Electric vehicle battery


An electric-vehicle battery ''' is a battery used to power the electric motors of a battery electric vehicle or hybrid electric vehicle. These batteries are usually rechargeable batteries, and are typically lithium-ion batteries. These batteries are specifically designed for a high ampere-hour capacity.
Electric-vehicle batteries differ from starting, lighting, and ignition batteries as they are designed to give power over sustained periods of time and are deep-cycle batteries. Batteries for electric vehicles are characterized by their relatively high power-to-weight ratio, specific energy and energy density; smaller, lighter batteries are desirable because they reduce the weight of the vehicle and therefore improve its performance. Compared to liquid fuels, most current battery technologies have much lower specific energy, and this often impacts the maximum all-electric range of the vehicles.
The most common battery type in modern electric vehicles are lithium-ion and lithium polymer, because of their high energy density compared to their weight. Other types of rechargeable batteries used in electric vehicles include lead–acid, nickel-cadmium, nickel–metal hydride, and, less commonly, zinc–air, and sodium nickel chloride batteries. The amount of electricity stored in batteries is measured in ampere hours or in coulombs, with the total energy often measured in kilowatt-hours.
Since the late 1990s, advances in lithium-ion battery technology have been driven by demands from portable electronics, laptop computers, mobile phones, and power tools. The BEV and HEV marketplace has reaped the benefits of these advances both in performance and energy density. Unlike earlier battery chemistries, notably nickel-cadmium, lithium-ion batteries can be discharged and recharged daily and at any state of charge.
The battery pack makes up a significant cost of a BEV or a HEV., the cost of electric-vehicle batteries has fallen 87% since 2010 on a per kilowatt-hour basis. As of 2018, vehicles with over of all-electric range, such as the Tesla Model S, have been commercialized and are now available in numerous vehicle segments.
In terms of operating costs, the price of electricity to run a BEV is a small fraction of the cost of fuel for equivalent internal combustion engines, reflecting higher energy efficiency.

Electric vehicle battery types

Lead-acid

Flooded lead-acid batteries are the cheapest and, in the past, most common vehicle batteries available. There are two main types of lead-acid batteries: automobile engine starter batteries, and deep cycle batteries. Automobile engine starter batteries are designed to use a small percentage of their capacity to provide high charge rates to start the engine, while deep cycle batteries are used to provide continuous electricity to run electric vehicles like forklifts or golf carts. Deep cycle batteries are also used as the auxiliary batteries in recreational vehicles, but they require different, multi-stage charging. No lead acid battery should be discharged below 50% of its capacity, as it shortens the battery's life. Flooded batteries require inspection of electrolyte levels and occasional replacement of water, which gases away during the normal charging cycle.
Previously, most electric vehicles used lead-acid batteries due to their mature technology, high availability, and low cost, with the notable exception of some early BEVs, such as the Detroit Electric which used a nickel–iron battery. Deep-cycle lead batteries are expensive and have a shorter life than the vehicle itself, typically needing replacement every 3 years.
Lead-acid batteries in EV applications end up being a significant portion of the final vehicle mass. Like all batteries, they have significantly lower specific energy than petroleum fuels—in this case, 30–50 Wh/kg. While the difference isn't as extreme as it first appears due to the lighter drive-train in an EV, even the best batteries tend to lead to higher masses when applied to vehicles with a normal range. The efficiency and storage capacity of the current generation of common deep cycle lead acid batteries decreases with lower temperatures, and diverting power to run a heating coil reduces efficiency and range by up to 40%.
Charging and operation of batteries typically results in the emission of hydrogen, oxygen and sulfur, which are naturally occurring and normally harmless if properly vented. Early Citicar owners discovered that, if not vented properly, unpleasant sulfur smells would leak into the cabin immediately after charging.
Lead-acid batteries powered such early modern EVs as the original versions of the EV1.

Nickel metal hydride

Nickel-metal hydride batteries are now considered a relatively mature technology. While less efficient in charging and discharging than even lead-acid, they have a specific energy of 30–80 Wh/kg, far higher than lead-acid. When used properly, nickel-metal hydride batteries can have exceptionally long lives, as has been demonstrated in their use in hybrid cars and in the surviving first-generation NiMH Toyota RAV4 EVs that still operate well after and over a decade of service. Downsides include the poor efficiency, high self-discharge, very finicky charge cycles, and poor performance in cold weather.
GM Ovonic produced the NiMH battery used in the second generation EV-1, and Cobasys makes a nearly identical battery. This worked very well in the EV-1. Patent encumbrance has limited the use of these batteries in recent years.

Zebra

The sodium nickel chloride or "Zebra" battery uses a molten sodium chloroaluminate salt as the electrolyte. A relatively mature technology, the Zebra battery has a specific energy of 120 Wh/kg. Since the battery must be heated for use, cold weather does not strongly affect its operation except for increasing heating costs. They have been used in several EVs such as the Modec commercial vehicle. Zebra batteries can last for a few thousand charge cycles and are nontoxic. The downsides to the Zebra battery include poor specific power and the requirement of having to heat the electrolyte to about, which wastes some energy, presents difficulties in long-term storage of charge, and is potentially a hazard.

Lithium-ion

batteries, were initially developed and commercialized for use in laptops and consumer electronics. With their high energy density and long cycle life they have become the leading battery type for use in EVs. The first commercialized lithium-ion chemistry was a lithium cobalt oxide cathode and a graphite anode first demonstrated by N. Godshall in 1979, and by John Goodenough, and Akira Yoshino shortly thereafter. The downside of traditional lithium-ion batteries include sensitivity to temperature, low temperature power performance, and performance degradation with age. Due to the volatility of organic electrolytes, the presence of highly oxidized metal oxides, and the thermal instability of the anode SEI layer, traditional lithium-ion batteries pose a fire safety risk if punctured or charged improperly. These early cells did not accept or supply charge when extremely cold, and so heaters can be necessary in some climates to warm them. The maturity of this technology is moderate. The Tesla Roadster and other cars produced by the company used a modified form of traditional lithium-ion "laptop battery" cells.
Recent EVs are using new variations on lithium-ion chemistry that sacrifice specific energy and specific power to provide fire resistance, environmental friendliness, rapid charging, and longer lifespans. These variants have been shown to have a much longer lifetime, with A123 types using lithium iron phosphate lasting at least more than 10 years and more than 7000 charge/discharge cycles, and LG Chem expecting their lithium-manganese spinel batteries to last up to 40 years.
Much work is being done on lithium ion batteries in the lab. Lithium vanadium oxide has already made its way into the Subaru prototype G4e, doubling energy density. Silicon nanowires, silicon nanoparticles, and tin nanoparticles promise several times the energy density in the anode, while composite and superlattice cathodes also promise significant density improvements.
New data has shown that exposure to heat and the use of fast charging promote the degradation of Li-ion batteries more than age and actual use, and that the average electric vehicle battery will retain 90% of its initial capacity after 6 years and 6 months of service. For example, the battery in a Nissan LEAF, will degrade twice as fast as the battery in a Tesla, because the LEAF does not have an active cooling system for its battery.

Example vehicles and their battery capacities

Full-electric

In 2010, scientists at the Technical University of Denmark paid US$10,000 for a certified EV battery with 25 kWh capacity, with no rebates or surcharges. Two out of 15 battery producers could supply the necessary technical documents about quality and fire safety. In 2010 it was estimated that at most 10 years would pass before the battery price would come down to one-third.
According to a 2010 study, by the United States National Research Council, the cost of a lithium-ion battery pack was about /kWh of usable energy, and considering that a PHEV-10 requires about 2.0 kWh and a PHEV-40 about 8 kWh, the manufacturer cost of the battery pack for a PHEV-10 is around and it goes up to for a PHEV-40. The MIT Technology Review estimated the cost of automotive battery packs to be between to per kilowatt hour by 2020. A 2013 study by the American Council for an Energy-Efficient Economy reported that battery costs came down from /kWh in 2007 to /kWh in 2012. The U.S. Department of Energy has set cost targets for its sponsored battery research of /kWh in 2015 and /kWh by 2022. Cost reductions through advances in battery technology and higher production volumes will allow plug-in electric vehicles to be more competitive with conventional internal combustion engine vehicles. In 2016, the world had a Li-ion production capacity of 41.57 GW⋅h.
The actual costs for cells are subject to much debate and speculation as most EV manufacturers refuse to discuss this topic in detail. However, in October 2015, car maker GM revealed at their annual Global Business Conference that they expected a price of /kWh for Li-ion cells entering 2016, substantially lower than other analyst's cost estimates. GM also expects a cost of /kWh by the end of 2021.
According to a study published in February 2016 by Bloomberg New Energy Finance, battery prices fell 65% since 2010, and 35% just in 2015, reaching /kWh. The study concludes that battery costs are on a trajectory to make electric vehicles without government subsidies as affordable as internal combustion engine cars in most countries by 2022. BNEF projects that by 2040, long-range electric cars will cost less than expressed in 2016 dollars. BNEF expects electric car battery costs to be well below /kWh by 2030, and to fall further thereafter as new chemistries become available.
;Battery cost estimate comparison
Battery typeYearCost
Li-ion2016130-145
Li-ion2014200–300
Li-ion2012500–600
Li-ion2012400
Li-ion2012520–650
Li-ion2012752
Li-ion2012689
Li-ion2013800–1000
Li-ion2010750
Nickel–metal hydride2004750
Nickel–metal hydride2013500–550
Nickel–metal hydride350
Lead–acid256.68

;Battery longevity estimate comparison
Battery typeYear of estimateCyclesMilesYears
Li-ion2016>40001,000,000>10
Li-ion2008100,0005
Li-ion60,0005
Li-ion20022-4
Li-ion1997>1,000
Nickel–metal hydride2001100,0004
Nickel–metal hydride1999>90,000
Nickel–metal hydride200,000
Nickel–metal hydride1999100093,205.7
Nickel–metal hydride1995<2,000
Nickel–metal hydride20022000
Nickel–metal hydride1997>1,000
Nickel–metal hydride1997>1,000
Lead–acid1997300–5003

EV parity

In 2010, battery professor Poul Norby stated that he believed that lithium batteries will need to double their specific energy and bring down the price from US$500 to US$100 per kWh capacity in order to make an impact on petrol cars. Citigroup indicates US$230/kWh.
Toyota Prius 2012 plug-in's official page declare of range and a battery capacity of 5.2 kWh with a ratio of /kWh, while the Addax utility vehicle already reaches 110 kilometres or a ratio of 7.5 kilometers /kWh.
Battery electric cars achieve about /kWh. The Chevrolet Volt is expected to achieve 50 MPGe when running on the auxiliary power unit at 33% thermodynamic efficiency that would mean 12 kWh for, or about 240 watt-hours per mile. For prices of 1 kWh of charge with various different battery technologies, see the "Energy/Consumer Price" column in the "Table of rechargeable battery technologies" section in the rechargeable battery article.
United States Secretary of Energy Steven Chu predicted costs for a 40-mile range battery will drop from a price in 2008 of US$12K to US$3,600 in 2015 and further to US$1,500 by 2020. Li-ion, Li-poly, Aluminium-air batteries and zinc-air batteries have demonstrated specific energies high enough to deliver range and recharge times comparable to conventional fossil fueled vehicles.

Cost parity

Different costs are important. One issue is purchase price, the other issue is total cost of ownership. As of 2015, electric cars are more expensive to initially purchase, but cheaper to run, and in at least some cases, total cost of ownership may be lower.
According to Kammen et al., 2008, new PEVs would become cost efficient to consumers if battery prices would decrease from US$1300/kWh to about US$500/kWh.
In 2010, the Nissan Leaf battery pack was reportedly produced at a cost of US$18,000. Nissan's initial production costs at the launch of the Leaf were therefore about US$750 per kilowatt hour.
In 2012, McKinsey Quarterly linked battery prices to gasoline prices on a basis of 5-year total cost of ownership for a car, estimating that US$3.50/gallon equates to US$250/kWh. In 2017 McKinsey estimated that electric cars will be competitive at a battery pack cost of US$100/kWh, and expects pack costs to be US$190/kWh by 2020.
In October 2015, car maker GM revealed at their annual Global Business Conference that they expected a price of US$145 per kilowatt hour for Li-ion cells entering 2016.

Range parity

Driving range parity means that the electric vehicle has the same range as an average all-combustion vehicle, with batteries of specific energy greater than 1 kWh/kg. Higher range means that the electric vehicles would run more kilometers without recharge.
Japanese and European Union officials are in talks to jointly develop advanced rechargeable batteries for electric cars to help nations reduce greenhouse-gas emissions. Developing a battery that can power an electric vehicle on a single charging is feasible, said Japanese battery maker GS Yuasa Corp. Sharp Corp and GS Yuasa are among Japanese solar-power cell and battery makers that may benefit from cooperation.

Internal components

Battery pack designs for Electric Vehicles are complex and vary widely by manufacturer and specific application. However, they all incorporate a combination of several simple mechanical and electrical component systems which perform the basic required functions of the pack.
The actual battery cells can have different chemistry, physical shapes, and sizes as preferred by various pack manufacturers. Battery packs will always incorporate many discrete cells connected in series and parallel to achieve the total voltage and current requirements of the pack. Battery packs for all electric drive EVs can contain several hundred individual cells. Each cell has a nominal voltage of 3-4 volts, depending on its chemical composition.
To assist in manufacturing and assembly, the large stack of cells is typically grouped into smaller stacks called modules. Several of these modules will be placed into a single pack. Within each module the cells are welded together to complete the electrical path for current flow. Modules can also incorporate cooling mechanisms, temperature monitors, and other devices. In most cases, modules also allow for monitoring the voltage produced by each battery cell in the stack by using a Battery Management System.
The battery cell stack has a main fuse which limits the current of the pack under a short circuit condition. A "service plug" or "service disconnect" can be removed to split the battery stack into two electrically isolated halves. With the service plug removed, the exposed main terminals of the battery present no high potential electrical danger to service technicians.
The battery pack also contains relays, or contactors, which control the distribution of the battery pack's electrical power to the output terminals. In most cases there will be a minimum of two main relays which connect the battery cell stack to the main positive and negative output terminals of the pack, which then supply high current to the electrical drive motor. Some pack designs will include alternate current paths for pre-charging the drive system through a pre-charge resistor or for powering an auxiliary buss which will also have their own associated control relays. For safety reasons these relays are all normally open.
The battery pack also contains a variety of temperature, voltage, and current sensors. Collection of data from the pack sensors and activation of the pack relays are accomplished by the pack's Battery Monitoring Unit or Battery Management System. The BMS is also responsible for communications with the vehicle outside the battery pack.

Recharging

Batteries in BEVs must be periodically recharged. BEVs most commonly charge from the power grid, which is in turn generated from a variety of domestic resources, such as coal, hydroelectricity, nuclear, natural gas, and others. Home or grid power, such as photovoltaic solar cell panels, wind, or microhydro may also be used and are promoted because of concerns regarding global warming.
With suitable power supplies, good battery lifespan is usually achieved at charging rates not exceeding half of the capacity of the battery per hour, thereby taking two or more hours for a full charge, but faster charging is available even for large capacity batteries.
Charging time at home is limited by the capacity of the household electrical outlet, unless specialized electrical wiring work is done. In the US, Canada, Japan, and other countries with 110 volt electricity, a normal household outlet delivers 1.5 kilowatts. In European countries with 230 volt electricity between 7 and 14 kilowatts can be delivered. In Europe, a 400 V grid connection is increasingly popular since newer houses don't have natural gas connection due to the European Union's safety regulations.

Recharging time

Electric cars like Tesla Model S, Renault Zoe, BMW i3, etc., can recharge their batteries to 80 percent at quick charging stations within 30 minutes. For example, a Tesla Model 3 Long Range charging on a 250 kW Tesla Version 3 Supercharger went from 2% state of charge with of range to 80% state of charge with of range in 27 minutes, which equates to per hour.

Connectors

The charging power can be connected to the car in two ways. The first is a direct electrical connection known as conductive coupling. This might be as simple as a mains lead into a weatherproof socket through special high capacity cables with connectors to protect the user from high voltages. The modern standard for plug-in vehicle charging is the SAE 1772 conductive connector in the US. The ACEA has chosen the VDE-AR-E 2623-2-2 for deployment in Europe, which, without a latch, means unnecessary extra power requirements for the locking mechanism.
The second approach is known as inductive charging. A special 'paddle' is inserted into a slot on the car. The paddle is one winding of a transformer, while the other is built into the car. When the paddle is inserted it completes a magnetic circuit which provides power to the battery pack. In one inductive charging system, one winding is attached to the underside of the car, and the other stays on the floor of the garage. The advantage of the inductive approach is that there is no possibility of electrocution as there are no exposed conductors, although interlocks, special connectors and ground fault detectors can make conductive coupling nearly as safe. Inductive charging can also reduce vehicle weight, by moving more charging componentry offboard. An inductive charging advocate from Toyota contended in 1998, that overall cost differences were minimal, while a conductive charging advocate from Ford contended that conductive charging was more cost efficient.

Recharging spots

, there are 93,439 locations and 178,381 EV charging stations worldwide.

Travel range before recharging

The range of a BEV depends on the number and type of batteries used. The weight and type of vehicle as well as terrain, weather, and the performance of the driver also have an impact, just as they do on the mileage of traditional vehicles. Electric vehicle conversion performance depends on a number of factors including the battery chemistry:
The internal resistance of some batteries may be significantly increased at low temperature which can cause noticeable reduction in the range of the vehicle and on the lifetime of the battery.
Finding the economic balance of range versus performance, battery capacity versus weight, and battery type versus cost challenges every EV manufacturer.
With an AC system or advanced DC system, regenerative braking can extend range by up to 50% under extreme traffic conditions without complete stopping. Otherwise, the range is extended by about 10 to 15% in city driving, and only negligibly in highway driving, depending upon terrain.
BEVs can also use genset trailers and pusher trailers in order to extend their range when desired without the additional weight during normal short range use. Discharged basket trailers can be replaced by recharged ones en route. If rented then maintenance costs can be deferred to the agency.
Some BEVs can become Hybrid vehicles depending on the trailer and car types of energy and powertrain.

Trailers

Auxiliary battery capacity carried in trailers can increase the overall vehicle range, but also increases the loss of power arising from aerodynamic drag, increases weight transfer effects and reduces traction capacity.

Swapping and removing

An alternative to recharging is to exchange drained or nearly drained batteries with fully charged batteries. This is called battery swapping and is done in exchange stations.
Features of swap stations include:
  1. The consumer is no longer concerned with battery capital cost, life cycle, technology, maintenance, or warranty issues;
  2. Swapping is far faster than charging: battery swap equipment built by the firm Better Place has demonstrated automated swaps in less than 60 seconds;
  3. Swap stations increase the feasibility of distributed energy storage via the electric grid;
Concerns about swap stations include:
  1. Potential for fraud
  2. Manufacturers' unwillingness to standardize battery access / implementation details
  3. Safety concerns

    Re-filling

can be re-filled using a liquid, instead of recharged by connectors, saving time.

Lifecycle of EV batteries

Down-cycling of end-of-life EV batteries

Electric vehicle batteries which are in the end-of-life stage can be reused for second-life applications such as use in e-bus power packs, backups for large buildings, use in home energy storage, supply stabilization for solar and wind power generators, backup power for telecom base stations and data centers, the powering of fork lifts, electric scooters and bikes, etc. Reuse of automotive batteries in second life applications requires special expertise in reverse logistics. Alexander Kupfer, responsible for sustainable product development/circular economy at Audi, states that “a common connection interface through which these automotive batteries can be controlled by a stationary storage management system" would need to be developed. This kind of interface would provide a mechanism for communication with the storage control system independent of the battery manufacturer. The interface would need to be developed together with storage suppliers.
Pacific Gas and Electric Company has suggested that utilities could purchase used batteries for backup and load levelling purposes. They state that while these used batteries may be no longer usable in vehicles, their residual capacity still has significant value.

Lifespan

Individual batteries are usually arranged into large battery packs of various voltage and ampere-hour capacity products to give the required energy capacity. Battery service life should be considered when calculating the extended cost of ownership, as all batteries eventually wear out and must be replaced. The rate at which they expire depends on a number of factors.
The depth of discharge is the recommended proportion of the total available energy storage for which that battery will achieve its rated cycles. Deep cycle lead-acid batteries generally should not be discharged to below 20% of total capacity. More modern formulations can survive deeper cycles.
In real world use, some fleet Toyota RAV4 EVs, using Nickel–metal hydride batteries, have exceeded 100,000 miles with little degradation in their daily range. From a Southern California Edison assessment:
Lithium ion batteries are perishable to some degree; they lose some of their maximum storage capacity per year even if they are not used. Nickel metal hydride batteries lose much less capacity and are cheaper for the storage capacity they give, but have a lower total capacity initially for the same weight.
Jay Leno's 1909 Baker Electric still operates on its original Edison cells. Battery replacement costs of BEVs may be partially or fully offset by the lack of regular maintenance such as oil and filter changes required for internal combustion engine vehicles, and by the greater reliability of BEVs due to their fewer moving parts. They also do away with many other parts that normally require servicing and maintenance in a regular car, such as on the gearbox, cooling system, and engine tuning. And by the time batteries do finally need replacement, they can be replaced with later generation ones which may offer better performance characteristics.
Lithium iron phosphate batteries reach, according to the manufacturer, more than 5000 cycles at respective depth of discharge of 70%. BYD, the world's largest manufacturer of lithium iron phosphate batteries, has developed a wide range of cells for deep cycle applications. Such batteries are in use in stationary storage systems. After 7500 cycles, with discharge of 85%, they still have a spare capacity of at least 80% at a rate of 1 C; which corresponds with a full cycle per day to a lifetime of min. 20.5 years. The lithium iron phosphate battery developed by Sony Fortelion has a residual capacity of 71% after 10,000 cycles at 100% discharge level. This battery has been on the market since 2009.
Used in conjunction with solar panels, lithium-ion batteries have partly a very high cycle resistance of more than 10,000 charge and discharge cycles and a long service life of up to 20 years.
Plug-in America conducted a survey of Tesla Roadster drivers regarding the service life of their batteries. It was found that after, the battery still had a remaining capacity of 80 to 85 percent, regardless of which climate zone the car was driven in. Tesla warranties the Model S with a 85-kWh battery for unlimited mileage within a period of 8 years.
Varta Storage offers a guarantee of 14,000 full cycles and a service life of 10 years.
, the world's all-time best-selling electric car is the Nissan Leaf, with more than 250,000 units sold since its inception in 2010. Nissan stated in 2015 that until then only 0.01 percent of batteries had to be replaced because of failures or problems and then only because of externally inflicted damage. There are a few vehicles that have already covered more than 200,000 km; none of these had any problems with the battery.
Li-ion batteries generally lose 2.3% capacity per year. Liquid-cooled Li-ion battery packs lose less capacity per year than air-cooled packs.

Recycling

At the end of their useful life batteries can be reused or recycled. With significant international growth in EV sales, the US Department of Energy has established a research program to investigate methodologies for recycling used EV lithium-ion batteries. Methods currently under investigation include pyrometallurgical, hydrometallurgical, and direct recycling.

Vehicle-to-grid

allows BEVs to provide power to the grid at any time, especially:
The safety issues of battery electric vehicles are largely dealt with by the international standard ISO . This standard is divided into three parts:
Firefighters and rescue personnel receive special training to deal with the higher voltages and chemicals encountered in electric and hybrid electric vehicle accidents. While BEV accidents may present unusual problems, such as fires and fumes resulting from rapid battery discharge, many experts agree that BEV batteries are safe in commercially available vehicles and in rear-end collisions, and are safer than gasoline-propelled cars with rear gasoline tanks.
Usually, battery performance testing includes the determination of:
Performance testing simulates the drive cycles for the drive trains of Battery Electric Vehicles, Hybrid Electric Vehicles and Plug in Hybrid Electric Vehicles as per the required specifications of car manufacturers. During these drive cycles, controlled cooling of the battery can be performed, simulating the thermal conditions in the car.
In addition, climatic chambers control environmental conditions during testing and allow simulation of the full automotive temperature range and climatic conditions.

Patents

s may be used to suppress development or deployment of battery technology. For example, patents relevant to the use of Nickel metal hydride cells in cars were held by an offshoot of Chevron Corporation, a petroleum company, who maintained veto power over any sale or licensing of NiMH technology.

Research, development and innovation

As of December 2019, billions of US dollars in research are planned to be invested around the world for improving batteries.
Europe has plans for heavy investment in electric vehicle battery development and production, and Indonesia also aims to produce electric vehicle batteries in 2023, inviting Chinese battery firm GEM and Contemporary Amperex Technology Ltd to invest in Indonesia.

Ultracapacitors

s are used in some electric vehicles, such as AFS Trinity's concept prototype, to store rapidly available energy with their high, in order to keep batteries within safe resistive heating limits and extend battery life.
Since commercially available ultracapacitors have a low specific energy, no production electric cars use ultracapacitors exclusively.
In January 2020, Elon Musk, CEO of Tesla, stated that the advancements in Li-ion battery technology have made ultra-capacitors unnecessary for electric vehicles.

Promotion in the United States

In 2009, President Barack Obama announced 48 new advanced battery and electric drive projects that would receive US$2.4 billion in funding under the American Recovery and Reinvestment Act. The government claimed that these projects would accelerate the development of U.S. manufacturing capacity for batteries and electric drive components as well as the deployment of electric drive vehicles, helping to establish American leadership in creating the next generation of advanced vehicles.
The announcement marked the single largest investment in advanced battery technology for hybrid and electric-drive vehicles ever made. Industry officials expected that this US$2.4 billion investment, coupled with another US$2.4 billion in cost share from the award winners, would result directly in the creation tens of thousands of manufacturing jobs in the U.S. battery and auto industries.
The awards cover US$1.5 billion in grants to United States-based manufacturers to produce batteries and their components and to expand battery recycling capacity.