The Latest in Electric Vehicle (EV) Battery Technology
Electric vehicles (EVs) are becoming more popular and affordable as the demand for clean and efficient transportation grows. However, one of the main challenges that EVs face is the performance and cost of their batteries. EV batteries determine how far an EV can travel on a single charge, how fast it can recharge, and how long it can last. Therefore, improving EV battery technology is crucial for advancing the EV industry and making electric mobility more accessible and attractive to consumers.
In this blog post, we will discuss some of the latest developments and trends in EV battery technology and what we can expect in the next five years. We will also look at what some of the leading EV manufacturers are doing to innovate and compete in the EV battery market.
What are the current challenges and limitations of EV batteries?
EV batteries are typically made of lithium-ion cells, which are composed of a positive electrode (cathode), a negative electrode (anode), and an electrolyte that allows the flow of ions between them. When an EV is plugged into a charger, electricity flows into the battery and forces the lithium ions to move from the cathode to the anode, where they are stored. When an EV is driven, the opposite happens: the lithium ions move from the anode to the cathode, releasing electricity that powers the motor.
Lithium-ion batteries have many advantages over other types of batteries, such as high energy density, long cycle life, low self-discharge rate, and no memory effect. However, they also have some drawbacks and limitations that affect their performance and cost. Some of these are:
- Limited range – The range of an EV depends on the capacity of its battery, which is measured in kilowatt-hours (kWh). The higher the capacity, the longer the range. However, increasing the capacity also means increasing the size and weight of the battery, which can reduce the efficiency and performance of the EV. Moreover, there is a limit to how much energy a lithium-ion cell can store per unit of volume or mass, which is known as its specific energy or energy density. The average energy density of current lithium-ion batteries is around 250 Wh/kg1, which means that a 60 kWh battery would weigh about 240 kg (529 lbs). To achieve a range of 500 miles or more, which is comparable to some gas-powered cars, an EV would need a much larger and heavier battery than what is currently available.
- Slow charging – The charging time of an EV depends on the power output of the charger and the power input of the battery. The power output of a charger is measured in kilowatts (kW), while the power input of a battery is measured in C-rate, which is the ratio of charge or discharge current to its capacity. For example, a 1C rate means that a battery can be fully charged or discharged in one hour. A higher C-rate means faster charging or discharging. However, charging a lithium-ion battery too fast can cause overheating, degradation, or even fire. Therefore, most lithium-ion batteries have a maximum C-rate of around 1C to 2C2, which means that they can be fully charged in about one to two hours at best. To reduce the charging time, some EV manufacturers use fast chargers that can deliver higher power output than conventional chargers. These fast chargers are also known as Level 3 or DC fast chargers, which can provide up to 350 kW3 of power output. However, not all EVs can accept such high power input due to their battery limitations. Moreover, fast chargers are more expensive and less available than regular chargers.
- High cost – The cost of an EV battery depends on several factors, such as its capacity, chemistry, design, manufacturing process, and supply chain. According to BloombergNEF4, the average cost of an EV battery pack was $137/kWh in 20205, which means that a 60 kWh battery would cost about $8,220. This accounts for about 25% to 30% of the total cost of an average EV6. Although the cost of EV batteries has been declining over the years due to economies of scale, technological improvements, and increased competition7, it is still one of the main barriers for mass adoption of EVs. To make EVs more affordable and competitive with gas-powered cars, many experts believe that the cost of EV batteries needs to drop below $100/kWh8, which is considered the tipping point for EVs to reach price parity with conventional cars.
What are the latest developments and trends in EV battery technology?
Despite the challenges and limitations of current EV batteries, there is a lot of research and innovation going on in the field of EV battery technology. Some of the latest developments and trends are:
- New battery chemistries – One of the ways to improve the performance and cost of EV batteries is to explore new battery chemistries that can offer higher energy density, faster charging, longer cycle life, and lower environmental impact than lithium-ion batteries. Some of the promising candidates are:
- Lithium-metal batteries – These batteries use metallic lithium as the anode instead of graphite, which can increase the energy density by up to 50%9. However, lithium-metal batteries also face some challenges, such as dendrite formation, which can cause short circuits and safety issues. To overcome this problem, some researchers and companies are developing solid-state electrolytes that can prevent dendrite growth and improve stability10. For example, QuantumScape11, a startup backed by Volkswagen and Bill Gates, claims to have developed a solid-state lithium-metal battery that can achieve 80% charge in 15 minutes and last for over 800 cycles12.
- Lithium-sulfur batteries – These batteries use sulfur as the cathode instead of metal oxides, which can increase the energy density by up to four times13. However, lithium-sulfur batteries also suffer from low cycle life and poor power performance due to the dissolution of sulfur and the formation of polysulfides. To solve this issue, some researchers and companies are developing various strategies to stabilize the sulfur cathode and inhibit polysulfide migration14. For example, Oxis Energy15, a UK-based company, claims to have developed a lithium-sulfur battery that can achieve an energy density of 500 Wh/kg and a cycle life of over 500 cycles16.
- Sodium-ion batteries – These batteries use sodium instead of lithium as the main charge carrier, which can reduce the cost and environmental impact of EV batteries. Sodium is more abundant, cheaper, and less toxic than lithium. However, sodium-ion batteries also have lower energy density and slower charging than lithium-ion batteries due to the larger size and weight of sodium atoms. To improve this situation, some researchers and companies are developing new materials and structures for sodium-ion batteries that can enhance their performance and efficiency. For example, CATL, a leading Chinese EV battery maker, claims to have developed a sodium-ion battery that can achieve an energy density of 160 Wh/kg and charge to 80% in 15 minutes.
- Battery recycling – Another way to improve the cost and sustainability of EV batteries is to recycle them after they reach their end-of-life. Recycling EV batteries can recover valuable materials such as lithium, cobalt, nickel, and copper that can be reused for making new batteries or other products. Recycling EV batteries can also reduce the environmental impact of mining and disposing of these materials. However, recycling EV batteries also faces some challenges, such as high cost, low efficiency, complex logistics, and lack of standards and regulations. To address these challenges, some researchers and companies are developing new technologies and business models for EV battery recycling that can increase the recovery rate, reduce the energy consumption, simplify the process, and create value from waste. For example, Redwood Materials, a startup founded by former Tesla CTO JB Straubel, claims to have developed a closed-loop system that can recycle over 95% of EV battery materials using advanced separation and extraction methods.
- Battery swapping – A third way to improve the convenience and accessibility of EVs is to offer battery swapping as an alternative or complementary option to charging. Battery swapping is a service that allows EV drivers to exchange their depleted batteries for fully charged ones at designated stations in a matter of minutes. Battery swapping can eliminate the waiting time and anxiety associated with charging EVs. However, battery swapping also faces some challenges, such as high capital cost, low compatibility, limited availability, and operational complexity. To overcome these challenges, some companies are developing new solutions and partnerships for battery swapping that can lower the cost, increase the standardization, expand the network, and optimize the management of battery swapping services. For example, NIO, a leading Chinese EV maker, claims to have built over 500 battery swapping stations across China that can swap over 3000 batteries per day for its customers.