An Aqueous Symmetric Sodium‐Ion Battery with NASICON‐Structured Na₃MnTi(PO₄)₃

Abstract

As ymmetric sodium-ion battery with an aqueous electrolyte is demonstrated;i tu tilizes the NASICON-structured Na 3 MnTi(PO 4 ) 3 as both the anode and the cathode.The NASICON-structured Na 3 MnTi(PO 4 ) 3 possesses two electrochemically active transition metals with the redoxc ouples of Ti 4+ /Ti 3+ and Mn 3+ /Mn 2+ working on the anode and cathode sides,r espectively.T he symmetric cell based on this bipolar electrode material exhibits aw ell-defined voltage plateau centered at about 1.4 Vi na na queous electrolyte with as table cycle performance and superior rate capability.T he advent of aqueous symmetric sodium-ion battery with high safety and low cost may provide as olution for large-scale stationary energy storage.

Realizing Three‐Electron Redox Reactions in NASICON‐Structured Na3MnTi(PO4)3 for Sodium‐Ion Batteries

“…Such a hollow structure with thin shell thickness would short the Na + diffusion distance when applied in SIBs. [21,22] The high-angle annular dark-field scanning TEM (HAADF-STEM) image further confirms the hollow microspherical structure of NMTP/C-650 ( Figure 2e). [21,22] The high-angle annular dark-field scanning TEM (HAADF-STEM) image further confirms the hollow microspherical structure of NMTP/C-650 ( Figure 2e).…”

Three Electron Reversible Redox Reaction in Sodium Vanadium Chromium Phosphate as a High‐Energy‐Density Cathode for Sodium‐Ion Batteries

“…Na 3 V 2 (PO 4 ) 3 is a typical NASICON‐structured cathode material; it has a theoretical specific capacity of 117 mAh g −1 with a potential plateau around 3.5 V versus Na/Na + . To date, several phosphates have been successfully synthesized based on cation substitution to increase energy and power densities, including Na 3 MnV(PO 4 ) 3 , Na 3 MnTi(PO 4 ) 3 , Na 3 MnZr(PO 4 ) 3 , and Na 2 VTi(PO 4 ) 3 . It is worth noting that the electrons participating in the electrochemical reactions for most of these reported NASICON‐structured electrodes is restricted to ≤2 per formula unit.…”

“…To date, several phosphates have been successfully synthesized based on cation substitution to increase energy and power densities, including Na 3 MnV(PO 4 ) 3 , Na 3 MnTi(PO 4 ) 3 , Na 3 MnZr(PO 4 ) 3 , and Na 2 VTi(PO 4 ) 3 . [10][11][12][13][14][15][16][17][18] It is worth noting that the electrons participating in the electrochemical reactions for most of these reported NASICONstructured electrodes is restricted to ≤2 per formula unit. Thus the development of an NASICONstructured cathode with more than two electron redox reactions and excellent cycling stability is of great interest.…”

A Dual‐Ion Organic Symmetric Battery Constructed from Phenazine‐Based Artificial Bipolar Molecules

“…Such cell architectures involve two different electrodes,which require aseparate fabrication process and composition optimization. [14][15][16][17][18][19][20] Due to the relatively narrow potential difference among the Fermi-energy level of these transition-metal redox couples, the demonstrated symmetric cells typically exhibit relatively low specific capacity (< 100 mA hg À1 )a nd/or low discharge voltage (< 2V)inmost cases (Table S1, Supporting Information). As an additional benefit, the inactive salt in the electrolyte can act as adual-ion charge carrier inside the cell and it is unnecessary for the bipolar organic material to be accompanied by cation/anion pre-insertion, which makes the cell ready-to-charge.…”

“…[12,13] Until now,m ost reported symmetric cells,h owever, are based on inorganic materials,g enerally employing binary transition-metal oxides with multiple valence states. [14][15][16][17][18][19][20] Due to the relatively narrow potential difference among the Fermi-energy level of these transition-metal redox couples, the demonstrated symmetric cells typically exhibit relatively low specific capacity (< 100 mA hg À1 )a nd/or low discharge voltage (< 2V)inmost cases (Table S1, Supporting Information). As aconsequence,the practical energy density of afully symmetric cell hardly meets the aim of > 100 Wh kg À1 for large batteries, [21] and the low discharge voltage makes the battery-pack design too complex to meet industrial specifications.…”