Description:

Introduction: In 2016,  William E. Diefenderfer, Chair of mechanical engineering and Director of the Electrochemical Engine Centre,  Chao-Yang Wang and his team developed a self-heating lithium battery that uses thin nickel foil with one end attached to the negative terminal and the other end extending outside the battery, creating a third terminal.

This self-heating battery can charge an electrical vehicle in 10-15 minutes for a 200- to 300-mile range while maintaining 2500 charging cycles or the equivalent of half a million miles of travel. Lithium-ion batteries degrade when rapidly charged at ambient temperatures under 50°F because, rather than the lithium ions smoothly being inserted into the carbon anodes, the lithium deposits in spikes on the anode surface. This lithium plating reduces cell capacity but also can cause electrical spikes and unsafe battery conditions. Batteries heated above the lithium plating threshold, whether by external or internal heating, will not exhibit lithium plating. Now, Wang and his team have taken their technology a step further by enabling the battery to charge itself in 15 minutes at temperatures as low as –45°F. 

Researchers discovered that if the batteries could heat up to 140 °F for 10 minutes and then rapidly cool to ambient temperatures, lithium spikes would not form and heat degradation of the battery would also not occur. The rapid cooling of the battery would be accomplished using the cooling system designed into the car. The large difference from 140 to about 75 °F will also help increase the speed of cooling.

Advantages:

• It is cost efficient as it normally uses nickel which is not so expensive
• It heats itself in sub-zero temperatures and may help electric vehicles function smoothly in winters
• These are designed it to go from -20 to 0 degrees Celsius within 20 seconds and from -5.5 to 0 degrees Celsius in 30 seconds and consume only 3.8 per cent and 5.5 per cent of the cell's capacity. This is far less than the 40 per cent loss in conventional lithium ion batteries.

Process: The self-heating battery uses a thin nickel foil 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 when the temperature is below room temperature. This rapidly heats up the nickel foil through resistance heating and warms the inside of the battery. Once the battery's internal temperature is above room temperature, the switch turns opens and the electric current flows into the battery to rapidly charge it. Batteries heated above the lithium plating threshold, whether by ambient temperature or by internal heating, will not exhibit lithium plating and will not lose capacity. This ubiquitous fast-charging method will also allow manufacturers to use smaller batteries that are lighter and also safer in a vehicle.

Commercialization:  LG Energy Solution, Panasonic, Samsung SDI, Tesla and many more.