SCiB (Super Charge Ion Battery)

Researchers have been working with other materials in the search for safer, and more energy-dense batteries. One material that is seen as an improvement on current Li-ion battery technology is lithium titanate (lithium titanium oxide or LTO) which replaces the graphite used in anodes. LTO has never gone mainstream because the batteries have provided lower energy density than Li-ion and have cost more to produce.

Toshiba claims that its new SCiBs address both energy density and cost. The anodes in its SCiBs are made from niobium-titanium oxide (NTO) which provides 350 Wh/l (Watt-hours per litre) energy density.

Electric batteries are rated two ways, either by Wh/l and Wh/kg (Watt-hours per kilogram). The higher the number, the more energy the battery stores by volume which appears as litres, or by weight which appears as kilograms. Where space volume is the limiting factor, battery energy density is measured in Wh/l. This is typically used in applications like EVs and grid storage. Where weight is limited such as in batteries used in small portable devices like laptops, tablets and smartphones, battery energy density is measured in Wh/kg.

SCiBs using NTO anodes provide twice the energy density of Li-ion batteries that use graphite anodes. In making this latest SCiB Toshiba has partnered with Sojitz, a Japanese aerospace company, and CBMM, a Brazil-based niobium miner. The three companies recently unveiled in Brazil a Volkswagen-designed electric bus powered by SCiBs. A June 19, 2024 press release describes the E-bus and its capabilities. The three companies intend to mass produce SCiBs with the first commercial EVs using them coming to the market in 2025.

Besides energy density, what makes SCiB technology attractive?

• SCiBs provide a low risk of fire or explosion and are therefore a better choice in applications requiring high levels of safety and reliability such as EVs and grid storage.
• SCiBs after 20,000 charge and discharge cycles retain better than 70% battery charge capacity.
• SCiBs can be charged to 80% capacity in 6 minutes, about the same amount of time it takes to pump gas or diesel into an internal combustion-powered vehicle.
• SCiBs are efficient with regenerative braking systems used by EVs, hybrids and trains.
• SCiBs are cold-tolerant, able to charge and discharge even in temperatures that drop to as low as -30 Celsius (-22 Fahrenheit).
• SCiBs provide drivers of EVs with reliable SOC (state of charge) data which replaces the fuel gauge used in internal combustion engine vehicles as a measure of driving range.

Toshiba sees SCiBs as ideal for use in EVs and hybrids, and for battery storage to stabilize power grids. The plan, currently, is to bring SCiBs in sufficient quantity to market in 2025 for use in commercial EVs and hybrids.

Lithium-ion batteries today dominate the electric vehicle (EV) industry. But the energy density and durability of the technology have led to range and ownership anxiety on the part of potential purchasers of EVs. A battery with greater density, lighter in weight, and more durable in terms of discharge-recharge cycles would be the breakthrough the planet needs to ween ourselves off the internal combustion engine and the greenhouse gas contributions this technology contributes to global warming.

The 631.1-watt-hours per kilogram (Wh/kg) measure achieved by this battery, and its ability to retain 82% capacity after 10,000 discharge-recharge cycles leaves lithium-ion battery packs in the dust. It means EVs equipped with these batteries will easily match the durability of gasoline and diesel-powered vehicles which on average is between 10 and 15 years.

In an interview by Anthony Cuthbertson of The Independent, Li is quoted stating, “This….design shows that lithium-metal solid-state batteries could be competitive with commercial lithium-ion batteries. And the flexibility and versatility of our multilayer design makes it potentially compatible with mass production procedures in the battery industry.”

Current lithium-ion battery packs produce around 250 Wh/kg. Hydrogen fuel cells in comparison produce 530 Wh/kg. Lithium-ion battery packs on average can be discharged and recharged about 900 times before the upper capacity begins to degrade. Even so, current lithium-ion batteries come with 8-year warranties or 160,000 kilometres (100,000 miles) drive limits which probably means if you currently own an EV, at some point that warranty is going to come into play requiring a new battery pack.

So the performance demonstrated by this Harvard team’s lithium-metal battery at 631.1 Wh/kg and 10,000 discharge and recharge cycles is indeed impressive. And one other thing, this new battery fully recharges in between 10 and 20 minutes. That too is an impressive performance improvement.

The secret to the design of the Harvard battery is an innovative multilayer self-healing assembly which deals with degradation common to lithium-ion battery technology. That degradation you may have experienced when your smartphone starts to overheat. That won’t happen with the lithium-metal solid-state technology design which can be compared to a bacon-lettuce-and-tomato (BLT) sandwich as seen in the illustration above.

Can the battery be scaled down for use where lithium-ion is found today? Think cell phones and A, AA, AAA rechargeables? For the moment, the Harvard invention is at the EV battery-pack scale. But the chemistry and design of lithium-metal should allow the technology to go small sometime in the near future.