High‐Safety Nonaqueous Electrolytes and Interphases for Sodium‐Ion Batteries

Abstract

to peak shift operation since the electric energy output from solar and wind energy is not stable. [1][2][3] Electrochemical energy storage technologies representative of lithium-ion batteries (LIBs) are expected to play a critical role because of their high energy density and energy conversion efficiency. [4,5] Recently, research on sodium-ion batteries (SIBs) has been motivated and expected to be better than lithium-ion batteries for the applications on large-scale energy storage because of their advantages on similarity with LIBs and much lower cost. [6,7] In a typical SIB, two electrodes (cathode and anode) and electrolyte are three necessary internal components, as illustrated in Figure 1a. In general, the electrolytes for SIBs can be classified into liquid nonaqueous electrolyte, aqueous electrolyte, gel polymer electrolyte mainly composed of liquid nonaqueous components, and solid electrolyte (including both inorganic and polymer electrolytes). In comparison with liquid nonaqueous and gel polymer electrolytes, aqueous and solid electrolytes (especially inorganic solid electrolyte) are intrinsically safer, and some reviews have been published recently. [8][9][10] From the cost and compatibilities with manufacturing equipment points of view, the SIBs using the nonaqueous electrolytes are believed to be preferential to those using other electrolytes. A typical electrolyte for SIBs is composed of sodium salts, flammable organic carbonate or ether solvents, and/or some functional additives. In conventional SIBs using nonaqueous electrolyte, as a sole liquid component, the electrolyte can infiltrate every vacant space in the inner of the battery. The electrolyte takes part in the buildup of solid electrolyte interphase (SEI) on the anode surface and cathode electrolyte interphase (CEI) by the electrochemical reactions between the electrolyte and anode/cathode electrodes. Therefore, the electrolyte strongly affects the SEI and CEI interphase properties, and further affects the cell performance and safety characteristics of SIBs.Safety concerns of LIBs have attracted much attention, especially in the electric vehicles (EVs) applications of largescale power batteries. In the energy storage stations, there are hundreds of the high-energy batteries. A safety accident in a large-scale energy storage station could trigger a disastrous consequence with a huge economic loss. Therefore, safety characteristics of SIBs are critical for their applications in the energy storage fields. Similar with the safety concerns of LIBs, [11] the safety of SIBs is also tightly related with active Rapidly developed Na-ion batteries are highly attractive for grid energy storage. Nevertheless, the safety issues of Na-ion batteries are still a bottleneck for large-scale applications. Similar to Li-ion batteries (LIBs), the safety of Na-ion batteries is considered to be tightly associated with the electrolyte and electrode/electrolyte interphase. Although the knowledge obtained from LIBs is helpful, designing safe electrolytes and obtaining ...

Advances in sodium secondary batteries utilizing ionic liquid electrolytes

“…1 Seawater and crust abundances of potential elements for use as charge carriers in secondary batteries and their theoretical gravimetric and volumetric capacities. 31 leveraging knowledge of LIBs, phenomenal progress has been realised in the development of electrode and electrolyte materials for Na secondary batteries, [38][39][40][41][42][43][44][45] which can now achieve comparable, or even better, performance characteristics than LIBs. [46][47][48][49][50] An electrolyte is an indispensable constituent of any battery, transferring and balancing charges in the form of ions between the electrodes.…”

Constructing Safe and Durable High‐Voltage P2 Layered Cathodes for Sodium Ion Batteries Enabled by Molecular Layer Deposition of Alucone

“…[ 26 ] However, electrolyte decomposition at high operating voltages also contributes to capacity decay upon cycling process, which is a major setback in developing high energy SIBs. [ 27 ] Hence, efforts have focused on tailoring electrolyte additives and utilizing ionic liquids or solid‐state electrolytes to enhance the stability of SIBs. [ 28,24 ] However, ionic liquids are costly, and the technical difficulty of solid‐state electrolytes require more detailed investigations to advance these systems.…”

S‐Doped Carbon Fibers Uniformly Embedded with Ultrasmall TiO2 for Na+/Li+ Storage with High Capacity and Long‐Time Stability

“…Since sodium is an abundant, widespread, and low-cost element, researchers have focused their attention on sodium-ion batteries (SIBs). [13] In addition, Na + ( 2.71V Na /Na + E = − ) has a similar redox potential to Li + ( 3.04 V Li /Li E = − + ), and it may become a candidate for the development of new energy sources. [7,14] Nevertheless, the use of sodium as the anode material of SIBs to produce long cycle life batteries remains a major challenge, [15] owing to its large radius (55% larger than that of Li + ).…”