Enabling intercalation‐type TiNb₂₄O₆₂ anode for sodium‐ and potassium‐ion batteries via a synergetic strategy of oxygen vacancy and carbon incorporation

Abstract

The key to develop earth-abundant energy storage technologies sodium-and potassium-ion batteries (SIBs and PIBs) is to identify low-cost electrode materials that allow fast and reversible Na + /K + intercalation. Here, we report an intercalation-type material TiNb 24 O 62 as a versatile anode for SIBs and PIBs, via a synergistic strategy of oxygen vacancy and carbon incorporation to enhance ion and electron diffusion. The TiNb 24 O 62−x /reduced graphene oxide (rGO) composite anode delivers high reversible capacities (130 mA h g −1 for SIBs and 178 mA h g −1 for PIBs), great rate performance (54 mA h g −1 for SIBs and 37 mA h g −1 for PIBs at 1 A g −1 ), and superior cycle stability (73.7% after 500 cycles for SIBs and 84% after 300 cycles for PIBs). The performance is among the best results of intercalation-type metal oxide anodes for SIBs and PIBs. The better performance of TiNb 24 O 62−x /rGO in SIBs than PIBs is due to the better reaction kinetics of the former. Moreover, mechanistic study confirms that the redox activity of Nb 4+ / 5+ is responsible for the reversible intercalation of Na + /K + . Our results suggest that TiNb 24 O 62−x /rGO is a promising anode for SIBs and PIBs and may stimulate further research on intercalation-type compounds as candidate anodes for large ion batteries.

Layered Potassium Titanium Niobate/Reduced Graphene Oxide Nanocomposite as a Potassium-Ion Battery Anode

“…Only after the plateau does the Nb significantly oxidise. Finally, full charging to 3 V still resulting in the contributions from Ti 3+ and Nb 4+ indicating that not all the intercalated K + is able to de-intercalate, with this partial irreversibility being previously reported [ 19 , 22 , 34 ]. This is likely a contributor of the discrepancy between the theoretical capacity and the observed capacity, as a partial re-oxidation will leave K + remaining in the structure, rendering it electrochemically inactive.…”

“…With increasing the current density, KTNO/rGO-12 achieved a reversible charge capacity of 94.8 mAh g −1 at 100 mA g −1 and 54.2 mAh g −1 at 1 A g −1 , amongst the highest reported rate performance in the KIB intercalation anode literature (Fig. 4 a, b) [ 22 , 58 ]. When comparing the pristine material to the nanocomposite, the addition of rGO clearly improved the rate performance, as charge capacity for KTNO dropped by 75%, from 66.7 mAh g −1 at 20 mA g −1 to 10.5 mAh g −1 at 1 A g −1 , although still showing good rate performance when compared to previous reports [ 20 , 53 ].…”

Fast-charging anodes for lithium ion batteries: progress and challenges

“…142,143 To date, the lithium storage performance of many NBMOs with Wadley-Roth shear structures has been explored, such as TiNb 2 O 7 , TiNb 24 O 62 , Cu 2 Nb 34 O 87 , AlNb 11 O 29 and VNb 9 O 25 . [144][145][146][147][148] Among them, Ti x Nb y O z usually exhibits the highest theoretical capacity, the fastest ion diffusion and the longest cycle life. 149,150 In the following, the structural features and lithium storage mechanism of Wadsley-Roth shear structure NBMOs are introduced, taking the most classical TiNb 2 O 7 as an example.…”

Enhancing reversible Na-ion intercalation by introducing K-ions into layered vanadyl phosphate for sodium-ion battery cathodes

“…Utilizing the knowledge gained from our and other groups' exploration of materials for potassium-ion batteries (PIBs) [23][24][25][26][27][28][29][30][31], K-containing layer-structured materials exhibit reversible K intercalation due to the larger interlayer spacings compared to their Na-containing counterparts, but they are usually formed with a lower K + content [32]. This is likely due to the strong K + -K + repulsion in the interlayer space and consequently, not every site in the interlayer space can be occupied by the large sized K + [33].…”