Lithium-ion Batteries: How To Drive The Future

- Aug 03, 2019-

In the coming decades, electric vehicles will be developed on a large scale. According to the IEA, global electric vehicle ownership will grow from 3.7 million in 2017 to 130 million by 2030, with annual sales reaching 21.5 million. Under this scenario, the annual increase in battery capacity will increase from 68 gigawatt hours in 2017 to 775 gigawatt hours in 2030, 84% of which will be used in light vehicles. China, the EU, India and the US accounted for 50%, 18%, 12% and 7% respectively.

As capacity has expanded over the past two decades, lithium-ion technology, which dominates electric vehicle batteries, has risen and fallen sharply in price, putting electric cars on a par with fuel-efficient ones.

 

Key driver:
Since its debut in 1990, lithium-ion batteries have been widely used in consumer electronics, energy storage (home, utility) and electric vehicles. With the expansion of production capacity, its performance has been greatly improved, and its price has been greatly reduced.


In the future, the four key factors driving the cost reduction and performance improvement of lithium-ion batteries are chemical materials, battery capacity, production scale and charging speed.

 

Chemical materials. The performance of the battery is affected by the bipolar chemical materials. Cathode materials mainly include lithium nickel-manganese cobalt (NMC), lithium nickel-cobalt aluminum oxide (NCA), lithium manganese oxide (LMO) and lithium iron phosphate (LFP). Most anode materials are graphite, and lithium titanate (LTO) is also used in heavy duty vehicles to increase cycle life. The main advantage of NMC and NCA technologies is their higher energy density, which dominates the lightweight battery market. The LFP has a low energy density but benefits from higher cycle life and safety, making it the main chemical used in heavy-duty electric vehicles, or buses. Chemical materials have a great impact on the cost of batteries. The price difference of batteries with different chemical materials can be up to 20%.

 

Battery capacity and size. Battery capacities of electric vehicles vary widely. The three best-selling small electric vehicles in China have battery capacities of 18.3~23 KWh. Mid-size car batteries in Europe and North America have a capacity of 23 to 60 KWh; Large cars have a battery capacity of 75 to 100 kilowatt-hours. The larger the battery, the lower the cost.

 

Production scale. Expanding production to achieve economies of scale is another important factor. At present, the typical factory capacity range is about 0.5~8 GWh/year, and the capacity of most factories is about 3 GWh/year. Based on the typical capacity of a single electric vehicle, which ranges from 20 to 75 kilowatt-hours, a single factory can produce the equivalent of 60 to 400, 000 battery packs a year. Germany, the United States, China and India are building new battery plants with greater capacity, including tesla's gigafactorwith an annual capacity of 35 gigawatt hours.

 

Charging rate. Current technology can achieve 80% charge in 40 to 60 minutes. This adds complexity to battery design, such as reducing the thickness of electrodes, which adds to the cost of batteries. Reduce the energy density of the battery, thereby shortening the battery life. An analysis by the us department of energy suggests that changing the battery design to accommodate a 400-kilowatt charge would almost double the cost of the battery.

 

The materials revolution dominates the future:

According to the IEA's analysis, lithium-ion batteries will remain dominant for the next two decades, but their chemistry will gradually change.


Around 2025, a new generation of lithium-ion batteries with low cobalt, high energy density and cathode lithium nickel-manganese cobalt (NMC) 811 will enter mass production. Adding a small amount of silicon to the graphite anode increases the energy density by 50 percent, while electrolyte salts that can withstand higher voltages also help improve performance.


Between 2025 and 2030, lithium-ion batteries with a lithium metal cathode and a graphite/silicon composite anode may enter the design phase, and even solid electrolytes could be introduced to further improve energy density and battery safety. In addition, lithium-ion technology could be replaced by other batteries with higher energy densities and lower theoretical costs, such as lithium air and sulfur. However, the development level of these technologies is still very low, and their actual performance has yet to be tested.

 

Measure of economy

The main factors that affect the cost of electric and fuel vehicles include battery price, body size (which affects fuel economy and battery size of electric vehicles), fuel price and annual mileage.

 

Battery price, for the lithium nickel manganese cobalt 811 / graphite electrode materials, production scale in 7.5 ~ 35 gw/year, when the battery capacity is 70 ~ 80 KWH battery, to 2030 in costs can drop to 100 ~ $122 / KWH, with the European Union ($93 / KWH), China ($116 / KWH) and Japan ($92 / KWH) cost reduction target.


The gap between the cost of an electric car and the cost of a gas-powered one shrinks as the mileage increases, but the price of batteries and the price of gasoline play a bigger role than the size of the car.

When electric cars have lower battery prices, higher gasoline prices, and higher daily mileage, it is more cost-effective to choose small electric or plug-in hybrids over small, gas-powered vehicles.For example, with a battery price of $120 per kilowatt-hour and gasoline prices higher than today's levels, all-electric cars would be a more economical option regardless of range. If the battery costs $260 per kilowatt hour, it will have a range of more than 35,000 kilometers per year and a fuel price of $1.50 per liter is more economical.


For large electric buses, if the battery price is less than $260 / KWH, electric buses traveling 40 to 50 km/year are cost competitive in areas with high diesel taxes.