WO2013056196A1

WO2013056196A1 - Battery system and method with voltage controller

Info

Publication number: WO2013056196A1
Application number: PCT/US2012/060156
Authority: WO
Inventors: Joseph Mcmenamin; Zeiad M. Muntasser; Andrew Hart STEWART; Demetrio M. BATAC; Andres Diego GONZALEZ
Original assignee: Contour Energy Systems Inc.
Priority date: 2011-10-14
Filing date: 2012-10-13
Publication date: 2013-04-18

Abstract

A battery system can include a battery section comprising at least one battery cell, the battery section providing a cut-off voltage after a first delay at battery outputs upon turn-on in response to a predetermined load; a boost section configured to supply a boost voltage; and a controller circuit coupled to the battery section and the booster section, and configured to couple the booster section to system outputs to provide the cut-off voltage at system outputs after a second delay upon turn-on, the second delay being shorter than the first delay, and de-couple the booster section from the system outputs once the battery outputs reach the cut-off voltage.

Description

BATTERY SYSTEM AND METHOD WITH VOLTAGE CONTROLLER

TECHNICAL FIELD

The present disclosure relates generally to battery systems, and more particularly to battery systems that include a controller that can vary power delivery.

BACKGROUND

Due to the proliferation of smaller and lighter portable electronic devices, there is a corresponding need for batteries of smaller weight but greater energy capacity and/or delivery. While some battery chemistries can provide high energy density, a common drawback to such systems can be voltage delay. Voltage delay manifests itself when a battery is initially connected to a load, and there is delay before the output voltage reaches a minimum voltage (referred to as a cut-off voltage).

Known battery chemistry systems use lithium in combination with a range of cathodes that can include metal oxides, sulfur compounds, or fluorides. One such cathode material, fluorinated carbon, is suitable for use in high performance lithium primary battery systems. Fluorinated carbon (known by the formula CF_X, where X is a number between 0 and 1.5) is a suitable material for use in high performance lithium primary battery systems. CF_X batteries have many advantages over other types of lithium batteries, including high energy density, flat discharge curve and long shelf life. However, lithium/carbon fluoride (CF_X) chemistry batteries can exhibit significant voltage delay, as compared to other battery chemistries, such as LiMn02 batteries. While voltage delay can manifest itself at room or higher temperatures, at low temperatures such a delay can be significantly longer.

As but one very particular example, some conventional CF_X batteries can take tens of seconds need to reach optimal voltage at room and higher temperatures, but as long as minutes at lower temperatures. Such performance can be unacceptable for some applications. As but one example, such a voltage delay greatly exceeds the MILSPEC (MIL-PRF-32271/1) specification of 60 seconds maximum at low temperature. In contrast, some lithium-manganese oxide (LiMn02) chemistry batteries can have a maximum turn-on voltage delay of but one second.

Attempts have been made to manufacture batteries with a decreased voltage delay. U.S. Patent No. 4,681 ,823 issued to Tung et al. describes a composition and process for forming lithium/fluorinated carbon battery for obviating initial voltage delay. A single step process uses a thick carbon bed in a static bed reactor to assure that the proper degree and type of under-fluorinated CF_X is admixed with fully- or over-fluorinated material. The fluorination time is controlled to give the right amount of inhomogeneity of the CFx product. These process conditions can apply to fluorination of both crystalline and amorphous carbon, and the end result has reduced voltage delay but also a much lower discharge capacity.

Another technique to eliminate or reduce initial voltage delay is the addition of fluorinated carbonaceous materials to the CFx to reduce or eliminate the initial voltage delay. This can include fluorinated carbon black made from a starting carbon black having a specific surface area, or carbon with adsorbed fluorine. Alternative admixtures of fluoride containing compounds such as aluminum fluoride or magnesium fluoride have also been used. In addition, non-fluorine additives such aluminum powder or Mn02 have been used. However, in practice, the active compositions responsible for fast turn-on voltage are quickly used. For example, when the battery is close to full charge and the MnC>2 is supplying most of the current the voltage delay is minimal. However, as the battery discharges over time, the MnC>2 is consumed in reactions, leaving the CFx to take over. The voltage delay will reappear after a resting period because there is no more Mn02 left to prevent the voltage delay.

For certain voltage critical applications, electronic devices can be manufactured to control input voltage and eliminate or reduce some of problems associated with carbon fluoride or similar battery chemistries. Such a controller can monitor and control power delivery to the load to optimally extend the run time of the battery maintaining a minimum required output voltage when the input voltage is below the cut-off voltage of electronic devices for which the battery is intended.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a block schematic diagram of a battery system with a series connected boost section according to one embodiment.

FIGS. 2 and 3 are timing diagrams showing responses for a system like that of FIG. 1 , according to particular embodiments.

FIGS. 4 to 5B are diagrams showing boost circuits that can be included in embodiments.

FIGS. 6A to 6C show a sequence of block schematic diagrams of a battery system and operations according to embodiments.

FIG. 7 is a block schematic diagram of a battery system according to a particular embodiment.

FIG. 8 is a block schematic diagram of a battery system with a series connected boost section according to another embodiment.

FIGS. 9A and 9B are diagrams showing systems with battery packs according to embodiments.

FIG. 10 is a block schematic diagram of a battery system with a temperature dependent boost operation according to one embodiment.

FIGS. 1 1A and 1 1 B are timing diagrams showing responses for a system like that of FIG. 10, according to particular embodiments.

FIGS. 12A and 12B are timing diagrams showing end of life responses of systems according to embodiments.

FIG. 13 is a perspective view of a battery system according to an embodiment.

FIG. 14 is a graph comparing a battery system with electronic boosting according to an embodiment with a conventional battery system.

FIGS. 15 and 16 are graphs comparing a battery system with a thermal spreader according to an embodiment with a conventional battery system. DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments disclosed herein show devices and corresponding methods for battery systems with a main battery and a boost section. A boost section can provide a boost voltage upon turn-on, to thereby reduce voltage delay as compared to the main battery alone. Once the main battery achieves a desired minimum voltage (e.g., a cut-off voltage), the boost section can be turned off.

In the various embodiments below, like sections are referred to by the same reference character but with leading digit(s) corresponding to the figure number.

FIG. 1 shows a battery system 100 according to a first embodiment. A battery system 100 can include a battery section 102, a boost section 104 and a controller circuit 106. System 100 can provide an output voltage (Vout) to power one or more devices at system outputs 108-0/1. A battery section 102 can provide a battery output voltage (Vbatt) at battery outputs 110-0/1. In the embodiment shown, a battery section 102 can be arranged in series with a boost section 104 between system outputs 108-0/1. Further, one battery output 110-0 can be same as a system output 180-0.

A battery section 102 can be formed from one or more battery cells formed from a material that introduces a voltage delay upon turn-on. Turn-on can occur when a load is initially connected across system outputs 108-0/1. In one very particular embodiment a battery section 102 can include multiple fluorinated carbon (CF_X) cells. A CF_X battery cell can be battery cell having an electrode formed from no less than 1% of a CF_X material.

A boost section 104 can provide a boost voltage (Vboost) for reducing voltage delay upon turn-on. In the series connected embodiment shown, boost section 104 can provide a boost voltage with reference to battery output 110-1 and system output 108-1. Thus, if an initial battery voltage (Vbatt) upon turn-on is less than a desired minimum voltage (cut-off voltage), the boost voltage (Vboost) can be provided to increase an output voltage (Vout). Once a battery voltage (Vbatt) reaches the cut-off voltage, the boost section can be disabled, and the battery voltage can be provided as the output voltage (Vbatt = Vout).

As will be described in more detail below, a boost voltage (Vboost) can be a dynamic voltage, varying until the boost section is disabled, a static voltage, remaining substantially the same until the boost section is disabled, or some combination thereof.

A controller circuit 106 can sense a battery voltage (Vbatt) output from battery section 102. In response to a detected battery voltage, a controller circuit 106 can enable or disable a boost section 104. In the embodiment shown, when a battery voltage (Vbatt) is below a cut-off voltage upon turn-on, controller circuit 106 can enable boost section 104, to generate a boost voltage. Once the battery voltage (Vbatt) reaches a cut-off voltage, controller circuit 106 can disable boost section 104, to disable the boost voltage.

While FIG. 1 shows one boost section 104 connected in series with a main battery section 102, alternate embodiments can include multiple boost sections connected in series with one or more battery sections. Such multiple boost sections can be controlled by one controller circuit (e.g., 106) or multiple controller circuits.

Referring to FIGS. 2 and 3, operations for an embodiment like that of FIG. 1 are shown in timing diagrams. In both FIGS. 2 and 3, a load can be connected to a battery system at time to. In addition, it is assumed that the battery system enables boosting when the output voltage (Vout) drops below a threshold voltage (Vth), which can be higher than a cut-off voltage (Vcut-off). FIG. 2 shows a turn-on operation with a dynamic boost voltage. FIG. 2 shows three waveforms: Vout shows an output voltage of a system following the connection of a load; Vbatt shows a battery voltage; and Vboost(dyn) shows a dynamic boost voltage. As shown, a battery voltage Vbatt does not reach a cut-off voltage (Vcut-off) until a time delay (tdelay). However, a boost voltage (Vboost(dyn)) enables Vout to rapidly reach Vcut-off. It is noted FIG. 2 shows but one embodiment. In alternate embodiments curves may differ. As but a few examples, a boost voltage (Vboost) may change in discrete steps and/or an output voltage (Vout) may have overshoot or ringing. Accordingly, the response of FIG. 2 should be considered but one representation of many possible responses.

FIG. 3 shows a turn-on operation with a static boost voltage. FIG. 3 shows three waveforms like those of

FIG. 2. However, unlike FIG. 2, in FIG. 3 a boost voltage is static (Vboost(static)). In FIG. 3, a battery voltage Vbatt can rise as in the case of FIG. 2. However, a boost voltage can be a substantially static value.

Referring to FIGS. 4 to 5B, various examples of voltage boost circuits that can be included in boost sections are shown. FIG. 4 shows a DC-to-DC converter boost circuit 412-A. A DC-to-DC converter 412-A can receive an input DC voltage Vin, and provide a corresponding output DC voltage Vout that can be some function of Vin. In the particular embodiment shown, DC-to-DC converter 412-A can be powered by voltage from a battery section of the same system (Vbatt 1/Vbatt2). In such an embodiment, a boost circuit (e.g., 412-A) will drain a battery section when enabled. A DC-to-DC converter 412-A can utilize any suitable conversion circuit, including but not limited to "buck", "boost" and "buck-boost" type circuits.

FIG. 5A shows a "fast" battery boost circuit 512-A. A fast battery 512-A can be a battery having a faster response time than a battery section of the same system. In one very particular embodiment, a battery section (i.e., a "slow" battery section) can be formed from high energy density (but slower responding) CFx type electrodes, while a fast battery boost circuit 512-A can be a Mn03 based battery.

FIG. 5B shows a capacitor based boost circuit 512-C. A capacitor boost circuit 512-C can charge a capacitor 514 prior to a turn-on event (or other event in which the boost voltage is utilized). A capacitor 514 can include any suitable capacitor structure, including a "supercapacitor" (also referred to as an electric double layer capacitor). In the embodiment shown, a capacitor boost circuit 512-C can include switching paths 516-0/1 to connect capacitor 514 to a charging source (Vcharge), or connect the capacitor 514 to a system output (Vout). In very particular embodiments, a charging source can be the battery section of the corresponding system (e.g., Vcharge = Vbatt).

FIG. 6A to 6C shows a battery system 600 and corresponding operations according to additional embodiments. A battery system 600 can include features like those of FIG. 1 , and in one very particular embodiment, can be one implementation of that shown in FIG. 1.

FIGS. 6A to 6C differ from FIG. 1 in that a battery section 602 is shown to be formed, all or in part, with CFx battery cells. A CF_X battery cell can include an electrode with at least 1 % CF_X, where X is between 0 and 1.5. In very particular embodiments, X can be between 0.05 and 0.95. Accordingly, battery section 602 can deliver relatively high energy density, but include some voltage delay. In addition, it is assumed that boost section 604 generates a boost voltage using a battery section voltage.

FIGS. 6A to 6C also differs from FIG. 1 in that controller circuit 606 is shown to include a controller 622, a first controllable impedance path 618 and a second controllable impedance path 620. It is noted that in some embodiments, a second controllable impedance path 620 need not be controlled by a controller 622, but can operate in response to a voltage difference (Vbatt(-) - Vout(-)). As but one very particular example, second controllable impedance path 620 can include one or more Schottky, or other diodes, to achieve a threshold voltage. A controller 622 can receive a battery voltage (Vbatt(+)-Vbatt(-), and in response, generate control signals that can control impedance paths 618/620 and boost section 604. Controllable impedance paths 618/622 can vary impedance in a gradual fashion, a switch like fashion (i.e., rapid change between high and low impedance), or a combination thereof.

Having described various sections of battery system 600, operations of the system will now be described.

FIG. 6A shows a system 600 prior to turn-on (e.g., prior to a load being connected, or a substantial/rapid change in load). Prior to turn-on, a battery output voltage (Vbatt(+) to Vbatt(-)) can be greater than a cut-off voltage. Controller 622 can detect the battery voltage level, and in response, disable (place into a high impedance) first controllable impedance path 618. As a result, power can be disconnected from boost section 604, and a boost voltage is not generated. It is noted, such an arrangement can place boost section 604 into a very low power consuming state. At the same time, second controllable impedance path 620 can be enabled (placed into a low impedance). As a result, a battery output (Vbatt(-)) can be provided as a system output (Vout(-)).

FIG. 6B shows a system 600 upon turn-on (e.g., when a load is connected or there is a substantial/rapid change in load). In FIG. 6B it is assumed that the connection of a load 624 across system outputs 608-0/1 results in a battery section voltage (Vbatt(+) - Vbatt(-)) dropping below a cut-off voltage. Controller 622 can detect the battery voltage level, and in response, disable second controllable impedance path 620. As a result, battery output (Vbatt(- )) can be disconnected from a system output (Vout(-)), and boost section 604 can be placed in series with battery section 602. In addition, first controllable impedance path 618 can be enabled, providing power to boost section 604, resulting in the generation of a boost voltage (Vboost). The inclusion of the boost voltage (Vboost) can raise the voltage at system outputs 608-0/1 above the cut-off voltage level. It is understood that in this state, a battery voltage can continue to increase and approach the cut-off voltage.

FIG. 6C shows a system 600 after a battery section voltage (Vbatt(+) - Vbatt(-)) had reached a cut-off voltage. Controller 622 can detect that the battery section voltage level is now at a desired level, and in response, can enable second controllable impedance path 620, bypassing boost section 604. In addition, first controllable impedance path 618 can be disabled, removing power from boost section 604.

Such an arrangement enables a boost operation to consume power from battery section 602 only when needed to achieve a cut-off voltage.

FIG. 7 shows a battery system 700 according to another embodiment. A battery system 700 can include features like those of FIGS. 6A to 6C, and in one very particular embodiment, can be one implementation of that shown in FIGS. 6A to 6C.

The system 700 of FIG. 7 differs from that of FIGS. 6A to 6C in that a first controllable impedance path 718 is shown to be a p-channel insulated gate field effect transistor (IGFET) Q70 and a second controllable impedance path 720 is shown to be an n-channel IGFET Q72. Transistor Q70 can have a source-drain path connected between battery output 710-0 (which is also be the system output 708-0 in this embodiment) and boost section 704, and a gate connected to an output bias network 732. Transistor Q72 can have a source-drain path connected between system output 708-1 and battery output 710-1 , and a gate connected to an output bias network 732.

FIG. 7 also differs from FIGS. 6A to 6C in that a controller circuit 706 is specifically shown to further include a reference voltage source 726, an input bias network 728, an amplifier 730, and an output bias network 732. A reference voltage source 726 can generate a reference input voltage to a first input (-) of amplifier 730. In the embodiment shown, reference voltage source 726 can be a voltage regulator that provides a substantially constant output reference voltage.

Input bias network 728 can generate an input voltage to a second input (+) of amplifier 730 that varies in response to an output voltage (Vbatt(+) - Vbatt(-)) of battery section 702. In the embodiment shown, input bias network 728 can be a voltage divider.

Amplifier 730 can amplify a voltage difference between the reference voltage provided by reference voltage source 726 and that generated by input bias network 728. Input bias network 728 and reference voltage source 730 can be designed to cause amplifier 730 to drive its output from high to low when a battery voltage is at, is approaching, or has fallen below a cut-off voltage, depending upon a desired system response.

Output bias network 730 can generate control voltages based in an output of amplifier 730. More particularly, when an amplifier output is high (i.e., a battery voltage is greater than a cut-off voltage), voltages generated by output bias network and turn transistor Q70 off and turn transistor Q72 on. Conversely, when an amplifier output is low (i.e., a battery voltage is less than a cut-off voltage), voltages generated by output bias network and turn transistor Q70 on and transistor Q72 off.

While FIGS. 6A to 7 have shown embodiments in which a boost section is situated in series between a low battery output (Vbatt(-)) and a low system output (Vout(-)), alternate embodiments can include a boost section between a high battery output (Vbatt(+)) and a high system output (Vout(+)). One such embodiment is shown in FIG. 8. FIG. 8 includes items with the reference characters corresponding to those of FIG. 6A to 6C, and can operate in the same general fashion.

While embodiments above have shown battery systems in schematic diagram form, other embodiments can include systems with battery packs enclosed in a housing. Such systems may, or may not, include a corresponding loading device that draws power from the battery pack. Particular examples of such embodiments are shown in FIGS. 9A and 9B.

FIG. 9A shows a system 900-A according to one embodiment. A system 900-A can include a number of battery cells (902-0 to -5) connected to one another and contained within a housing 934. Battery cells (902-0 to -5) can be connected in parallel, series, or combinations thereof, to form a battery section as described in the embodiments herein. In particular embodiments, battery cells (902-0 to -5) can be separated from one another by a filler structure or material 946. Battery cells (902-0 to -5) can provide a battery voltage to a controller module 936.

In the embodiment of FIG. 9A, controller module 936 can be included within housing 934. A controller module 936 can include a controller circuit and boost section as described in the embodiments herein, or equivalents. A controller module 936 can provide a system output voltage (Vout) to loading device 940 via a connector 938.

FIG. 9B shows a system 900-B according to another embodiment. A system 900-B can include items like those of FIG. 9A. System 900-B differs from that of FIG. 9A in that a controller module 936 can be situated within the loading device 940'. Battery cells (902-0 to -5) can provide a battery voltage to controller module 936 within loading device 940 via a connector 938.

In the embodiments of FIG. 9A and 9B, when power is turned on in the loading device 940/940', if battery cells (902-0 to -5) cannot immediately provide a cut-off voltage, controller module 936 can provide a boost voltage to supplements or replaces a battery voltage in order to reach the cut-off voltage, as described in the embodiments herein, or equivalents.

FIG. 10 shows a system 1000 according to another embodiment that can modulate a boost voltage based on a detected temperature. System 1000 includes items like those of FIG. 1. FIG. 10 differs from FIG. 1 in that system 1000 can include a temperature detector 1042. A temperature detector 1042 can provide a temperature value to a controller circuit 1006' and/or a boost section 1004'. In response to the temperature value, a boost voltage Vboost can be changed. As but one example, a battery section 1002 may provide a varying turn-on response according to temperature. A temperature detector 1042 can provide a temperature value to enable boost operations to compensate for such changes. According to embodiments, a controller 1006' can vary control of a boost section 1004' in response to a temperature value, a boost section 1004' can vary the amount of boost it provides in response to a temperature value, or combinations thereof.

Referring to FIGS. 11A and 11 B, boost voltages for an embodiment like that of FIG. 10 are shown in timing diagrams. FIG. 11 A shows a dynamic boost voltage that varies according to temperature according to one very particular embodiment. FIG. 11 A shows three voltage boost waveforms, each corresponding to a different temperature (T1 , T2, T3). In one embodiment, T1 < T2 < T3.

FIG. 11 B shows a static boost voltage that varies according to temperature, and shows three voltage boost waveforms, each corresponding to a different temperature (T1 , T2, T3). In one embodiment, T1 < T2 < T3.

It is understood that the boost waveforms shown in FIGS. 11 A/B are exemplary, and should not be construed as limiting. Boost voltages can have stepped waveforms, linear changed, etc.

While boost sections and controller circuits as described herein can operate upon turn-on, to reduce or eliminate voltage delay, in some embodiments, boost sections and controller circuits can serve to maintain an output voltage as a battery section nears the end of its charge. FIGS. 12A and 12B contrast embodiments that do and do not boost end-of-life voltage in this fashion.

FIG. 12A shows a boost operation that can maintain voltage at an end of a battery charge. As shown, when a battery section (Vbatt) falls below a cut-off voltage (Vcut-off), a boost section can enabled, as shown by the Vboost waveform rising. This can push an output voltage (Vout) back up to the cut-off voltage (Vcut-off). While FIG. 12A shows a dynamic boost voltage, it is understood that such a boost voltage could also be static.

In contrast, FIG. 12B shows a system that does not enable boosting at an end of battery section charge. According to embodiments herein, electrical controllers can be included in battery systems, including battery packs that can compensate for voltage delay without having to rely on additives or other changes to battery chemistry. An electronic circuit in electrical connection with a battery pack can be used to boost battery pack voltage above a cutoff value until the cells reach a high enough voltage that the boost is no longer needed and the boosting can end.

Controller and booster circuits can increase a current drawn from battery cells when boosting is occurring.

The higher current draw can speed up a warm-up process that reduces a voltage delay of the battery cells.

In embodiments that provide boosting toward the end of a battery section charge, a longer run time may be provided by using more of the energy stored in the battery section (by boosting an output). As noted above, in particular embodiments, a battery pack can have a built-in controller that includes a DC/DC converter capable of operating below a cut-off voltage of powered device (e.g., loading device).

In particular embodiments, a controller can be formed by one or more integrated circuits in a module, such as a printed circuit board or multi-chip module. In addition or alternatively, all or a portion of a controller can be disposed on a mixed-mode silicon chip, having low voltage and high voltage transistors.

Controllers as described herein and equivalents, can be designed for operation with a particular type of electrochemical cell such as a lithium, carbon fluoride containing, alkaline, zinc-carbon, NiCd, silver oxide or hybrid cell, or with a particular electronic device.

The controllers also allow use of the batteries of the present invention in a wide range of devices. Battery systems according to embodiments can provide advantages over known batteries regardless of whether they are used with electric or electronic devices that have a cut-off voltage such as the ones listed above or with an electric device that does not have a cut-off voltage such as a flashlight.

Battery systems according to the embodiments shown herein, or equivalents, can be used in various applications. Industrial, military, and consumer users can benefit from supply of a substantially constant voltage over the expected battery pack lifetime. Use can include long term operation of electronic devices such as radios, cameras, cellular phones, computer devices, heating, cooling (e.g., Peltier coolers) or sensor systems (including acoustic, imaging, thermal, RF or laser scanning).

Battery systems according to the embodiments shown herein, or equivalents, electronic devices can benefit from a substantially constant voltage over the expected battery system. While conventional battery pack systems can respond slowly when initially turned on, or with voltage slowly rising or even overshooting a nominal voltage, systems as described herein can provide a substantially constant output voltage.

Battery systems according to the embodiments shown herein, or equivalents, that employ boosting at the end of a battery section charge, can more efficiently utilize stored energy and/or provide for a deeper discharge. Conventionally, near battery end-of-life, voltage drop may be cause poor operation of electronics, or drop below the cut-off voltage needed for electronic device operation. Typically, once a cut-off voltage cannot be achieved, the primary battery is disposed of. However, only about 75- 80% of the conventional battery's total storage capacity will have been used. According to embodiments herein, by boosting voltage, battery systems may not only have less voltage delay, but may also utilize more capacity. Further, by employing boosting at the end of a battery section life, a deeper discharge can occur.

Certain battery chemistries are suited for long duration, high current, high voltage, and high discharge rate operation. In particular, lithium-based primary batteries have many operating characteristics useful for primary battery pack systems. Fluorinated carbon (CFx) cathodes for lithium primary batteries are long lasting, have a high power and energy density, and can be economically produced. However, a significant lag in start-up voltage has limited use in primary battery packs. This warm-up time can range from several seconds to minutes, or even hours at low temperatures. Such long delays can be unacceptable for many applications. Embodiments as described herein, or equivalents, can enable CFX batteries to be employed in systems with short voltage delays.

While battery systems as described herein can benefit commercial devices, such systems may also benefit military applications. Commercial Off-the-Shelf (COTS) batteries used in military applications today include lithium/sulfur dioxide (U/SO2) and lithium/manganese dioxide (Li/Mn02). While these batteries have similar energy densities of 200-250 Watt-hours/kilogram (Wh/kg), their volumetric energy densities are on average somewhat different at 350-450 Watt-hours/liter (Wh/I) and 500-650 Wh/I, respectively. In applications where weight is a significant design consideration, the similar gravimetric energy densities shared by sulfur dioxide and manganese dioxide batteries give neither an advantage. But manganese dioxide batteries are increasingly preferred owing to other reasons, including their enhanced safety over pressurized sulfur dioxide batteries. In a conventional BA- 5X90/U battery pack (commonly used in military radios and other systems), for example, manganese dioxide's increased volumetric energy density delivers about 11.5 Amp-hours (Ah) of service corn-pared to about 7.5 Ah with sulfur dioxide.

Advanced carbon fluoride batteries such as lithium/carbon fluoride (Li/(CFx)) batteries maintain the benefits of high energy and power densities, wide operating temperature range and long shelf life found in sulfur dioxide batteries, while employing a solid cathode (with no heavy metals or other toxic materials) to eliminate the safety and environmental concerns. At the same time, a carbon fluoride battery can have a higher gravimetric and volumetric energy densities of >600 Wh/kg and 700-1000 Wh/I, respectively. Such gravimetric and volumetric energy density improvements may allow as much as a doubling of operating time in BA-5X90/U battery packs, while weighing about the same as a traditional sulfur dioxide version of this product. Carbon fluoride batteries can also exceed manganese dioxide and carbon fluoride batteries, among others, in both power density and maximum safe current draw. Carbon fluoride battery chemistry is well suited for applications that require high sustained or pulse currents. As noted herein, a drawback to carbon fluoride batteries, however, can be their voltage delay.

By incorporating carbon fluoride batteries in a battery section, as described in the embodiments herein, or equivalents, battery systems can enjoy the various benefits of a carbon fluoride system, without the voltage delay.

FIG. 13 shows a primary battery pack system 1300 according to another embodiment. A battery pack system 1300 can include multiple batteries (one shown as 1302) supported within a housing 1334. The housing 1334 is shown partially removed to show placement of batteries (e.g., 1302), a filler structure/material (e.g., 1346) and a controller module 1336. The batteries (e.g., 1302) can be held in place by a filler 1346, which can include a thermal spreader.

A thermal spreader can completely, or partially surround the batteries (e.g., 1302) and transfer heat from the batteries (e.g., 1302) through the housing 1334 and into the environment.

In some embodiments, a selected subset of batteries (e.g., 1302) can serve as a boost section, as described in embodiments herein, or equivalents. Devices (e.g., load devices, not shown) can be connected to the battery pack system 1300 through output plug 1342.

A controller module 1336 can control an output voltage of the system 1300 utilizing boosting, as described herein, or in an equivalent manner. In some embodiments, a controller module 1336 can provide other functions such as battery status (LED status lights 1344) or indicate a state of charge of the batteries (including individually and/or by groups).

In some embodiments, a controller module 1336 can include an electronic booster section (e.g., DC-DC converter) as described in embodiments herein, or equivalents. Such an electronic booster can boost the battery pack output voltage above a pre-selected minimum value until the voltage provided by batteries (e.g., 1302) reaches a high enough voltage that the boost is no longer needed and the booster circuit can shut itself off. This circuit can increase the current drawn from the cells in the battery pack while it is operating.

As noted above, in some embodiments, controller module 1336 can be operated to provide a boost to voltage sufficient to keep the battery pack within operating parameters toward and end of life of the batteries (e.g., 1302). Service life of a battery pack can be measured by the ability to remain above a predetermined "cut-off voltage". Accordingly, embodiments herein that provide such end-of-life boosting can increase service life, with voltages above a cut-off voltage being sustainable for hours or days longer.

Electronic devices generally have a cut-off voltage. Electric devices that have mechanical moving parts, such as electric motors also have a cut-off voltage that is necessary to provide enough current to create an electromagnetic field strong enough to move the mechanical parts. An electronic device having a cut-off voltage of about 9 volts, for example, will shut down when the battery output voltage drops below 9 volts, even though the electrochemical cell may still have some of its energy storage capacity remaining. Once a conventional the battery pack cannot exceed the cut-off voltage, it may be thrown away. In contrast, battery systems according to embodiments herein, and equivalents, can utilize more energy with voltage boosting.

Embodiments utilizing constant voltage boosting (i.e., at both turn-on and afterward) can also extend the service run time of the battery by protecting the cell against current fluctuations that reduce battery lifetime. The controller can monitor both the cell voltage and the output load current and turn on the converter if either the cell voltage reaches the predetermined voltage level or the load current reaches a predetermined current level.

Alternatively, a controller module 1336 can monitor both the cell voltage and the output load current and determine if supplying the required load current will drop the cell voltage below a cut-off voltage level.

In embodiments in which a controller module is contained within a housing 1334, a housing 1334 may contain conductive shielding around the controller module to protect nearby electronic circuits from possible electromagnetic interference ("EMI") caused by components within the controller module.

A controller module can also be configured to monitor conditions in each electrochemical cell and ensure that each electrochemical cell is exhausted as completely as possible before the electronic device shuts down.

Battery cells generate heat during discharge. For carbon fluoride (CFx) or other battery chemistries, this heat can be significant and for some applications, must be reduced and/or transmitted to the outside surface of the battery pack or the internal temperature can reach a shutdown temperature of the cells. As noted above, filler 1346 can include a thermal spreader. A thermal spreader can include one or more plates, blocks or spreaders that are contained in battery pack system 1300. A thermal spreader can dissipate heat in normal operations, but may provide additional benefits for high discharge events. Additionally, a thermal spreader can reduce internal housing heat build-up that could reduce battery lifetime or result in thermal runaway events that could destroy the battery pack.

A thermal spreader can surround all of a battery (e.g., 1302), most of a battery, or be limited to only a portion of a battery. In certain embodiments, the thermal spreader can be formed from a single block of material with apertures sized to accommodate each battery (e.g., 1302), while in other embodiments multiple discrete thermal spreaders can be used. In particular embodiments, a thermal spreader can contact housing 1334 for convective, conductive, or radiative heat dispersal, while in other embodiments, passive or active fluid cooling systems can be arranged internal to the housing 1334. A thermal spreader 1334 can be formed from materials that have a high thermal conductivity and a low weight and cost. Metals such as copper are suitable, and can be used. High thermal conductivity ceramics, such as aluminum nitride can also be used. Other materials can include polymers loaded with high thermal conductive components such as carbon black, metal or heat conductive ceramic or glass fillings. It can be desirable to use thermally conductive materials that are easily cast, machined or injection moldable. Examples of suitable heat conducting polymers are made by Cool Polymers, Inc. Other manufacturers include Ovation Polymers and PolyOne.

In some embodiments, a thermal spreader can include heat absorbing materials commonly referred to as phase change materials (PCM). Phase change materials change their structure at a defined temperature and absorb heat during that change. Transmission of heat from the battery pack to the surrounding air increases as the temperature difference between the battery and the air increases. For that reason, a material that changes phase and absorbs heat a little below the maximum allowed temperature is desirable. For many applications, phase change transition temperatures can range from 50-90°C, with 70-80°C being typical. For military battery packs a maximum surface temperature can be 85°C. For that case, a material with a phase transition around 75-80°C can be used. Paraffin based materials are available with a transition temperatures in the 70-80°C range. One specific manufacturer of such phase change materials is All Cell Technologies LLC (http://www.allcelltech.com/). Other providers of PCM include Microtek Laboratories and PCM Products.

In particular embodiments, phase change materials do not just absorb heat, but also provide an effective heat conduction path from the inside of the battery pack to the outside. In such embodiments, phase change materials provide high thermal conductivity in addition to the heat absorption. Suitable materials having a thermal conductivity greater than or equal to 5 W/m*K. For either phase change materials or thermally conductive materials a low mass density is desirable to keep the weight of the finished product as low as possible. For the case of a conductive polymer, a product such as Cool Polymers E3603 is a suitable choice because it combines a high thermal conductivity of 20 W/m*K with a relatively low density of 1.56 g/cc.

Referring back to FIGS. 9A/B and 13, in some embodiments multiple batteries/cells can be contained in a housing 934/1334 formed of plastic and having an attached metallic foil. In addition or alternatively, a filler 1346 can include electrically conductive materials. As noted above, such conductive structure can reduce or eliminates emission of unwanted electromagnetic radiation from a controller module or other associated electronics contained in the housing. In other embodiments, all or a portion of housing 934/1334 can be formed of metal. Such an arrangement can also reduce EM radiation.

In embodiments like that of FIGS. 9A and 13, multiple batteries/cells with different performance characteristics can be packaged together in the same housing. In one embodiment, one battery/cell can be a smaller battery (a boost battery) with better voltage delay characteristics than other battery/cells within the housing. By operation of a controller module, such a boost battery can be used for supplying current at a nominal voltage for the first few seconds or minutes of battery pack turn-on operation. In particular embodiments, a boost battery can be a vanadium/silver, lithium/manganese oxide, or other suitable low voltage delay material.

As understood from above, in embodiments like that of FIGS. 9A and 13, capacitors or supercapacitors can be used instead of purely battery-based systems, as boost elements. In such capacitor-based systems, the capacitor can be recharged before a battery pack is deactivated, to ensure a boost charge is available upon turn-on. Embodiments can include controller circuits that can switch from a boost section (i.e., boost battery/boost capacitor/boost electronics), to longer term batteries formed from lithium/carbon fluoride or other battery chemistries that have an unacceptable voltage delay for a given application, but a desirable energy density and discharge characteristics. In very particular embodiments, a switch-over from a boost operation to a non-boost operation, can be indicated by status lights (e.g., 1344), or the like.

In particular embodiments, a battery system input battery section voltage of between 7-18 volts can be increased to nominal operating voltage between 10-18 volts. In alternative embodiments, buck-boost converters can be used to alternately increase or reduce the voltage so that battery pack voltage supply remains within a designated nominal range (typically +/- 0.5 volts). Depending on cost and desired current/voltage supply quality needed, a wide range of power converter devices can be used. Custom designed power converters can be used, or commercially available power regulator chips such as provided by Linear Technology can be used. For many types of boost, buck, and inverter (flyback) type inductor converters, changing the duty cycle can be used to control the steady-state output with respect to the input voltage. One method can be pulse-width modulation (PWM). This method takes a sample of the output voltage and subtracts this from a reference voltage to establish a small error signal. This error signal is compared to an oscillator ramp signal. The comparator outputs a digital output (PWM) that operates the power switch. When the circuit output voltage changes, the error signal also changes and causes the comparator threshold to change. Consequently, the output pulse width (PWM) also changes. This duty cycle change then moves the output voltage to reduce to error signal to zero, thus completing the control loop. In addition PWM control, other variations such as current pulse width or direct voltage control modes are also contemplated.

As understood from FIGS. 9A/B and 13, battery packs according to embodiments can have structural elements designed to dissipate and transfer heat generated by the batteries. Plastic housings can act as heat insulators, and long duration operation at high discharge rates can result in temperatures within the batteries outside of normal operating parameters. Using machined, cast, or molded thermally conductive blocks that mechanically hold the batteries and transfer or temporarily store heat (e.g. with phase change material) is contemplated. A thermal sensor can be used to monitor housing temperature, and changes to available power discharge rate or activation of active air or other cooling systems can be initiated if necessary.

FIG. 14 shows experimental results for a battery pack with boosting electronics according to one very particular embodiment, as compared to a conventional battery pack. The results of FIG. 14 correspond to two packs of 5 Li/MnOrCFx D-size cells connected in series, and tested at 2A discharge, at -29°C. Each pack included its own boost circuits. Label 1435 shows points at which boost electronics are active, to maintain an output voltage greater than 20 volts. Thus, FIG. 14 shows active boosting both at power-on and end of life.

FIG. 15 shows experimental results for a battery pack with thermal spreading fillers according to embodiments, as compared to a conventional battery pack. Curve 1533 shows a battery pack response for a pack using a PCM. Curve 1535 shows a battery pack response for a pack using a thermally-conductive material (polymer) (TCM) as a filler. Curve 1556 shows a conventional battery pack. Packs of 5 Li/MnO CFx D-size cells connected in series were tested at 2A discharge, at 21 °C. The pack with either PCM or thermally conductive polymer delivered greater capacity to 2V cut-off.

FIG. 16 shows additional experimental results for a battery packs with thermal spreaders, as compared to a conventional battery pack. Curve 1633 shows a battery pack response for a pack using a PCM. Curve 1635 shows a battery pack response for a pack using a thermally-conductive material (polymer) (TCM) as a filler. Curve 1637 shows a conventional battery pack. Packs of 5 Li/MnC -CFx D-size cells connected in series were tested at 2A discharge, at 21 °C. The pack with either PCM or thermally-conductive polymer was found to generate significantly less heat measured in the "hot zone" in between cells. The temperature measured in this "hot zone" for the control pack was 33°C greater than in the packs featuring either PCM or thermally-conductive polymer.

It should be appreciated that in the foregoing description of exemplary embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

It is also understood that the embodiments of the invention may be practiced in the absence of an element and/or step not specifically disclosed. That is, an inventive feature of the invention can be elimination of an element.

Accordingly, while the various aspects of the particular embodiments set forth herein have been described in detail, the present invention could be subject to various changes, substitutions, and alterations without departing from the spirit and scope of the invention.

Claims

IN THE CLAIMS What is claimed is:

1. A battery system, comprising:

a battery section comprising at least one battery cell and configured to provide a battery voltage at battery outputs, the battery voltage reaching a cut-off voltage upon turn-on after a first delay in response to a predetermined load;

a boost section configured to supply a boost voltage; and

a controller circuit coupled to the battery section and the booster section, and configured to

couple the booster section to system outputs to provide the cut-off voltage at system outputs after a second delay upon turn-on, the second delay being shorter than the first delay, and

de-couple the booster section from the system outputs once the battery outputs reach the cut-off voltage.

2. The battery system of claim 1 , wherein:

the battery cell comprises a battery material of no less than 1% CFx, where X is between 0 and 1.5.

3. The battery system of claim 2, wherein:

where X is between 0.05 and 0.95.

The battery system of claim 1 , wherein:

the battery cell comprises lithium.

5. The battery system of claim 1 , wherein:

the booster section is in series with the battery outputs between the system outputs.

6. The battery system of claim 5, wherein:

a first battery output of the battery section is the same as a first system output, and a second battery output of the battery section is coupled to the boost section; and

a second system output is coupled to the boost section.

7. The battery system of claim 6, wherein:

the first system output is a DC (+) terminal.

8. The battery system of claim 1 , wherein:

the boost section is configured to provide a boost voltage selected from: a dynamic boost voltage that varies over time and a static boost voltage that substantially does not vary over time.

9. The battery system of claim 1 , wherein:

the boost section includes a circuit selected from: a DC-to-DC converter circuit; at least one boost battery cell having a smaller or no voltage delay than the battery section; and a capacitor.

10. The battery system of claim 1 , wherein:

the controller circuit is further configured to couple the boost section to system outputs in response to a voltage at the battery outputs falling below the cut-off voltage.

11. The battery system of claim 1 , wherein:

the controller circuit is further configured to continue to de-couple the booster section from the system outputs if the battery outputs fall below the cut-off voltage at an end-of-life of the battery section.

12. The battery system of claim 1 , further including:

a temperature detection circuit configured to generate a temperature value; and

the boost voltage varies in response to at least the temperature value.

13. A battery system, comprising:

a battery section comprising at least one battery cell;

a boost section configured to supply a boost voltage; and

a controller circuit coupled to the battery section and the booster section, and configured to couple the booster section to system outputs upon turn-on in the event a battery section output voltage is less than a cut-off voltage.

14. The battery system of claim 13, wherein:

the battery cell comprises a battery material of no less than 1 % CFx, where X is between 0 and 1.5.

15. The battery system of claim 13, wherein:

the boost section includes a circuit selected from: a DC-to-DC converter circuit; at least one boost battery cell having a shorter voltage delay than the battery section; and a capacitor.

16. The battery system of claim 13, wherein:

the boost section is coupled between a first battery output and a first system output; and

the controller circuit comprises a controllable impedance path coupled in between the first battery output and the first system output, and a controller configured to place the controllable impedance path into

a high impedance state when the battery section outputs less than the cut-off voltage, and a low impedance state once the battery section outputs the cut-off voltage.

The battery system of claim 13, wherein: the boost section generates the boost voltage with power from the battery section; and

the controller circuit comprises a controllable impedance path coupled between the boost section and at least a first battery output, and a controller configured to place the controllable impedance path into

a low impedance state when the battery section outputs less than the cut-off voltage to supply power to the boost section, and

a high impedance state once the battery section outputs the cut-off voltage to cut-off power to the boost section.

18. The battery system of claim 13, wherein:

the controller circuit comprises

a reference voltage generator configured to generate a reference voltage,

an amplifier having a first input coupled to receive the reference voltage and a second input coupled to an output of the battery section, and

a bias network coupled to the output of the amplifier that generates at least one control voltage that varies in response to the amplifier output.

19. The battery system of claim 18, wherein: the controller circuit further includes a controllable impedance path selected from: a power enable path that enables and disables the boost section in response to the control voltage, and a boost enable path that selectively connects one system output to a battery section output in response to the control voltage.

20. A battery system, comprising:

a plurality of battery cells formed from a first battery material and coupled to system outputs;

a housing to contain at least the battery cells; and

a controller module including

a boost section configured to supply a boost voltage, and

a controller circuit configured to couple the boost voltage to the system outputs at turn-on to reduce a delay in providing a cut-off voltage at the system outputs, as compared to the battery cells alone.

21. The battery system of claim 20, wherein:

22. The battery system of claim 20, wherein:

the boost section has a configuration selected from: a series connection with the battery cells between the system outputs and a parallel connection with the battery cells between the system outputs.

23. The battery system of claim 20, wherein:

24. The battery system of claim 20, wherein:

the controller module has a location selected from:

within the housing, and

within a device, separate from the housing, which is connected to the battery cells via an electrical connection.

25. The battery system of claim 20, further including:

a visual indicator configured to visually display a current charge of the battery system.