High Rate Battery Systems

Abstract

The present invention relates to a battery with a power conditioning circuit operable to condition the power discharged from a plurality of connected cells to provide an output voltage range narrower than the input voltage of the plurality of connected cells. The present invention also relates to a method of discharging a high-rate energy storage system, comprising using the power conditioning circuit to discharge the plurality of connected cells over a first voltage range, and conditioning the power discharged from the plurality of connected cells to provide an output voltage over a second range, the second range being less than the first range on a per-cell basis. The power conditioning circuit may comprise a two-stage boost converter coupled to the plurality of connected cells. The battery can be used to discharge the cells over a wide cell voltage range to provide a narrower and more usable voltage range to the load to facilitate fast cell cycling.

Description

[Technical field]

[0001] Related Applications This case claims priority to and the benefit of GB2115818.3, filed on November 3, 2021 (03.11.2021), the contents of which are incorporated herein by reference in their entirety.

[0002] Disclosed is a battery with a power conditioning circuit that provides a high rate battery system and a method for discharging a high rate battery. [Background technology]

[0003] Batteries are available in a wide variety of types and sizes and are used as power sources in a wide range of portable devices. There remains a need to provide batteries capable of providing higher rates of discharge for high rate applications, such as battery powered tools. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] EP2685635 [Patent Document 2] WO2005 / 060023 [Patent Document 3] US Patent Application Publication No. 2019 / 0305586 [Patent Document 4] US Patent Application Publication No. 2017 / 0126131 [Patent Document 5] US Patent Application Publication No. 2013 / 0320932 [Patent Document 6] US Patent Application Publication No. 2013 / 0043839 [Patent Document 7] US Patent Application Publication No. 2010 / 0156175 [Patent Document 8] U.S. Patent No. 7,702,369 [Patent Document 9] U.S. Patent Publication No. 2021 / 0218075 Summary of the Invention [Means for solving the problem]

[0005] Generally, the present invention relates to a battery with a power conditioning circuit operable to condition the power discharged from a plurality of connected cells to provide an output voltage range narrower than the voltage range of the plurality of connected cells.

[0006] In a first aspect, the present invention provides a method for producing a composition comprising the steps of: a plurality of connected cells; a power conditioning circuit coupled to the plurality of connected cells, the power conditioning circuit comprising: the power conditioning circuit is operable to discharge the plurality of connected cells through a first range defined as a difference between a lower voltage limit per cell and an upper voltage limit per cell; a power conditioning circuit operable to adjust power discharged from the plurality of connected cells to provide an output voltage in a second range, the second range being less than the first range on a per cell basis; A battery is provided having an output terminal electrically connected to the power conditioning circuit for providing an output voltage to a load.

[0007] The embodiments are directed to high rate batteries.

[0008] In general, the present invention also relates to a method of discharging a battery, the method including discharging the battery using a power conditioning circuit to provide an output voltage range that is narrower than the voltage range of the plurality of connected cells. One non-limiting example includes discharging the plurality of connected cells using a power conditioning circuit over a first range defined as the difference between a lower voltage limit per cell to an upper voltage limit per cell, adjusting the power discharged from the plurality of connected cells to provide an output voltage over a second range, the second range being less than the first range on a per cell basis, and outputting the output voltage to a load.

[0009] In a second aspect, the present invention provides a method for producing a pharmaceutical composition comprising the steps of: discharging the plurality of connected cells using a power conditioning circuit through a first range defined as a difference between a lower voltage limit per cell and an upper voltage limit per cell; adjusting power discharged from the plurality of connected cells to provide an output voltage in a second range, the second range being less than the first range on a per cell basis; and outputting an output voltage to a load.

[0010] In one embodiment, the battery is a component of a high rate energy storage system.

[0011] The first range is typically the difference between the upper and lower per cell voltage limits of the cell. This refers to the voltage of the cell itself before (i.e. without) any power conditioning. In other words, the first range = the upper per cell voltage limit of the cell - the lower per cell voltage limit of the cell. The upper per cell voltage may be the per cell voltage when the cell is at 100% state of charge (SOC). That is, the upper per cell voltage limit is typically the highest voltage generated by the cell. The lower per cell voltage limit may be the per cell voltage when the cell is at 0% state of charge (SOC). That is, the lower per cell voltage limit is typically the lowest voltage generated by the cell. The first range may also be referred to as the "input" range.

[0012] The second range is typically the difference between the upper and lower per cell voltage limits provided to the load. This refers to the voltage after power conditioning (i.e. after power conditioning by the power conditioning circuit). This may be the voltage of the output from the power conditioning circuit. The voltage is also that provided to the load after power conditioning. In other words, the second range = the upper per cell voltage limit provided to the load - the lower per cell voltage limit provided to the load. The upper per cell voltage limit provided to the load may be achieved when the cell is providing the upper per cell voltage limit of the cell (e.g. when the cell is at 100% state of charge (SOC)). The lower per cell voltage limit provided to the load may be achieved when the cell is providing the lower per cell voltage limit of the cell (e.g. when the cell is at 0% state of charge (SOC)). The second range may also be referred to as the "output" range.

[0013] The second range is smaller than the first range on a per cell basis, i.e., the magnitude of the second range is smaller than the first range.

[0014] The end point of the second range (upper or lower voltage limit per cell provided to the load) may be outside or inside the end point of the first range (upper or lower voltage limit per cell of the cell). The upper end point of the second range (upper voltage limit per cell provided to the load) may be smaller than the upper end point of the first range (upper voltage limit per cell of the cell). The lower end point of the second range (lower voltage limit per cell provided to the load) may be larger than the lower end point of the first range (lower voltage limit per cell of the cell). Preferably, the upper and lower end points of the second range are inside the upper and lower end points of the first range. More preferably, one end point of the second range is enclosed by the end points of the first range. In this case, preferably, the upper end point of the second range is larger than the upper end point of the first range.

[0015] The power conditioning circuit may be operable to boost the output voltage provided to the load when the per cell voltage of the plurality of connected cells is less than a first threshold voltage. The power conditioning circuit may include a boost converter that boosts the output voltage provided to the load. The boost converter is typically operable to boost the per cell output voltage to the load relative to the per cell voltage of the plurality of connected cells, such as when the per cell voltage of the plurality of connected cells is less than the first threshold voltage.

[0016] The power conditioning circuit may be operable to reduce the output voltage provided to the load when the per cell voltage of the plurality of connected cells is greater than a second threshold voltage. The power conditioning circuit may include a step-down converter that reduces the output voltage provided to the load. The step-down converter is typically operable to reduce the per cell output voltage to the load compared to the per cell voltage of the plurality of connected cells, such as when the per cell voltage of the plurality of connected cells is greater than the second threshold voltage.

[0017] Preferably, the power conditioning circuit is operable to increase the output voltage provided to the load when the per cell voltage of the plurality of connected cells is less than a first threshold voltage and to decrease the output voltage provided to the load when the per cell voltage of the plurality of connected cells is greater than a second threshold voltage. The power conditioning circuit may include a step-down converter to decrease the output voltage and a step-up converter to increase the output voltage provided to the load.

[0018] In this manner, the power conditioning circuitry is operable to reduce or increase the voltage in response to the input voltage of the cell. The input voltage of the cell may be compared to a threshold voltage (e.g., a predetermined threshold voltage). This allows for improved battery utilization and efficiency. This differs from known systems in which the power conditioning circuitry is operable in response to a load demand or a signal from the load.

[0019] The power conditioning circuit may be in an unregulated mode when a per cell voltage of the plurality of connected cells is between a first threshold voltage and a second threshold voltage.

[0020] The battery may include a battery pack housing containing a plurality of connected cells and a power conditioning circuit, or in other words, the power conditioning circuit may be integral to the battery.

[0021] The plurality of connected cells may be connected in series, in parallel, or a combination thereof. In some embodiments, the plurality of connected cells is two or more cells connected in series, such as three or more cells in series, four or more cells in series, six or more cells in series. Preferably, the plurality of connected cells is two to ten cells connected in series, more preferably four to eight cells in series, and even more preferably five to seven cells in series.

[0022] In some embodiments, the plurality of connected cells is a bank of two or more cells connected in parallel, and the bank of two or more cells is two or more cells connected in series. Preferably, the plurality of connected cells is a bank of two cells connected in parallel, and the bank of two cells is two or more cells connected in series, preferably two to ten cells connected in series, more preferably four to eight cells in series, and even more preferably five to seven cells in series. Particularly preferably, the plurality of connected cells is a bank of two cells connected in parallel, and the bank of two cells is two cells connected in series.

[0023] Other embodiments implement features of the above methods in systems and devices.

[0024] The embodiments are also directed to a battery including a plurality of connected cells and a two-stage boost converter coupled to the plurality of connected cells. The two-stage boost converter comprises a controller and a first boost converter and a second boost converter coupled to a power source and in parallel with each other. The first boost converter and the second boost converter are operably coupled to the controller. The first boost converter is configured to generate a power signal for operating the second boost converter, and the second boost converter is configured to boost an input voltage from the power source to provide an output voltage to a load when the second boost converter receives the power signal from the first boost converter. The two-stage boost converter allows a very low input voltage to be stepped up to a higher output voltage. The two-stage boost converter allows a large voltage step-up to be performed more efficiently.

[0025] Additional technical features and advantages are realized through the disclosed techniques. Embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed subject matter. For a better understanding, reference is made to the detailed description and drawings.

[0026] The particulars of the proprietary rights set forth herein are particularly pointed out and distinctly claimed in the claims at the end of this specification. The above and other features and advantages of embodiments of the present invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0027] [Figure 1] FIG. 1 is a block diagram of components of a high-rate energy storage system in accordance with one or more embodiments. [Diagram 2] 1 is an example voltage profile for a battery cell used in a high-rate energy storage system in accordance with one or more embodiments. [Diagram 3] FIG. 2 is a circuit diagram for a power conditioning circuit having a boost converter circuit for use in a high-rate energy storage system in accordance with one or more embodiments of the present invention. [Figure 4]1 is an example power conditioning circuit having a step-down converter circuit for use in a high-rate energy storage system in accordance with one or more embodiments of the present invention. [Diagram 5] 1 is an example power conditioning circuit having a buck-boost converter circuit for use in a high-rate energy storage system in accordance with one or more embodiments of the present invention. [Figure 6] 1 is an example power conditioning circuit having a two-stage boost converter circuit for use in a high-rate energy storage system in accordance with one or more embodiments of the present invention. [Figure 7] 7 is an example battery pack 700 incorporating a buck-boost converter circuit within the battery pack housing in accordance with one or more embodiments of the present invention. [Figure 8] 1 is a flowchart of a method for discharging a high-rate energy storage system in accordance with one or more embodiments of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] The diagrams depicted herein are exemplary. There may be many variations in the diagrams or operations described therein without departing from the spirit of this disclosure. For example, actions may be performed in a different order, or actions may be added, deleted, or modified. Also, the term "coupled" and variations thereof refer to having a communication path between two elements, and do not imply a direct connection between elements without an intervening element / connection between them. All of these variations are considered part of this specification.

[0029] One or more embodiments provide a high-rate battery that is operable to discharge energy over a wide voltage range. The battery can be used to provide electrical energy for a variety of applications ranging from power tools to electric vehicles. The rate at which electrical energy is provided to a load can be a function of the type and size of the power source or power supply used for each specific application. In accordance with one or more embodiments, a battery pack is integrated with a power conditioning circuit to discharge energy at a high rate to a load. The power conditioning circuit is operable to step down the voltage when an upper threshold is reached and step up the voltage when a lower threshold is reached. As a result, the output voltage range remains narrow and usable over a large range of input (cell) voltages.

[0030] The combination of multiple connected cells coupled with a power conditioning circuit is used to recover remaining capacity of battery cells that would otherwise remain unused. In known systems, when the cell voltage drops (e.g., at low SOC), the relatively low cell voltage leads to a low output voltage, so that power is not usable by a load that can only operate in a narrow voltage window. However, in the present invention, the low cell voltage (e.g., at low SOC) may be stepped up to increase the output voltage to the load. Thus, a larger percentage of the cell voltage range is usable by the load. This leads to an increase in the efficiency of the energy storage system.

[0031] This improvement is especially important for high-rate batteries that operate over a large voltage range. For example, niobium oxide-based battery cells typically have a voltage range of 0.5V to 3.2V, such as 0.6V to 3.1V, or 0.7V to 3.0V. The large voltage range means that the load may only be able to normally use the battery for a portion of the voltage range, reducing the usable capacity of the cell. However, the present invention regulates the power from the cell to provide a smaller output voltage range. As a result, the cell has a higher usable capacity because the full range of the cell's voltage is usable by the load. The load may use power from the cell from about 100% to 0% SOC.

[0032] Current technology, such as available lithium ion cells, is not capable of rapid charging and / or discharging over a long cycle life. Lithium ion battery cells are generally limited to operating over a range of 3 to 4.2 V. Niobium oxide-based battery cells provide higher charge / discharge rates and can operate at lower voltages than lithium ion cells using carbonaceous anode active materials. In addition, niobium oxide-based battery cells have a wider voltage range between fully charged and discharged states. The present invention may also allow replacement batteries (e.g., niobium oxide-based cells) to be used in devices that are adapted for previous lithium ion cells by adjusting the voltage of the replacement (e.g., niobium oxide-based cell) cell to replicate that of the previous lithium ion cell.

[0033] EP2685635 describes a mobile terminal device in which the power converter includes a buck-boost converter which varies the output voltage. The document describes using multiple power management integrated circuits (PMICs) to step the voltage of the cells up and down to match various components of the device. Different output voltages are provided to the different components. The document does not disclose that the output voltage range to the load is less on a per cell basis than the input voltage from the cells.

[0034] WO2005 / 060023 relates to a constant output voltage battery module, which can compensate for single cell failures in the battery module by stepping up the output voltage to account for the cell failure. WO2005 / 060023 also relates to providing a monoblock battery structure that provides voltages over a wider range than that defined by the potential of the electrochemical cells, meaning that the output range to the load is not less than the input voltage from the cells. The document does not relate to extending the usable voltage range of cells, particularly non-niobium oxide based cells.

[0035] US Patent Application Publication No. 2019 / 0305586 is a backup energy device for a computing device. The device includes a buck-boost converter that adjusts the output voltage in response to the demands of the computing device. The output voltage is determined by the computing device, not by the battery itself, and the output voltage range is no less than the input voltage. The document does not concern improving the usable voltage range of the battery, particularly not niobium oxide-containing cells.

[0036] US 2017 / 0126131 describes a particular circuit that provides a low voltage driver for a field effect transistor (FET). The document is concerned with reducing excess voltage consumed by circuitry. It does not concern improving the usable voltage range of cells, such as niobium oxide-containing cells. US 2017 / 0126131 describes a circuit in which buck and boost converter circuits are provided in separate circuits. The present invention may include a buck-boost converter in the same circuit.

[0037] US Patent Application Publication No. 2013 / 0320932 describes a specific circuit intended to reduce the number of switches required to increase or decrease the current by using an inductor as a step-down or step-up converter. The document is not concerned with improving the usable voltage range of a battery.

[0038] US Patent Application Publication No. 2013 / 0043839 relates to a battery system that can tolerate a variety of battery chemistries. The invention may use a single battery chemistry, such as a niobium oxide-based battery. The document is not concerned with improving the usable voltage range of the battery.

[0039] US Patent Application Publication No. 2010 / 0156175 and US Patent No. 7702369 relate to a system including a battery and a boost converter that steps up the battery voltage. Therefore, the output voltage to the load can only be equal to or greater than the input voltage from the battery. The invention may include step-down and boost converters that step-down and step-up the battery voltage to provide an output voltage range that is smaller than the input voltage range. US Patent Application Publication No. 2010 / 0156175 and US Patent No. 7702369 are not concerned with improving the usable voltage range, and do not describe niobium oxide-based cells. US Patent No. 7702369 is specific to a wireless computer mouse, and the boost converter is only activated when the wireless signal does not function.

[0040] In general, the present invention uses an internal power regulation circuit, which is part of the battery. The output voltage is determined by the internal power regulation circuit and the battery voltage threshold. Prior art systems described in EP2685635, US2013 / 0043839, US7702369 and US2019 / 0305586 instead use external signals and power regulation to determine the output voltage. In addition, none of the prior art discussed above uses a niobium oxide-based battery.

[0041] One or more embodiments address one or more of the above-mentioned shortcomings of the prior art by integrating a power conditioning circuit with a battery pack comprising a niobium oxide-based cell. The embodiments may include a switch mode converter including any combination of a buck converter, a boost converter, or a buck-boost converter to regulate the output voltage. In particular, one or more embodiments are configured to use a power conditioning circuit to regulate the voltage provided to the load, in contrast to modern energy storage systems in which the output voltage is provided to the load over a limited range. For example, current lithium-ion cells are limited to cycle between a range of approximately 3V to 4.2V. On the other hand, the niobium oxide-based battery cells for the technology described herein provide a wider range, for example, 0.5V, 0.6V, or 0.7V to 3.2V, 3.1V, or 3V. The first range may be 0.5V to 3.2V, preferably 0.6V to 3.1V, and more preferably 0.7V to 3.0V. Thus, the niobium oxide-based battery cells provide a cell voltage range of more than 2V, for example, 2.7V, 2.6V, or 2.5V. Additionally, because the disclosed battery includes a power conditioning circuit that includes a buck-boost converter, the output voltage can be stepped up and down to take advantage of the wider operable voltage range of the niobium oxide-based cells to provide more energy.

[0042] One or more embodiments provide technical solutions to one or more of the disadvantages of these existing solutions by integrating power conditioning circuitry with niobium oxide-based cells to maximize output across the entire voltage range of the battery cell.

[0043] The plurality of connected cells may include niobium oxide-based cells. That is, the cells include a niobium oxide material as an electrode active material. The plurality of connected cells may essentially include niobium oxide-based cells. Niobium oxide-based cells typically have a niobium oxide material as one of the negative electrode active materials. The negative electrode active material is an anode during galvanic discharge. The niobium oxide material may be a niobium oxide, a niobium metal oxide, a niobium semi-metal oxide, a niobium phosphorus oxide, or a niobium chalcogenide, which may be a chalcogenide containing oxygen, as described below. Preferably, the niobium oxide material is a niobium metal oxide, such as niobium tungsten oxide.

[0044] Preferably, the niobium oxide material is the negative electrode active material, in other words, the niobium oxide electrode active material is the anode during discharge (e.g., galvanic discharge) of the electrochemical cell.

[0045] Turning now to FIG. 1 , an example high-rate energy storage system 100 is illustrated in accordance with one or more embodiments. The high-rate energy storage system 100 includes a battery pack 102 having a plurality of battery cells 104 and a power conditioning circuit 110. The battery pack 102 is electrically coupled to the power conditioning circuit 110. However, in other embodiments, the power conditioning circuit 110 can be integrated within the battery pack 102. It can be appreciated that while the battery pack 102 includes four battery cells, any number of battery cells 104 can be incorporated into the battery pack 102 and is not limited to four battery cells. Each battery cell 104 is characterized by an upper voltage limit per cell and a lower voltage limit per cell that define a discharge voltage range for each battery cell 104. For example, a niobium oxide material-based cell can be discharged from a range of 3.2V to 0.5V, providing a greater voltage range, e.g., 2.8V, than that provided by a lithium-ion cell using a carbonaceous anode.

[0046] Niobium oxide-based cells have an anode active material that includes a niobium oxide material that includes at least one of niobium oxide, niobium metal oxide, niobium metalloid oxide, niobium phosphorus oxide, or niobium chalcogenide, including chalcogenides that include oxygen. The niobium oxide material may include niobium, oxygen, and at least one of Na, Mg, Al, Si, P, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Y, Zr, Mo, In, Sn, Sb, Ta, or W. The niobium oxide may be Nb2O5, and the niobium metal oxide may include Nb and at least one of Ti, V, Cr, Mo, Ta, or W. In niobium metal oxides, the molar ratio of niobium to metal, e.g., Nb:M, may be 0.1, 0.2, 0.5 or 1 to 2, 3, 4, 5, 8, 10 or 12 based on the total amount of niobium and metal, where metal M may be at least one of Ti, V, Cr, Mo, Ta or W. Niobium metal oxides containing Nb and W or Mo are mentioned. Niobium oxide materials include those containing Nb 12 WO 33 , Nb 26 W4O 77 , Nb 14 W3O 44 , Nb 16 W5O 55 , Nb 18 W8O 69 , Nb2WO8, Nb 18 W 16 O 93 , Nb 22 W 20 O 115 , Nb8W9O 47 , Nb 54 W 82 O 381 , Nb 20 W 31 O 143 , Nb4W7O 31 , NbW 15 O 50 , Nb2WO8, Nb2Mo3O 14 , Nb 14 Mo3O 44 , Nb 12 MoO 44 , Nb2TiO7, Nb 10 Ti2O29 or Nb 24 TiO 62 Preferably, the niobium oxide material comprises at least one of Nb 16 W5O 55 , Nb 18 W 16 O 93 and combinations thereof. Combinations comprising at least one of the above may also be used. It can be appreciated that the list of example niobium oxide materials is not intended to limit the scope of the invention, but is provided to provide illustrative examples for niobium oxides and niobium metal oxides.

[0047] The cathode active material may be a lithium metal oxide, where the metal is a transition metal such as Co, Fe, Ni, V, or Mn, or a combination thereof. Examples include lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt oxide (NMC, LiNiMnCoO2, e.g., LiNi 0.6 Coo2Mn 0.2 O2), lithium vanadium fluorophosphate (LiVPO4F), lithium nickel cobalt aluminum oxide (NCA, LiNiCoAlO2), lithium iron phosphate (LFP, LiFePO4) or manganese-based spinels (e.g. LiMn2O4).

[0048] The electrolyte may be a non-aqueous electrolyte. The electrolyte may include a polar aprotic organic solvent and a lithium salt. Suitable solvents and salts for the electrolyte can be determined by one of ordinary skill in the art without undue experimentation. A solution of LiPF6 in a mixture of carbonates, such as ethylene carbonate, dimethyl carbonate, or ethyl methyl carbonate, is mentioned.

[0049] The electrochemical cell may also include a porous membrane between the negative and positive electrodes. The porous membrane may include a polymer, such as polyethylene, polypropylene, or copolymers thereof.

[0050] Additional details of niobium oxide-based cells are disclosed in U.S. Patent Publication No. 2021 / 0218075, the contents of which are incorporated by reference in their entirety into this specification.

[0051] FIG. 1 depicts a power conditioning circuit 110. The power conditioning circuit 110 may include DC-DC converters of various topologies, including, for example, a buck converter, a boost converter, or a buck-boost converter. Details of the various topologies are described below with reference to FIGS. 3-5. The power conditioning circuit 110 is configured to discharge the plurality of connected cells of the battery pack 102 in a first range, the first range being defined as the difference between a lower voltage limit per cell to an upper voltage limit per cell. The power conditioning circuit 110 is operable to condition the power discharged from the plurality of connected cells to provide an output voltage in a second range to a load (not shown) coupled to the high-rate energy storage system 100, the second range being less than the first range on a per-cell basis. For example, for a battery pack 102 with four cells, the power conditioning circuit 110 provides power at a desired output voltage. To determine the output voltage for the second range on a per-cell basis, the output voltage is divided by the number of cells in the battery pack 102. In this example, the output voltage is divided by the four cells of the battery pack 102 to determine the second range on a per cell basis. It can be appreciated that the battery pack 102 is not limited to four battery cells, but can include any number of batteries, such as 2, 4, 8, etc.

[0052] In one or more embodiments, the first range is equal to or greater than 1.8V per cell and greater than 2V per cell, e.g., 2.7V, 2.6V, or 2.5V per cell, greater than that provided by current lithium-ion cells, and the second range for the output voltage provided by the power conditioning circuit 110 is equal to or less than 1V per cell. The first range is different from the second range. In other embodiments of the invention, a battery cell such as a LiFePO4 / NbWO-based cell can have an upper voltage limit per cell of at least 2.7V per cell, while the lower voltage limit per cell is 0.5V per cell, providing an output voltage in a second range of 4.2V per cell to 3V per cell.

[0053] In a further embodiment of the present invention, a battery cell, such as an LCO / NbWO based cell, can be discharged from an upper voltage limit per cell of 3.3V per cell to a lower voltage limit per cell of 0.5V per cell by power conditioning circuit 110. In a different embodiment of the present invention, a battery cell, such as an LMO / NbWO based cell, can be discharged from an upper voltage limit per cell of 3.7V per cell to a lower voltage limit per cell of 0.5V per cell by power conditioning circuit 110.

[0054] Preferably, the first range is 1.8 V per cell or more, more preferably 2.0 V per cell or more. Preferably, the upper voltage limit per cell provided by the cell is at least 2.7 V per cell, more preferably at least 2.9 V per cell, even more preferably at least 3.0 V per cell. Preferably, the lower voltage limit per cell provided by the cell is 0.8 V per cell or less, more preferably 0.7 V per cell or less, even more preferably 0.6 V per cell or less.

[0055] Preferably, the second range is 1.5V per cell or less, more preferably 1.0V per cell or less. Preferably, the upper per cell voltage limit output from the power conditioning circuit is 4.5V per cell or less, more preferably 4.3V per cell or less, even more preferably 4.2V per cell or less. Preferably, the lower per cell voltage limit output from the power conditioning circuit is 2.7V per cell or more, more preferably 2.9V per cell or more, even more preferably 3.0V per cell or more.

[0056] One or more exemplary embodiments of the present disclosure are described herein. Such embodiments are merely illustrative of the scope of the present disclosure and are not intended to be limiting in any way. Therefore, variations, modifications and equivalents of the embodiments disclosed herein are also within the scope of the present disclosure.

[0057] 2 depicts an example voltage profile 200 for a niobium-based cell used in the high-rate energy storage system 100 of FIG. 1 in accordance with one or more embodiments of the present invention. The x-axis of the voltage profile 200 represents the "depth of discharge" for the battery cell, and the y-axis represents the cell voltage (V) for the battery cell. As illustrated in the voltage profile 200, a discharge voltage curve 210 for the battery pack 102 is discharged from approximately 3.3V to 0.5V.

[0058] In some embodiments, a load coupled to the battery pack 102 may only receive an input voltage over a restricted or limited range. In this example, the load may receive a voltage within the range of 1.8V to 2.6V illustrated in the first range 220. As illustrated, the entire range for the depth of discharge for each battery cell 104 is not used, leading to inefficiencies.

[0059] A high rate energy storage system 100 such as that illustrated in Figure 1 can be operated to capture a portion of the unused capacity of the battery cells that are outside the input range of the load. For example, the second range 230 can be discharged from 3.3V to 0.5V. Given the same voltage constraints considered for the first range 220, full utilization of the full depth of discharge of the individual cells can be achieved by incorporating power conditioning circuitry, such as a buck-boost converter.

[0060] To recapture the upper range of the cell, approximately 3.3V to 2.5V, the battery initiates the buck-boost converter's buck mode of operation to reduce the input voltage to the desired output voltage level. To recapture the lower range of the cell, approximately 1.8V to 0.5V, the battery uses the buck-boost converter's boost mode of operation to increase the voltage to the desired output voltage level. The high rate energy storage system 100 thus allows utilization of the full discharge of the niobium oxide based cell, which is graphically illustrated as the difference between the first range 220 and the second range 230. The usable energy of the battery cell 104 is increased.

[0061] In some embodiments, the power conditioning circuit does not regulate the input voltage for a portion of the input voltage range. As a result, the output voltage to the load is equal to the input voltage of the cell within this portion of the input voltage range. For example, the power conditioning circuit may not regulate the input voltage for a portion of the voltage range from 1.8V to 2.5V.

[0062] The power conditioning circuit may only regulate power at the upper or lower ends of the input voltage range. In some embodiments, the power conditioning circuit only reduces the input voltage to the desired output voltage level to the load using the converter's step-down mode of operation. In other embodiments, the power conditioning circuit only increases the input voltage to the desired output voltage level to the load using the converter's step-up mode of operation.

[0063] Preferably, the power conditioning circuit regulates power at the upper and lower ends of the input voltage range. Preferably, the power conditioning circuit uses the converter's step-down mode of operation to step down the input voltage to the desired output voltage level to the load, and the converter's step-up mode of operation to step-up the input voltage to the desired output voltage level to the load.

[0064] Figures 3-6 depict example architectures for power conditioning circuitry 110 of Figure 1. Power conditioning circuitry 110 can include DC-DC converters of various topologies, such as, but not limited to, a buck converter, a boost converter, a buck-boost converter, etc.

[0065] FIG. 3 depicts a boost converter circuit 300 that may be operated in a boost mode of operation to boost or step up the output voltage Vout of the boost converter circuit 300. The boost converter circuit 300 includes an arrangement of circuit elements including, but not limited to, an inductor (L1), a switch (S1) and a diode (D1). A capacitor (C1) may be provided in parallel with a load to filter the output voltage Vout. The inductor L1 and the diode D1 are connected in series between the input and output of the boost converter circuit 300. The switch S1 may be implemented as a metal oxide semiconductor device, a silicon carbide (SiC) device or a gallium nitride (GaN) device. In other embodiments, the switch S1 may be implemented as other controllable devices such as a bipolar junction transistor (BJT) device, an insulated gate bipolar junction transistor (IGBT) device, etc.

[0066] In one or more embodiments of the present invention, a controller 306 is provided to control the operation of a boost converter circuit 300 coupled to a battery pack 302. The controller 306 may detect an input voltage Vin and an output voltage Vout that can be used to provide a control signal (gate driver signal) to operate the switch S1. It can also be appreciated that the controller 306 may detect other signals as inputs used to generate the gate drive signal, such as an input or output current. It should be understood that the controller 306 may be implemented as a pulse width modulation (PWM) based controller, or the controller 306 may be implemented as a digital controller, such as a microcontroller, digital signal processor, or the like. The controller 306 may additionally or alternatively include computer software with an algorithm configured to generate timing to control the duty cycle, as well as associated computer hardware, such as one or more data storage devices, processors, and input / output devices. The boost converter circuit 300 and the controller 306 are provided for illustrative purposes and are not intended to limit the scope of various embodiments of the present invention.

[0067] The controller 306 generates a control signal that controls the output voltage Vout to a desired level. The control signal operates the on / off time for switch S1. The duty cycle is the fraction of time switch S1 is in an on state relative to the duration of the cycle. In one non-limiting example, a switch that is on for 1 millisecond (ms) and off for 3 ms would have a duty cycle of 25%. The controller 306 can be configured to detect the voltage per cell for each of the battery cells in the battery pack 302 and use the input to modify the output voltage Vout.

[0068] In operation, when the controller 306 first switches the switch S1, the inductor L1 will start storing energy in its magnetic field. Subsequently, when the controller 306 switches the switch S1 off, the energy stored in the magnetic field of the inductor L1 will cause the output voltage Vout to rise. When the controller 306 switches the switch S1 on again, energy is provided from the battery pack 102 to the magnetic field, and the energy stored in the capacitor C1 can be discharged to the load to maintain the desired output voltage Vout. The cycle can continue during operation of the device at the load. The controller 306 controls the duty cycle of the switch S1 to maintain the desired output voltage Vout.

[0069] In one or more embodiments, the power conditioning circuit 110 is operable to boost the output voltage Vout provided to the load while discharging the plurality of connected cells when the per-cell voltage of the plurality of connected cells is less than a first threshold voltage. In one or more embodiments of the invention, the per-cell voltage may be detected by the controller 306 and used as an input to generate a gate drive signal that controls the duty cycle of the switch S1. During the boost mode of operation, the output voltage Vout may be controlled by the controller 306 to remain at a configurable level.

[0070] FIG. 4 depicts a buck converter circuit 400 that may be implemented as the power conditioning circuit 110 of the high-rate energy storage system 100 illustrated in FIG. 1. The buck converter circuit 400 coupled to a battery pack 402 may be operated by a controller 406 to step down or step down an output voltage Vout to a desired voltage for a load 404. As illustrated in FIG. 4, the buck converter circuit 400 includes an arrangement of circuit elements including, but not limited to, an inductor (L2), a switch (S2), and a diode (D2). A capacitor C2 is also provided at the output of the buck converter circuit 400 to filter the output voltage Vout for the load. FIG. 4 also illustrates the controller 406, which may include similar components as the controller 306 described with reference to FIG. 3.

[0071] During initial operation, the controller 406 provides a gate drive signal that closes the switch S2. The inductor L2 begins to store energy in its magnetic field. When the switch S2 is closed, the diode D2 is in cutoff mode and does not allow current to flow through it. As the inductor L2 stores energy from the battery pack 102, the input voltage Vin is stepped down and the output voltage Vout is brought closer to being the difference between the input voltage Vin and the voltage across the inductor L2. When the switch S2 is opened, the inductor L2 and the capacitor C2 provide the output voltage Vout to the load 404. The controller 406 controls the duty cycle of the switch S2 to maintain the output voltage Vout at a desired voltage.

[0072] In one or more embodiments, the power conditioning circuit 110 is operable to reduce or step down the output voltage Vout provided to the load 404 when the per cell voltage of the plurality of connected cells is greater than a second threshold voltage. With reference to the voltage profile 200, an example second threshold voltage may be 3.3V for the load 404 to be limited to receiving voltage at a predefined voltage. In one or more embodiments, the buck mode of operation of the buck converter circuit 400 may be discontinued when the per cell voltage for the plurality of cells reaches the second threshold.

[0073] 5 depicts a buck-boost converter circuit 500 that can be operated to regulate the output voltage of the high-rate energy storage system 100 to a voltage range. The buck-boost converter circuit 500 can be operated in various modes. The buck-boost converter circuit 500 coupled to a battery pack 502 can be operated in a buck mode of operation, a boost mode of operation, and a buck-boost mode of operation. In one or more embodiments, the buck-boost converter circuit 500 is operable to increase the output voltage provided to the load when the per cell voltage of the plurality of connected cells is less than a first threshold voltage, and is further operable to decrease the output voltage provided to the load when the per cell voltage of the plurality of connected cells is greater than a second threshold voltage.

[0074] The buck-boost converter circuit 500 includes an arrangement of circuit elements including, but not limited to, an inductor (L3), a switch (S3) and a diode (D3) as shown in FIG. 5. In operation, when the controller 506 first switches on the switch S3, the inductor L3 is charged by the battery pack 502 and the diode D3 is in a blocking mode. Then, when the switch S3 is switched off, the load 504 and the capacitor C3 will be charged from the inductor L3. The diode D3 will be forward biased and will allow current to flow through the diode D3 again to the inductor L3. When the switch S3 is switched on, the inductor L3 will be charged again and the capacitor C3 can be discharged through the load 504 to maintain the output voltage Vout.

[0075] In one or more embodiments, the power conditioning circuit 110 may be operated in an unregulated mode by the controller 506 when the per-cell voltage of the plurality of connected cells is between a first threshold voltage and a second threshold voltage. The output voltage Vout of the power conditioning circuit 110 may be in a range that is acceptable to the load 504 without any conversion of the voltage. In such a case, the controller 506 may be configured to allow power from the battery pack 502 to be directly coupled to the load 504 without regulation.

[0076] 6 depicts a two-stage boost converter circuit 600 that may be operated to boost or step up the output voltage Vout of the two-stage boost converter circuit 600 when the input voltage Vin from the battery pack 602 is very low or below a lower threshold. This is advantageous compared to the conventional boost converter circuit 300 illustrated in FIG. 3 because it allows operation under a wider range of battery voltages. For example, in the reference system, lithium-ion cells are operated in the range between 4.2V and 3V per cell. However, niobium-based cells can operate between 3.2V and 0.5V per cell.

[0077] In the reference boost converter circuit architecture, when the input voltage reaches a level less than the lower voltage threshold for each cell (e.g., 3V per cell for lithium-ion based battery cells), there may not be enough power to operate the switches of the boost converter circuit. At this stage, the boost converter circuit may cease to provide an output voltage to the load due to circuit limitations. The architecture of the two-stage boost converter circuit 600 described herein is provided to operate at a lower operating voltage range (e.g., less than 3V) beyond the capabilities of existing boost converter architectures. Thus, the two-stage boost converter circuit 600 may be operated by the controller 606 to raise the output voltage Vout to a desired voltage for the load 604 even when the voltage per cell for each battery cell is in a lower range.

[0078] 6, the two-stage boost converter circuit 600 may comprise an arrangement of circuit elements including, but not limited to, two inductors (L1 and L2), two switches (S1 and S2), and two diodes (D1 and D2). Two capacitors (C1 and C2) may further be provided, where the capacitor C1 is in parallel with the load 604 to filter the output voltage Vout, and the capacitor C2 is in parallel with the switch control signal (Scon) to filter the voltage used to power the switch S1. The inductor L1 and the diode D1 may be connected in series between the input and output of the primary subcircuit 610, and the inductor L2 and the diode D2 may be connected in series between the input and output of the control subcircuit 608. The switches S1 and S2 may be implemented as metal oxide semiconductor devices, silicon carbide (SiC) devices, or gallium nitride (GaN) devices. In other embodiments, switches S1 and S2 may be implemented as other controllable devices, such as bipolar junction transistor (BJT) devices, insulated gate bipolar junction transistor (IGBT) devices, etc. Switches S1 and S2 do not have to be implemented as the same type of device.

[0079] The controller 606 may detect an input voltage Vin and an output voltage Vout that can be used to provide control signals (gate driver signals) to operate the switches S1 and S2. It can be appreciated that the controller 606 may also detect other signals as inputs used to generate the gate drive signals, such as input or output currents.

[0080] The controller 606 generates a control signal that controls the output voltage Vout to a desired level. In operation, the controller 606 provides a gate drive signal that closes switch S2 in the control subcircuit 608. The inductor L2 then starts storing energy in its magnetic field. When switch S2 is closed, diode D2 is in blocking mode and does not allow current to flow through it. When the controller 606 switches switch S2 off, the energy stored in the magnetic field of inductor L2 increases the output voltage of the control subcircuit 608, which is conveyed through Scon and used as a signal to close switch S1 in the primary subcircuit 610. Thus, if the input voltage Vin is too low to power switch S1, for example because some metal oxide semiconductor devices require a minimum operating voltage to operate, the primary subcircuit 610 can still remain operational. In one or more embodiments of the present disclosure, the control subcircuit 608 is configured to operate at an operating voltage lower than the operating voltage of the primary subcircuit 610. When the controller 606 switches switch S2 on again, energy can be provided to the magnetic field from the battery pack 602 and the energy stored in capacitor C2 can be discharged to Scon to maintain the desired output voltage and further maintain operation of the primary sub-circuit 610. This allows the primary sub-circuit 610 to be operated in a manner similar to the boost converter circuit 300 previously described in Figure 3. The controller 606 may also control the duty cycle of switch S1 to maintain the desired total output voltage Vout of the two-stage boost converter circuit 600.

[0081] In one or more embodiments, the two-stage boost converter circuit 600 is operable to boost the output voltage Vout provided to a load while discharging cells of the battery pack 602 when the per cell voltage of the battery pack 602 is less than a first threshold voltage. In one or more embodiments of the invention, the per cell voltage may be detected by the controller 606 and used as an input to generate gate drive signals that control the duty cycle of the switches S1 and S2.

[0082] 7 depicts an architecture for a battery pack 700 that integrates a power conditioning circuit 730 within a battery pack housing 720 that includes multiple battery cells 710 coupled in series. Although the battery pack 700 depicts a buck-boost converter circuit 740 such as that depicted in FIG. 5, it can be appreciated that different types of converters can be used and are not limited by the converter illustrated in FIG. 7. The battery pack 700 includes, in this example, seven battery cells 710 connected in series and coupled to the buck-boost converter circuit 740 through a switch 750. It can be appreciated that the battery pack 700 can include any suitable number of battery cells 710 and is not limited by this example. The battery pack 700 may provide a single integrated solution for devices where the power conditioning circuitry is provided within the battery pack 700 and can be provided outside of the device to which it is coupled.

[0083] FIG. 8 depicts a flow chart of a method 800 for operating a high-rate energy storage system 100 such as that illustrated in FIG. 1. The method 800 begins at block 802 and proceeds to block 804, which defines discharging a plurality of connected cells using a power conditioning circuit over a first range defined as a difference between an upper voltage per cell limit to a lower voltage per cell limit. The first range, in such a case, may be defined by an upper voltage per cell limit and a lower voltage per cell limit, greater than that provided by a lithium-ion battery cell with a carbonaceous anode. The power conditioning circuit is operable to regulate a voltage received from the battery cells by raising and / or lowering the output voltage based on one or more thresholds. The power conditioning circuit is also operable to neither raise nor lower the output voltage when the voltage per cell of each battery cell is between a first threshold and a second threshold for regulating the voltage for the load.

[0084] Block 806 adjusts the power discharged from the multiple connected cells to provide an output voltage in a second range, the second range being less than the first range on a per-cell basis. In one or more embodiments, the second range can correspond to an acceptable input voltage range for the load.

[0085] Block 808 outputs the output voltage to the load. Method 800 ends at block 810. The process flow diagram of Figure 8 is not intended to indicate that the operations of method 800 are to be performed in any particular order or that all of the operations of method 800 are to be included in every instance. Additionally, method 800 may include any suitable number of additional operations and is not limited by the operations illustrated in Figure 8.

[0086] The high-rate energy storage system 100 including niobium oxide-based battery cells and power conditioning circuitry improves over the prior art by enabling discharge of the battery cells over a wider range than existing technologies and allowing use of a greater portion of the energy available in the cells for applications that prioritize output voltages having a smaller per-cell range. Technical effects and benefits include improved utilization of the available capacity in each of the battery cells, which can provide a longer useful life for the battery cells.

[0087] Various embodiments are described herein with reference to the associated drawings. Alternative embodiments may be devised without departing from the scope of the present disclosure. Various connections and relationships (e.g., above, below, adjacent, etc.) are defined between elements in the following description and in the drawings. These connections and / or relationships may be direct or indirect unless otherwise specified, and the invention is not intended to be limited in this respect. Thus, coupling of entities may refer to direct or indirect coupling, and relationships between entities may be direct or indirect. Moreover, various tasks and process steps described herein may be combined into a more comprehensive procedure or process having additional steps or functionality not specifically described herein.

[0088] For the sake of brevity, conventional techniques related to making and using aspects of the present invention may or may not be described in detail herein. In particular, various aspects of computing systems and specific computer programs that implement various technical features described herein are well known. Thus, for the sake of brevity, many conventional implementation details are only briefly mentioned herein or are omitted entirely without providing details of well-known systems and / or processes.

[0089] In some embodiments, various functions or acts may occur at a given location and / or in conjunction with the operation of one or more devices or systems. In some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations.

[0090] The terminology used herein is merely for the purpose of describing particular embodiments and is not intended to be limiting. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly dictates otherwise. It will be further understood that the terms "comprises" and / or "comprising," as used herein, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0091] The corresponding structures, materials, acts and equivalents of all means or steps plus functional elements in the following claims are intended to include any structures, materials or acts for performing a function in combination with other claim elements specifically claimed. The present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the disclosed form. Many changes and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present disclosure. The embodiments have been chosen and described in order to best explain the principles, practical applications of the present disclosure, and to enable those skilled in the art to understand the present disclosure in terms of various embodiments with various modifications suitable for the particular use contemplated.

[0092] The diagrams depicted herein are illustrative. There may be many variations in the diagrams or steps (or operations) described therein without departing from the spirit of the disclosure. For example, actions may be performed in a different order, or actions may be added, deleted, or modified. Also, the term "coupled" describes having a signal path between two elements, and does not imply a direct connection between elements with no intervening elements / connections therebetween. All of these variations are considered part of the disclosure.

[0093] The following definitions and abbreviations will be used for interpretation of the claims and the specification. As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contains," or "containing," or any other variant thereof, are intended to cover a non-exclusive inclusion. For example, a composition, mixture, process, method, article, or device that comprises a list of elements is not necessarily limited to only those elements but can include other elements not expressly listed or inherent to such composition, mixture, process, method, article, or device.

[0094] Additionally, the term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. The terms "at least one" and "one or more" are understood to include any integer number greater than or equal to one, i.e., 1, 2, 3, 4, etc. The term "multiple" is understood to include any integer number greater than or equal to two, i.e., 2, 3, 4, 5, etc. The term "connected" can include both indirect and direct "connections."

[0095] The terms "about," "substantially," "approximately," and variations thereof are intended to include the degree of error associated with the measurement of a particular quantity based on the equipment available at the time the application is filed. For example, "about" can include a range of ±8% or 5%, or 2% of a given value.

[0096] The description of various embodiments has been presented for illustrative purposes, but is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The technical terms used in this specification are selected to best explain the principles of the embodiments, practical applications or technical improvements to the technology found in the market, or to enable those skilled in the art to understand the embodiments disclosed in this specification.

[0097] (References) A number of publications have been cited above in order to more fully describe and disclose the present invention and the state of the art to which it pertains. Full citations for these publications are set forth below. Each of these publications is incorporated herein in its entirety. EP 2685635 WO 2005 / 060023 US 2019 / 0305586 US 2017 / 0126131 US 2013 / 0320932 US 2013 / 0043839 US 2010 / 0156175 US 7,702,369 US 2021 / 0218075 [Explanation of symbols]

[0098] 100 High Rate Energy Storage System 102 Battery pack 104 Battery Cell 110 Power adjustment circuit 200 Voltage Profiles 210 Discharge voltage curve 220 First Range 230 Second Range 300 Boost Converter Circuit 302 Battery Pack 304 Load 306 Controller 400 Buck Converter Circuit 402 Battery Pack 404 Load 406 Controller 500 Buck-boost converter circuit 502 Battery Pack 504 Load 506 Controller 600 Two-stage boost converter circuit 602 Battery Pack 604 Load 606 Controller 608 Control Subcircuit 610 Primary Subcircuit 700 Battery Pack 710 Battery Cell 720 Housing 730 Power adjustment circuit 740 Buck-boost converter circuit 750 Switch C1 Capacitor C2 Capacitor C3 Capacitor D1 Diode D2 Diode D3 Diode L1 Inductor L2 inductor L3 inductor S1 Switch S2 Switch S3 Switch Scon Switch control signal

Claims

1. a plurality of connected cells; a power conditioning circuit coupled to the plurality of connected cells, the power conditioning circuit comprising: the power conditioning circuitry is operable to discharge power from the plurality of connected cells in a first range, the first range being defined as the difference between a lower voltage limit per cell and an upper voltage limit per cell; a power conditioning circuit operable to adjust the power discharged from the plurality of connected cells to provide an output voltage in a second range, the second range being less than the first range on a per cell basis; and an output terminal electrically connected to the power conditioning circuit for providing the output voltage to a load; A battery.

2. 10. The battery of claim 1, wherein the first range is greater than or equal to 1.8V per cell.

3. 10. The battery of claim 1, wherein the second range is less than or equal to 1 V per cell.

4. With respect to the first range, (i) the upper voltage limit per cell is 2.7 V or more per cell and / or the lower voltage limit per cell is 0.7 V or less per cell; or (ii) the upper voltage limit per cell is 3.0 V or more per cell and / or the lower voltage limit per cell is 0.5 V or less per cell.

5. 2. The battery of claim 1, wherein the output voltage in the second range is the difference between an upper voltage limit per cell output from the power conditioning circuit and a lower voltage limit per cell output from the power conditioning circuit, wherein the upper voltage limit per cell is less than or equal to 4.5 V per cell and / or the lower voltage limit per cell is greater than or equal to 2.7 V per cell.

6. 6. The battery of claim 5, wherein the upper voltage limit per cell output from the power conditioning circuit is 4.2V per cell or less, and / or the lower voltage limit per cell output from the power conditioning circuit is 3.0V per cell or more.

7. the power conditioning circuit (i) operable to discharge each cell of the plurality of connected cells from the upper per cell voltage limit of 3.3V per cell to the lower per cell voltage limit of 0.5V per cell; or 2. The battery of claim 1, wherein: (ii) the battery is operable to discharge each cell of the plurality of connected cells from the upper voltage per cell limit of 3.7V per cell to the lower voltage per cell limit of 0.5V per cell.

8. the power conditioning circuit (i) operable to increase the output voltage provided to the load while discharging the plurality of connected cells when a per-cell voltage of the plurality of connected cells is less than a first threshold voltage; and / or 2. The battery of claim 1, wherein (ii) the battery is operable to reduce the output voltage provided to the load when a per-cell voltage of the plurality of connected cells is greater than a second threshold voltage.

9. 9. The battery of claim 8, wherein the power conditioning circuit is in an unregulated mode when the per-cell voltage of the plurality of connected cells is between the first threshold voltage and the second threshold voltage.

10. 9. The battery of claim 8, wherein the first threshold voltage is from 1.5 to 2 V, preferably from 1.6 to 1.9 V, more preferably from 1.7 to 1.8 V, and / or the second threshold voltage is from 2.5 to 3 V, preferably from 2.6 to 2.9 V, more preferably from 2.7 to 2.8 V.

11. 11. The battery of claim 1, wherein each cell of the plurality of cells comprises a niobium oxide material as an electrode active material.

12. 12. The battery of claim 11, wherein the niobium oxide material is selected from niobium oxide, niobium metal oxide, niobium metalloid oxide, niobium phosphorus oxide, niobium chalcogenide, and combinations thereof, preferably niobium oxide, niobium metal oxide, and combinations thereof, more preferably niobium metal oxide, and combinations thereof.

13. The niobium oxide is Nb 2 O 5 and the niobium metal oxide is Nb 12 WO 33 , Nb 26 W 4 O 77 , Nb 14 W 3 O 44 , Nb 16 W 5 O 55 , Nb 18 W 8 O 69 , Nb 2 WO 8 , Nb 18 W 16 O 93 , Nb 22 W 20 O 115 , Nb 8 W 9 O 47 , Nb 54 W 82 O 381 , Nb 20 W 31 O 143 , Nb 4 W 7 O 31 , Nb 2 W 15 O 50 , Nb 2 WO 8 , Nb 2 Mo 3 O 14 , Nb 14 Mo 3 O 44 , Nb 12 MoO 44 , Nb 2 TiO 7 , Nb 10 Ti 2 O 29 or Nb 24 TiO 62 13. The battery of claim 12, wherein:

14. The niobium oxide material is Nb 16 W 5 O 55 , Nb 18 W 16 O 93 and combinations thereof.

15. 12. The battery of claim 11, wherein the niobium oxide material is an anode during discharge of the cell.

16. 10. The battery of claim 1, wherein the plurality of connected cells are connected in series.

17. 10. The battery of claim 1, further comprising a battery pack housing containing the plurality of connected cells and the power conditioning circuitry.

18. 10. The battery of claim 1, wherein the power conditioning circuit comprises a step-down converter, the step-down converter operable to reduce the per-cell output voltage to the load compared to the per-cell voltage of the plurality of connected cells.

19. 10. The battery of claim 1, wherein the power conditioning circuit comprises a boost converter, the boost converter operable to increase the per-cell output voltage to the load compared to the per-cell voltage of the plurality of connected cells.

20. The boost converter is a two-stage boost converter, and the two-stage boost converter comprises: A controller; a first boost converter and a second boost converter coupled to the plurality of connected cells and in parallel with each other, the first boost converter and the second boost converter being operably coupled to the controller; and Equipped with the first boost converter is configured to generate a power signal for operating the second boost converter; 20. The battery of claim 19, wherein the second boost converter is configured to boost an input voltage from the power source when the second boost converter receives the power signal from the first boost converter to provide an output voltage to a load.

21. 21. The battery of claim 20, wherein the first boost converter is configured to generate the power signal for operating the second boost converter when the input voltage of the plurality of connected cells is between an upper voltage per cell limit and a lower voltage per cell limit.

22. (i) the upper voltage limit per cell is at least 2.7V per cell and the lower voltage limit per cell is 0.5V to 0.7V per cell; (ii) the upper voltage limit per cell is at least 3.3 V per cell and the lower voltage limit per cell is 0.5 V to 0.7 V per cell; or (iii) the upper voltage limit per cell is at least 3.7 V per cell and the lower voltage limit per cell is 0.5 V to 0.7 V per cell; 22. The battery of claim 21.

23. 21. The battery of claim 20, wherein the first boost converter is configured to operate at an operating voltage lower than an operating voltage of the second boost converter.

24. using a power conditioning circuit to discharge power from a plurality of connected cells in a first range, the first range being defined as the difference between a lower voltage limit per cell and an upper voltage limit per cell; adjusting the power discharged from the plurality of connected cells to provide an output voltage in a second range, the second range being less than the first range on a per cell basis; and outputting the output voltage to a load; 12. A method for discharging a battery, comprising:

25. 25. The method of claim 24, wherein the first range is greater than or equal to 1.8V per cell.

26. 25. The method of claim 24, wherein the second range is 1 V per cell or less.

27. With respect to the first range, (i) the upper voltage limit per cell is 2.7 V or more per cell and / or the lower voltage limit per cell is 0.7 V or less per cell; or 25. The method of claim 24, wherein (ii) the upper voltage limit per cell is 3.0 V per cell or more and / or the lower voltage limit per cell is 0.5 V per cell or less.

28. 25. The method of claim 24, wherein the second range is defined as the difference between an upper per cell voltage limit provided to the load and a lower per cell voltage limit provided to the load, and is 4.5 V per cell or less relative to the upper per cell voltage limit provided to the load and / or 2.7 V per cell or more relative to the lower per cell voltage limit provided to the load.

29. (i) discharging each cell of the plurality of connected cells from the upper per cell voltage limit of 3.3V per cell to the lower per cell voltage limit of 0.5V per cell; or (ii) discharging each cell of the plurality of connected cells from the upper per cell voltage limit of 3.7V per cell to the lower per cell voltage limit of 0.5V per cell.

25. The method of claim 24, further comprising:

30. adjusting the power (i) increasing the output voltage provided to the load while discharging the plurality of connected cells when the per-cell voltage of the plurality of connected cells is less than a first threshold voltage; and / or 25. The method of claim 24, comprising: (ii) reducing the output voltage provided to the load when a per-cell voltage of the plurality of connected cells is greater than a second threshold voltage.

31. 31. The method of claim 30, further comprising operating the power conditioning circuit in an unregulated mode when the per-cell voltage of the plurality of connected cells is between the first threshold voltage and the second threshold voltage.

32. 32. The method of claim 30 or 31, wherein the first threshold voltage is from 1.5 to 2 V, preferably from 1.6 to 1.9 V, more preferably from 1.7 to 1.8 V, and / or the second threshold voltage is from 2.5 to 3 V, preferably from 2.6 to 2.9 V, more preferably from 2.7 to 2.8 V.

33. 25. The method of claim 24, wherein each cell of the plurality of cells comprises a negative active material comprising niobium oxide, niobium metal oxide, or a combination thereof.

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