Cool metric for lithium-ion batteries could spur progress

Abstract

Lithium-ion batteries get hot, and it is hard to keep them cool. Industry has paid too little attention to this problem for the past decade. The focus has been elsewhere: on cutting costs and on boosting the amount of energy a single cell in a battery can store (energy density). This strategy has, for example, increased the longevity and capabilities of mobile phones. Future applications, such as electric vehicles and smart grids, need thousands of cells in a battery pack. These are prone to overheating.Manufacturers of large, high-energy battery packs must design complicated systems to manage heat. The battery pack in electric-vehicle maker Tesla's Model 3 car, for example, holds more energy than 6,000 iPhone 11 handsets. Coolant fluid is pumped through a network of channels to carry heat away from the individual cells. But these cumbersome additions make the battery pack heavy and drain its energy 1 . Developers are wasting time and money on these inefficient designs. Heat-removal strategies must be improved to make battery packs both light and powerful.Why this lack of attention? One reason is that there is no standard way of judging the thermal performance of battery packs. Manufacturers of single cells compete by chasing ever greater energy density. Their product-specification sheets do not cover how easy it is to remove heat from a cell. Designers of battery packs A new measure for the rate of heat removal from battery packs gives manufacturers a simple way to compare products.

Recent Progress and Emerging Application Areas for Lithium–Sulfur Battery Technology

“…With respect to the cell-level limitations, one important consideration is the geometry of commercially available lithium foil (minimum thickness of 50 μm and maximum width of 10 cm [58] ), which limits the overall cell geometry and the optimization of the ratio between the active and inactive component mass. Consequently, nickel tabs have to be adapted for these electrode geometries and for each application (high power vs high energy, see Section 2.3), as these tabs usually play a key role in cell cooling [59] as well as transfer current. Another limitation is the pouch cell as a cell type, as some applications prefer cylindrical cells with a stainless steel casing.…”

Energy Efficiency, Emissions, Tribological Challenges and Fluid Requirements of Electrified Passenger Car Vehicles

“…If the battery becomes too hot, there is a possibility of a thermal runaway reaction, which could lead to a battery fire. Good recent reviews of (fast) battery charging and cooling methods for batteries can be found in references [31,32].…”

“…As discussed in reference [32], some electric vehicles (such as the Nissan Leaf) are air cooled-they simply rely on the flow of air through the battery cells to cool the battery (some cars rely on the motion of the vehicle for airflow through the battery, whereas others actively pump the external air so that it flows faster through the battery cells). However, this is not entirely satisfactory as the air ambient temperature can vary widely.…”

Energy Efficiency, Emissions, Tribological Challenges and Fluid Requirements of Electrified Passenger Car Vehicles

“…If the battery becomes too hot, there is a possibility of a thermal runaway reaction, which could lead to a battery fire. Good recent reviews of (fast) battery charging, and cooling methods for batteries can be found in references [26] and [27].…”