How Solid State EV Batteries Compare To Lithium

Car companies are scrambling to develop solid-state batteries to get ahead in the EV race. Let's compare it to lithium-ion batteries.

Electric cars have grown out of niche status and into the mainstream. In 2020, electric vehicles (EVs) comprised less than 5% of the world's passenger car sales. But in just 2 years, this market share roughly tripled (14% in 2022). Car manufacturers are now rushing to develop their own electrified model offerings to take a piece of the growing EV pie.

Although a few automakers are still investing in hydrogen fuel cell electric vehicles (HFCEVs), the sales figures tell us that battery electric vehicles (BEVs) make up a great majority of EVs being sold today. Out of approximately 10.5 million EVs sold in the world last 2022, pure BEVs accounted for 73% while plug-in hybrid EVs (PHEVs) took up almost the entire 27% that remained. Fuel cells may still grow in industrial and commercial applications in the future, but batteries will likely be the dominant energy storage solution for the EV industry for the rest of this decade.

For this purpose, car companies are undertaking extensive in-house and partnership-based research and development efforts to improve EV battery technology. Based on recent automotive press releases, it seems that solid-state batteries may be the next big breakthrough in vehicle electrification.

So what is a solid-state battery, and how is it different from the conventional lithium-ion battery that EVs use today? Read on and find out how solid-state batteries can change the EV industry.

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A solid-state battery is a device that stores energy using a solid electrolyte material instead of the traditional liquid electrolyte. The electrolyte acts as a transport medium for lithium ions so that they can move between a negative (anode) and a positive (cathode) electrode. Depending on the movement direction of the ions, energy is either released (i.e. during battery usage) or stored (i.e. during battery charging). Aside from being a transport medium, the solid electrolyte also serves as a physical separator between the two electrodes.

Most conventional lithium-ion batteries in today's EVs use lithium-salt liquid electrolyte solutions.

Solid-state batteries have plenty of advantages compared to the current liquid-electrolyte lithium-ion batteries.

The following sections will discuss these advantages in greater detail.

Today's conventional lithium-ion EV batteries can store 100 to 265 watt-hours per kilogram (Wh/kg). According to the National Aeronautics and Space Administration (NASA), solid-state batteries are capable of storing up to 500 Wh/kg. Based on these figures, we can see that solid-state batteries can store 2 to 5 times more energy for the same battery weight. Lighter and denser solid-state batteries will result in many operational improvements across different industries and applications, but for us car buyers, perhaps the most important benefit is a longer electric driving range.

Range anxiety is one of the main roadblocks to widespread EV adoption. After all, no one wants to have their EVs run out of charge in the middle of nowhere, with no charging stations in sight. As of 2023, EVs in the US have an average range of 291 miles. Holding all other factors constant, solid-state batteries can theoretically increase the average EV driving range to 600 miles. That's almost 100 miles more than the driving range of a 2.5-liter, gas-only 2023 Toyota Camry (505.6 miles). If 600 miles still isn't impressive, Toyota announced that it may offer a 900-mile solid-state battery sometime after 2028.

Future EV buyers can look forward to 3 more important benefits that stem from the higher energy density of solid-state batteries: space, handling, and utility.

According to a 2022 article in the Science Direct Journal, solid-state batteries are assumed to be safer than conventional lithium-ion ones.

Because of the solid electrolyte material between the electrodes, solid-state batteries will be less prone to toxic leakages and EV battery fires. EV fires that are caused by the thermal runaway chemical reaction of conventional lithium-ion batteries are very hard to put out. It can take 20 times more water to put out an EV fire compared to one from an internal combustion engine (ICE) vehicle. EV fires can burn very hot and very violently, particularly because the hydrogen gas produced by lithium's reaction to water will fuel the fire even further.

Aside from having greater energy density, solid-state batteries also charge faster than conventional lithium-ion batteries. Here are the factors that contribute to the faster charging time:

Currently, EVs with conventional lithium-ion batteries need 30 to 40 minutes to get from 10% to 80% state-of-charge (SOC) using the fastest level 3 DC chargers. In contrast, Toyota claims that its solid-state batteries only need 10 minutes to charge from 10% to 80% SOC.

Many current EV owners have already complained about poor EV performance during cold weather, with particular emphasis on shorter driving ranges, slower charging, and weaker torque output. These problems are to be expected because lithium-ion EV batteries have an operating temperature range between 50 and 86 degrees Fahrenheit (10 to 30 degrees Celsius). Many EVs will struggle during North America's coldest winters. Moreover, many of today's EVs will not operate optimally in the hottest climate zones.

In contrast, published scientific studies have shown that solid-state batteries can operate efficiently from -40 to 338 degrees Fahrenheit, or from -40 to 170 degrees Celsius.

So you may be asking - if solid-state batteries are so good, why aren't car companies using them now? Here are a few reasons:

Solid-state batteries are still relatively new, and there still isn't a standardized process and set of materials that can make way for mass production. Thus, solid-state batteries have the following disadvantages:

Some companies are trying to develop solid electrolytes with ceramic layers to improve the interface between the electrolyte and electrodes. However, ceramic electrolytes are naturally brittle, thus making the production of thin ceramic electrolyte layers very challenging.

As of June 2023, no car manufacturer has released a solid-state battery-powered production EV. Last 2020, however, Toyota did showcase an LQ Concept prototype EV powered by solid-state batteries. Nevertheless, several car brands have invested significantly in solid-state battery research and development.

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US federal law requires EV batteries to be covered by warranty for a minimum of 8 years/100,000 miles. However, today's conventional lithium-ion EV batteries are expected to last much longer. For instance, the Tesla Model 3's battery is designed to last between 10 to 20 years - or between 300,000 and 500,000 miles.

As of 2023, some battery research and development companies have claimed that solid-state batteries can last for 400,000 miles. Moreover, solid-state batteries will likely degrade noticeably only after 10,000 cycles of charging and discharging - almost 5 times longer than the conventional lithium-ion batteries' 2,000 to 3,000 cycles.

Ron has worked in the strategy and marketing departments of a few automotive brands. When he's not writing about cars, he likes to analyze auto industry data to share with fellow enthusiasts.. or his pet dogs.