As it works toward an entry in the U.S. and works on a next generation of vehicles that may be sold here, China's NIO is thinking a lot about batteries getting hot—more specifically, how to avoid the issue altogether.
The U.S. Patent and Trademark Office published Thursday a number of new patent applications from NIO USA, Inc., the American arm of the Chinese electric vehicle manufacturer. The patent applications all cover battery heat management in some form, showing just how important temperature control is in electric vehicles.
They're examples of the kind of innovation that may help a new market entry like NIO distinguish itself in the market and get an advantage over rivals.
One of the patent applications notes that as more and more electric vehicles use larger batteries, managing the battery's heat becomes more important. Current cooling systems, like ones that use a phase-change material or other liquid, are "less efficient and less effective" than they could be because they "often focus on cooling only the batteries or another singular system," according to the patent filing.
NIO's idea in the patent application is a heatsink that can cool the busbars—the metallic strip that carries a current—inside a BEV's junction box as well as the power electronics in that same junction box.
NIO battery cooling - phase change material
A second solution aimed at reducing heat buildup in the junction box, uses a phase-change material that can passively capture that heat.
NIO says that "traditional" passenger electric vehicles don't generate that much heat thanks to their lower average current, but when fast charging standards are used, "the amount of sustained current on all high voltage components" is increased. This means new solutions for heat dissipation are required.
Overheating batteries are bad for EVs. This much should be obvious by now, and another patent application among the filings covers a way to prevent such overheating when the pumps that move liquid coolant through a battery pack break.
One solution, of course, would be redundant components and systems. But you can't just throw in two of everything, because that, "significantly increases the total mass of the cooling system which, in an electric vehicle, negatively impacts the range of the vehicle," NIO says in the patent.
NIO battery cooling - coolant loop patent
The company proposes what it thinks is the best way to have the minimum number of coolant loops and pumps on board to handle redundancy without excess. This means two pumps with valves in the tubing that can redirect coolant flow as needed should one of the pumps fail.
NIO has delivered around 10,000 of its ES8 all-electric SUV in China and will start deliveries of the smaller ES6 later this year. Both models can use either a 70-kwh or new 84-kwh battery pack, and thanks to NIO's battery-swapping technology, current ES8 owners will be able to upgrade to the larger pack, for a fee, when it becomes available.
NIO did not return Green Car Reports' request for comments on these patent applications, which were all originally filed in August 2017.