Ebike Batteries with Double Range And Duration: Solid-State Are Coming

Electric vehicles, bikes, ships and even small aircraft are spreading around the globe. They are less expensive and arguably more ecologic to operate than those with internal combustion engines (ICE). Nevertheless, they have a weakness: their lithium-ion batteries are expensive, heavy, don’t last as long as their electric motors, offer a limited range, and can even catch fire. Solid state batteries could be much better, be it for ebikes or other vehicles.

Solid-state batteries could be a game changer for ebikes

Solid-state batteries don’t have liquid electrodes like li-ion batteries. They are solid, much smaller and lighter for the same watt power. Li-ion batteries have a liquid electrolyte separating anode from cathode, whereas solid-state have a solid electrolyte that separates the two. They can use metallic lithium for the anode and oxides or sulfides for the cathode, increasing energy density. The solid electrolyte acts as an ideal separator that allows only lithium ions to pass through. See the picture below.

Lithium-ion and solid-state batteries

Solid-state batteries could unleash ebikes potential

At least one ebike manufacturer, the Swiss Stromer, has already built a prototype of ebike equipped with a solid-state battery, which they claim to be revolutionary, pratically doubling the potential of ebike lithium-ion batteries, be it for power density, range, duration. It is in development stage, forecast to sell within a few years. Since solid-state batteries are already deployed for small devices and even heart pacemakers, there are no reasons to fear that they are unsuitable for ebikes.

Stromer solid-state ceramic ebike battery

Solid-state state batteries pros & cons compared to lithium-ion ones

• They don’t explode nor catch fire.
• They provide at least 50% more capacity and hence range.
• They can fully charge in about 15 minutes.
• They can last twice as long before losing more than 10% of their capacity.
• They contain no rare metals such as cobalt.
• They are are smaller and lighter.
• Since they don’t contain liquids, that can expand their volume with heat and shrink with cold, they are much more stable and can better withstand extreme temperatures.
• They are forecast to be expensive, at least so far, in this early stage.
• Their mass production could take years to kick in, experts forecasting at the end of this decade at the earliest. Of course the buzz is focused on cars, but such batteries are very likely going to be deployed on ebikes.

Schaeffler automotive all solid-state batteries

Battery weakness is hindering the upcoming electric age

Range limits and anxiety

After the stone and the iron age, came the oil age, which is slowly replaced by the electric age. Indeed, electric motors are way superior to internal combustion engines, being lighter, more silent, more durable, more powerful and more economical to manufacture and operate. Where electricity can be continuously supplied to the motor at reasonable costs, like on trains, internal combustion engines have been abandoned. Yet, there is a hurdle. Fuels must be lit up and burned to produce energy, whereas electricity is soon available. The problem is when you have to store it, for instance for vehicles and ebikes. Indeed, a kilogram of fuel stored in a tank delivers about 12 times more energy than a kilogram of battery. Of course a battery can be recharged, whereas a kilogram of fuel is burnt and pollutes, soils and wears the engine more than electricity; nevertheless, the low energy density limits the range of any electric vehicle, ebikes included. Both ebikes and electric cars use lithium-ion batteries which, for ebikes, take at least 90 minutes to charge from 20 to 80% on a domestic socket. For cars it takes an average 250 kg of battery for 100 km of range, for ebikes you need roughly 3.5 kg of battery to reach the same range, provided that you add sound leg power. These limits create range anxiety, the often exaggerated fear of remaining stuck in the middle of nowhere, or else of having to pedal all the way home on a 25 kg ebike, since recharging stations are still scarce. With an internal combustion engine, you can always manage go to buy a couple of liters of fuel at the next gas station and reach back to your car.

Lithium-ion batteries are expensive and wear off rather quickly

For ebikes, lithium-ion batteries cost at least one euro per watt of power. They lose about 2% of their capacity every year even staying idle. If they are well taken care of, they lose about 3% of their capacity altogether every thousand kilometers and year. These values can be worsened or bettered depending on usage and storage conditions. Many car manufacturers guarantee their batteries to keep at least 70% of their capacity after 10 years or 180,000 km, whichever comes first.

They can catch fire

One of the biggest defaults of lithium-ion batteries is the formation of dendrites on the surface of the anode. These structures grow like roots into the electrolyte and pierce the barrier separating the anode and cathode, causing the battery to short circuit or even catch fire. Moreover, that accelerates loss of capacity.

QuantumScape technology platform projected improvements

Solid-state batteries are already a reality, although only at dawning stage

1. Just last week, QuantumScape, a Californian company, and Volkswagen, its main investor, announced having reached the duration of 500,000 km and 40% more range with solid-state batteries. After a thousand recharging cycles, i.e more than 500,000 km, their batteries kept still 95% of their initial capacity. Moreover, they can fully charge in less than 15 minutes and boast at least 40%  more range than lithium-ion batteries. The company has got already 800 employees and plenty of cash to continue its operations until 2027, when it plans to slowly start commercializing its batteries, although isn’t expected to deliver production-ready prototypes to its clients before 2025.
2. Solid Power is another solid-state battery company from Colorado, USA. They already delivered to BMW some solid-state car batteries just for testing, planning to launch them on the market for 2028. They have 50 employees and a solid financial situation, thanks to investors. Solid Power website reads “The cell manufacturing processes we have developed are already used globally for high volume traditional lithium-ion battery cell production, which we anticipate will enable manufacturers of our all-solid-state battery cells to meet volume and cost requirements of OEMs.”
3. Nio is an established Chinese car manufacturer. Very recently, with one of its series car, its CEO drove 1145 kilometers (711 miles) nonstop on a single charge with its new patented semi-solid-state battery. He constantly filmed himself on live streaming, to prove the authenticity of the test.
4. Toyota has recently declared that it will launch a solid state battery electric car in 2027, although we don’t know whether it will be an expensive model or a popular one.
5. Harvard’s John A. Paulson School of Engineering and Applied Sciences researchers have developed a new lithium metal battery that can be charged and discharged at least 6,000 times.
6. At the upcoming CES 2024, German automotive supplier Schaeffler Americas will display a “next-generation” all-solid-state EV battery.  A Schaeffler executive said the supplier already has a customer for its solid-state technology, but he declined to name the automaker.
7. Toyota, Mercedes, BMW, Volkswagen, Volvo, General Motors, Ford, and Hyunday are just some of the big car manufacturers investing in solid-state batteries.
8. Beginning in 2020, Mercedes has already sold a few (probably more than 100) eCitaro buses with solid state batteries, although now they are producing also eCitaros with NMC (Nickel Manganese Cobalt) batteries.

Mercedes eCitaro G with solid state batteries

There seems to be still a long way for batteries to become really inexpensive and powerful, yet…

Nevertheless, just 40 years ago there were no rechargeable batteries besides heavy and weak lead batteries. We have come a long way ever since, what bodes well for the near future. A 200 km range battery weighing less than 1 kg and lasting 20 years may not to be too far for our ebikes, although it should take longer to become inexpensive.

Pictures, from top to bottom: Solid Power, Samsung, Stromer, Schaeffler Americas, QuantumScape, Mercedes.