charge and discharge cycles. Generally, the void volume fraction of this anode active material is 0.1 or more. However, typically, the void volume fraction of the anode active material is 0.8 or less. For example, in one embodiment, the void volume fraction of the anode active material is from about 0.15 to about 0.75. As a further example, in one embodiment, the void volume fraction of the anode active material is from about 0.2 to about 0.7. As a further example, in one embodiment, the void volume fraction of the anode active material is from about 0.25 to about 0.6.

[0053] Depending on the composition of the microstructured anode active material and its formation method, the microstructured anode active material may comprise a macroporous, microporous or mesoporous material layer, or a combination thereof, such as, for example, microporous and mesoporous, or mesoporous and macroporous. Microporous materials are typically characterized by pore dimensions of less than 10 nm, wall dimensions of less than 10 nm, pore depths of 1 to 50 micrometers, and a pore morphology generally characterized by a "spongy" and irregular appearance, non-smooth walls, and branched pores. Mesoporous materials are typically characterized by pore dimensions of 10 to 50 nm, wall dimensions of 10 to 50 nm, pore depths of 1 to 100 micrometers, and a pore morphology generally characterized by somewhat well-defined branched or dendritic pores. Macroporous materials are typically characterized by pore dimensions greater than 50 nm, wall dimensions greater than 50 nm, pore depths of 1 to 500 micrometers, and a pore morphology that can be variously linear, branched or dendritic, and have smooth or rough walls. Further, the void volume can include open or closed voids, or a combination thereof. In one embodiment, the void volume includes open voids. That is, the anode active material includes voids having openings on the side surface of this anode active material (that is, the surface facing the separator and the cathode active material). Through the voids, lithium ions (or other carrier ions) can enter or leave the anode active material. For example, lithium ions can enter the anode active material through the void openings after leaving the cathode active material. In another embodiment, the void volume includes closed voids. That is, the anode active material includes voids surrounded by the anode active material. Generally, open voids provide a larger interfacial surface area for carrier ions, while closed voids tend to be less affected by the solid electrolyte interphase ("SEI"). Along with that, each of the open voids and the closed voids provides room for the anode active material to expand upon entry of carrier ions. Therefore, in certain embodiments, it is preferred that the anode active material includes a combination of open voids and closed voids.

[0054] In one embodiment, the negative electrode structure 22 includes porous silicon or an alloy thereof. The porous silicon layer can be formed, for example, by anodization, etching (e.g., depositing a noble metal such as gold, platinum, silver, or gold / palladium on the (100) plane of single-crystalline silicon and etching its surface with a mixture of hydrofluoric acid and hydrogen peroxide), or by other methods known in the art such as patterned chemical etching. Further, the porous anode active material generally has a void volume fraction of at least about 0.1 but less than 0.8 as described above.

[0055] In another embodiment, the negative electrode structure 22 includes silicon fibers or an alloy thereof. The individual fibers can have a diameter (thickness dimension) of about 5 nm to about 10,000 nm. The silicon fibers (nanowires) can be formed by chemical vapor deposition or other techniques known in the art such as vapor-liquid-solid (VLS) growth and solid-liquid-solid (SLS) growth. Further, the anode active material 22 generally has a void volume fraction of at least about 0.1 but less than 0.8 as described above.

[0056] In one embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is at least 120% of the reversible Coulombic capacity of the positive electrode. For example, in one such embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is at least 130% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is at least 200% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is at least 300% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is at least 400% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is at least 500% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the positive electrode and the negative electrode are sized such that when cycled with respect to a reference electrode after formation, the reversible Coulombic capacity of the negative electrode is from about 120% to about 175%, or from about 120% to about 150% of the reversible Coulombic capacity of the positive electrode.

[0057] The positive and negative electrode structures 20, 22 may be provided as flat or planar components of the battery 10, may be wound in a spiral or other configuration, or may be provided in a folded form. For example, the electrodes may be wound around a relatively rectangular mandrel to form a coil wound elliptically for insertion into a relatively prismatic battery case.

[0058] The auxiliary electrode includes a source of carrier ions for replenishing the energy capacity lost after the formation of the battery (i.e., for compensating for the loss of carrier ions during the formation of the SEI in the first charge and / or discharge cycle and other carrier ion losses). The auxiliary electrode can include a foil of carrier ions in metallic form (e.g., foils of lithium, magnesium, or aluminum), or either of the aforementioned positive or anode active materials in their carrier ion-containing forms. For example, the auxiliary electrode can include lithiated silicon or a lithiated silicon alloy. The auxiliary electrode is formed by placing an electrode made of the desired material in an inert region of the battery cell, but is still electrolytically coupled to the negative and / or positive electrodes through the separator. Alternatively, the auxiliary electrode can be formed by depositing the desired auxiliary electrode material using techniques such as electrochemical deposition, electroless deposition, electrophoretic deposition, vacuum-assisted filling, stencil-assisted filling, dip coating, etc.

[0059] In one embodiment, the auxiliary electrode is sized to provide at least 15% of the reversible Coulombic capacity of the positive electrode. For example, in one such embodiment, the auxiliary electrode is sized to contain sufficient carrier ions (e.g., lithium ions, magnesium ions, or aluminum ions) such that it provides at least 30% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the auxiliary electrode is sized to contain sufficient carrier ions such that it provides at least 100% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the auxiliary electrode is sized to contain sufficient carrier ions such that it provides at least 200% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the auxiliary electrode is sized to contain sufficient carrier ions such that it provides at least 300% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the auxiliary electrode is sized to contain sufficient carrier ions such that it provides approximately 100% to approximately 200% of the reversible Coulombic capacity of the positive electrode.

[0060] When the cell is assembled, the cell is charged by transporting carrier ions from the positive electrode to the negative electrode. Charging is stopped when the positive electrode reaches the designed value of Vpos,eoc. During the initial charge cycle, SEI is readily formed on the surface of the negative electrode structure. Referring again to FIG. 5, to compensate for the loss of carrier ions to the SEI, switch 32 is closed to apply a voltage between the auxiliary electrode 24 and the positive electrode structure 20 to transport carrier ions from the auxiliary electrode to the positive electrode, whereby the positive electrode structure 20 can be replenished. When the transport of carrier ions from the auxiliary electrode to the positive electrode is complete, the negative electrode is charged again, this time with the carrier ions transferred from the auxiliary electrode, until the Vcell,eoc value is reached. This typically corresponds to a Vneg,eoc value of 0.1V and a Vpos,eoc value equal to the sum of Vcell and 0.1V (versus Li).

[0061] In yet another embodiment, while transporting carrier ions from the positive electrode to the negative electrode, the positive electrode can be replenished with carrier ions by simultaneously transporting carrier ions from the auxiliary electrode to the positive electrode. Referring to FIG. 5, a voltage is applied between the positive electrode structure 20 and the negative electrode structure 22, and carrier ions are transported from the positive electrode structure 20 to the negative electrode structure 22. While the carrier ions are being transported from the positive electrode structure 20 to the negative electrode structure 22, the switch 32 can be closed to apply a voltage between the auxiliary electrode 24 and the positive electrode structure 20 to transport carrier ions from the auxiliary electrode 24 to the positive electrode structure 20. In this way, carrier ions are transported from the auxiliary electrode 24 to the positive electrode structure 20 at the same time as the carrier ions are transported from the positive electrode structure 20 to the negative electrode. That is, a voltage sufficient to transport carrier ions from the positive electrode structure 20 to the negative electrode structure 22 is maintained between the positive electrode structure 20 and the negative electrode structure 22, and at the same time, a voltage sufficient to transport carrier ions from the auxiliary electrode to the positive electrode structure is maintained between the auxiliary electrode 24 and the positive electrode structure 20. In one embodiment, applying a voltage between the positive electrode structure 20 and the negative electrode structure 22 to transport carrier ions to the negative electrode structure starts at t0, and then the switch 32 is closed at a time t1 which is a predetermined time later, and a voltage is applied between the auxiliary electrode 24 and the positive electrode structure 20, and carrier ions are transported to the positive electrode structure 20. That is, the start of the transport of carrier ions from the positive electrode structure 20 to the negative electrode structure 22 starts from the initial time t0, the start of the transport of carrier ions from the auxiliary electrode 24 to the positive electrode structure 20 starts at the time t1 which is a predetermined time after the time t0, and at the time after the time t1, carrier ions are transported from the auxiliary electrode 24 to the positive electrode structure 20 at the same time as the transport of carrier ions from the positive electrode structure to the negative electrode structure 22. In another embodiment, the start of the transport of carrier ions from the auxiliary electrode 24 to the positive electrode structure 20 may start at the time t0 simultaneously with the start of the transfer of carrier ions from the positive electrode structure 20 to the negative electrode structure 22.Similarly, in one embodiment, the transport of carrier ions from the auxiliary electrode 24 to the positive electrode structure 20 is stopped at time t2 simultaneously with the time when the transport of carrier ions from the positive electrode structure 20 to the negative electrode structure 22 is stopped, and / or the transport of carrier ions from the auxiliary electrode 24 may be stopped at time t2 which is a predetermined time before time t3 when the transport of carrier ions from the positive electrode structure 20 to the negative electrode structure 22 is stopped.

[0062] In one embodiment, the transport rate of carrier ions from the positive electrode structure 20 to the negative electrode structure 22 is equal to or higher than the transport rate of carrier ions from the auxiliary electrode 24 to the positive electrode structure 20. Thereby, the total transport rate of carrier ions from the auxiliary electrode 24 to the negative electrode structure 22 via the positive electrode structure 20 can be maintained well. That is, the relative transport rates between the positive electrode structure 20 and the negative electrode structure 22 and between the auxiliary electrode 24 and the positive electrode structure 20 can be maintained such that the total capacity of the positive electrode structure 20 is not exceeded for additional carrier ions. In this way, the positive electrode structure 20 can be maintained in a state having the ability to accept new carrier ions from the auxiliary electrode 24, thereby enabling continuous transport of carrier ions to the negative electrode structure 22. For example, in one embodiment, the voltage applied between the positive electrode structure 20 and the negative electrode structure 22 and the voltage applied between the auxiliary electrode 24 and the positive electrode structure 20 are selected to provide a transport rate of carrier ions between the positive electrode structure and the negative electrode structure 22 that is equal to or higher than the transport rate of carrier ions between the auxiliary electrode 24 and the positive electrode structure 20. The transport rate of carrier ions between electrodes is related to, for example, the current between the electrodes that can be measured using a sensor. Thus, in one example, reflecting a transport rate of carrier ions between the auxiliary electrode 24 and the positive electrode structure 20 that is lower than the transport rate of carrier ions between the positive electrode structure 20 and the negative electrode structure 22, the current between the auxiliary electrode 24 and the positive electrode structure 20 is smaller than the current between the positive electrode structure 20 and the negative electrode structure 22. For example, in one embodiment, the current between the auxiliary electrode 24 and the positive electrode structure 20 may be 80% or less of the current between the positive electrode structure 20 and the negative electrode structure 22. Further, in one embodiment, the current between the auxiliary electrode 24 and the positive electrode structure 20 may be 60% or less of the current between the positive electrode structure 20 and the negative electrode structure 22. As yet another example, in one embodiment, the current between the auxiliary electrode 24 and the positive electrode structure 20 may be 50% or less of the current between the positive electrode structure 20 and the negative electrode structure 22. As yet another example, in one embodiment, the current between the auxiliary electrode 24 and the positive electrode structure 20 may be 30% or less of the current between the positive electrode structure 20 and the negative electrode structure 22.As yet another example, in one embodiment, the current between the auxiliary electrode 24 and the positive electrode structure 20 may be 20% or less of the current between the positive electrode structure 20 and the negative electrode structure 22.

[0063] In one embodiment, without being limited to a particular theory, carrier ions are transported from the auxiliary electrode 24 to the positive electrode structure 20 as part of the replenishment of the negative electrode structure 22 (as opposed to direct transport from the auxiliary electrode 24 to the negative electrode structure 22). The reason is that the positive electrode structure 20 can receive carrier ions uniformly across its entire surface, and thus the carrier ions can participate more uniformly in their transport between the positive electrode structure 20 and the negative electrode structure 22. In contrast, in the case of certain materials used to form the negative electrode structure 22, such as silicon-containing materials, direct transport of carrier ions from the auxiliary electrode 24 to the negative electrode structure 22 results in a non-uniform accumulation of carrier ions on the surface of the negative electrode structure, such as on the surface of the negative electrode structure 22 closest to the auxiliary electrode 24. Thus, the ability of the accumulated carrier ions to participate uniformly in the transport between the positive electrode structure 20 and the negative electrode structure 22 during the charge and discharge process is limited. Thus, by transporting carrier ions from the auxiliary electrode 24 to the positive electrode structure 20, more uniform transport of carrier ions to the negative electrode structure 22 becomes possible, and the overall performance of the battery with the replenished negative electrode structure 22 can be improved.

[0064] Generally, the amount of carrier ions transported from the auxiliary electrode to the positive electrode (and ultimately to the negative electrode) is sufficient to match the reversible capacity of the positive electrode to the discharge capacity of the negative electrode (where when the secondary battery reaches the cell discharge end voltage Vcell,eod, the negative electrode discharge end voltage Vneg,eod is greater than 0.4 V (versus Li) and less than 0.9 V (versus Li)). In one embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 10% of the reversible capacity of the positive electrode. For example, in one such embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 15% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 20% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 25% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 30% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 40% of the reversible Coulombic capacity of the positive electrode. As a further example, in one such embodiment, the amount of carrier ions transported from the auxiliary electrode to the positive electrode is at least 50% of the reversible Coulombic capacity of the positive electrode.

[0065] Referring again to FIG. 5, a porous separator (not shown) is disposed between the positive electrode structure 20 and the negative electrode structure 22, and between the auxiliary electrode 24 and the positive electrode structure and / or the negative electrode structure. The porous separator material is, for example, microporous polyethylene, polypropylene, TiO 2 -polymer composite, SiO 2 , Al 2 O 3Any of the porous materials conventionally used as secondary battery separators, including etc., can be included (P. Arora and J. Zhang, "Battery Separators", Chemical Reviews, 2004, Vol. 104, pp. 4419 - 4462). Such materials can be deposited, for example, by electrophoretic deposition of particulate separator materials, slurry deposition of particulate separator materials (including spin or spray coating), or sputter coating of ion-conductive particulate separator materials. In one embodiment, the porous separator material includes pores having a diameter of at least 50 Å, more typically about 2500 Å, and a pore volume fraction in the range of about 25% to about 75%, more typically about 35 - 55%.

[0066] The porous separator material is impregnated with a non-aqueous electrolyte that serves as a medium for conducting carrier ions between the positive electrode, the negative electrode, and the auxiliary electrode. Generally, this non-aqueous electrolyte can be any of a series of non-aqueous electrolytes suitable for use as a secondary battery electrolyte. Typically, this non-aqueous electrolyte includes a salt of a carrier ion such as magnesium, aluminum, or lithium salt dissolved in an organic solvent. Exemplary lithium salts include LiClO 4 ,LiBF 4 ,LiPF 6 ,LiAsF 6 ,LiCl, LiBr and other inorganic lithium salts, LiB(C 6 H 5 ) 4 ,LiN(SO 2 CF 3 ) 2 ,LiN(SO 2 CF 3 ) 3 ,LiNSO 2 CF 3 ,LiNSO 2 CF 5 ,LiNSO 2 C 4 F 9 ,LiNSO 2 C 5 F11 , LiNSO 2 C 6 F 13 , LiNSO 2 C 7 F 15 It contains organolithium salts such as these. Exemplary organic solvents for dissolving the lithium salt include cyclic esters, chain esters, cyclic ethers, and chain ethers. Specific examples of cyclic esters include propylene carbonate, butylene carbonate, γ-butyrolactone, vinylene carbonate, 2-methyl-γ-butyrolactone, acetyl-γ-butyrolactone, and γ-valerolactone. Specific examples of chain esters include dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dipropyl carbonate, methyl ethyl carbonate, methyl butyl carbonate, methyl propyl carbonate, ethyl butyl carbonate, ethyl propyl carbonate, butyl propyl carbonate, alkyl propionate, dialkyl malonate, and alkyl acetate. Specific examples of cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, dialkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, and 1,4-dioxolane. Specific examples of chain ethers include 1,2-dimethoxyethane, 1,2-diethoxyethane, diethyl ether, ethylene glycol dialkyl ether, diethylene glycol dialkyl ether, triethylene glycol dialkyl ether, and tetraethylene glycol dialkyl ether. Specific examples of cyclic ethers include tetrahydrofuran, alkyltetrahydrofuran, dialkyltetrahydrofuran, alkoxytetrahydrofuran, dialkoxytetrahydrofuran, 1,3-dioxolane, alkyl-1,3-dioxolane, 1,4-dioxolane. Further examples include alkoxy solutions having carrier ions, dichloro complex electrolytes, organic borates, organohalides, organohaloaluminates, Grignard organohaloaluminates, boron hydrides, phenolates, and halooxides.

[0067] As shown in FIG. 5, the auxiliary electrode is a component of the completed secondary battery. In an alternative embodiment, the auxiliary electrode is removed from the secondary battery cell after replenishment of the positive or negative electrode but before final packaging.

[0068] Including an auxiliary electrode in the secondary battery cell has important advantages for battery monitoring and maintenance. For example, the auxiliary electrode functions as a reference electrode and is used for accurate measurement of the state of charge and state of health, enabling measurement of the change in the relationship between the cell voltage and the state of charge over time, or when the cell voltage is relatively independent of the state of charge. For example, the auxiliary electrode can act as a reference electrode to interrupt discharge when the voltage of the negative electrode exceeds a certain limit with respect to the auxiliary electrode. In one such embodiment, this can be implemented by detecting the voltage at the negative electrode with respect to the auxiliary electrode using a sensor, and the controller separates the cell from the circuit that was supplying power when a predetermined voltage limit is exceeded.

[0069] In one embodiment, when the charge state of one electrode is outside a predetermined range, the auxiliary electrode is accessed to transport carrier ions to the positive electrode and / or the negative electrode to restore the charge state to a predetermined charge state. For example, at a certain point in the life of a secondary battery, when the control unit detects that the negative electrode has a discharge end voltage Vneg,eod value exceeding 0.9 V (vs. Li), the control unit can activate the transport of carrier ions from the auxiliary electrode to the positive electrode and / or the negative electrode to restore Vneg,eod to a value less than 0.9 V (vs. Li). As a further example, at a certain point in the life of a secondary battery, when the control unit detects that the negative electrode has a discharge end voltage Vneg,eod value exceeding 0.8 V (vs. Li), the control unit can activate the transport of carrier ions from the auxiliary electrode to the positive electrode and / or the negative electrode (as described above) to restore Vneg,eod to a value less than 0.8 V (vs. Li). As a further example, at a certain point in the life of a secondary battery, when the control unit detects that the negative electrode has a discharge end voltage Vneg,eod value exceeding 0.7 V (vs. Li), the control unit can activate the transport of carrier ions from the auxiliary electrode to the positive electrode and / or the negative electrode (as described above) to restore Vneg,eod to a value less than 0.7 V (vs. Li). As a further example, at a certain point in the life of a secondary battery, when the control unit detects that the negative electrode has a discharge end voltage Vneg,eod value exceeding 0.6 V (vs. Li), the control unit can activate the transport of carrier ions from the auxiliary electrode to the positive electrode and / or the negative electrode (as described above) to restore Vneg,eod to a value less than 0.6 V (vs. Li).

[0070] In one alternative embodiment, carrier ions can be transported from the positive electrode to the auxiliary electrode to restore a pre-determined state of charge or to balance the electrode(s). For example, some positive electrode materials have a first cycle loss that significantly exceeds the first cycle of the negative electrode of the cell. In such embodiments, the difference in the first cycle losses of the positive and negative electrodes can be compensated by providing a negative electrode having a reversible coulombic capacity that significantly exceeds the reversible coulombic capacity of the positive electrode. Alternatively, or in addition, the difference in the first cycle losses can be accommodated by transporting carrier ions from the positive electrode to the auxiliary electrode during formation of the battery.

[0071] Referring to FIG. 6, in one alternative embodiment, the secondary battery 10 includes a plurality of positive electrode structures 20, a plurality of negative electrode structures 22, one auxiliary electrode 24, one control unit 27, and a substrate 29 that supports those positive and negative electrode structures. Each positive electrode structure includes a positive electrode current collector 21 and a cathode active material 120 that directly contacts and covers the positive electrode current collector 21. Also, each negative electrode structure includes a negative electrode current collector 23 and an anode active material 122 that directly contacts and covers the negative electrode current collector 23. When the secondary battery 10 includes a plurality of positive electrode structures 20 as shown in FIG. 6, those positive electrode structures may be electrically coupled to each other. Similarly, when the secondary battery 10 includes a plurality of negative electrode structures 22 as shown in FIG. 6, those negative electrode structures may be electrically coupled to each other. The control unit 27 includes sensors for detecting the cell voltage (i.e., the voltage difference between the positive and negative electrodes) and for detecting the voltage difference between the auxiliary electrode and (i) the positive electrode, (ii) the negative electrode, or (iii) each of the positive and negative electrodes. The control unit further includes a controller for communicating with its sensors to control the charge and discharge operation of the battery and the transport of carrier ions from the auxiliary electrode to the positive and / or negative electrodes, as described elsewhere herein.

[0072] In one embodiment, the anode active material 122 is in the form of a layer having a thickness of about 1 to about 100 micrometers. For example, in one embodiment, the anode active material 122 comprises porous silicon, has a thickness of about 5 to about 100 micrometers, and has a void volume fraction of about 0.15 to about 0.75. As a further example, in one embodiment, the anode active material 122 comprises porous silicon, has a thickness of about 10 to about 80 micrometers, and has a void volume fraction of about 0.15 to about 0.7. As a further example, in one such embodiment, the anode active material 122 comprises porous silicon, has a thickness of about 20 to about 50 micrometers, and has a void volume fraction of about 0.25 to about 0.6. As a further example, in one embodiment, the anode active material 122 comprises a porous silicon alloy (such as nickel silicide), has a thickness of about 5 to about 100 micrometers, and has a void volume fraction of about 0.15 to about 0.75.

[0073] In another embodiment, the anode active material 122 comprises silicon nanowire(s), has a thickness of about 5 to about 100 micrometers, and has a void volume fraction of about 0.15 to about 0.75. For example, in one such embodiment, the anode active material 122 comprises silicon nanowire(s), has a thickness of about 10 to about 80 micrometers, and has a void volume fraction of about 0.15 to about 0.7. As a further example, in one such embodiment, the anode active material 122 comprises silicon nanowire(s), has a thickness of about 20 to about 50 micrometers, and has a void volume fraction of about 0.25 to about 0.6. As a further example, in one embodiment, the anode active material 122 comprises nanowire(s) of a silicon alloy (such as nickel silicide), has a thickness of about 5 to about 100 micrometers, and has a void volume fraction of about 0.15 to about 0.75.

[0074] The negative electrode current collector 23 typically has a conductivity of at least about 10 3 Siemens / cm. For example, in one such embodiment, the negative electrode current collector 23 has a conductivity of at least about 10 4It has a conductivity of Siemens / cm. As a further example, in one such embodiment, the negative current collector 23 is at least about 10 5 It has a conductivity of Siemens / cm. Generally, the negative current collector 23 can include any metal or other conductor conventionally used as a current collector material for the negative electrode, such as carbon, cobalt, chromium, copper, nickel, titanium, or an alloy of one or more of them. The negative current collector 23 can be manufactured by processes such as electrodeposition, electroless deposition, immersion deposition, physical vapor deposition, chemical vapor deposition, etc.

[0075] The separator 25 surrounds each member element 20 of the positive electrode structure population and electrically separates it from each member element 22 of the negative electrode structure population, and includes a microporous separator material that can be impregnated with a non-aqueous electrolyte as described above. For example, in one embodiment, the microporous separator material includes pores with a diameter of at least 50 Å, more typically about 2500 Å, and has a void volume fraction in the range of about 25% to about 75%, more typically in the range of about 35% to about 55%.

[0076] Also, the separator 25 electrically insulates the auxiliary electrode 24 from the positive and negative electrode structures 20, 22. As shown in the figure, the separator 25 can include the same microporous material in the region between the auxiliary electrode 24 and the negative and positive electrode structures 20, 22 as in the region between the positive electrode structure 20 and the negative electrode structure 22. Alternatively, the separator 25 can include a microporous material compositionally different from the microporous material in the region between the positive electrode structure 20 and the negative electrode structure 22 in the region between the auxiliary electrode 24 and the negative and positive electrode structures 20, 22.

[0077] In an embodiment where the voltage difference between the auxiliary electrode and the positive electrode is greater than the voltage difference between the auxiliary electrode and the negative electrode between the charge limit and the discharge limit, the positive electrode can be replenished more rapidly than the negative electrode. Further, in an embodiment where the transport of carrier ions involves a phase change reaction, i.e., converting crystalline silicon to amorphous silicon, directly transporting carrier ions from the auxiliary electrode to the negative electrode may result in a non-uniform concentration of carrier ions within the negative electrode (carrier ions tend to concentrate in the location closest to the auxiliary electrode). Thus, in such an embodiment, it may be preferable to recharge the secondary battery by transporting carrier ions from the auxiliary electrode to the positive electrode and then to the negative electrode, rather than directly from the auxiliary electrode to the negative electrode. Nevertheless, there are some embodiments in which it may be advantageous to electrically couple the auxiliary electrode 24 to the negative electrode structure 22 instead of (or in addition to) the positive electrode structure 20 (and otherwise as shown in FIG. 6). For example, in one such embodiment, the auxiliary electrode 24 is electrically coupled to the negative electrode structure 22 and has the ability to function as an auxiliary negative electrode. The combination of the negative electrode structure 22 and the auxiliary negative electrode can achieve better performance than the negative electrode alone.

[0078] As described above, the secondary battery 10 includes a group of negative electrode structures 22 and a group of positive electrode structures 20. As shown in FIG. 6, in one embodiment, the member elements of the two groups are engaged with each other and stacked in an alternating order (that is, negative electrode structure, positive electrode structure, negative electrode structure, positive electrode structure,...). For ease of illustration, in FIG. 6, the group of positive electrode structures includes four member elements 20, and the group of negative electrode structures includes three member elements 22. However, in practice, the group of negative electrode structures and the group of positive electrode structures can each include a greater or lesser number of member elements. For example, in one embodiment, the group of negative electrode structures and the group of positive electrode structures included in the secondary battery of the present disclosure can each include at least five member elements. As a further example, in one embodiment, the group of negative electrode structures and the group of positive electrode structures each include at least ten member elements. As a further example, in one embodiment, the group of negative electrode structures and the group of positive electrode structures each include at least fifty member elements. As a further example, in one embodiment, the group of negative electrode structures and the group of positive electrode structures each include at least one hundred member elements.

[0079] In FIG. 6, each member element 22 of the negative electrode group is between two member elements 20 of the positive electrode structure group, and the engaged series starts and ends with the positive electrode structure 20, and each negative electrode structure 22 is between two positive electrode structures 20 (for example, a series of electrodes has the following repeating order: positive electrode, negative electrode, positive electrode, negative electrode, positive electrode,...). For example, in one such embodiment, the negative electrode structure group has N member elements, the positive electrode structure group has N + 1 member elements, each negative electrode is between two positive electrodes, and N is at least 5, at least 10, at least 25, at least 50, or at least 100.

[0080] In one alternative embodiment, with one exception, each member element 22 of the population of negative electrode structures is between two member elements 20 of the population of positive electrode structures, and with one exception, each member element 20 of the population of positive electrode structures is between two member elements 22 of the population of negative electrode structures. More generally, in one embodiment, the population of positive electrode structures and the population of negative electrode structures each have N member elements, each of the N - 1 positive electrode structures is between two negative electrode structures, each of the N - 1 negative electrode structures is between two positive electrode structures, and N is at least 2. For example, in one embodiment, N is at least 4 (as shown in FIG. 4), at least 5, at least 10, at least 25, at least 50, or even at least 100.

[0081] In another alternative embodiment, for example, each member element 20 of the population of positive electrode structures is between two member elements 22 of the population of negative electrode structures, such that the intermeshed sequence starts and ends with a negative electrode structure 22 and each positive electrode structure 20 is between two negative electrode structures 22 (e.g., including a sequence of electrodes having the following repeating order: negative electrode, positive electrode, negative electrode, positive electrode, negative electrode,...). In one such embodiment, the population of positive electrode structures has N member elements, the population of negative electrode structures has N + 1 member elements, each positive electrode structure is between two negative structures, and N is at least 5, at least 25, at least 50, or even at least 100.

[0082] As shown in FIG. 6, the auxiliary electrode 24 is shown as a single element. In certain embodiments, the auxiliary electrode can include a plurality of auxiliary electrode elements or portions. For example, in one embodiment, the auxiliary electrode can include a lithium metal layer deposited (e.g., sputter deposited) on the positive current collector, the negative current collector, a substrate supporting the positive electrode structure, a substrate supporting the negative electrode structure (see, e.g., FIG. 6), or other surfaces or structures within the secondary battery such as, for example, the battery enclosure. Further, the auxiliary electrode may be consumed during the battery formation process or, after formation, the auxiliary electrode may contain sufficient lithium such that it can be accessed to provide additional lithium to the positive or negative electrode structures.

[0083] Referring now to FIG. 7, in one alternative embodiment, the secondary battery 10 includes an electrode assembly laminate 74 and a control unit 27. In this embodiment, the electrode assembly laminate 74 includes two electrode assemblies 75, each including a population of positive electrode structures 20, a population of negative electrode structures 22, a substrate 29 supporting the positive and negative electrode structures, and an auxiliary electrode 24. In this embodiment, the electrode assemblies are stacked relative to each other in a direction perpendicular to the planar substrate 29. The populations of positive and negative electrode structures are stacked relative to each other in a direction parallel to the planar substrate 29 within each electrode assembly 75. The control unit 27 is electrically connected to the positive electrode structure, the negative electrode structure, and the auxiliary electrode and is operable to replenish each electrode assembly 75 with carrier ions as described above. For ease of illustration, each of the electrode assemblies 75 is shown including two populations of negative electrode structures and two populations of positive electrode structures. In practice, each of these populations can include a greater number of member elements. Further, in certain embodiments, the substrate 29 can be omitted, in which case the stacking (layering) direction (as described in this paragraph) is referenced to a virtual plane parallel to the substrate 29.

[0084] Now, referring to FIG. 8, in one embodiment, the secondary battery 10 of the present disclosure includes a battery enclosure 72, an electrode assembly laminate 74, an auxiliary electrode 24, a negative tab 41 and a positive tab 42 for electrically connecting the electrode assembly laminate 74 to an external energy supply source or consumer (not shown), and a control unit (not shown) including the sensors and controllers as described above. The electrode assembly laminate 74 includes a group of six electrode assemblies 75 stacked vertically with respect to each other, and the stacking direction is perpendicular to the stacking direction of the positive and negative electrodes within each electrode assembly 75 (see FIG. 9). The number of electrode assemblies 75 within the electrode assembly laminate 74 is not of critical significance and can be, for example, in the range of 1 to 50, and it is typical to have 2 to 20 electrode structures within one electrode laminate. After filling the battery enclosure with a non-aqueous electrolyte, the battery enclosure 72 can be sealed by folding a lid 72A with a hinge 72B and adhering the lid 72A to an upper surface 72C. As will be described in more detail below, the auxiliary electrode 24 may be incorporated (i.e., as one of its components) within the sealed secondary battery. Alternatively, it may be accessed during the formation of the secondary battery and removed prior to sealing as described above.

[0085] The negative tab extension 25 is electrically connected to each negative electrode structure 22 (see FIG. 9) of each electrode assembly 75, and the positive tab extension 26 is electrically connected to the positive electrode structure 20 (see FIG. 8) of each electrode assembly 75. The tab 41 can be electrically connected to the negative tab extension 25 using, for example, a conductive adhesive, and the tab 42 can be electrically connected to the positive tab extension 26 using, for example, a conductive adhesive. Alternatively, the tabs 41, 42 may be the folded ends of the negative tab extension 25 and the positive tab extension 26, respectively.

[0086] Now, referring to FIG. 9, each electrode assembly 75 includes a population of negative electrode structures 22, a population of positive electrode structures 20, and a porous separator (not shown), as described in more detail with respect to FIGS. 5 and 6. The member elements of the two populations are intermeshed and stacked in an alternating order in a direction D (which is perpendicular to the stacking direction of the electrode assemblies 75 in the electrode assembly laminate 74 (see FIG. 7)).

[0087] Now, referring to FIG. 10, in one alternative embodiment, the secondary battery 10 of the present disclosure, although separately described with respect to FIG. 9, includes two auxiliary electrode structures at the upper and lower portions of the laminate 74. A control unit (not shown) included in the battery is operable to replenish each of the electrode assemblies 75 from one or both of the auxiliary electrodes, as described above.

[0088] Here, referring to FIG. 11, in another embodiment, the electrode assembly 75 includes an auxiliary electrode 24 and populations of positive electrode structures 20 and negative electrode structures 22 each including a positive electrode backbone 80 and a negative electrode backbone 82, respectively. Also, in this embodiment, each member element 20 of the population of positive electrode structures includes a current collector 21 disposed between the backbone 80 and the cathode active material 120. Each member element 22 of the negative electrode structure includes a current collector 23 on the surface of the member element (i.e., at the interface between the anode active material 122 and the separator 25). The positive electrode backbone 80 and the negative electrode backbone 82 each provide mechanical stability to the cathode active material layer 120 and the anode active material layer 122. Typically, those backbones have a thickness of at least 1 micrometer. Depending on the application, the positive electrode backbone 80 and the negative electrode backbone 82 may be independently conductive or insulating.

[0089] Now, referring to FIG. 12, in this alternative embodiment, although the electrode assembly laminate 74 has been separately described with respect to FIGS. 7 and 11, in this embodiment, the electrode assembly laminate 74 includes more auxiliary electrode structures 24 than the electrode assemblies in those electrode assembly laminates. A control unit (not shown) included in the battery is operable to replenish each electrode assembly 75 from one or more of the auxiliary electrode structures, as described above.

[0090] In the following further embodiments numbered 1 to 84, aspects of the present disclosure include the following.

[0091] Embodiment 1 A method for activating a secondary battery, wherein the secondary battery includes a negative electrode, a positive electrode, a microporous separator impregnated with a carrier ion-containing electrolyte in ionic contact with the negative electrode and the positive electrode, and a control unit, the negative electrode includes an anodically active silicon or an alloy of this anodically active silicon and has a Coulombic capacity for the carrier ions, the positive electrode includes a cathodically active material and has a Coulombic capacity for the carrier ions, the Coulombic capacity of the negative electrode exceeds the Coulombic capacity of the positive electrode, the method includes (i) transporting carrier ions from the positive electrode to the negative electrode to at least partially charge the secondary battery, and forming a solid electrolyte interphase on the surface of the negative electrode during the transport, (ii) after step (i), transporting carrier ions from an auxiliary electrode to the positive electrode, (iii) after step (ii), transporting carrier ions from the positive electrode to the negative electrode to charge the secondary battery, and (iv) programming the control unit with a predetermined cell discharge end voltage Vcell,eod value. When the above-activated secondary battery has the cell at the above predetermined Vcell,eod value, it has a positive electrode discharge cut-off voltage Vpos,eod and a negative electrode discharge cut-off voltage Vneg,eod. The value of Vpos,eod corresponds to the voltage at which the state of charge of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0092] Embodiment 2 In the method of Embodiment 1, When the above cell is at Vcell,eod, the value of the above Vpos,eod corresponds to the voltage at which the state of charge of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0093] Embodiment 3 In the method of Embodiment 1, When the above cell is at Vcell,eod, the value of the above Vpos,eod corresponds to the voltage at which the state of charge of the positive electrode is at least 96% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0094] Embodiment 4 In the method of Embodiment 1, When the above cell is at Vcell,eod, the value of the above Vpos,eod corresponds to the voltage at which the state of charge of the positive electrode is at least 97% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0095] Embodiment 5 In the method of Embodiment 1, When the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 98% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li).

[0096] Embodiment 6 In the method of Embodiment 1, When the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 99% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li).

[0097] Embodiment 7 In any of the methods of Embodiments 1 to 6, When the cell is at Vcell,eod, Vneg,eod is at least 0.4 V (versus Li) but less than 0.8 V (versus Li).

[0098] Embodiment 8 In any of the methods of Embodiments 1 to 6, When the cell is at Vcell,eod, Vneg,eod is at least 0.5 V (versus Li) but less than 0.8 V (versus Li).

[0099] Embodiment 9 In any of the methods of Embodiments 1 to 6, When the cell is at Vcell,eod, Vneg,eod is at least 0.4 V (versus Li) but less than 0.7 V (versus Li).

[0100] Embodiment 10 In any of the methods of Embodiments 1 to 6, When the cell is at Vcell,eod, Vneg,eod is at least 0.5 V (versus Li) but less than 0.7 V (versus Li).

[0101] Embodiment 11 A secondary battery having a negative electrode, a positive electrode, a microporous separator impregnated with a carrier ion-containing electrolyte in ion contact with the negative electrode and the positive electrode between the negative electrode and the positive electrode, an auxiliary electrode, and a control unit, The positive electrode includes a cathode active material and has a Coulomb capacity for the carrier ions, The negative electrode includes an anodic active silicon or an alloy of the anodic active silicon and has a Coulomb capacity for the carrier ions that exceeds the Coulomb capacity of the positive electrode, The control unit includes a controller and a sensor electrically coupled to the sensor, The sensor is configured to measure the cell voltage of the secondary battery and the voltage of the positive electrode or the negative electrode with respect to the auxiliary electrode of the secondary battery during operation of the secondary battery, The controller has a predetermined cell charge termination voltage Vcell,eoc value and a predetermined cell discharge termination voltage Vcell,eod value, When the cell is at the predetermined Vcell,eod value, the positive electrode has a discharge termination voltage Vpos,eod, and the negative electrode has a discharge termination voltage Vneg,eod. The value of Vpos,eod corresponds to a voltage at which the charge state of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li). A secondary battery characterized by this.

[0102] Embodiment 12 In the secondary battery of Embodiment 11, The controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode when the value of Vneg,eod exceeds 0.9 V (versus Li) when the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery. A secondary battery characterized by this.

[0103] Embodiment 13 In the secondary battery of Embodiment 11, when the controller determines that the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery, and when the value of Vneg,eod exceeds 0.8 V (versus Li), the controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode. The secondary battery is characterized by this.

[0104] Embodiment 14 In the secondary battery of Embodiment 11, when the controller determines that the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery, and when the value of Vneg,eod exceeds 0.7 V (versus Li), the controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode. The secondary battery is characterized by this.

[0105] Embodiment 15 In the secondary battery of Embodiment 11, when the controller determines that the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery, and when the value of Vneg,eod exceeds 0.6 V (versus Li), the controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode. The secondary battery is characterized by this.

[0106] Embodiment 16 In the secondary battery of Embodiment 11, when the controller determines that the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery, and when the value of Vneg,eod exceeds 0.5 V (versus Li), the controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode. The secondary battery is characterized by this.

[0107] Embodiment 17 Any method of Embodiments 1 to 10 or any secondary battery of Embodiments 11 to 16, The carrier ions are lithium ions, sodium ions, potassium ions, magnesium ions or aluminum ions.

[0108] Embodiment 18 A method according to any one of Embodiments 1 to 10 or a secondary battery according to any one of Embodiments 11 to 16, wherein the carrier ions are lithium ions, magnesium ions or aluminum ions.

[0109] Embodiment 19 A method according to any one of Embodiments 1 to 10 or a secondary battery according to any one of Embodiments 11 to 16, wherein the carrier ions are lithium ions.

[0110] Embodiment 20 A method according to any one of Embodiments 1 to 10 or a secondary battery according to any one of Embodiments 11 to 16, wherein the carrier ions are magnesium ions.

[0111] Embodiment 21 A method or a secondary battery according to any of the above embodiments, when circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 1.2:1 in this order.

[0112] Embodiment 22 A method or a secondary battery according to any of the above embodiments, when circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 1.3:1 in this order.

[0113] Embodiment 23 A method or a secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 1.5:1 in this order.

[0114] Embodiment 24 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 2:1 in this order.

[0115] Embodiment 25 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 3:1 in this order.

[0116] Embodiment 26 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 4:1 in this order.

[0117] Embodiment 27 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 5:1 in this order.

[0118] Embodiment 28 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacity of the auxiliary electrode to the reversible Coulomb capacity of the positive electrode is at least 1.2:1 in this order.

[0119] Embodiment 29 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 1.3:1 in this order.

[0120] Embodiment 30 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 1.5:1 in this order.

[0121] Embodiment 31 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 2:1 in this order.

[0122] Embodiment 32 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 3:1 in this order.

[0123] Embodiment 33 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 4:1 in this order.

[0124] Embodiment 34 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 5:1 in this order.

[0125] Embodiment 35 The method or secondary battery according to any of the above embodiments, wherein the negative electrode includes a microstructured silicon-containing active material having a significant void volume ratio to accommodate volume expansion and contraction associated with the incorporation or release of carrier ions into or from the negative electrode during charge and discharge cycles.

[0126] Embodiment 36 The method or secondary battery according to Embodiment 35, wherein the void volume ratio of the anode active material is at least 0.1.

[0127] Embodiment 37 The method or secondary battery according to Embodiment 35 or 36, wherein the void volume ratio of the anode active material is less than 0.8.

[0128] Embodiment 38 The method or secondary battery according to Embodiment 35 or 36, wherein the void volume ratio of the anode active material is from about 0.15 to about 0.75.

[0129] Embodiment 39 The method or secondary battery according to Embodiment 35 or 36, wherein the void volume ratio of the anode active material is from about 0.2 to about 0.7.

[0130] Embodiment 40 The method or secondary battery according to Embodiment 35 or 36, wherein the void volume ratio of the anode active material is from about 0.25 to about 0.6.

[0131] Embodiment 41 The method or secondary battery according to Embodiment 35 or 36, wherein the microstructured anode active material comprises a macroporous, microporous or mesoporous material layer, or a combination of these material layers.

[0132] Embodiment 42 A method for activating a secondary battery, wherein the secondary battery includes a negative electrode, a positive electrode, a microporous separator impregnated with a carrier ion-containing electrolyte that is in ionic contact with the negative electrode and the positive electrode between the negative electrode and the positive electrode, and a control unit programmed with a predetermined cell discharge end voltage Vcell,eod value, the negative electrode includes an anode active silicon or an alloy of the anode active silicon and has a Coulomb capacity for the carrier ions, the positive electrode includes a cathode active material and has a Coulomb capacity for the carrier ions, the Coulomb capacity of the negative electrode exceeds the Coulomb capacity of the positive electrode, the method includes (i) transporting carrier ions from the positive electrode to the negative electrode to at least partially charge the secondary battery, and forming a solid electrolyte interphase on the surface of the negative electrode during the transport, and (ii) transporting carrier ions from an auxiliary electrode to the positive electrode to apply a positive electrode discharge end voltage Vpos,eod and a negative electrode discharge end voltage Vneg,eod to the secondary battery when the cell is at the predetermined Vcell,eod value, where the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

[0133] Embodiment 43 In the method of Embodiment 42, the method is characterized in that step (ii) is performed after step (i) or simultaneously with step (i).

[0134] Embodiment 44 In the method of Embodiment 43, when step (ii) is performed after step (i), Furthermore, after step (ii), the method is characterized by comprising a step (iii) of transporting carrier ions from the positive electrode to the negative electrode to charge the secondary battery.

[0135] Embodiment 45 In the method of Embodiment 43, step (ii) is performed simultaneously with step (i), step (ii) includes transporting carrier ions from the auxiliary electrode to the negative electrode at a first rate, and step (i) includes transporting carrier ions from the positive electrode to the negative electrode at a second rate, the method is characterized in that the second rate is higher than the first rate.

[0136] Embodiment 46 In the method of Embodiment 42, when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li), the method being characterized thereby.

[0137] Embodiment 47 In the method of Embodiment 42, when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 96% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li), the method being characterized thereby.

[0138] Embodiment 48 In the method of Embodiment 42, when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 97% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li), the method being characterized thereby.

[0139] Embodiment 49 In the method of Embodiment 42, when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 98% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li).

[0140] Embodiment 50 In the method of Embodiment 42, when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 99% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (versus Li) but less than 0.9 V (versus Li).

[0141] Embodiment 51 In any of the methods from Embodiment 42 to 50, when the cell is at Vcell,eod, Vneg,eod is at least 0.4 V (versus Li) but less than 0.8 V (versus Li).

[0142] Embodiment 52 In any of the methods from Embodiment 42 to 50, when the cell is at Vcell,eod, Vneg,eod is at least 0.5 V (versus Li) but less than 0.8 V (versus Li).

[0143] Embodiment 53 In any of the methods from Embodiment 42 to 50, when the cell is at Vcell,eod, Vneg,eod is at least 0.4 V (versus Li) but less than 0.7 V (versus Li).

[0144] Embodiment 54 In any of the methods from Embodiment 42 to 50, A method characterized in that when the above cell is at Vcell,eod, Vneg,eod is at least 0.5 V (vs. Li) but less than 0.7 V (vs. Li).

[0145] Embodiment 55 A secondary battery having a negative electrode, a positive electrode, a microporous separator impregnated with a carrier-ion-containing electrolyte that is in ionic contact with the negative electrode and the positive electrode between the negative electrode and the positive electrode, an auxiliary electrode, and a control unit, The positive electrode includes a cathode active material and has a Coulomb capacity for the carrier ions, The negative electrode includes an anodic active silicon or an alloy of this anodic active silicon and has a Coulomb capacity for the carrier ions that exceeds the Coulomb capacity of the positive electrode, The control unit includes a controller and a sensor electrically coupled to the sensor, The sensor is configured to measure the cell voltage of the secondary battery and the voltage of the positive electrode or the negative electrode with respect to the auxiliary electrode of the secondary battery during operation of the secondary battery, The controller is programmed with a predetermined cell charge termination voltage Vcell,eoc value and a predetermined cell discharge termination voltage Vcell,eod value, When the cell is at the predetermined Vcell,eod value, the positive electrode has a discharge termination voltage Vpos,eod, the negative electrode has a discharge termination voltage Vneg,eod, the value of Vpos,eod corresponds to a voltage at which the charge state of the positive electrode is at least 95% of the Coulomb capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li). A secondary battery characterized by this.

[0146] Embodiment 56 In the secondary battery of Embodiment 55, The controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode when the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery and the value of Vneg,eod exceeds 0.9 V (vs. Li). A secondary battery characterized by this.

[0147] Embodiment 57 In the secondary battery of Embodiment 55, The controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode when the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery and the value of Vneg,eod exceeds 0.8 V (vs. Li). A secondary battery characterized by this.

[0148] Embodiment 58 In the secondary battery of Embodiment 55, The controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode when the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery and the value of Vneg,eod exceeds 0.7 V (vs. Li). A secondary battery characterized by this.

[0149] Embodiment 59 In the secondary battery of Embodiment 55, The controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode when the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery and the value of Vneg,eod exceeds 0.6 V (vs. Li). A secondary battery characterized by this.

[0150] Embodiment 60 In the secondary battery of Embodiment 55, When the secondary battery is at the predetermined Vcell,eod value at the end of the discharge cycle of the secondary battery, the controller is programmed to transport carrier ions from the auxiliary electrode to the positive electrode or the negative electrode when the value of Vneg,eod exceeds 0.5 V (versus Li). A secondary battery characterized by this.

[0151] Embodiment 61 A method according to any one of Embodiments 42 to 54 or a secondary battery according to any one of Embodiments 55 to 60, wherein the carrier ions are lithium ions, sodium ions, potassium ions, magnesium ions or aluminum ions.

[0152] Embodiment 62 A method according to any one of Embodiments 42 to 54 or a secondary battery according to any one of Embodiments 55 to 60, wherein the carrier ions are lithium ions, magnesium ions or aluminum ions.

[0153] Embodiment 62 A method according to any one of Embodiments 42 to 54 or a secondary battery according to any one of Embodiments 55 to 60, wherein the carrier ions are lithium ions.

[0154] Embodiment 63 A method according to any one of Embodiments 42 to 54 or a secondary battery according to any one of Embodiments 55 to 60, wherein the carrier ions are magnesium ions.

[0155] Embodiment 64 A method or secondary battery according to any of the above embodiments, when circulated with respect to the counter electrode, the ratio of the reversible Coulombic capacity of the negative electrode to the reversible Coulombic capacity of the positive electrode is at least 1.2:1 in this order.

[0156] Embodiment 65 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 1.3:1 in this order.

[0157] Embodiment 66 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 1.5:1 in this order.

[0158] Embodiment 67 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 2:1 in this order.

[0159] Embodiment 68 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 3:1 in this order.

[0160] Embodiment 69 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 4:1 in this order.

[0161] Embodiment 70 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the reversible Coulomb capacity of the negative electrode to the reversible Coulomb capacity of the positive electrode is at least 5:1 in this order.

[0162] Embodiment 71 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 1.2:1 in this order.

[0163] Embodiment 72 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 1.3:1 in this order.

[0164] Embodiment 73 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 1.5:1 in this order.

[0165] Embodiment 74 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 2:1 in this order.

[0166] Embodiment 75 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 3:1 in this order.

[0167] Embodiment 76 The method or secondary battery according to any of the above embodiments, When circulated with respect to the counter electrode, the ratio of the Coulomb capacitance of the auxiliary electrode to the reversible Coulomb capacitance of the positive electrode is at least 4:1 in this order.

[0168] Embodiment 77 A method or secondary battery according to any of the above embodiments, when circulated with respect to the counter electrode, the ratio of the Coulombic capacity of the auxiliary electrode to the reversible Coulombic capacity of the positive electrode is at least 5:1 in this order.

[0169] Embodiment 78 A method or secondary battery according to any of the above embodiments, wherein the negative electrode includes a microstructured silicon-containing active material having a significant void volume ratio to adapt to the volume expansion and contraction accompanying the incorporation or departure of carrier ions into or from the negative electrode during charge and discharge cycles.

[0170] Embodiment 79 A method or secondary battery according to Embodiment 78, wherein the void volume ratio of the anode active material is at least 0.1.

[0171] Embodiment 80 A method or secondary battery according to Embodiment 78, wherein the void volume ratio of the anode active material is less than 0.8.

[0172] Embodiment 81 A method or secondary battery according to Embodiment 78, wherein the void volume ratio of the anode active material is about 0.15 to about 0.75.

[0173] Embodiment 82 A method or secondary battery according to Embodiment 78, wherein the void volume ratio of the anode active material is about 0.2 to about 0.7.

[0174] Embodiment 83 A method or secondary battery according to Embodiment 78, wherein the void volume ratio of the anode active material is about 0.25 to about 0.6.

[0175] Embodiment 84 The method or secondary battery of Embodiment 78, wherein the microstructured anode active material comprises a macroporous, microporous or mesoporous material layer, or a combination of those material layers.

[0176] Without departing from the scope of the present disclosure, various changes can be made to the above articles, compositions and methods. In that case, all matters included in the above description and shown in the accompanying drawings are intended to be illustrative and not construed in a limiting sense.

Claims

1. 1. A method for compensating for loss of carrier ions due to formation of a solid electrolyte interphase in a secondary battery during a first or subsequent charge cycle of the battery, comprising: The secondary battery comprises a negative electrode, a positive electrode, a microporous separator between the negative electrode and the positive electrode, impregnated with a carrier ion-containing electrolyte in ionic contact with the negative electrode and the positive electrode, and a control unit programmed to cycle the secondary battery between a predetermined cell end-of-charge voltage Vcell,eoc value and a predetermined cell end-of-discharge voltage Vcell,eod value; the negative electrode comprises an anode-active silicon or an alloy of the anode-active silicon and has a coulombic capacity for the carrier ions; the positive electrode includes a cathode active material and has a coulombic capacity for the carrier ions; the coulombic capacity of the negative electrode exceeds the coulombic capacity of the positive electrode; The above method is (i) transporting carrier ions from the positive electrode to the negative electrode during a first or subsequent charging cycle to at least partially charge the secondary battery, thereby forming a solid electrolyte interphase at a surface of the negative electrode during said transport; and (ii) transporting carrier ions from an auxiliary electrode including a source of carrier ions and electrolytically coupled to the negative electrode and / or the positive electrode through the separator until, when the cell is at the predetermined value of Vcell,eod, the positive electrode has an end-of-discharge voltage Vpos,eod, and the negative electrode has an end-of-discharge voltage Vneg,eod, where Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of its coulombic capacity, and Vneg,eod is at least 0.4 V vs. Li but less than 0.9 V vs. Li.

2. 10. The method of claim 1 , A method characterized in that step (ii) is carried out after or simultaneously with step (i).

3. 3. The method of claim 2, When step (ii) is carried out after step (i), The method further comprises, after step (ii), a step (iii) of transporting carrier ions from the positive electrode to the negative electrode to charge the secondary battery.

4. 3. The method of claim 2, step (ii) is performed simultaneously with step (i), step (ii) including transporting carrier ions from the auxiliary electrode to the negative electrode at a first rate, and step (i) including transporting carrier ions from the positive electrode to the negative electrode at a second rate; The method of claim 1, wherein the second speed is greater than the first speed.

5. 10. The method of claim 1 , when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage where the state of charge of the positive electrode is at least 95% of the coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

6. 10. The method of claim 1 , when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage where the state of charge of the positive electrode is at least 96% of the coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

7. 10. The method of claim 1 , when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage where the state of charge of the positive electrode is at least 97% of the coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

8. 10. The method of claim 1 , when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage where the state of charge of the positive electrode is at least 98% of the coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

9. 10. The method of claim 1 , when the cell is at Vcell,eod, the value of Vpos,eod corresponds to a voltage where the state of charge of the positive electrode is at least 99% of the coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

10. The method according to any one of claims 1 to 9, The method of claim 1, wherein when the cell is at Vcell,eod, Vneg,eod is at least 0.4 V (vs. Li) but less than 0.8 V (vs. Li).

11. The method according to any one of claims 1 to 9, The method of claim 1, wherein when the cell is at Vcell,eod, Vneg,eod is at least 0.5 V (vs. Li) but less than 0.8 V (vs. Li).

12. The method according to any one of claims 1 to 9, The method of claim 1, wherein when the cell is at Vcell,eod, Vneg,eod is at least 0.4 V (vs. Li) but less than 0.7 V (vs. Li).

13. The method according to any one of claims 1 to 9, The method of claim 1, wherein when the cell is at Vcell,eod, Vneg,eod is at least 0.5 V (vs. Li) but less than 0.7 V (vs. Li).

14. A secondary battery having a negative electrode, a positive electrode, a microporous separator between the negative electrode and the positive electrode, the microporous separator being impregnated with a carrier ion-containing electrolyte in ionic contact with the negative electrode and the positive electrode, and a control unit, the positive electrode includes a cathode active material and has a coulombic capacity for the carrier ions; the negative electrode comprises anode-active silicon or an alloy of anode-active silicon and has a coulombic capacity for the carrier ions that exceeds the coulombic capacity of the positive electrode; The control unit includes a controller and a sensor electrically coupled to the controller; the sensor is configured to measure a cell voltage of the secondary battery during operation of the secondary battery, measuring a voltage of the positive or negative electrode relative to a removable auxiliary electrode that includes a source of carrier ions and is electrolytically coupled to the negative electrode and / or the positive electrode through the separator; the controller is programmed to cycle between a predetermined cell charging end voltage Vcell,eoc value and a predetermined cell discharging end voltage Vcell,eod value; During a first or subsequent charging cycle, carrier ions are transported from the positive electrode to the negative electrode to at least partially charge the secondary battery, forming a solid electrolyte interphase at the surface of the negative electrode during the transport; and A secondary battery characterized in that, when the cell is at the predetermined Vcell,eod value by transporting carrier ions from the removable auxiliary electrode, the positive electrode has an end-of-discharge voltage Vpos,eod and the negative electrode has an end-of-discharge voltage Vneg,eod, the value of Vpos,eod corresponds to a voltage at which the state of charge of the positive electrode is at least 95% of the coulombic capacity of the positive electrode, and Vneg,eod is at least 0.4 V (vs. Li) but less than 0.9 V (vs. Li).

15. The secondary battery according to claim 14, a controller programmed to transport carrier ions from the auxiliary electrode to the positive electrode or negative electrode when the value of Vneg,eod exceeds 0.9 V (vs. Li) when the secondary battery is at the predetermined Vcell,eod value at the end of a discharge cycle of the secondary battery.

16. The secondary battery according to claim 14, a controller programmed to transport carrier ions from the auxiliary electrode to the positive electrode or negative electrode when the value of Vneg,eod exceeds 0.8 V (vs. Li) when the secondary battery is at the predetermined Vcell,eod value at the end of a discharge cycle of the secondary battery.

17. The secondary battery according to claim 14, a controller programmed to transport carrier ions from the auxiliary electrode to the positive electrode or negative electrode when the value of Vneg,eod exceeds 0.7 V (vs. Li) when the secondary battery is at the predetermined Vcell,eod value at the end of a discharge cycle of the secondary battery.

18. The secondary battery according to claim 14, a controller programmed to transport carrier ions from the auxiliary electrode to the positive electrode or negative electrode when the value of Vneg,eod exceeds 0.6 V (vs. Li) when the secondary battery is at the predetermined Vcell,eod value at the end of a discharge cycle of the secondary battery.

19. The secondary battery according to claim 14, a controller programmed to transport carrier ions from the auxiliary electrode to the positive electrode or negative electrode when the value of Vneg,eod exceeds 0.5 V (vs. Li) when the secondary battery is at the predetermined Vcell,eod value at the end of a discharge cycle of the secondary battery.

20. The method according to any one of claims 1 to 13, The method wherein the carrier ions are lithium ions, sodium ions, potassium ions, magnesium ions or aluminum ions.

21. The method according to any one of claims 1 to 13, The method wherein the carrier ions are lithium ions, magnesium ions or aluminum ions.

22. The method according to any one of claims 1 to 13, The method wherein the carrier ions are lithium ions.

23. The method according to any one of claims 1 to 13, The method wherein the carrier ion is a magnesium ion.

24. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of said negative electrode to the reversible coulombic capacity of said positive electrode, when cycled against a counter electrode, in that order, is at least 1.2:

1.

25. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of said negative electrode to the reversible coulombic capacity of said positive electrode, when cycled against a counter electrode, in that order, is at least 1.3:

1.

26. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of said negative electrode to the reversible coulombic capacity of said positive electrode, when cycled against a counter electrode, in that order, is at least 1.5:

1.

27. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of the negative electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 2:

1.

28. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of the negative electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 3:

1.

29. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of the negative electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 4:

1.

30. The method according to any one of claims 1 to 13, The method wherein the ratio of the reversible coulombic capacity of the negative electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 5:

1.

31. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of said auxiliary electrode to the reversible coulombic capacity of said positive electrode, when cycled against a counter electrode, in that order, is at least 1.2:

1.

32. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of the auxiliary electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 1.3:

1.

33. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of the auxiliary electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 1.5:

1.

34. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of the auxiliary electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 2:

1.

35. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of the auxiliary electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 3:

1.

36. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of the auxiliary electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 4:

1.

37. The method according to any one of claims 1 to 13, The method wherein the ratio of the coulombic capacity of the auxiliary electrode to the reversible coulombic capacity of the positive electrode, when cycled against a counter electrode, in that order, is at least 5:

1.

38. The method according to any one of claims 1 to 13, The negative electrode comprises as an anode active material a microstructured silicon-containing active material having a significant void volume fraction to accommodate volume expansion and contraction as carrier ions are incorporated into or leave the negative electrode during charge and discharge cycles.

39. 39. The method of claim 38, The anode active material has a void volume fraction of at least 0.

1.

40. 39. The method of claim 38, The anode active material has a void volume fraction of less than 0.

8.

41. 39. The method of claim 38, The anode active material has a void volume fraction of about 0.15 to about 0.

75.

42. 39. The method of claim 38, The anode active material has a void volume fraction of about 0.2 to about 0.

7.

43. 39. The method of claim 38, The anode active material has a void volume fraction of about 0.25 to about 0.

6.

44. 39. The method of claim 38, The microstructured anode active material comprises macroporous, microporous or mesoporous material layers, or a combination of such material layers.

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