Challenges and Opportunities for 2D Materials in Energy Storage Technologies
Authors: Hersam Mark C 
Published: August 2024

Efficient energy storage systems represent a critical technology across many sectors including consumer electronics, electrified transportation, and a smart grid accommodating intermittent renewable energy sources. Arguably, the most important advance in energy storage over the past three decades is the lithium-ion battery, which was recognized with the Nobel Prize in Chemistry. However, despite its many successes, issues related to safety, energy density, charging time, and operating temperature range have hindered the realization of the full potential of lithium-ion battery technology, particularly in large-scale applications such as grid-level storage and full electrification of transportation networks. Nanostructured materials were once thought to present compelling opportunities for next-generation lithium-ion batteries, but inherent problems related to high surface area to volume ratios at the nanometer-scale (e.g., undesirable surface chemical interactions between electrodes and electrolytes) have impeded their adoption for commercial applications. This talk will explore how chemically inert two-dimensional (2D) materials are driving a resurgence in nanostructured lithium-ion battery materials [1,2]. For example, conformal graphene coatings on battery anode and cathode powders mitigate surface degradation and minimize the formation of the solid electrolyte interphase, thus improving cycling stability [3,4]. In addition, the high electrical conductivity of graphene reduces cell impedance, resulting in enhanced kinetics that enable high-rate capability and low-temperature performance down to –20 °C [5]. On the other hand, ionogel electrolytes based on ionic liquids and hexagonal boron nitride (hBN) nanoplatelets provide safe, high-rate operation at high temperatures up to 175 °C, which represents the highest operating temperature to date for solid-state lithium-ion batteries [6,7]. The strong interfacial interactions between hBN and ionic liquids further enable novel electrolyte architectures based on layered heterostructure ionogels that result in unprecedently high energy densities and rate performance for solid-state batteries [8]. Since hBN ionogels can be formulated into printable inks and slurries, these electrolytes also present promising opportunities for additive manufacturing of solid-state batteries, supercapacitors, and related energy storage technologies [9-11].
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