9:15 AM - EN01.06.04
Advancing Sodium Batteries—Future Material Design and Development
Teofilo Rojo1,2,Nicholas Drewett1,Marina Enterria1,Nagore Ortiz-Vitoriano1,Idoia Ruiz de Larramendi2,Devaraj Shanmukaraj1,Guoxiu Wang3,Montse Galceran1
CIC Energigune1,University of the Basque Country2,University of Technology Sydney3
For modern society, energy storage and distribution are critical, with sodium ion batteries (SIB) potentially filling a critical role as a low-cost technology from earth abundant resources well-positioned to augment - or where suitable replace - lithium ion batteries (LIBs). Thus, SIBs have gained prominence due to strong interest from both research and industry.
Here we explore current state-of-the-art Na-ion batteries in terms of both electrodes. Hard carbon-based materials are currently preferred due to their low cost and operating voltage (and hence high energy density). Meanwhile, the most promising cathodes include sodium manganese-rich layered oxides (with the formula NaxMn1-yMyO2; y ≤ 0.33, M is one or more transition metals, e.g. Ni, Ti, Fe, etc.), due to their potentially attractive physical, electrochemical, and commercial properties. However, these suffer from Jahn–Teller distortion, which may cause loss of capacity and multiple step plateaus. Nevertheless, doping and substitution have been employed to stabilize the structure and/or increase the average Mn oxidation state – resulting in many new materials with improved performances.[3–5] Critically, it has been shown that even small quantities can affect a significant improvement without sacrificing the advantages of these systems.
Given that many of these first-generation technologies are approaching commercialisation, as highlighted in our prototyping and commercialisation section, it is important to consider which future areas of research will best unlock the potential of SIBs.
Improving the power density and rate capability of Na-ion systems has led to interest in nascent Na-ion hybrid capacitors (a coupled supercapacitor- and faradic-type electrode). We will discuss the topic, including remaining challenges (e.g. initial pre-metalation, safety and cost) and the promising development of low-cost hard carbon and high-performance intermetallic electrodes.[6,7]
High energy density, by contrast, is being targeted through advances in Na-air and Na-Sulfur (NaS) systems. Recent work has highlighted the great versatility offered by graphene-based aerogels as air-cathodes, thanks to their low density, high electronic conductivity, and adjustable porosity. From this work, we will examine the specific role of this porosity on both cell capacity and efficiency - which has led to the development of a high-performance cathode, and represents a foundation for future Na-O2 cathode design.
The challenges and advances in ambient-temperature sodium-sulfur (Na-S) batteries will also be presented. This system is a safe alternative to commercialized high-temperature Na-S batteries (working at 300-350 oC), offering high theoretical energy density and low cost. Different optimization approaches, such as applying fluorine-containing electrolyte solvents with redox mediator additives or gel polymer electrolytes, will be highlighted.[9,10]
Meanwhile, safety and cyclability (key factors for any energy storage system) are being addressed by the ongoing development of all solid-state systems, and advances in this area will be discussed briefly.
Through this presentation, we hope to highlight the benefits of sodium-based energy storage systems, provide context for the current state-of-art, and provide insights into the future pathways for development.
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