Production hurdles worth overcoming as Nissan targets solid state battery success

The automotive industry is invested in reducing its impact on the environment.

The most notable example of this is the shift to electrified powertrains. But the move, which is helping reduce harmful local emissions such as particulate matter and NOx and greenhouse gases such as carbon dioxide, also poses problems.

Electrified powertrains tend to require battery technology, and batteries chew through a huge range of raw materials and resources when they’re produced.

Lithium, nickel, cobalt and manganese all need to be mined and then brought together in the manufacturing process to produce the final battery pack used in vehicles. The impact on the environment is substantial and undeniable, but OEMs are looking to lessen the effects as battery technologies progress.

Nissan is looking to shift away from reliance on traditional lithium-ion battery technology that uses liquid systems to all-solid-state batteries (ASSBs). The carmaker aims to launch an EV with in-house-developed ASSBs by 2028.

Solid-state batteries have a host of benefits compared to current technology: energy density approximately twice that of conventional lithium-ion batteries, significantly shorter charging time owing to superior charge/discharge performance, and lower cost thanks to the opportunity of using less-expensive materials. Nissan believes all-solid-state batteries can be reduced to $75 per kWh in 2028 and to $65 per kWh thereafter, helping to bring cost parity between EVs and combustion engine vehicles.

Material choices

Nissan is honest about the challenges that ASSBs hold if they are to make an impact on the market, namely making sure they don’t cause more harm to the environment.

The first part of the puzzle is shifting emphasis on material choices, and it’s something Yoshiaki Nitta, expert leader at Nissan’s advanced materials and processing laboratory, pays close attention to.

He said: “In current liquid lithium-ion technology cathode material, we use nickel, cobalt and manganese. If we apply the same materials, we won’t see a lot of benefits, but we can use sulphur or manganese, which are more available in the world, and we can switch to these materials. If we apply the more-available materials, we can reduce the burden on the lifecycle assessment.” 

But solid-state batteries are about more than simply cathode material choices. Every part of the process needs to be assessed to lessen any possible impact. 

Kazuhiro Doi, corporate vice-president at Nissan Research Centre, said: “The materials we consume will be reduced as a result of adopting ASSB, which means the cathode and anode materials. But, at the same time, when we produce ASSB there’s CO2 emitted in the production process. Today, for the current liquid lithium-ion battery, we have a dry process and, if we can apply that dry process, we can reduce CO2 emissions.”

But tweaking the manufacturing process isn’t just about carbon, and also brings into play other unwanted emissions. Doi explained: “Solid electrolyte reacts with moisture and releases hydrogen sulphide so we need to control the humidity in the production process. 

“To make it less humid means that we need energy because we need power to dry it. We need to control this smartly in the small chamber where we produce the battery. 

“If you try to maintain a low level of temperature in a big factory, we’ll use a lot of electricity so we need to smartly design the production process because this may increase the emission of CO2.” 

Game changer?

Solid-state batteries could be a game changer for the industry, and with all the benefits they offer Nissan expects to use the technology in a wide range of vehicle segments, including pickup trucks, making its EVs more competitive.

Using the prototype production facility to streamline the manufacturing process will be crucial to reducing its environmental impact as well as that of the battery technology itself, helping make Nissan’s ASSBs a commercial success.