Sodium‐rich NASICON‐structured cathodes for boosting the energy density and lifespan of sodium‐free‐anode sodium metal batteries

Abstract

Rechargeable sodium metal batteries (SMBs) have emerged as promising alternatives to commercial Li-ion batteries because of the natural abundance and low cost of sodium resources. However, the overuse of metallic sodium in conventional SMBs limits their energy densities and leads to severe safety concerns. Herein, we propose a sodium-free-anode SMB (SFA-SMB) configuration consisting of a sodium-rich Na superionic conductor-structured cathode and a bare Al/C current collector to address the above challenges. Sodiated Na 3 V 2 (PO 4 ) 3 in the form of Na 5 V 2 (PO 4 ) 3 was investigated as a cathode to provide a stable and controllable sodium source in the SFA-SMB. It provides not only remarkable Coulombic efficiencies of Na plating/stripping cycles but also a highly reversible three-electron redox reaction within 1.0-3.8 V versus Na/ Na + confirmed by structural/electrochemical measurements. Consequently, an ultrahigh energy density of 400 Wh kg À1 was achieved for the SFA-SMB with fast Na storage kinetics and impressive capacity retention of 93% after 130 cycles. A narrowed voltage window (3.0-3.8 V vs. Na/Na + ) further increased the lifespan to over 300 cycles with a high retained specific energy of 320 Wh kg À1 . Therefore, the proposed SFA-SMB configuration opens a new

Engineering current collectors for advanced alkali metal anodes: A review and perspective

“…They own ultrahigh theoretical capacities of 3860, 1166, and 685 mAh g −1 and low redox potentials of −3.040, −2.714, and − 2.930 V vs. standard hydrogen electrode (SHE) for Li, Na, and K, respectively 4 . Despite the inferior electrochemical potential and specific capacity of Na and K to those of Li, the natural abundance, wide distribution, and low cost of Na and K resources make them great promising anodes for large‐scale energy storage 5,6 …”

“…4 Despite the inferior electrochemical potential and specific capacity of Na and K to those of Li, the natural abundance, wide distribution, and low cost of Na and K resources make them great promising anodes for large-scale energy storage. 5,6 Currently, the practical applications of alkali metal batteries (AMBs) are still hindered by their short cycle lives and severe safety issue. Alkali metals are highly reactive with the components in liquid electrolytes and would form solid electrolyte interphase (SEI) on the metal anode surface.…”

Na+-Activation Engineering in the Na3V2(PO4)3 Cathode with Boosting Kinetics for Fast-Charging Na-Ion Batteries

“…With the larger radius, the deintercalation of Na + ions results in more serious structural distortion during the charging and discharging process. − Therefore, it is important to seek stable electrode materials for improving the electrochemical properties of NIBs. Among the available electrode materials, polyanionic phosphates possessing high working voltage and excellent structural stability have offered the possibility of high-power NIBs for their robust three-dimensional structure framework, especially for the sodium superionic conductor (NASICON) compounds. − As the representative NASICON-type cathode, Na 3 V 2 (PO 4 ) 3 (NVP) exhibits flat/stable redox plateaus (3.4 V) and rich diffusion channels for Na + -ion migration with a theoretical specific capacity of 118 mA h g –1 , showing a wide application prospect for the rechargeable energy storage system. − However, the intrinsic low electronic conductivity originating from the high covalency retards the effective development of electrochemical reaction, leading to low-rate capacity and poor cycling stability.…”

Uniform Lithium Deposition Induced by ZnFx(OH)y for High-Performance Sulfurized Polyacrylonitrile-Based Lithium-Sulfur Batteries

“…However, the current commercial LIB cathode and anode materials are approaching their capacity limit and it is quite difficult to achieve further improvement. With the rapid development of electric vehicles and portable electronics, the large-scale development of LIBs is constrained, so the demand for high-density energy storage systems is increasingly urgent [ 3 , 4 ]. Lithium metal anodes (LMAs) have attracted extensive research attention because of their ultra-high specific capacity (3860 mAh g −1 ) and ultra-low electrochemical potential (−3.04 V vs. standard hydrogen electrode) [ 5 , 6 ].…”