Next-Gen EV Batteries: Toyota Plans Lithium-Ion Improvements

Toyota has been criticized for dragging its feet on developing electric vehicles (EVs). The company had a huge electrification head start when it introduced its gasoline-electric hybrid Prius in 1997 and offered it for sale in the U.S. in 2000. More than 5 million Prius vehicles have been sold since its launch, and Toyota has sold more than 15 million hybrid electrics since 1997. 

 

Toyota’s all-electric car, the b74x. Image used courtesy of Toyota Motor Corp 

 

For all that success with low-emission vehicles, Toyota only has one true battery EV for sale in the U.S., the bZ4X SUV.  However, Toytota claims that by 2025, it will have an electrified version of every one of its Toyota and Lexus models available worldwide. To help, Toyota is building a battery plant in North Carolina, adding a $2.1 billion investment to produce lithium-ion batteries beginning in 2025. The plant will have six battery production lines. Significantly, four will be dedicated to supplying batteries to hybrid vehicles, while two production lines will provide battery electric vehicles for the U.S. market. 

 

Toyota’s Next-Gen Batteries

To demonstrate it hasn’t fallen behind in the electrification race, Toyota recently unveiled four next-generation battery technologies it will produce. These include three advances for lithium-ion batteries that use liquid electrolytes and a preview of its new solid-state electrolyte battery system. Solid-state lithium batteries are considered the Holy Grail of battery development, as they promise higher energy and power density plus increased safety. 

Lithium-ion batteries with liquid electrolytes are used in all mainstream EVs. The liquid electrolyte, composed of organic solvents, allows the easy transport of lithium ions between the battery electrodes during charging and discharging. The downside is that these solvents are extremely flammable and can cause safety issues if the battery cells overheat and catch fire. 

Toyota is working on increasing the energy density of conventional lithium-ion cells while also improving charging speeds and cost competitiveness. The company says it has three main technologies under development: Performance, Popularized, and High Performance. 

 

Performance (Lithium-Ion)

Toyota will apply its new technologies to the next generation of EVs, slated for introduction in 2026. The goal is to increase EV range to over 800 kilometers (roughly 500 miles) when the battery technology is combined with improved vehicle aerodynamics and reduced weight. 

Goals include:

• 20 percent cost reduction (compared to the battery system in the current bZ4X EV model)
• Rapid recharging time of 20 minutes or less, going from a state of charge (SOC) of 10 percent to 80 percent

 

Popularization (Lithium Iron Phosphate)

Many current lithium-ion batteries use a cathode composed of nickel, cobalt, aluminum, or manganese oxides, which are expensive and difficult to source. 

Cathodes can also be made using lithium iron phosphate (LFP), which is less expensive and considered safer but doesn’t have as much energy density, which reduces the overall EV range. Toyota is one of several automakers adopting lower-cost LFP batteries to reduce the cost of some of its entry-level EVs and increase their appeal. 

The LFP Popularization battery that Toyota is developing uses bipolar technology that Toyota has used in its Nickel Metal Hydride (NiMh), which has been used in its hybrid electric vehicle batteries. These batteries are expected to be ready by 2026 or 2027.

 

Monopolar vs. bipolar structure. Image used courtesy of Toyota Motor Company 

 

The Popularization battery will offer:

• A 20 percent increase in cruising range when compared to the current bZ4X SUV
• 40 percent reduction in cost (compared to current bZ4X)
• Fast recharging time of 30 minutes or less from 10 percent to 80 percent SOC

 

High-Performance (Lithium-Ion)

In addition to its LFP battery, Toyota is tweaking its high nickel cathode battery chemistries to achieve more than 620 miles (1,000 kilometers) on a single charge. It can be expected that these types of batteries with nickel-based cathodes will be used in the company’s premium and high-performance EV models by 2027 or 2028.

The High-Performance battery is also expected to offer:

• An expected 10 percent reduction in cost compared to the Performance battery
• Rapid charging time of 20 minutes or less  from 10 percent to 80 percent SOC

 

Solid-State Batteries

Toyota has been working on solid-state batteries for several years and now claims to have developed lithium-ion batteries with a solid-state electrolyte that increases the durability of these batteries, long one of the stumbling blocks of the technology. The company claims that its solid-state batteries will allow more rapid charging and discharging, thanks to faster ion movement through the electrolyte and a greater tolerance for higher voltages and temperatures. The higher power and energy density will also allow solid-state batteries to be smaller, taking up less space in the vehicle. 

 

Toyota is researching solid-state batteries with solid electrolytes. Image used courtesy of Toyota Motor Corp.

 

Toyota’s first solid-state battery is expected to offer:

•  20 percent increase in cruising range versus the Performance battery (approx. 1000 km)
•  Fast charge time of 10 minutes or less from 10 percent to 80 percent SOC 

 

Reducing EV Battery Size

Packaging traction batteries in EVs is a challenge. By the time battery cells are built into modules and modules are stacked into packs, the battery takes up significant space. 

Typically, battery packs are located under the vehicle floor, which can result in an overall increase in vehicle height and the vehicle's frontal area. The vehicle’s aerodynamic drag depends upon a form factor called its aerodynamic drag coefficient (Cd) and the vehicle’s frontal area. The drag caused by driving through the air becomes significant at speeds above 50 mph. Toyota is working on a concept to reduce the battery height by creating flatter batteries to reduce vehicle frontal area and improve the EV drag, resulting in a longer range for a given battery capacity.

The Toyota bZ4X battery pack, including its casing, is around 150 mm (5.9 inches) high. Toyota plans to reduce the battery height to 120 mm (4.7 inches) and possibly 100 mm (3.9 inches) to improve vehicle aerodynamics with a lower overall vehicle height and smaller frontal area.  

By presenting these innovations, Toyota is telling the world it is finally getting serious about joining the electric vehicle game.