Sodium vanadium titanium phosphate electrode for symmetric sodium-ion batteries with high power and long lifespan

Abstract

Sodium-ion batteries operating at ambient temperature hold great promise for use in grid energy storage owing to their significant cost advantages. However, challenges remain in the development of suitable electrode materials to enable long lifespan and high rate capability. Here we report a sodium super-ionic conductor structured electrode, sodium vanadium titanium phosphate, which delivers a high specific capacity of 147 mA h g−1 at a rate of 0.1 C and excellent capacity retentions at high rates. A symmetric sodium-ion full cell demonstrates a superior rate capability with a specific capacity of about 49 mA h g−1 at 20 C rate and ultralong lifetime over 10,000 cycles. Furthermore, in situ synchrotron diffraction and X-ray absorption spectroscopy measurement are carried out to unravel the underlying sodium storage mechanism and charge compensation behaviour. Our results suggest the potential application of symmetric batteries for electrochemical energy storage given the superior rate capability and long cycle life.

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.…”

Rational Architecture Design Enables Superior Na Storage in Greener NASICON‐Na4MnV(PO4)3 Cathode

“…Although the layered transition-metal oxide materials normally exhibit high theoretical capacity, they suffer from structural instability and unsatisfactory cycle-life. [14][15][16][17][18] Among diverse NASICON-structured compounds, Na 3 V 2 (PO 4 ) 3 is a hotspot, which can deliver a highly reversible capacity over 110 mAh g −1 , and an energy density of over 370 Wh kg −1 as a result of a flat voltage plateau located at 3.3-3.4 V. [19] Although massive work has been reported to promote the development of Na 3 V 2 (PO 4 ) 3 by nanosizing and/or optimizing its poor electronic conductivity, [20][21][22][23] in order to meet the demand of practical applications of Na 3 V 2 (PO 4 ) 3 , improving its operating voltage to reach a higher energy density is urgent. [8][9][10] In this context, great attention has been paid on the polyanion-type materials due to their robust crystal framework with high-level thermal stability, and the moderate capacity with tunable high redox potential, which can achieve high energy density.…”

Towards High‐Performance Aqueous Sodium‐Ion Batteries: Stabilizing the Solid/Liquid Interface for NASICON‐Type Na2VTi(PO4)3 using Concentrated Electrolytes

“…[29] In at ypical synthesis, CH 3 COONa·3H 2 O( 0.02 mol;V WR, ! [29] In at ypical synthesis, CH 3 COONa·3H 2 O( 0.02 mol;V WR, !…”

“…[18,19] On the other hand, pristine Na 3 V 2 (PO 4 ) 3 suffers from structural degradationi na queous electrolytes within af ew cycles. [29] In addition, the NVTP electrode was also used in as ymmetric, aqueous Na-ion battery with an output voltage of approximately 1.2 Vi nc onventional 1 m Na 2 SO 4 aqueous electrolyte. [20][21][22][23][24][25] In consequence,a mphoteric insertion hosts that can be used as cathode and anode materials are being developed.…”