Penn State team develops self-heating battery; addressing Li-ion energy loss in cold temperatures
21 January 2016
Researchers at Penn State, with colleagues at EC Power, a Penn State spin-off, have developed a lithium-ion battery structure—the ‘all-climate battery’ (ACB) cell—that heats itself up from below 0 degrees Celsius without requiring external heating devices or electrolyte additives. The self-heating mechanism creates an electrochemical interface that is favorable for high discharge/charge power. Because only a fraction of the battery energy is used for self-heating, the ACB could address winter range anxiety issues for EV drivers, as well as proving useful for applications in robotics and space exploration, the team said in a paper published in the journal Nature.
The ACB warms itself up to 0 degrees Celsius within 20 seconds starting at -20 ˚C and within 30 seconds at -30 ˚C, consuming 3.8% and 5.5% of cell capacity, respectively. (EC Power projects that it will be able further to reduce the self-heating time from -20˚C to 0 ˚C to 5 seconds by 2017, and reduce energy consumption to 1%.) The self-heated all-climate battery cell yields a discharge/regeneration power of 1,061/1,425 watts per kilogram at a 50% state of charge and at -30 ˚C, delivering 6.4–12.3 times the power of state-of-the-art lithium-ion cells.
The researchers calculated that the all-climate battery could enable engine stop–start technology capable of saving 5–10% of the fuel for 80 million new vehicles manufactured every year.
Lead author on the work is Chao-Yang Wang, William E. Diefenderfer Chair of mechanical engineering, professor of chemical engineering and professor of materials science and engineering and director, Electrochemical Engine Center at Penn State. Professor Wang also founded and is the chief technology officer of and has an equity stake in EC Power.
Lithium-ion batteries suffer severe power loss at temperatures below zero degrees Celsius, limiting their use in applications such as electric cars in cold climates and high-altitude drones. The practical consequences of such power loss are the need for larger, more expensive battery packs to perform engine cold cranking, slow charging in cold weather, restricted regenerative braking, and reduction of vehicle cruise range by as much as 40%. Previous attempts to improve the low-temperature performance of lithium-ion batteries4 have focused on developing additives to improve the low-temperature behaviour of electrolytes, and on externally heating and insulating the cells.
—Wang et al.
The all-climate battery uses a nickel foil of 50-micrometer thickness with one end attached to the negative terminal and the other extending outside the cell to create a third terminal. A temperature sensor attached to a switch causes electrons to flow through the nickel foil to complete the circuit. This rapidly heats up the nickel foil through resistance heating and warms the inside of the battery. Once the battery is at 32 degrees Fahrenheit, the switch turns off and the electric current flows in the normal manner.
While other materials could also serve as a resistance-heating element, nickel is low cost and works well.
The researchers, relying on previous patents by EC Power, developed the all-climate battery to weigh only 1.5% more and cost only 0.04% of the base battery.
Next we would like to broaden the work to a new paradigm called SmartBattery. We think we can use similar structures or principles to actively regulate the battery's safety, performance and life.
—Chao-Yang Wang
Also working on this project were Guangsheng Zhang and Yongjun Leng, research associates in mechanical engineering; and Xiao-Guang Yang, postdoctoral Fellow, all at Penn State. Terrence Xu, Shanhai Ge, Yan Ji, innovation engineers, all at EC Power also collaborated on this research and supported this project.
Resources
Chao-Yang Wang, Guangsheng Zhang, Shanhai Ge, Terrence Xu, Yan Ji, Xiao-Guang Yang & Yongjun Leng (2016) “Lithium-ion battery structure that self-heats at low temperatures” Nature doi: 10.1038/nature16502
-30 -20oC implies extreme weather conditions for (guestimating) say 70+% of journeys and closer to 85 -90% of regular operations globally.
Not likely good candidates for solar R.E. either.
That suggests there is a limited need and market for this design.
O/heating would seem to be the only real world consideration for the larger part of the remaining usage.
Either way thermal management would benefit most systems and seems to be often minimised or avoided for simplicity and or cost reasons.
The author points out that there are existing designs utilising heat developed in ordinary operation.
It is surprising that standard motor and cell cooling heat exchange is not more developed for thermal regulation across all areas of operation.
If the reason is that there is not sufficient waste heat generated owing to low resistance that would be surprising in a good way.
More likely there is insufficient development owing to cost considerations and the limited market need.
Thermally insulated heat transfer pathways should be considered as an option in cold markets in conjunction with something along the lines suggested by he authors integrated battery solution to the degree needed to kick start the system.
That would help solve the range issue and one of the other cabin heating options as often mentioned on GCC Alcohol or plug in preheating etc would help keep the occupants from freezing.
Posted by: Arnold | 21 January 2016 at 05:13 AM
Heating the cabin, fighting snow drifts, slippery roads and cold winds uses more energy than keeping the batteries warm.
BEVs range go down about 50+% in winter time in our area. HEVs, PHEVs, FCEVs and ICEVs take a 20% hit in the same adverse conditions.
Posted by: HarveyD | 21 January 2016 at 09:12 AM
All batteries in operation are self heating when the internal heat is combined with controller and motor heat. You run the heat through the cabin and then the pack.
Posted by: SJC | 21 January 2016 at 11:19 AM
Reducing that internal heat from resistance is the holy grail for electric machines.
The I.C.E. sends about 50% of its energy out as heat heat with the other transmission tyres brakes noise consuming a substantial amount of the remainder.
The global market estimates of well to wheel energy costs for ICE are 'not less than 2 to 1' and rising. Another analysis found that only 2% of energy contained in fossil fuels can be accounted for by the work intended.
My own estimates for the 'intended work' and 'work' performed is that 90% of that is a 'meaningless' waste of time and energy. Of those that know me - no one calls me lazy.
Plenty of other worse things, but that's 'normal'.
Gridlocked cities and social systems remind me of the hoarders dilemma where it is impossible to function, to find anything takes days so it becomes economically 'sensible' to make and buy another widget for the job and dispose of after use. Probably into the hoarders storage.
Don't waste (any) mantra's end game.
Posted by: Arnold | 21 January 2016 at 11:46 AM
Typo
Should read 'well to tank'.
Posted by: Arnold | 21 January 2016 at 11:47 AM
The ongoing quest for higher profits is the priority, not more e-range nor passengers comfort in cold weather operations nor reduced GHG and pollution.
The Ebola vaccin was ready 5 years before the last 11,000 victims in West Africa but not produced because the 1000% normal profit margin was not there.
Posted by: HarveyD | 05 February 2016 at 02:16 PM