Sodium Dual‐Ion Batteries with Concentrated Electrolytes

Abstract

Na‐based dual‐ion batteries (DIBs) are a class of post‐lithium technology with advantages including extremely fast charging, cost‐effectiveness, and high natural abundance of raw materials. Operating up to high voltages (≈5.0 V), the decomposition of classic carbonate‐based electrolyte formulations and the subsequent fade of capacity continues to be a major drawback in the development of these systems. Here, the performance of a Na‐DIB was investigated in different commonly employed electrolyte system, and a highly concentrated (3 m NaPF6) and fluorine‐rich carbonate‐based formulation was optimized to achieve a good performance when compared with literature (based on energy and power density, calculated at coin cell and only using the active mass of active materials).

Optimization Strategies Toward Functional Sodium‐Ion Batteries

“…This was ascertained through concentration optimization of sodium hexafluorophosphate (NaPF 6 ) in EMC/PC (1:1) and 10 vol.% fluoroethylene carbonate (FEC). [ 92 ] This thin layer allows rapid diffusion kinetics and therefore unaffected ion migration under various current densities. With 3 m NaPF 6 electrolyte, carbon fiber mat anode, and graphite cathode, the as‐assembled cell showed a power density of 6494 W kg −1 at 269 Wh kg −1 at a high current density of 1.6 A g −1 .…”

“…With 3 m NaPF 6 electrolyte, carbon fiber mat anode, and graphite cathode, the as‐assembled cell showed a power density of 6494 W kg −1 at 269 Wh kg −1 at a high current density of 1.6 A g −1 . [ 92 ]…”

“…With 3 M NaPF 6 electrolyte, carbon fiber mat anode, and graphite cathode, the as-assembled cell showed a power density of 6494 W kg −1 at 269 Wh kg −1 at a high current density of 1.6 A g −1 . [92] Yan Jin et al reported an advanced highly concentrated electrolyte using sodium bis(fluorosulfonyl)imide (NaFSI) salt in TEP for highvoltage SIBs. The full cell based on hard carbon anode and NaNi 0.68 Mn 0.22 Co 0.10 O 2 cathode showed a high capacity retention of 83.5% after 200 cycles (at 0.2 C) because of the stability of CEI (cathode electrolyte interphase) and SEI layers.…”

Sustainable Dual‐Ion Batteries beyond Li

“…Among various electrode options, Na-metal anode is undoubtedly considered the "holy grail" for SIBs due to their exceptional combination of a high theoretical specific capacity [55] Copyright 2022, The Authors, published by Wiley-VCH. b) Transmission electron microscopy (TEM) images of graphite cathodes obtained from Na/0.5 m NaPF 6 -PC:EMC/graphite cells after a 48 h charging period.…”

Insight into the Role of Fluoroethylene Carbonate on the Stability of Sb||Graphite Dual‐Ion Batteries in Propylene Carbonate‐Based Electrolyte

“…[6] Specifically, the electrolyte directly determines the formation of electrodeelectrolyte interphase (EEI) and the transfer process of cations and anions between liquid and solid phases. [7] Until now, the research on electrolyte of dual ion batteries is still in the primary stage and several strategies such as highly concentrated electrolytes (HCEs), [8] ionic liquid electrolytes (ILs), [9] gel polymer electrolytes (GPEs) [10] and fluorinated electrolyte [11] have been proposed. However, HCEs and ILs are not cost-effective, and the high viscosity of these electrolytes, leads to under-utilization of the full battery performance.…”