TECHNICAL FIELD

The present application relates to systems for holding battery pouch cells together as a unit for use in electric vehicles and to systems that remove heat from such pouch cell units so as to enhance battery performance.

BACKGROUND

The battery power source used in electric vehicles such as, for example, automobiles, typically comprises a large number of individual battery pouch cell modules in close contact with one another. Pouch cells provide optimal use of space and packaging efficiencies. Unfortunately, a major problem with stacking these electric vehicle battery pouch cells close together is the heat generated by the individual battery cells. Battery overheating causes problems. First, it results in overall power efficiency being compromised. Second, such overheating also presents safety concerns.

Unfortunately, efficiently removing heat from electric vehicle battery cells has proven to be difficult. One existing solution to this problem has been to use a cooling gel in the battery module. In this approach, the thermal glue or gel is applied inside of the bottom enclosure to remove heat from the bottom enclosure. This typically results in a large temperature difference across the cell perpendicular to the cooling surface because the glue or gel is only at the bottom of the enclosure. Another approach has been to hold the individual battery cells together in a plastic frame and then to cool the plastic frame together with a cooling foam. This is not cost effective and has a high risk of liquid leaking inside the module. It would instead be desirable to provide a system of enhanced electric vehicle battery cooling for battery cells stacked close together that provides better temperature control at a lower cost. In addition, it would be desirable to provide a battery cell stacking system that physically protects the individual battery cells.

SUMMARY

In accordance with the present application, a system for holding together a plurality of electric vehicle battery pouch cells is disclosed herein. As will be shown, the present system both protects the individual cells and also efficiently removes heat from them. In a preferred aspect, the present system comprises: (a) a plurality of pouch cell modules positioned together side-by-side, wherein each pouch cell module comprises: (i) a first bracket, (ii) a second bracket, (iii) a pair of battery cells positioned between the first and second brackets, and (iv) an insulation pad positioned between the pair of battery cells; (b) a pair of pressure plates, with one pressure plate disposed on each side end of the battery module; (c) at least two compression bands wrapped around the plurality of side-by-side pouch cells and the end pressure plates; and (d) a busbar electrically connecting the plurality of side-by-side pouch cell modules together. Preferably also included are a top cover spanning across the tops of the plurality of side-by-side pouch cell modules; and a bottom cover spanning across the bottoms of the plurality of side-by-side pouch cell modules.

In preferred embodiments, each of the parallel connected cells in the pouch cell modules have top and bottom tabs that are fastened together. A busbar is then welded to the top and bottom tabs of the cell modules to provide electric communication between all of the cells.

In preferred embodiments, each individual pouch cell module's first bracket has longitudinally extending side edges and the second bracket is positioned between (i.e.: received within) the longitudinally extending side edges of the first bracket. As such, a pouch cell module is provided with two battery cells held between the first and second brackets with the insulation pad positioned between these two cells. As a result, each individual battery cell has one face in contact with a metal bracket and the other face in contact with an insulation pad. This pattern is repeated across the length of the overall assembly as the pouch cell modules are stacked together side-by-side. This novel design offers enhanced cooling benefits since every battery cell in the assembly is in direct physical contact with a metal bracket on one side. This allows excess heat to be quickly and efficiently conducted away from the battery cells. Additionally, having the insulation pad positioned between the cells keeps the excess heat from each individual battery cell directed away from the insulation pad and into one of the adjacent metal brackets. To assist with heat conduction, the first and second brackets may preferably be made of aluminum, and to prevent heat transmission, the insulation pad may be made of a thermally insulating material having a low thermal conductivity.

Preferably as well, the top and bottom covers of the device may have edges that wrap around the top and bottom ends of the plurality of pouch cell modules and the first brackets may have notches therein for the compression band to be received therein as it wraps around the full assembly.

A first advantage of the present system is that it provides enhanced cooling performance by conducting heat away from each battery cell, as each battery cell is in contact with one or the other of the module's first and second metal brackets.

A second advantage of the present system is that there is no possibility for coolant leakage in the modules (as compared to existing systems that circulate a cooling fluid through a cold plate between the individual cells).

A third advantage of the present system is that it's design is completely modular. As such, different numbers of pouch cell modules can be stacked together side-by-side with the present system operating the same way in each of its various arrangements (i.e.: with more or fewer pouch cells). As a result, more pouch cell modules may be added, or pouch cell modules removed from the system, all depending upon user requirements.

A fourth advantage of the present system is that it can be used with different pouch cell wirings such as pouch cells can be wired together in 3S8P (i.e.: 3 batteries in series, 8 batteries in parallel) or 3P12S (i.e.: 3 batteries in series, 12 batteries in parallel), 6P8S (i.e.: 6 batteries in parallel, 8 batteries in series) and or any other desired configuration.

A fifth advantage of the present system is that it provides structural protection to the battery cells. Specifically, its metal brackets are much stiffer than comparable plastic frames which had been used in existing foam designs. Additionally, the present brackets will not cause any internal leaking of coolant.

