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.

由于锂资源的可用性有限和随之而来的预期价格上涨，对锂资源可持续性的担忧日益增加，这提高了人们对开发能够维持不断增长的能源需求的替代能源存储候选者的重要性的认识。此外，用于制造正极材料的过渡金属的可用性限制，以及可疑的采矿实践，正在推动向更可持续的元素发展。鉴于钠的高丰度和成本效益，以及非常合适的氧化还原电位（接近锂的），钠离子电池技术具有巨大的潜力，可以在不同的领域与锂离子电池（LIBs）相媲美。应用场景，如固定式储能和低成本汽车。这种潜力体现在行业对各种市场和各种材料组合进行的重大投资上。尽管作为 LIB 的替代品具有相关优势，但钠和锂之间的物理化学性质存在显着差异，从而导致不同的行为，例如，化合物中不同的配位偏好、去溶剂化能或固体的溶解度-电解质界面无机盐成分。这需要对钠离子电池中发生的潜在物理和化学过程进行更详细的研究，并为该领域的突破性进展提供了广阔的空间，从实验室规模到扩大规模。该路线图由学术界和工业界的专家对 2021 年的当前技术水平以及目前为提高钠离子电池性能而进行的不同研究方向和策略进行了广泛审查。目的是就当前的挑战和机遇提供意见，从该技术的基本特性到实际应用。