What Battery Technologies Will Power the Electric Vehicle Revolution?

August 2022

Sustainability & Smart Cities

Nick Maynard

VP of Research

The growing demand and adoption rates of EVs (electric vehicles) means that battery manufacture levels need to rise considerably in the coming years, which will push manufacturers to find more cost-effective and scalable solutions for battery production.
 
But what battery technologies lend themselves to EVs? And how are they being refined to meet the changing performance and vehicle range demands?
 
Lithium-ion Batteries
 
Lithium-ion batteries are widely used in consumer electronics due to their high energy generation capabilities compared to their size and weight. Their higher energy efficiency, low self-discharge, and high temperature performance, as well as relative stability vis-à-vis other batteries make them the best available solution in the EV market. Most components of lithium-ion batteries can also be recycled, however, as was discussed briefly, the cost of repurposing and utilising recycled batteries remains a complex issue.
 
Furthermore, standardisation and regulation of recycling needs to be ensured. Carbon emissions involving recycling and repurposing processes should not cause other environmental hazards; defeating their purpose. Perhaps the most essential consideration is the dependency on mining materials, especially cobalt and nickel.
 
Numerous OEMs, including Tesla and Ford, have opted for LFP (Lithium-Iron-Phosphate) batteries in some of their EVs. For instance, Tesla used them in all its standard-range vehicles. These batteries are significantly cheaper but less energy dense, widely used in EV manufacturing in China. Ford has opted for batteries with a higher percentage of energy-dense nickel for its forthcoming electric pick-up truck. It is likely that lithium-ion and its variations will continue to dominate the EV battery market for the next decade, as they remain the most commercially viable EV battery solution and provide a reliable base of research for new battery technologies.
 
Solid-state Batteries
 
Emerging as a potential alternative to lithium-ion batteries in recent years, solid-state batteries currently possess lower technology maturity and market readiness in comparison to their counterparts. These batteries pack solid electrolytes rather than liquid ones; decreasing volatility and ultimately risks associated with lithium-ion batteries. Moreover, they are capable of holding more energy compared to lithium-ion ones with better performance at both low and high temperatures.
 
Nickel-metal Hydride Batteries
 
Nickel-metal hydride batteries are batteries which yield better energy compared to lead-acid batteries and are used in numerous PHEVs; having longer lifecycles. They are also safer and more abuse tolerant, compared to both lead-acid and lithium-ion batteries. The reasons why nickel-metal hydride batteries remained only as an alternative to other EV battery solutions are their high costs of production for EVs and poorer performance in self-discharge.
 
In addition, although they are more abuse tolerant, these batteries generate heat in high temperatures and overcharging can potentially cause hydrogen to form; damaging the battery cells. In such cases, batteries release hydrogen gas, which needs to be controlled.
 
Lead-acid Batteries
 
Widely used in ICE vehicles as starting batteries, lead-acid batteries are inexpensive and safe battery options. However, their low energy density and short lifecycles, as well as poor performance under cold temperatures make them secondary energy sources/ancillary loads to be utilised in EVs, even though advancements in their technology have been made. Lead-acid batteries are therefore best used as deep-cycle batteries in applications requiring regular battery discharge.
 
Moreover, since lead is hazardous to human health and the environment, and carries risks inherent to its chemical composure, recycling of lead-acid batteries is not simple. Although lead can be reclaimed, reusing/repurposing batteries, lending themselves to other applications ie powering microgrids) remains limited.
 
Ultracapacitors
 
Although ultracapacitors are not batteries per se, they provide energy storage capacity. This is achieved by storing energy in a polarised liquid between the electrode and electrolyte; meaning electrostatically rather than chemically. Energy storage capacity increases when the liquid’s surface increases, however, they are able to store less energy than a similar-sized battery. Ultracapacitors can discharge energy more rapidly and thus are better suited to uses requiring rapid charge and discharge cycles, since such discharge is an electrostatic event.
 
They can be utilised to provide EVs with additional power when driving, such as when accelerating and climbing hills, as well as assisting in recovering braking energy. As such, they are useful as a secondary source of power and storage, thanks to their ability to assist other batteries levelling their loads. Ultracapacitors are utilised in numerous PHEVs, especially in improving start and stop features and acceleration performance.
 
Zebra Batteries
 
Zebra batteries are sodium-nickel chloride batteries that are cheaper than lithium-ion batteries but have lower specific power. They were initially developed to power grids, mining materials, and train locomotives (as was with the case of General Electric’s sodium-nickel-chloride Durathon batteries), and were then used to power numerous early EV concept cars and public transport vehicles. Despite their high energy density, lower discharge rate and weight, one important setback for these batteries is their temperature to operate at maximum efficiency (270°C-350°C); making them safer and more viable for public transport.

• The volume of electric vehicle battery pack shipments will reach 30 million in 2027; from just 10 million in 2022.
• Falling vehicle costs, often directly caused by government subsidies, and increasing awareness around the environmental impact of current mobility services are key drivers behind the growth in electric vehicle battery production. This growth will be strongest within the commercial segment, with commercial electric vehicle battery pack shipments growing from 1.4 million in 2022 to over 7 million by 2027.
• Mass electrification of fleet vehicles is required for meeting corporate decarbonisation goals and will drive investment into electric vehicles from enterprises. In turn, this provides an opportunity for manufacturers to develop batteries designed for energy-intensive commercial use cases.
• For electric vehicles to reach mass adoption across commercial use cases, including heavy goods haulage and passenger transport, scaling the production of new battery technologies is essential. This includes solid state batteries and new chemical mixes.
• The most pressing issue for electric vehicle adoption is the rare earth minerals required in battery production, including cobalt, which is difficult to source, in terms of both cost and the ethics around procurement.
• Accordingly, manufacturers must rapidly move to new, higher capacity technologies including solid-state batteries to unlock energy intensive use cases. However, these changes in technologies must continue to prioritise the sustainability goals electrification is based upon.