Thermal insulation battery system and thermal insulation battery pack

Abstract

To provide an insulated battery system that protects battery cells and other battery components from thermal degradation during autoclave or steam sterilization procedures.SOLUTION: The insulated battery system may include a vacuum insulated housing with an outer wall and an inner wall that have a vacuum space therebetween. One or more battery cells and other components are receivable in the vacuum insulated housing. The vacuum insulated housing is sealed with a lid or casing. The insulated battery system protects the battery cells and other battery components from thermal degradation, for example, during autoclave or steam sterilization procedures.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This application generally relates to battery systems, and more specifically, to an insulated battery pack for a rechargeable battery, for example, for a surgical power device.

Background Art

[0002] Cordless power devices require a battery. A rechargeable battery takes in energy as electrical energy from an external power source, typically commercial power, and stores it as chemical energy within the battery cell. When the tool requires energy, the battery converts the stored chemical energy back to electrical energy to supply useful power to the tool. The means by which energy is stored in the battery can vary widely in chemical nature, for example, from lead acid to nickel metal hydride, nickel-cadmium, and lithium ion. As the temperature of the cell increases due to the breakdown of the layers of materials within the cell at higher temperatures, all of these chemicals begin to decompose and lose their cycle life. These degradation effects are exacerbated when the cell is in a high state of charge during these temperature fluctuations.

[0003] In a surgical setting, it is often desirable to have a power device, for example, to assist in surgeries such as bone cutting, drilling, or screwing. This creates a need for power tools in a sterile operating room environment. The most common sterilization technique found in all sterile surgical settings is autoclaving or high-pressure steam sterilization.

[0004] Due to the nature of the sterile surgical environment, the battery may not be able to be charged immediately before use. This may be due to the time required to charge the pack or the limitation that the charger must be sterilized. Due to these constraints, batteries used in a sterile environment are often fully charged before autoclave sterilization. This results in the worst-case scenario for the battery's cycle life, namely, very high temperatures and a fully charged state.

[0005] The status quo of the sterilization battery market is to use lithium iron phosphate batteries and accept that they get hot. This chemical property is most resistant to large temperature fluctuations but still significantly increases the degradation rate of the cells. In some designs, for example, a thin fiber blanket impregnated with aerogel particles was used to try to limit the heat received by the cells. Aerogels have a very low thermal conductivity, which can limit the heat experienced by the cells by increasing the surrounding thermal resistance. These designs can help lower the temperature of the cells in an autoclave and improve the cycle life, but only by a small amount. Aerogels provide a battery life of several hundred cycles, which is far from the 2000 cycles expected based on the type of cell.

[0006] Due to the high degradation rate, a large number of discarded battery cells are generated. Because of the short battery life, hospitals also need to repurchase additional batteries, leading to environmental and financial waste. Therefore, a robust system with a sterilization battery system that can protect the cells at high temperatures even when fully charged is needed.

Summary of the Invention

[0007] To meet this and other needs, vacuum-insulated battery housings, systems, and methods are provided. The vacuum-insulated system reduces the heating of the internal battery pack components, including the cells and the battery management system (BMS) components. The vacuum-insulated housing suppresses the thermal degradation of the battery pack, thereby enabling a longer service life. The insulation system enables alternative battery chemistries that can significantly increase the energy and power density compared to conventional designs. The vacuum-insulated system results in excellent battery packs with longer life, longer runtime, and / or higher power at a similar package size and unit cost.

[0008] According to one embodiment, a thermally insulated battery system includes a vacuum-insulated housing, one or more battery cells, a printed circuit board or battery management system, and a lid or casing. The vacuum-insulated housing includes an outer wall and an inner wall, and has a vacuum space between the outer wall and the inner wall. The inner wall defines a central hollow chamber. The battery cells are receivable within a battery holder. The printed circuit board is electrically connected to the battery holder. The battery cells, the battery holder, and the printed circuit board are receivable within the hollow chamber of the vacuum-insulated housing. The casing is configured to seal the vacuum-insulated housing, thereby protecting the components from moisture and high temperatures during autoclave sterilization.

[0009] The thermally insulated battery system may include one or more of the following features. The outer wall of the vacuum-insulated housing may include an outer side wall and an outer bottom wall, and the inner wall may include an inner side wall and an inner bottom wall. The outer side wall and the inner side wall may meet at an upper lip so as to completely surround the vacuum space. The vacuum-insulated housing may have a generally cylindrical body. The vacuum-insulated housing may include a narrow neck, and the casing may engage the narrow neck, thereby sealing the battery system. The vacuum-insulated housing may include two 0.5 mm walls with a 3 - 4 mm vacuum gap therebetween. One or more electrical pass-throughs may be provided to allow current to exit the vacuum-insulated housing. The electrical pass-through may include a conductor within or through the casing. The conductor may include a body having a blind hole through the top surface, a seat for contacting the printed circuit board, and a central ring having an O-ring seat for receiving an O-ring positioned between the conductor and the casing. A screw may be screwed into the blind hole and the head of the screw pressed against a spring terminal to secure, thereby sealing the pass-through. The conductor may be connected to the printed circuit board with a wire. The conductor may include a round bottom seat having a wire trap configured to hold the wire.

[0010] According to one embodiment, the insulated battery pack includes a vacuum insulated housing, a casing, a battery holder, a rechargeable battery cell, a printed circuit board, and an electrical pass-through. The vacuum insulated housing extends from an upper lip to a bottom wall and may define a central hollow chamber. The vacuum insulated housing may include an outer wall and an inner wall having a vacuum space therebetween. The casing is configured to seal the vacuum insulated housing. The battery holder is positionable within the hollow chamber of the vacuum insulated housing. The rechargeable battery cell is connected to the battery holder. The printed circuit board is electrically connected to the battery holder. The electrical pass-through within the casing connects the printed circuit board to a spring terminal to supply power to a tool. The casing may include a tool interface configured to removably secure the battery pack to a power tool such as a drill, a cutter, or a driver. The casing may include a check valve embedded therein and can release any gas.

[0011] According to another embodiment, the vacuum insulated battery system includes a vacuum insulated housing, a vacuum insulated lid, and a separator. The vacuum insulated housing may extend from an upper lip to a bottom wall and may have a narrow neck near the upper lip. The vacuum insulated housing may include an outer wall and an inner wall having a vacuum space therebetween. The inner wall may define a central hollow chamber. The vacuum insulated lid for sealing the vacuum insulated housing may include an outer wall and an inner wall having a vacuum space therebetween. The separator may be positioned between the vacuum insulated lid and the vacuum insulated housing. The separator may include a ring having an upper band with a concave outer surface configured to fit the lid and a lower band with a concave inner surface configured to fit the neck of the vacuum insulated housing. The separator may function as an electrical pass-through. The vacuum insulated battery system is configured to hold rechargeable battery cell(s), thereby protecting the battery cell(s) from thermal degradation, for example, during steam sterilization or autoclave procedures. The vacuum insulated battery system may include a phase change material such as paraffin wax or polyethylene oxide to further enhance the thermal efficiency of the system.

[0012] According to another embodiment, the cordless power tool includes a handle and a thermal insulation battery pack configured to be attached to the handle. The thermal insulation battery pack includes a vacuum insulation housing and a casing for insulating battery cells and other battery components during autoclaving and / or sterilization. The casing may have a tool interface configured to slidably interface with the handle of the tool. The power tool may include a drill, a cutter, a driver, or other surgical instrument.

[0013] According to yet another embodiment, a method for insulating a rechargeable battery cell during sterilization includes: (1) charging one or more rechargeable battery cells, preferably to a fully charged state; (2) positioning the rechargeable battery cells within a vacuum insulation housing; (3) sealing the vacuum insulation housing with a lid or casing to form a battery pack; (4) subjecting the battery pack to high temperature, high pressure, steam, and / or other autoclaving or sterilization procedures to sterilize the battery pack; and (5) attaching the battery pack to a cordless power tool before or after sterilization to perform a surgical procedure. The thermal insulation battery pack is configured to protect the battery and other components during sterilization even when fully charged, thereby preventing thermal degradation and improving battery performance and cycle life.

[0014] Also provided is a kit including a battery pack, a rechargeable battery, a power tool and tool, and other components.

Brief Description of the Drawings

[0015] A more complete understanding of the present invention, as well as the attendant advantages and features thereof, will be more readily understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiments of the present disclosure generally relate to vacuum insulation housings, systems, and methods. Specifically, embodiments relate to vacuum insulation housings and systems configured to protect components of battery cells and battery packs at high temperatures even when fully charged. The vacuum insulation housings and systems are configured to be sterilized, for example, using standard steam sterilization autoclave procedures used in surgical settings while protecting internal components.

[0017] Cordless electric devices such as drills, drivers, and other instruments used during surgical procedures require a battery. Portable rechargeable or secondary batteries are often used to power the instrument during operation. Rechargeable batteries can include nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), and lithium-ion (Li-ion) cells in order of increasing power density and cost. Lithium-ion batteries have a higher average voltage and typically a higher energy density than other chemistries.

[0018] Within lithium ions, there are also a range of sub - chemical substances based on the composition of the metals used in the cathode. The main ones are nickel manganese cobalt (NMC), which is commonly used in electric vehicles (EVs); nickel cobalt aluminum (NCA), which is the highest energy density chemical substance and is commonly seen in power tools and some EVs; and finally, the main chemical substance is lithium iron phosphate (LiFePO4), which has a much lower energy density and a lower voltage than NCA or NMC. Higher currents promote cell degradation and result in higher heat during discharge of both the cell and any motor that the cell is powering. That is, the lithium iron phosphate chemical substance is much more resistant to heat and abuse, with a slower degradation rate at high temperatures. Also, the cycle life is much longer, for example, about 2000 cycles (one charge and one discharge = 1 cycle), compared to about 500 cycles for other chemical substances. This means that lithium iron phosphate will be used mostly in grid storage or other environments where reliability and lifespan are major motivations.

[0019] Due to the destruction of the layers of materials within the cell at these higher temperatures, as the cell temperature increases, all of these chemical substances begin to decompose and lose their cycle life. Degradation is nearly zero at 25°C and begins to increase acceleratively as the temperature rises. Above 60°C, the degradation of the cell progresses rapidly. These degradation effects worsen when the cell is in a high state of charge during these temperature fluctuations.

[0020] For example, in a surgical setting involving bone cutting, drilling, or screwing, it is often desirable to have a powered device to assist with the procedure. This creates a need for powered instruments in a sterile operating room (OR) environment. The most common sterilization technique found in sterile surgical settings is autoclaving or steam sterilization under high pressure and temperature. This may include sealing the battery pack in a chamber filled with steam at 134 °C and 2.2 bar and holding it at that temperature and pressure for at least 4 minutes. However, due to the slow temperature rise and typical drying period, the time above 60 °C in the chamber can be much longer, for example, about 40 - 50 minutes, most of which is above 90 °C.

[0021] Due to the nature of the sterile surgical environment, the battery may not be able to be charged immediately before use. This may be due to the time required to charge the pack, especially in environments where there may be an unexpected immediate need for a charged pack, such as in the case of trauma. It may also be due to the limitation that the charger must be sterilized. Due to these limitations, the batteries used in sterile environments must be fully charged before autoclave sterilization. This results in the worst-case scenario for the battery cycle life, namely a very high temperature (134 °C) and a fully charged state.

[0022] This creates the need for a battery housing that can withstand the temperature rise of the cells inside the housing in order to limit the degradation rate of the cells. The current state of the sterilizable battery market is to use LiFePO4 cells and simply accept that they get hot. This chemical is the most resistant to large temperature fluctuations. However, it still significantly increases the degradation rate of the cells. Cells that normally achieve over 2000 cycles can be expected to achieve only 100 - 200 cycles under these conditions. In some designs, a thin (about 3 mm) fiber blanket impregnated with aerogel particles is used to try to limit some of the heat the cells receive. Aerogels have a very low thermal conductivity and, when surrounding the cells, can limit the heat the cells experience by increasing the surrounding thermal resistance. These designs may be excellent in both the temperature of the cells in the autoclave and cycle life, but only achieve a few hundred cycles, far from the 2000 cycles expected based on the type of cell.

[0023] Due to the high degradation rate, a large amount of scrap is generated for recycling the battery cells, leading to more hospital repurchases of batteries and resulting in environmental and financial waste. Furthermore, even designs encapsulated with aerogel are still hot, preventing the use of higher energy density and higher voltage chemical cells such as NMC.

[0024] One way some people use to avoid the whole autoclave problem is to autoclave the secondary housing with the non-sterile battery instead of autoclaving the battery itself. This creates other risks where the sterile user has to hold the sterile housing and a second non-sterile user carefully inserts the non-sterile battery into the housing and then the sterile user closes the housing. This movement has to be done preoperatively in the sterile OR. This increases the points of poor sterility, increases the personnel in the OR, adds parts and pieces to the battery assembly, and / or increases the overall size of the battery during use. Despite there being options to use better cells that can stress the cells less, these complexities have prevented this from becoming the primary way to power the OR.

[0025] In some applications, insulation materials such as aerogel blankets have been introduced that simply try to trap as much air as possible by separating it from convection. Air has the lowest thermal conductivity among common materials, being surpassed only by other pure gases. Under normal circumstances, air can convect, increasing the overall heat transfer rate of the insulation. Some insulation materials try to trap this air from convection while introducing as few other materials as possible and keeping the conductivity of the materials as low as possible. This limits the heat transfer means to mostly just radiation and conduction through poor conductors. Aerogels are over 99% air with the remaining material being silica, which is also a very poor conductor. For general battery applications, pure aerogel blocks cannot be used due to cost, manufacturing, and durability reasons. For this reason, it is more common to see aerogel powder in fabrics. This reduces the benefits as it introduces another conduction path through the fabric while leaving gaps for air to move between the aerogel crystals and between the fabric fibers.

[0026] This leaves a need for a sterilizable battery that can completely insulate the cells, an option to use LiFePO4 cells that can actually meet the expected cycle life of over 2000 cycles, perhaps an option to increase the life of the pack by more than 10 times, and / or an option to use alternative chemistries that double or more the runtime of a pack of the same size and increase the voltage.

[0027] Additional aspects, advantages, and / or other features of exemplary embodiments of the present invention will become apparent in view of the following detailed description. It will be apparent to those skilled in the art that the described embodiments provided herein are merely exemplary and illustrative and not limiting. Numerous embodiments of modifications thereof are contemplated as falling within the scope of the present disclosure and equivalents thereto.

[0028] Referring now to FIG. 1, a thermal battery system or battery pack 10 attached to a cordless power tool or instrument 12 according to one embodiment is shown. The thermal battery system or battery pack 10 can be attached, for example, to the underside of the handle 14 of the cordless instrument 12. The cordless power instrument 12 can include a drill, driver, cutter, or other power instrument. For example, a drill bit, screwdriver, curette, etc. can be positioned through and interfaced with the sleeve 16 of the instrument 12 to perform a desired procedure. Although only the handle 14 and sleeve 16 of the instrument 12 are depicted, it should be understood that there are other suitable components for the proper functioning of the instrument 12. The battery pack 10 is configured to supply power to the tool 12 to perform an intended function, such as drilling, driving, cutting, etc. Although the instrument 12 is assumed to be configured to perform a surgical procedure, it should be understood that the battery pack 10 can also be suitable for other uses.

[0029] Referring now to FIGS. 2 - 4, the thermal battery system or battery pack 10 is shown in more detail. The battery pack 10 may include a lid or casing 20 for receiving a vacuum insulated bottle, container, or housing 50. The casing 20 may include a hollow cylindrical cap or body 22 having an internal opening 24. The battery pack 10 may include a plastic cap or tool interface 26 configured to secure the battery pack 10 to the power tool 12. For example, the tool interface 26 may include a plurality of fingers or rails configured to slidably engage a corresponding interface at the bottom of the handle 14. The tool interface 26 includes one or more electrical connections configured to electrically couple to internal components of the tool 12, thereby supplying power to the tool 12. The interface 26 may include a latch 28 for removably securing the battery pack 10 to the tool 12. The latch 28 is released by a button 30 that can be depressed by the user, thereby allowing the battery pack 10 to be removed from the tool 12. The lower side of the casing 20 may include one or more feet 32 configured to stabilize the battery pack 10 and the tool 12 when they are attached.

[0030] The lid or casing 20 and / or other components of the battery pack 10 can be formed of one or more metals, plastics, or other suitable materials. In one embodiment, the lid or casing 20 is formed of a solid plastic such as injection molded plastic or vacuum formed plastic. The plastic can include polypropylene (PP), polyethylene (PE), PEEK PSU, poly(phenylene oxide) (PPO), polyester, polycarbonate (PC), acrylonitrile butadiene styrene (ABS), acrylic, nylon, or combinations thereof.

[0031] Looking at FIG. 4 in more detail, the thermal battery pack 10 is configured to house one or more battery cells 40. The battery cells 40 can include disposable batteries or rechargeable batteries that are charged prior to use. In an exemplary embodiment, the battery cells 40 are preferably rechargeable batteries that are charged prior to an autoclave or sterilization process. The batteries 40 can include nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium ion (Li-ion), or any suitable rechargeable cell. Although cylindrical batteries 40 are shown, it should be understood that the batteries can include any suitable battery that is currently available or later developed. The thermal battery pack 10 can house one, two, three, four, or more adjacent battery cells. It should be understood that any suitable number, type, and configuration of battery cells 40 can be selected based on the application. Each of the battery cells 40 can be housed in a battery holder 42. Each battery holder 42 is configured to hold the battery 40 such that the holder 42 makes proper electrical contact with the battery terminals (e.g., the positive terminal is the cathode and the negative terminal is the anode).

[0032] The battery holder 42 is electrically connected to a printed circuit module or a printed circuit board (PCB) 44. The printed circuit board 44 protects the battery pack 10 from overcharging, over-discharging, and over-draining. The PCB 44 prevents damage, ignition, or explosion of the battery pack 10. In one embodiment, the PCB 44 is replaceable with, or is part of, a battery management system (BMS). The BMS is an electronic system that manages a rechargeable battery by monitoring the state of the rechargeable battery, calculating data, protecting the battery, controlling the environment, and / or balancing. In particular, a lithium-ion battery system can include a BMS to manage real-time control of each battery cell 40, measure temperature and voltage, communicate with external devices, and / or manage calculations. The BMS can include a microcontroller having intelligent integrated software that calculates and interprets various types of measurements such as state of charge (SOC) or state of health (SOH). The sealed electrical pass-through 46 can connect the PCB 44 to the spring terminal 48, and the spring terminal 48 supplies power to the tool 12 when coupled to the battery pack 10.

[0033] The casing 20 can include a check valve 49 embedded therein and can vent any gas in the event of a catastrophic battery failure. The check valve 49 prevents the battery pack 10 from becoming a pressure vessel that poses a further danger. Further, the check valve 49 can vent the air inside the container 50 during the vacuum phase of an autoclave cycle for appropriate ratings. The check valve 49 also prevents re-inflow of vapor or air, thereby further amplifying the heat insulation effect from the autoclave heat by eliminating conduction and convection within the cell space.

[0034] Referring now to FIG. 5, a vacuum insulated bottle, container, or housing 50 according to one embodiment is shown. The vacuum insulated housing 50 can include a double wall container or bottle. The double wall container 50 includes an outer wall 52 and an inner wall 54 having a vacuum space 56 therebetween. The double wall container 50 forms an airtight enclosure around the vacuum space 56 from which air is completely or substantially completely evacuated. The outer wall 52 includes an outer side wall 58 and an outer bottom wall 60. The inner wall 54 includes an inner side wall 62 and an inner bottom wall 64. The outer side wall 58 and the inner side wall 62 may meet at an upper lip 66 so as to completely surround the vacuum space 56. It should be understood that the outer side wall 58 and the inner side wall 62 may form a generally cylindrical body, although other suitable shapes may be selected. The outer bottom wall 60 and the inner bottom wall 64 may form a generally flat bottom, although it should be understood that the bottom walls 60, 64 can be configured in another way. Although a double wall container 50 is illustrated, it should be understood that the housing 50 can have additional insulating layers including additional walls having additional vacuum layers therebetween. In some embodiments, the outer surface of the inner wall can be mirror finished or coated with a reflective layer to further improve the insulation properties by reflecting radiant heat transfer.

[0035] The vacuum insulation housing 50 may have a narrow neck 68 near the upper lip 64. For example, the outer wall 58 can be narrowed inwardly towards the inner wall 58 to form the neck 68. The neck 68 may be configured to receive a cap or lid 20, 100 and thereby seal the container 50. As best shown in the embodiment of FIG. 4, the cap or lid may be an integral component of the casing 20. The neck 68 may include one or more mating members 70 configured to engage corresponding features of the cap, lid, or casing 20. The mating member 70 may include one or more protrusions, rings, threads, ridges, beads, or other features configured to seal a cap or lid to the neck 68 of the housing 50. In a preferred embodiment, the mating feature is a thread. In one embodiment, the mating member 70 includes a ridge extending circumferentially around the neck 68, and a plurality of corresponding recesses are formed inside the casing 20 to mate with the ridge, thereby fixing the casing 20 to the housing 50. The casing 20 is configured to seal the housing 50 such that little or no moisture, temperature, or pressure enters the chamber 72, for example, during autoclave sterilization.

[0036] The distance between the outer wall 52 and the inner wall 54 may be constant or variable. In an exemplary embodiment, the outer wall 52 and the inner wall 54 have a constant width between the bottom walls 60 and 64 and between the side walls 58 and 62 up to the region of the narrowed neck 68. The walls 52, 54 may include, for example, 24-gauge (0.635 mm), 25-gauge (0.556 mm), 26-gauge (0.475 mm), or thinner stainless steel walls. The vacuum gap 56 may be in the range of about 1 - 5 mm, about 2 - 4 mm, or about 2 - 3 mm. In one embodiment, the double-walled container 50 may include two steel walls 52, 54 each less than 0.5 mm thick with a 3 - 4 mm vacuum gap 56 therebetween. The size of the double-walled container 50 may be similar to the plastic housing of a battery and generally has a thickness of 2 - 3 mm and 2 - 3 mm of insulation material (if insulation material is used). Thus, the double-walled container 50 may also have a total wall thickness of about 4 - 6 mm, about 4 - 5 mm, or about 5 - 6 mm.

[0037] The inner wall 54 of the housing 50 defines a central hollow chamber 72. The central hollow chamber 72 may include a generally cylindrical recess defined by the inner wall 54 of the bottle 50. The chamber 72 may have the same diameter from the mouth to the bottom of the bottle 50 or may be different. In an exemplary embodiment, the diameter of the chamber is constant. As best shown in FIG. 4, the hollow chamber 72 is configured to receive the battery cell 40 and the battery holder 42. The hollow chamber 72 may also accommodate a printed circuit board 44 or battery management system components. It should be understood that the shape and size of the chamber 72 can be modified based on the configuration of the contents.

[0038] The double - wall container 50 can be formed of one or more metals, plastics, or phase - change materials, as will be described in more detail below. In an exemplary embodiment, the double - wall container 50 can be formed of a metal such as steel or stainless steel. The double - wall container 50 provides very good thermal insulation. The space 56 between the walls 52 and 54 is evacuated to a high vacuum. The high vacuum can have a pressure in the range of 100 mPa to 100 nPa. The vacuum eliminates both conduction and convection as heat - transfer paths, leaving only radiation as the means of heat transfer through most of the bottle 50. There is still an electrical conduction path through the lip 64 of the bottle 50 where the two walls 58, 62 meet. However, this path is a region where the transfer is significantly reduced compared to fabric or other thermal insulation means. Radiative heat transfer can be further reduced by increasing the albedo of the inner wall 54 by reflecting it. For example, the albedo can be greater than 0.5, greater than 0.6, greater than 0.7, or greater than 0.8. Combining these processes results in a much lower heat - transfer rate than other systems.

[0039] The vacuum insulation housing 50 can be used to withstand the heat from steam-based sterilization or autoclave processes. This is particularly suitable for components that are greatly affected by heat, such as lithium-ion battery cells. When constructing a battery 10 where most of the housing is composed of a vacuum insulated bottle 50, the heat felt by the cell 40 is reduced compared to when compared to only an aerogel blanket or a conventional plastic housing.

[0040] The battery cell 40 is disposed inside the container 50 and requires one or more ways to allow current to exit the container 50. In one embodiment, the current may exit, for example, through one or more electrical pass-throughs 46 within the lid or casing 20. This can be done in the same way as a typical battery pack when the lid or casing 20 is made in a simple plastic shape. Since one end is no longer a vacuum insulation wall, this limits the effectiveness of the vacuum bottle 50, but it is a relatively small portion of the surface area of the pack. To overcome this, the lid or casing 20 can be insulated, for example, with an aerogel blanket. In this case, the shape of these blankets becomes much simpler and can be more completely covered, and the surface area through which heat can pass in the uninsulated portion is much smaller compared to existing designs.

[0041] Highlighting FIGS. 6 - 12 further, the electrical pass-through 46 can include conductive components within the plastic lid or casing 20. In one embodiment, the electrical pass-through 46 can include one or more insert-molded conductive pieces within the plastic lid 20 wired to the battery core pack. In another embodiment, the electrical pass-through 46 can include one or more conductors 80 having an O-ring 82 passing through the plastic lid 20. Any of the designs can keep the seal around the internal core pack and make the interior invisible so that high-temperature steam does not enter the internal chamber 72. The terminals outside the pack 10 can be screwed or soldered to the pass-through 46.

[0042] As shown in FIGS. 6-9, the electrical pass-through 46 can include one or more conductors 80 that connect to a battery management system (BMS) and / or a printed circuit board (PCB) 44. The PCB 44 can be soldered or screwed directly to the inner surface of the pass-through 46. As best seen in FIG. 7, the conductor 80 can include a body with a blind hole 86 through the top surface, a base or seat 88 for contacting the PCB 44, and a central ring with an O-ring seat 84. As shown in the assembly of FIG. 8, the seat 88 can be positioned in the opening and soldered to the PCB 44. The threaded portion of the screw 90 can be positioned within the blind hole 86 with the head of the screw 90 pressing against and securing the spring terminal 48. The O-ring 82 can be positioned within the O-ring seat 84 between the conductor 80 and the casing 20. The screw 90 can serve to maintain pressure on the O-ring 82 with an O-ring seal, thereby sealing around the pass-through 46. It should be understood that other means of securing the conductor 80 can be used. Soldering and / or screwing connections ensure alignment between the PCB 44 and any features on the lid 20, such as the charge state LED window. As shown by the depiction of the arrows in FIG. 9, this configuration can directly transmit stress from housing flexure and / or shock to the PCB 44.

[0043] Figures 10 through 12 illustrate another embodiment of conductor 80 for electrical via 46. To avoid stress being transmitted directly to substrate 44 through via 46, via 46 may be connected to wire 94 that extends from BMS and / or PCB 44 to via 46. As shown in Figure 10, conductor 80 may include a round bottom seat 88 having a wire trap 92 to hold wire 94. As shown in the assembly of Figure 11, seat 88 receives one end of wire 94 and the opposite end of wire 94 is soldered to PCB 44. Screw 90 may still be positioned within a tapped hole 86 with the head of screw 90 pressing against spring terminal 48 to secure conductor 80. O-ring 82 is positioned within an O-ring seat 84 between conductor 80 and housing 20. Screw 90 maintains pressure on O-ring 82 to seal via 46. In this case, as shown by the depiction of the arrow in Figure 12, force applied to housing 20 or via 46 is not propagated to substrate 44. Wire 94 allows PCB 44 to be isolated from any housing stress at via 46, but other means may be necessary to rotationally align PCB 44 to any features on lid 20, such as an LED window for charge status.

[0044] Referring now to FIGS. 13 and 14, an embodiment of a sealed vacuum insulated container 50 is shown with a lid, cap, or top 100. The top 100 may replace or be a component of the lid or casing 20. In this embodiment, the top 100 is fabricated as a vacuum insulated top or lid. The top 100 may include the same vacuum continuous bubbles as the container 50. The vacuum insulated top 100 may include a double wall lid having an outer wall 102 and an inner wall 104 with a vacuum space 106 therebetween. The outer wall 102 includes an outer side wall 108 and an outer upper wall 110. The inner wall 104 includes an inner side wall 112 and an inner upper wall 114. The outer side wall 108 and the inner side wall 112 may meet at a lower lip 116. The outer wall 102 and the inner wall 104, or portions thereof, completely enclose the vacuum space 106. The outer upper wall 110 and the inner upper wall 114 may form a generally flat top, but it should be understood that the upper walls 110, 114 can be configured in another way for the overall battery design.

[0045] As shown in FIG. 13, the insulated lid 100 may be configured to fit over the neck 68 of the container 50. For example, the inner side wall 112 may be recessed such that the inner side wall 112 fits over the outer side wall 52 of the container 50 at the neck 68. The neck 68 of the container 50 and / or the mating member 70 may be configured to engage or fit with the inner side wall 112 of the lid 100, thereby removably securing the lid 100 to the container 50. For example, the mating member 70 may engage one or more recesses, threads, or other friction enhancing elements on the lid 100, thereby sealing the lid 100 to the container 50.

[0046] Since a vacuum pressure is required, it may be desirable for the upper part 100 or a part thereof to be made of metal. The metal may include steel such as stainless steel, titanium, nickel, or other suitable metals, or combinations thereof. In some cases, the metal vacuum lid 100 can complicate the design of the electrical pass-through. In one embodiment shown in FIG. 14, the electrical pass-through 120 can be achieved with an intervening plastic ring 122 between the two halves 50 and 100. In another embodiment, the pass-through can use the bottle 50 itself as a means of conducting current to the outside of the pack with a thinner electrical insulating ring for separating the upper and bottom parts 50, 100. In some cases, it can be difficult to incorporate charge state leading activation in the metal lid 100. Due to these complexities, in some cases, it may be desirable to use, for example, a plastic upper part, lid, or casing 20, 100 with conventional insulation to complete the vacuum insulated pack 10.

[0047] To further emphasize FIG. 14, the insulated lid 100 can be separated from the container 50 by a separator 122. The separator 122 can include a plastic separator that allows for a possible electrical pass-through 120 to the outside of the chamber 72. The separator 122 can include a ring having a stepped contour for fitting with the container 50 and the lid 100. The separator ring 122 can include an upper band 124 having a concave outer surface configured to fit with the inner wall 112 of the lid 100 and a lower band 126 having a concave inner surface configured to fit with the neck 68 of the outer wall 58 of the container 50. The separator ring 122 can also be configured to separate the lid 100 from the container 50 while maintaining a proper seal of the pack 10 and providing the desired electrical pass-through 120.

[0048] By using metal in the housing of the vacuum insulated bottle 50, unique features for charge state (SOC)-led activation can be made possible. The surface of the conductive bottle 50 can function as a capacitive touch sensor that enables user control of the SOC indicator without the need for separate pass-throughs or sealed mechanical button pass-throughs. Thereby, the user can manually activate the charge state indicator by touching the bottle 50 of the battery pack. This feature may typically resemble a commercially available battery pack having a button for on-demand checking of the charge state, bringing a more familiar feature from the area of power tools to the surgical space.

[0049] According to another embodiment, the thermal resistance of the system can be further extended by using one or more phase change materials (PCMs). Phase change materials absorb or release large amounts of latent heat during the process of changing their physical properties. Suitable phase change materials may include paraffin wax, polyethylene oxide (PEO), or other unique formulations for, for example, lithium batteries. The phase change materials can be incorporated into part or components of the bottle 50, the casing 20, the lid 100, or the battery pack 10 to insulate the battery cell 40 and other battery components.

[0050] Paraffin wax is one of the PCMs with the highest latent heat, exceeding only molten salts, metals, and water. Paraffin wax has an ideal melting temperature for lithium-ion batteries in the range of 40 - 50 °C. When paraffin wax (paraffin max) melts, it can expand by at least 10%, and often the volume approaches 20%, becoming a very low-viscosity fluid. This may require sealing the pack to a watertight level, which is done for sterilized packs by steam in an autoclave, but the wax also needs to expand and contract within the container. This can be achieved, for example, by partially filling the PCM space in the pack, using a diaphragm to allow the wax to expand and contract, or incorporating a space for expansion into the pack. A partially filled space can lead to a significant reduction in the accuracy of temperature measurements from the built-in thermistor, an increased imbalance rate, a situation where a charged cell is left in contact with the PCM, and / or a dangerous situation where the thermistor reads the coldest cell and other cells in contact with the PCM are significantly hotter.

[0051] The second option is a crystalline-to-amorphous PCM such as polyethylene oxide (PEO). The latent heat of PEO is only about half that of paraffin wax, but PEO expands very little during the phase change. In the amorphous state, PEO is still a very viscous fluid, mostly staying in place, eliminating the sealing and expansion problems caused by wax. PEO can be injected into the battery housing as a fine powder covering the entire cell or compressed into a block and then fixed in place by a cell holder.

[0052] As described in the embodiments provided herein, thermal protection from the heat of the autoclave provides potential benefits that are not possible with current sterilization batteries. As previously mentioned, cycle life is greatly affected by the heat of the battery cells. A typical LiFePO4 cell should last about 2000 cycles, but case evidence shows that the cycle life of a typical sterilization battery is very short, at 100 cycles. Selecting the same cells and enhancing thermal protection results in a significant increase in the battery cycles to the expected level of about 2000 cycles, thereby multiplying the life of a product of the same package size by 20.

[0053] It should also be understood that other battery chemistries can be used if the internal space of the battery never reaches high temperature levels (e.g., about 70 °C or less) during sterilization. The LiFePO4 chemistry is typically used to prevent thermal degradation of the pack, and while that chemistry can better handle higher temperatures than most products with useful power, it can still significantly shorten battery life. Chemistries commonly used in power tool applications such as NMC and NCA have a higher voltage per cell (10 - 15% or more) and a much larger capacity (100 - 300% or more). This allows for the same voltage and higher capacity with fewer cells than a typical iron phosphate pack and should translate to higher energy and power density. A higher voltage means lower current in the tool and pack at the same power level. This should result in an extended cycle life for the pack and the tool. Joule heat from power is directly related to the square of the current, meaning less heat is generated in the cells and less heat is generated in the motor coils.

[0054] Due to the design of the vacuum insulated bottle, the heating of the internal pack components, especially the cells as well as the BMS components, is reduced, thereby reducing the thermal degradation of the pack and increasing the service life of the pack. With this improved thermal performance, it is also possible to use alternative chemical substances that can significantly increase the energy and power density compared to the conventional design. By combining these factors, a much superior pack with a longer life, longer runtime, and / or higher power can be obtained at a similar package size and unit cost.

[0055] The present invention has been described in detail and with reference to specific embodiments, but it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, the present invention is intended to cover the modifications and variations of the present invention provided within the scope of the appended claims and their equivalents. For example, it is clearly intended that all components of the various devices disclosed above can be combined or modified in any suitable configuration.

Claims

**Claim 1**: A heat-insulated battery system, comprising: A vacuum heat-insulating housing including an outer wall and an inner wall, having a vacuum space between the outer wall and the inner wall, wherein the inner wall defines a central hollow chamber; A battery cell that can be received within a battery holder; A printed circuit board electrically connected to the battery holder, wherein the battery cell, the battery holder, and the printed circuit board can be accommodated within the central hollow chamber of the vacuum heat-insulating housing; A casing for sealing the vacuum heat-insulating housing, the casing including a plurality of feet configured to stabilize the heat-insulated battery system and the appliance when the heat-insulated battery system is attached to the appliance; One or more electrical pass-throughs configured to allow current to exit the vacuum heat-insulating housing; The electrical pass-through being a conductor within the casing; The conductor including a body having a blind hole passing through an upper surface, a seat for contacting the printed circuit board, and a central ring having an O-ring seat for receiving an O-ring positioned between the conductor and the casing, wherein a screw is screwed into the blind hole and the head of the screw is pressed against a spring terminal to fix it, thereby sealing the electrical pass-through. **Claim 2** The heat-insulated battery system according to claim 1, wherein the outer wall of the vacuum heat-insulating housing includes an outer side wall and an outer bottom wall, the inner wall includes an inner side wall and an inner bottom wall, and the outer side wall and the inner side wall intersect at an upper lip so as to completely surround the vacuum space. **Claim 3** The heat-insulated battery system according to claim 1, wherein the vacuum heat-insulating housing has a substantially cylindrical body. **Claim 4** The heat-insulated battery system according to claim 1, wherein the vacuum heat-insulating housing includes a narrow neck, and the casing engages with the narrow neck to thereby seal the heat-insulated battery system. **Claim 5** The heat-insulated battery system according to claim 1, wherein the vacuum heat-insulating housing includes two 0.5-mm walls having a 3-4-mm vacuum gap therebetween. **Claim 6**: A heat-insulated battery system, comprising: A vacuum heat-insulating housing including an outer wall and an inner wall, having a vacuum space between the outer wall and the inner wall, wherein the inner wall defines a central hollow chamber; A battery cell that can be received within a battery holder; A printed circuit board electrically connected to the battery holder, wherein the battery cell, the battery holder, and the printed circuit board can be accommodated in the central hollow chamber of the vacuum insulation housing, the printed circuit board; A casing for sealing the vacuum insulation housing, the casing including a plurality of feet configured to stabilize the insulated battery system and the appliance when the insulated battery system is attached to the appliance; One or more electrical pass-throughs allow current to exit the vacuum insulation housing; The electrical pass-through is a conductor within the casing; The conductor is connected to the printed circuit board by a wire and includes a round bottom seat having a wire trap configured to hold the wire, an insulated battery system. **Claim 7**: An insulated battery pack, A vacuum insulation housing extending from an upper lip to a bottom wall and defining a central hollow chamber, the vacuum insulation housing including an outer wall and an inner wall having a vacuum space therebetween; A casing for sealing the vacuum insulation housing; A battery holder positioned within the central hollow chamber of the vacuum insulation housing; A rechargeable battery cell connected to the battery holder; A printed circuit board electrically connected to the battery holder and housed within the central hollow chamber; An electrical pass-through within the casing connecting the printed circuit board to a spring terminal; The casing includes a tool interface configured to removably secure the insulated battery pack to a power tool, the tool interface including a latch for removably securing the insulated battery pack to the power tool; The electrical pass-through is a conductor having a body with a blind hole through an upper surface, a seat, and a central ring having an O-ring seat. A screw is threaded into the blind hole and the head of the screw is pressed against the spring terminal for fixation. An O-ring is positioned between the conductor within the O-ring seat and the casing to seal the electrical pass-through, an insulated battery pack. **Claim 8** The insulated battery pack according to claim 7, wherein the casing includes a check valve embedded therein and can release any gas. **Claim 9** The heat-insulated battery pack according to claim 7, wherein the vacuum heat-insulating housing has a substantially cylindrical main body.

10. The heat-insulated battery pack according to claim 7, wherein the vacuum heat-insulating housing includes a narrow neck, and the casing engages with a ridge on the narrow neck, thereby sealing the heat-insulated battery pack.

11. The heat-insulated battery pack according to claim 7, wherein the conductor is directly welded to the printed circuit board or connected to the printed circuit board by a wire.

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