GO-induced preparation of flake-shaped Na₃V₂(PO₄)₃@rGO as high-rate and long-life cathodes for sodium-ion batteries

Abstract

Flake-shaped Na3V2(PO4)3@rGO induced by GO is proposed to improve Na+ and electron transfer of Na3V2(PO4)3 as high-rate and long-life cathodes for sodium-ion batteries.

Designed One‐Pot Strategy for Dual‐Carbon‐Protected Na3V2(PO4)3 Hybrid Structure as High‐Rate and Ultrastable Cathode for Sodium‐Ion Batteries

“…It is therefore highly desired to develop af acile one-pot strategy to synthesize high quality NVP-carbon nanohybrids;2 )Simple carbon coating of NVP nanoparticles can indeed optimize the cycling stability and rate performance to some extent, while the high rate cycling life is still unsatisfactory due to the high polarization and sluggishk inetics. [20,32,40] The intensity ratios of I D /I G are 0.983, 0.979 and0 .972 for NVP@C, NVP@C-300 and NVP@C&C, respectively,i ndicating as light higherg raphitization degree of the carbon matrix.In order to verify the effect of the dual carbon protected hybrid structure,t he electrochemical performance of NVP@C&Cw as then investigated as ac athode for SIBs. Specifically, the NVP@C&Cc athode can deliver an outstanding rate performance withacapacity retention rate of 51.5 %w ith the rate ranging from 0.5 to 100 C( 46.1 mAh À1 g À1 at 100 C) and ultralong cycling stability of 80.86 %c apacity retention after 6000 cycles at the high rate of 20 C, when evaluated as ac athode for SIBs.…”

“…Besides, the XRD patterns of NVP@C and NVP@C-300 (Figure S3, Supporting Information) confirmt he formation of Na 3 V 2 (PO4) 3 phase. [20,32,40] The intensity ratios of I D /I G are 0.983, 0.979 and0 .972 for NVP@C, NVP@C-300 and NVP@C&C, respectively,i ndicating as light higherg raphitization degree of the carbon matrix. [20,32,40] The intensity ratios of I D /I G are 0.983, 0.979 and0 .972 for NVP@C, NVP@C-300 and NVP@C&C, respectively,i ndicating as light higherg raphitization degree of the carbon matrix.…”

“…Importantly,t he HRTEMa nalysis (Figure 2i) disclosed that there was an extra thin layer of carbon coating on the surfaceo fe ach NVP nanoparticle, besides the whole carbon matrix, to form the dual-carbon protected hierarchical NVP hybrid structure. [20,32,40] The intensity ratios of I D /I G are 0.983, 0.979 and0 .972 for NVP@C, NVP@C-300 and NVP@C&C, respectively,i ndicating as light higherg raphitization degree of the carbon matrix. The elemental mapping results ( Figure 3) can illustrate the uniform distribution Na, V, P, Oa nd Ce lements and the overall image could also indicatet he carbon matrix with well encapsulatedN VP,w hich is consistent with TEM results.I ti sw orth mentioning that the addition of glucose during the hydrothermal process was necessary to ensure the formation of hierarchical carbon matrix to protect the active NVP nanoparticles, through the comparative observation of the productso btainedw ith different amountso fg lucose ( Figure S2, Supporting Information), which could be critical to achieve largely enhanced electrochemical performance.…”

“…[11] Therefore, it is always imperative to exploit high performance electrode materials with excellentr ate performance and cycling stability forS IBs, in order to meet the requiremento fc ommercialization. [22,25,[31][32][33][34][35][36][37][38][39] For example,S ong et al [24] reported the synthesis of thin-layer graphene-encapsulated NVP nanoparticles with about 100 nm, whiche xhibited optimized rate performance with discharge capacityo f7 0.1 mAh À1 g À1 at 30 Ca nd enhanced cyclings tability with about 86.0 %c apacity retention at 5Cafter 300 cycles. [13,14] Among variousc athode candidates, such as sodium-based layered metalo xides, [15,16] phosphates, [17,18] andP russian blue analogs (PBAs), [19] NASICON-type Na 3 V 2 (PO 4 ) 3 (denoted as NVP) has been considered as ap romising candidate because of the high theoretical specific capacity,e xcellent thermala nd structural stability.…”

“…[13,14] Among variousc athode candidates, such as sodium-based layered metalo xides, [15,16] phosphates, [17,18] andP russian blue analogs (PBAs), [19] NASICON-type Na 3 V 2 (PO 4 ) 3 (denoted as NVP) has been considered as ap romising candidate because of the high theoretical specific capacity,e xcellent thermala nd structural stability. [22,25,[31][32][33][34][35][36][37][38][39] For example,S ong et al [24] reported the synthesis of thin-layer graphene-encapsulated NVP nanoparticles with about 100 nm, whiche xhibited optimized rate performance with discharge capacityo f7 0.1 mAh À1 g À1 at 30 Ca nd enhanced cyclings tability with about 86.0 %c apacity retention at 5Cafter 300 cycles. [28][29][30] However,t he intrinsicl ow electronic conductivity results in poor rate performance and unsatisfactory cycle life, whichs eriously impedes its practical application.…”