Nb-Based Mixed Oxides As Anodes for Metal-Ion Capacitors: Progress, Challenge, and Perspective

Abstract

To reduce the kinetic imbalance between the anode and cathode electrodes of metal-ion capacitors (MICs), researchers have conducted intensive explorations to develop new anode materials. Niobium-based oxides (NBOs) have been established as typical anodes for MICs. Unfortunately, conventional NBOs can hardly meet the future demands for high-power applications. The niobium-based mixed oxides (NBMOs) formed by doping niobium oxides with other elements (Ti, P, V, Cr, etc.) are drawing immense interest for advanced MICs as competitive anodes. Unlike the conventional layered Nb2O5, NBMOs exhibit diverse structures (Wadsley–Roth phase, tungsten bronze structure, ABO3 perovskite structure, etc.), which renders them appealing merits including enhanced specific capacities, higher electronic/ionic conductivities, etc., for MICs. Even so, there is still extensive room for progress to further improve their electrochemical kinetics. In this Review, we systematically summarize the doping species, crystal structures, charge-storage mechanism, synthesis strategies, and recent contributions/progress of diverse NBMOs for advanced MICs toward advancing the process of practical applications. Besides, the challenges and prospects in the booming field are proposed. The review will guide future purposeful design and controllable synthesis of high-performance anodes for next-generation MICs.

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

“…128 In addition, other niobium-based mixed oxides with higher capacity, such as the Wadsley–Roth shear structure, have also received widespread attention in recent years. 129–131 For providing some valuable guidance for researchers in the field of fast-charging electrodes, we summarized the structures, properties, and lithium storage mechanisms of various NBOs as follows. In addition, we also summarized and commented on typical strategies to enhance the lithium storage properties of NBOs.…”

“…Depending on the types and proportions of the introduced metal elements, the crystal structures of NBMO can be classified into the Wadsley–Roth shear structure, the tungsten bronze structure, and the perovskite structure. 131 In particular, the NBMOs with a Wadsley–Roth shear structure have the most expansive lithium ion diffusion pathway and stable crystal structure, exhibit higher potential to the fast-charging application, and thus have gained wide attention. 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 .…”

Archetypical 2D sheet-like Cu2MoS4 for all-solid-state symmetric pseudocapacitors with ultra-steady performance efficiency

“…[7][8][9] However, the unsatisfactory energy density (lower than that of conventional batteries) of pseudocapacitors hinders their potential integration in ultra-efficient electronic architectures. 10,11 Based on the conguration (i.e., characteristics of electrode materials) of electrodes, a typical symmetric pseudocapacitor possess the same material in its positive and negative electrodes, which is advantageous, given that this conguration leads to extremely low electrode-electrode charge transfer resistance. 12 Further, the presence of the same material in the positive and negative electrodes of a symmetric pseudocapacitor offers rich electromicrostructural compatibility between the electrodes for charge transfer.…”

PEDOT Nanowires Connecting Exfoliated HNb3O8 Nanosheets as High-Rate Anode for Lithium-Ion Capacitor

“…Niobium-based oxides are considered as promising anodes materials for LICs because they have the inherent features of open tunnel-like structure, suitable discharge plateau and reversible redox couples (Nb 5+ /Nb 4+ and Nb 4+ /Nb 3+ ). − Although the representative Nb 2 O 5 has been extensively investigated and exhibits excellent electrochemical properties, it stores limited energy in view of its low theoretical capacity (∼200 mAh g –1 ). On the other hand, with higher specific capacity, rich redox reactions, and unique crystal structures, niobium-based compounds have attracted increasing attention in recent years. , For instance, the KNb 3 O 8 supported on the carbon substrate exhibits a large specific capacity of 271 mAh g –1 (0.01 A g –1 ) and a safe discharge voltage plateau (1.2 V vs Li + /Li) .…”