Reality check | Nature Energy

Electric motors are replacing combustion engines in vehicles thanks to the tremendous progress in battery development, but issues remain in navigating transportation with battery

technologies. We are at the dawn of a new era of electric mobility. Governments in nations such as France, the Netherlands and the United Kingdom have all announced plans to ban the sale of

internal combustion engine vehicles (ICVs) between 2030 and 20401. China, the world’s largest auto market, is also considering implementing such a ban2. Meanwhile, automakers are embracing

electric mobility, showcasing dazzling ranges of electrified vehicles (EVs) including hybrid, plug-in hybrid and all-electric models. In 2017, worldwide sales of new EVs rose to a record

high of more than one million3. Vehicle electrification is largely driven by the need to reduce greenhouse gas emissions. Subsidies, as well as government EV sales mandates, have been vital

in building EV markets, while improvements in charging infrastructure are making things easier for EV owners than in the past4. Last but certainly not least, advancements in battery

technologies over recent decades, along with their substantial cost reductions, have been a major driver in transforming the automotive industry. The last time that EVs experienced a

significant market share was over 100 years ago. In 1900, EVs accounted for around one-third of all vehicles on the road5, in sharp contrast to today’s meagre 1% market share. The success

was short-lived, however, primarily due to the rise of ICVs in the 1920s. Battery technological limitations and mass production of ICVs were largely responsible for the eventual decline in

usage of EVs. The first batteries used in EVs were not rechargeable. The oldest rechargeable battery — lead–acid — has a low energy density, making it suitable only for low-range driving or

assistive roles such as starting and lighting. Another rechargeable type with a long history is the nickel–metal hydride battery, which was invented in the 1970s and is still finding uses in

today’s EVs, especially in hybrid models. More recently, since its commercialization in the early 1990s, the Li-ion battery (LIB) has gradually become the mainstream power solution, with

the best combination of properties such as energy density, cycling stability, safety and cost. Today, it is the world’s best-selling EV battery technology. Yet, despite tremendous

improvements over recent decades, LIBs still fall short of industrial requirements and customer expectations. Current LIB packs have an energy density of about 130 Wh kg–1 (or 210 Wh l–1),

but this is a lot lower than the 235 Wh kg–1 (or 500 Wh l–1) required for a drive range of 500 km in a single charge, a typical requirement considered to ease range anxiety and achieve mass

market penetration6. LIB-powered EVs also remain expensive largely due to the battery material cost compared to ICVs, even with their remarkable cost reductions in recent years. Meanwhile,

battery accidents such as fires and explosions make the headlines from time to time, continuing to affect people’s perceptions of battery safety. In the meantime, research labs have been

reporting promising results, especially on batteries beyond Li-ion — the so-called next-generation batteries. Though breakthroughs are often hailed by the media, little progress has yet been

made for real applications because of the transformational gap in taking advancements from labs to market7. In this context, we present this Insight as a reality check on the current status

of existing LIB technologies for EVs and to explore challenges and realistic solutions in moving the technologies forward. This is particularly relevant when considering that the current

LIBs are unlikely to be replaced by any next-generation technologies for automotive applications anytime soon. “We cannot expect a quantum leap”, notes Stan Whittingham in our Q&A with

him and Kent Snyder. The two interviewees, from academia and industry, highlight that there is a lot of room for improvement, especially in going from cell level to pack level and call for

innovation in both fundamental chemistry and practical implementation in existing LIB technologies. In addition to the Q&A, this Insight covers several important aspects of the

state-of-the-art of EV batteries including battery materials, production processes, safety and market needs. Battery materials are at the heart of battery performance. In their Review,

Tobias Placke, Martin Winter and colleagues present a comprehensive survey of electrodes and electrolytes used in EV batteries. They also discuss the cost and production aspects of battery

materials. Battery safety is a primary concern. In their Perspective, Jie Deng and colleagues at Ford emphasize the importance of combining electrochemical, electrical, mechanical and

thermal behaviours of batteries and propose a framework based on large-scale multi-physics modelling and experimental data to address safety issues of EV batteries. For automotive

applications, batteries come in the form of modules and packs, not the single cells that are often used in research labs. Arno Kwade and colleagues provide an overview of production

technologies for automotive batteries, and discuss the relationships between manufacturing process, product quality and performance, as well as challenges in scale-up processes. Though they

are currently the dominant technology, LIBs are only one of many available technologies for powering EVs. Due to their inherent storage ability limits, safety and cost, it is unlikely that

LIBs will be suitable for all automotive needs. Zhongwei Chen and colleagues analyse the emerging EV markets — categorized into long-range, low-cost and high-utilization transportation

sectors — and discuss the suitability of various technologies, including fuel cells, for different markets. Despite the current small market share, belief in full electrification of the

future automotive industry is growing strong. Though LIB technologies dominate today, it is hard to imagine that the future power system will remain the same as now. In the end, how

significantly EVs will penetrate the market and what technologies will become mainstream in the future largely depends on how much performance advancement and cost reduction a technology can

offer. We hope that this issue offers some insights into how that may play out. REFERENCES * Countries are announcing plans to phase out petrol and diesel cars. Is yours on the list? _World

Economic Forum_ (26 September 2017); https://go.nature.com/2Ge9WnG * China is looking at banning the sale of petrol and diesel cars. _World Economic Forum_ (11 September 2017);

https://go.nature.com/2pJ5FNM * Monthly plug-in sales scorecard. _InsideEVs_ https://insideevs.com/monthly-plug-in-sales-scorecard/ (2017). * An infrastructure for charging electric vehicles

takes shape. _The Economist_ (7 September 2017). * _The History of the Electric Car_ (DOE, 2014); https://energy.gov/articles/history-electric-car * Schmuch, R., Wagner, R., Hörpel, G.,

Placke, T. & Winter, M. _Nat. Energy_ https://doi.org/10.1038/s41560-018-0107-2 (2018). * _Nat. Energy_ 2, 17126 (2017). Download references RIGHTS AND PERMISSIONS Reprints and

permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Reality check. _Nat Energy_ 3, 245 (2018). https://doi.org/10.1038/s41560-018-0143-y Download citation * Published: 12 April 2018 * Issue

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