Promises and challenges of nanomaterials for lithium-based rechargeable batteries

1 Energy storage is an essential element of the complete landscape of energy processes, closely coupled with energy generation, transmission and usage. Development of lithium-based rechargeable batteries with higher energy density, lower costs and improved safety is highly desirable1–3. Over the past 25 years, lithiumion batteries based on conventional intercalation electrode materials have played a critical role in enabling the widespread availability of consumer electronics and emergence of electrical transportation; however, intercalation-type electrode materials will reach their performance limit in the near future4. Significant advancements in battery performance and reductions in cost are expected to come from new battery chemistries, based on different storage mechanisms at the materials level, and different configurations at the cell and system level5–7. Among them, alloy-type Si8–10, Sn11, P12,13 and Al14 anodes, platingand stripping-type lithium metal anodes15,16, conversion-type transition metal oxides/sulfides/ fluorides/phosphides/nitrides17–22, and S (Li–S batteries)23–27 and O2 (Li–air batteries)28–30 cathodes are some recent examples demonstrating great promise and broad research interest. While these new electrode materials offer much higher lithium storage capacity, their reaction mechanisms with lithium are significantly different from those of conventional electrodes, resulting in many challenges across multiple length scales, such as: complete destruction of crystal structure; chemical bond breaking/reformation and significant shuffling of host material atoms and molecules; colossal volume change at the particle level; volume change at the electrode and cell level; low electronic conductivity and solid-state lithium diffusivity; and instability of the electrode–electrolyte interface. As such, these problems proved difficult to solve until nanotechnology enabled a materials design paradigm shift from that of conventional battery materials. The emergence and development of nanotechnology in the past three decades has provided new methods and tools to design battery materials on the nanoscale31–36. Since the pioneering study of Si nanowires as a battery anode in 20088, an exciting research field to exploit nanomaterials design for battery electrodes has emerged to overcome the problems associated with new battery chemistries. A deep understanding of these nano structured electrode materials has also been obtained, based on advanced nanocharacterization techniques. Promises and challenges of nanomaterials for lithium-based rechargeable batteries