Patent Application
20230411705
The present disclosure relates to the chemical and electrical arts. More specifically, the present disclosure relates to lithium iron phosphate (LiFePO4) modules that are configurable to make several different series and parallel configurations to serve different markets and applications.
A lead-acid battery includes a housing containing a positive electrode plate and a negative electrode plate. The electrode plates are typically formed of an electrode grid coated with an active material. While primarily constructed of lead, the electrode grids are often alloyed with antimony, calcium, or tin to improve their mechanical characteristics. Antimony is generally a preferred alloying material. It is a drawback of such batteries that antimony may leach or migrate out of the positive electrode. Antimony deposition/poisoning of the negative plate leads to increased hydrogen evolution, electrolyte expenditure and loss of capacity and cycle life. Once the antimony deposits on the surface of the negative electrode, it will change potential of the negative electrode and cause the battery to be easily overcharged during use. This will undesirably shorten the battery life.
One approach to overcoming this problem of lead-acid batteries is to use prismatic cells. Prismatic cells are light, thin, and effectively use up space. Prismatic cells do not contain any acid or lead, which eliminates the problem of gasses being emitted while charging.
Unfortunately, there are numerous drawbacks to the use of prismatic cells in addition to its expense. These drawbacks include short lifespans due to ineffective thermal management systems, high sensitivity to deformation when exposed to high-pressure, and a fixed cell arrangement with no flexibility.
Consequently, there remains a long felt need to produce a 48V lithium battery in the GC2 size. GC2 batteries can fit aftermarket golf cart applications. Typical products in this size are either prismatic cells, i.e., which does not allow for flexible configurations, or hold a lesser quantity of cells, i.e., around 100 cells. Additionally, the connection method used for voltage monitoring and cell balancing is usually conducted with a ring lug with mechanical fasteners or a soldered wire. Thus, there remains a further long felt need for a smart battery that includes lithium iron phosphate (LiFePO4) modules with cylindrical cells and a current collector plate design with quick disconnect tab connections as voltage sensors that possess desirable physical and mechanical properties such as resistance to vibration and shock, faster charging, longer range, easy assembly, and a heavy-duty off-road ready automotive design.
Now in accordance with the present disclosure, there has been discovered a lithium iron phosphate module that overcomes these related disadvantages. The lithium iron phosphate module which in one embodiment is part of a lithium battery pack, comprises a housing containing a positive and a negative single stud terminal post. A cover with lifting brackets is placed on top of the housing, which can be removed to insert the lithium iron phosphate module and a battery management system.
In one embodiment, a first lithium iron phosphate module contains a first set of lithium iron phosphate cylindrical cells and at least two current collector plates that are interconnected by a resistive welding process and enclosed in at least two cell holders. In some embodiments, a front side of the first lithium iron phosphate module contains five current collector plates interconnected to the cells and a rear side of the first lithium iron phosphate module contains four current collector plates interconnected to the cells. In another embodiment, the first lithium iron phosphate module is connected to a second lithium iron phosphate module in series. The second lithium iron phosphate module is identical to the first lithium iron phosphate module.
In one aspect of the embodiment, the first and the second lithium iron phosphate module each contain seventy-two (72) lithium iron phosphate cylindrical cells configured in an 8S9P configuration with a 24V output and about a 34 Ah current. In another embodiment, when the first lithium iron phosphate module, known as the low module, is connected to the second lithium iron phosphate module, known as the high module, in series, the one hundred and forty-four (144) lithium iron phosphate cylindrical cells are arranged in an 16S9P configuration with a 48V output and about a 34 Ah current and are able to be packed into a GC2 battery group size.
Each lithium iron phosphate cylindrical cell is a 26650 lithium iron phosphate cylindrical cell, meaning the lithium iron phosphate cylindrical cell has a diameter of about twenty-six (26) millimeters and a length of about sixty-five (65) millimeters. In some embodiments, the seventy-two (72) lithium iron phosphate cylindrical cells are arranged in an alternative series and parallel configuration. When the lithium iron phosphate cylindrical cells are arranged in an alternative series and parallel configuration, a different voltage output and current flow is produced.
In another aspect of the embodiment, the current collector plates are comprised of a five-layer clad material that includes two layers of corrosion resistant nickel on the surface, two layers of stainless steel between the two layers of nickel for welding, and a copper layer at the core for current carrying.
In yet another aspect of the embodiment, the lithium iron phosphate module further contains tabs that are custom stamped in the current collector plates. Each current collector plate includes one custom stamped tab. Through the custom stamped tabs, the battery management system monitors and balances the voltage of the lithium iron phosphate cylindrical cells. This is done by connecting the custom stamped tabs to the battery management system by running voltage sense wires with quick disconnect tabs on the end from the battery management system to the custom stamped tab. In some embodiments, the voltage sense wires are taped onto the current collector plates by a polyimide material.
In still another aspect, the lithium iron phosphate modules further include temperature sensors. The temperature sensors are connected to the battery management system and mounted on the lithium iron phosphate module at predetermined locations. If the temperature sensor reads a temperature outside of the recommended operating temperature range, the battery management system shuts down. The recommended operating temperatures are as follows: 0° C. to 45° C. (32° F. to 113° F.) during charge; −20° C. to 60° C. (−4° F. to 140° F.) during discharge; and −40° C. to 60° C. (−40° F. to 140° F.) in storage. In some embodiments where the low module is connected to the high module in series, the low module contains three temperature sensors and the high module contains one temperature sensor.
According to all of the foregoing, a few of the main advantages of this invention is providing a heavy-duty off-road ready automotive design that has faster charging and a longer range. Compared to a lead acid battery, this invention is a flexible, smart battery that is lighter in weight, easy to assemble, and does not emit gasses while charging, thereby achieving an improvement in the safety of a battery.
The above and other features, elements, characteristics, steps, and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.
The accompanying drawings, together with the specification, illustrate exemplary embodiments, and, together with the description, serve to explain the principles of these embodiments.
In
An example of use of the components inside the lithium battery pack 10 will now be described with reference to
Referring now to
With there being a plurality of 26650 lithium iron phosphate cylindrical cells 120, the design allows for simple changes in the way in which 26650 cylindrical cells 120 are stacked (orientation wise) in a module. Additionally, the cells 120 can be connected in various series and parallel combinations to alter the voltage and power in the same footprint with minimal changes to the design and manufacturing process. In an alternative embodiment, as long as the cells used are still 26650 cylindrical cells, different capacity cells can be used to alter the overall capacity of the module.
In a preferred embodiment, the module 100 is a 16S9P module where the low module 101 is connected to the high module 103 in series, producing about a 48V output (16 supercells multiplied by 3.2V output of each singular cell) with about a 34 Ah current (9 cells connected in parallel multiplied by 3.8 Ah). In the 16S9P module, for example, the low module 101 refers to the lithium iron phosphate cylindrical cells 120 one (1) through eight (8) and the high module 103 refers to the lithium iron phosphate cylindrical calls 120 nine (9) through sixteen (16), with lithium iron phosphate cylindrical cell sixteen (16) being the most positive or high cell of the battery and lithium iron phosphate cylindrical cell one (1) being the most negative or low cell of the battery.
Referring now to
In some embodiments of the present invention, the module 200 contains seventy-two (72) 26650 lithium iron phosphate cylindrical cells 220. The lithium iron phosphate cylindrical cells 220 are connected to one another by current collect plates 212 that are fully connected by a resistive welding process that forms strong, reliable welds intended to withstand high vibration applications. By limiting the number of mechanical connections with the module, the risk of connection issues due to vibration and shock is reduced. Although a resistive welding process is described, one of ordinary skill will appreciate, based on the present disclosure, that alternatively, the lithium iron phosphate cylindrical cells 220 can be interconnected to the current collector plates 212 by any suitable connection mechanism, such as, but not limited to, soldering, hard wiring, or connectors, according to embodiments of the present invention. Once the lithium iron phosphate cylindrical cells 220 are interconnected to the current collector plates 212, the lithium iron phosphate cylindrical cells 220 and the current collector plates 212 are enclosed in a flame retardant cell holder 218. In an embodiment, the flame retardant material of the cell 218 will be an acrylonitrile butadiene styrene (ABS) with a UL94-V-0 plastics flammability rating.
Referring now to
In one aspect of the embodiment, the quick disconnect tabs 422 are standard faston tabs. Although the standard faston tab is described, one of ordinary skill will appreciate, based on the present disclosure, that various alternatives, such as, but not limited to, a ring terminal, can be used, according to embodiments of the present invention. The benefit of using faston tabs for the quick disconnect tabs 422, for example, is that they take up minimal space and, when connected to the tabs 424, the connection does not require a bolted mechanical connection, which can increase the chance of the connection loosening due to vibration. The faston tab 422 easily slides onto the mating tab 424 and uses a special detent feature to prevent it from detaching inadvertently.
Referring back to
In one aspect of the embodiment, each voltage sense wire 214 has a piece of polyimide material 216 taped onto it to route and maintain the position of the voltage sense wires 214 to prevent the voltage sense wires 214 from being pinched during the assembly process. Additionally, polyimide material 216 has good insulation properties and is difficult to tear. Although a polyimide material 216 is described, one of ordinary skill will appreciate, based on the present disclosure, that any suitable alternative adhesive, such as a dab of silicon RVT, can be used, according to embodiments of the present invention.
In yet another aspect of the embodiment, temperature sensors 210, which are connected to the battery management system, are strategically mounted on the module 200 to measure and monitor the cells' 220 surface for temperature excursions. In the event that the lithium iron phosphate cylindrical cells 220 are outside of their recommended operating temperature range, the battery management system acts and prevents an unsafe condition by temporarily shutting down until the proper parameters are restored or, in an extreme case, a hard shut down occurs that will prevent future use of the battery. The recommended operating temperatures are as follows: 0° C. to 45° C. (32° F. to 113° F.) during charge; −20° C. to 60° C. (−4° F. to 140° F.) during discharge; and −40° C. to 60° C. (−40° F. to 140° F.) in storage. In an embodiment, three temperature sensors 210 are mounted on the low module 200 and one temperature sensor is mounted on the high module 300. Although four temperature sensors are shown, any number is possible to provide the battery management system with a sufficient understanding of the temperatures throughout the modules.
Referring now to
Various modifications and additions can be made to the exemplary embodiments discussed without departing from the scope of the present invention. For example, while the embodiments described above refer to particular features, the scope of this invention also includes embodiments having different combinations of features and embodiments that do not include all of the described features. Accordingly, the scope of the present invention is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof.
