Eye on Lithium: Better e-Bike Batteries

The micromobility market is huge, but it has a battery problem. Is LTO the solution?

Electric bicycles and other micromobility vehicles are booming, but their batteries shouldn’t be. (Source: ZappBatt.)

Electric bicycles and other micromobility vehicles are booming, but their batteries shouldn’t be. (Source: ZappBatt.)

The global micromobility market, comprising small, lightweight, battery-powered vehicles like electric bicycles and scooters, is booming. It’s expected to be worth over $198 billion by 2030, according to Precedence Research, up from $56 billion this year. However, the lithium-ion batteries powering most micromobility vehicles today need to improve drastically. For one thing, charging times are too long. But the most pressing concern is the fires. Last year in New York City alone there were 104 reported e-bike and e-scooter battery fires. They resulted in 79 injuries and four deaths.

The micromobility battery problems might be one step closer to being solved if battery company ZapBatt has its way. The California-based firm recently announced a collaboration with Toshiba to improve the latter’s lithium titanium oxide (LTO) battery chemistry through a combination of AI software and new battery hardware. ZapBatt says that its technology will provide real-time battery management and usage optimization, as well as enable the LTO batteries to be fully charged in just 20 minutes while decreasing the risk of thermal runaway and battery fires.

Intro to LTO

LTO batteries are long-lasting and reliable, charge quickly, and can meet high power requirements while maintaining their performance even after thousands of cycles. However, because of their lower energy density compared to other lithium-ion chemistries, LTO batteries have not historically been the first choice for micromobility applications.

Most electric bikes and scooters today use lithium-ion batteries containing oxides of nickel, manganese, aluminum or cobalt. Those oxides are the main cause of the fires that can occur when the battery is damaged or overused. Since LTO batteries do not have these oxides, they are immune to thermal runaway and fires. LTO batteries use nanocrystals on the anode surface instead of carbon, which allows for their fast charging and fire resistance.

ZapBatt says that its LTO batteries can use up to 100 percent of their usable charge without affecting the batteries’ cycle life. They are also suitable for many environmental conditions and can operate at temperatures down to −30°C (−22°F), which is significantly lower than temperatures other lithium-ion batteries can operate at (though low-temperature batteries are an active area of research).

Solving Three LTO Problems

The partnership between ZapBatt and Toshiba aims to make LTO batteries a commercial reality for the micromobility market. As Greg Mack, VP and general manager of Power Electronics at Toshiba, put it in a press release: “ZapBatt unlocked the potential of Toshiba’s LTO chemistry for a variety of industries and new markets with disruptive technology, moving away from the ‘miracle battery’ trap and providing a real solution hitting the market today.”

ZapBatt helped solve three problems with Toshiba’s LTO chemistry. One was the lack of chips suitable for use with LTO batteries. ZapBatt says that it developed a custom battery management system that can handle the unique voltages of Toshiba’s LTO cells. The programmable chip can adapt to new battery specifications, chemistries, voltages and system requirements, according to ZapBatt.

The second problem ZapBatt solved was how to make LTO batteries a drop-in replacement for other lithium-ion chemistries. The company created what it likens to a “universal adaptor” for LTO in the form of its bi-directional adaptive terminal voltage (BATV) technology. This enables the battery system’s voltage to be controlled digitally, meaning the batteries can be reconfigured “at software speed.”

Amiad Zionpur, chief operating officer of ZapBatt, said that “BATV technology allows the battery to reconfigure itself based on the customer’s needs.… Because of this unique ability, the e-bike battery can be used in many different applications, from micro-mobility to consumer products.”

The ZapBatt/Toshiba LTO battery for micromobility. (Source: ZapBatt.)

The ZapBatt/Toshiba LTO battery for micromobility. (Source: ZapBatt.)

But the biggest problem with LTO batteries—and the reason they’ve not been widely used in micromobility applications—is their low energy density compared to other lithium-ion batteries. Energy density is an especially important parameter for micromobility applications, since battery size is so limited. ZapBatt says that it has improved the energy density of Toshiba’s LTO batteries through integrated artificial intelligence that analyzes energy use.

It is important to understand that although the definition of energy density indicates that it is the amount of power per unit of volume, effective energy density is not such a static parameter. Energy density is affected by many variables, including temperature, cycle efficiency, discharge rate, depth of discharge, and more. For example, a battery will run out of charge sooner if it is fast-charged or used in a cold environment.

ZapBatt’s AI software constantly measures the charging and discharging rate (C-rate) to determine the effective energy density of the LTO batteries, and it learns from every cycle. The software can adjust the voltage in real time to optimize the battery usage for different conditions. ZapBatt says that it analyzes 26 data points to continuously improve performance.

ZapBatt says that it’s conducting several micromobility pilot demonstrations in North America and estimates that the LTO batteries will be commercially available by early 2023.