Patent Application
20140333267
Battery performance generally varies with temperature. Similarly, battery charge characteristics also vary with temperature. Ambient battery temperatures can be 0° C. or lower, whereas efficient battery charging temperatures can approach temperatures of 25° C. to 35° C. Various technologies exist with respect to battery charging and temperature. For example, Wang et al. U.S. Pat. No. 8,334,675 heats a battery at low temperature by pulse charging and discharging up to a desired temperature and then charging using a normal charging mode. However, said pulse charging and discharging to heat the battery wastes power, requires time, and unnecessarily cycles the battery. In contrast, Miyano US Patent Application No. 20120305662 blows warm, dehumidified wind toward the battery to warm the battery without dew condensation. However, such a system requires a dehumidifier to reduce dew condensation on the battery pack from the warm wind.
This document discusses, among other things, a temperature measurement component configured to determine a temperature of a battery (e.g., a mobile phone battery), a heater configured to provide heat to the battery, and a controller configured to enable and disable the heater using the battery temperature to optimize charge efficiency and capacity of the battery.
This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the invention. The detailed description is included to provide further information about the present patent application.
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals having different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
The present inventors have recognized, among other things, a heater and a temperature measurement component that work in unison to optimize charge efficiency (e.g., enable increased charge rates) and capacity of a battery with respect to battery temperature. The temperature measurement component can measure the battery temperature, for example, directly (e.g., at the battery surface), using a direct temperature measurement component (e.g., a thermistor, etc.), or indirectly using one or more measurements of the battery, such as battery voltage or current measurements, and one or more known temperature characteristics of the battery, such as the state-of-charge (SOC) or the open-circuit voltage (OCV). Charging power to the battery can then be optimized using the battery temperature.
In the example of
In an example, the heater 115 can be configured to ensure that the battery anode is above a minimum temperature to ensure an efficient charge rate of the battery. In certain examples, the temperature measurement component (e.g., the thermistor 120) can be physically located proximate the battery anode to facilitate such measurement, or the temperature measurement component can include a plurality of components, one being located proximate the battery anode or one or more other specific locations, such as the battery cathode, a portion of the battery 110 away from (e.g., farthest away from) other heat-producing circuit components (e.g., a baseband processor, transmission circuitry, the battery charger 105, etc.), etc.
The heater 115 can receive power from the battery charger 105. In certain examples, the heater 115 can include a thin film electrical heater configured to surround or be coupled to the outside of the battery 110. In an example, the heater 115 can provide a specified temperature, or the heater 115 can provide a range of temperature depending on the power received from the battery charger 105. In an example, the heater 115 can be configured to heat the battery 110 only during battery charging, e.g., beginning at the same time the battery charging begins. In another example, the heater 115 can be configured to heat the battery 115 before battery charging, such to ensure that the battery temperature is above the minimum temperature at the beginning of battery charging, e.g., by calculating an estimated battery charging time using one or more characteristics of the battery 110, the battery temperature, or an estimated heating time for the battery 110 by the heater 115. However, the present inventors have recognized that minimizing the heating time of the battery 110 can minimize the impact of heating on solid electrolyte interphase (SEI) growth, a major driver of battery capacity loss. The present inventors have recognized that, in certain examples, a 10° C. temperature change can double or half the rate of chemical reactions in a battery 110 leading to, for example, SEI growth and reduced battery capacity. Thus, heating the battery 110 only during charging, or in another example, only during and leading up to charging, or holding the battery temperature within a specified temperature range, can balance charging efficiency and SEI growth.
In the example of
The resistance of a battery can change as a battery ages. In certain examples, battery fuel gauges can track the age or use of the battery. Further, battery resistance can be known at different temperatures and ages.
At 301, the battery temperature can be read or estimated using one or more battery parameters. At 302, if the temperature is less than 25° C., heater power (e.g., current or voltage) can be enabled or increased. At 303, if the temperature is greater than 35° C., heater power can be disabled or reduced.
In certain examples, if the battery temperature is below the desired range, charging of the battery can start conservatively and then ramp as the battery temperature approaches the desired range.
Power consumption of the thin film heaters illustrated in
Anode and Cathode Reactions in a Lithium (Li) Battery
As Li ions are removed from a cathode of a battery during charging, an electron is removed. A similar action occurs at an anode of the battery. Mass diffusion carries Li to anode where intercalation occurs. This mass transfer is limited, however, by chemical reaction rate. Diffusion is a result of the concentration differences at the cathode to the anode. During fast charging, Li+ concentrations reach a level where an Li metal layer forms, resisting future diffusion events and decreasing the maximum level of charge storage.
Chemical reactions occur more quickly with higher temperatures, driven by Arrhenius depencence, namely D=Aê(−E/(kBT)), where D is the rate of diffusion, A is a constant based on the materials in question, E is the activation energy, kB is Boltzmann's constant, and T is temperature. Typically, a 10° C. temperature change can double or half the rate of chemical reactions.
Additional Notes and Examples
The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments in which the invention can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.
All publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference(s) should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
Method examples described herein can be machine or computer-implemented at least in part. Some examples can include a computer-readable medium or machine-readable medium encoded with instructions operable to configure an electronic device to perform methods as described in the above examples. An implementation of such methods can include code, such as microcode, assembly language code, a higher-level language code, or the like. Such code can include computer readable instructions for performing various methods. The code may form portions of computer program products. Further, the code can be tangibly stored on one or more volatile or non-volatile tangible computer-readable media, such as during execution or at other times. Examples of these tangible computer-readable media can include, but are not limited to, hard disks, removable magnetic disks, removable optical disks (e.g., compact disks and digital video disks), magnetic cassettes, memory cards or sticks, random access memories (RAMs), read only memories (ROMs), and the like.
The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
The present application claims the benefit of priority to U.S. Provisional Patent Application Ser. No. 61/821,771, filed May 10, 2013, which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61821771 | May 2013 | US |
