2021 roadmap for sodium-ion batteries

Abstract

Increasing concerns regarding the sustainability of lithium sources, due to their limited availability and consequent expected price increase, have raised awareness of the importance of developing alternative energy-storage candidates that can sustain the ever-growing energy demand. Furthermore, limitations on the availability of the transition metals used in the manufacturing of cathode materials, together with questionable mining practices, are driving development towards more sustainable elements. Given the uniformly high abundance and cost-effectiveness of sodium, as well as its very suitable redox potential (close to that of lithium), sodium-ion battery technology offers tremendous potential to be a counterpart to lithium-ion batteries (LIBs) in different application scenarios, such as stationary energy storage and low-cost vehicles. This potential is reflected by the major investments that are being made by industry in a wide variety of markets and in diverse material combinations. Despite the associated advantages of being a drop-in replacement for LIBs, there are remarkable differences in the physicochemical properties between sodium and lithium that give rise to different behaviours, for example, different coordination preferences in compounds, desolvation energies, or solubility of the solid–electrolyte interphase inorganic salt components. This demands a more detailed study of the underlying physical and chemical processes occurring in sodium-ion batteries and allows great scope for groundbreaking advances in the field, from lab-scale to scale-up. This roadmap provides an extensive review by experts in academia and industry of the current state of the art in 2021 and the different research directions and strategies currently underway to improve the performance of sodium-ion batteries. The aim is to provide an opinion with respect to the current challenges and opportunities, from the fundamental properties to the practical applications of this technology.

Enhanced Cycling Stability in the Anion Redox Material P3‐Type Zn‐Substituted Sodium Manganese Oxide

“…[6] The possibility of obtaining additional capacity in Mn-based materials originating from oxygen redox chemistry has attracted considerable attention. [4,7] For example Na 4/7 [& 1/ 7 Mn 6/7 ]O 2 (where & represents a transition metal vacancy), contains Mn vacancies and therefore O 2p nonbonding orbitals which enable reversible oxygen redox. [7] Upon cycling Na 4/7 [& 1/ 7 Mn 6/7 ]O 2 , its layered structure and P3-type oxygen stacking sequence (ABBCCA) are maintained.…”

Investigation of Valence Mixing in Sodium-Ion Battery Cathode Material Prussian White by Mössbauer Spectroscopy

“…However, achieving this capacity is extremely difficult due to the presence of [Fe(CN) 6 ] n− vacancies (Hurlbutt et al, 2018). Furthermore, the presence of severe phase transitions which damage the structure during operation in a battery is strongly dependent on the A + cation and [M′(CN) 6 ] n− vacancy content (Rudola et al, 2017;Tapia-Ruiz et al, 2021;Boström and Brant 2022). Despite the importance of PBAs, their accurate and consistent compositions are rarely reported.…”

Na2.4Al0.4Mn2.6O7 anionic redox cathode material for sodium-ion batteries – a combined experimental and theoretical approach to elucidate its charge storage mechanism

“…Moreover, the chemical similarities of Li and Na coupled with the already well-established knowledge in lithium-ion battery (LIB) technology allow for rapid implementation of SIBs in applications such as the grid or low-cost transportation. 1,2 Among the cathode materials researched in the field of SIBs, layered Na–Mn–O ternary compounds have been particularly relevant due to their high capacity, abundance, non-toxicity and low cost. The Na x MnO 2 ( x > 0.5) composition has been the most studied, showing a maximum theoretical capacity of 244 mA h g −1 based on the Mn 3+/4+ redox-active couple.…”