Surface‐Engineered Black Niobium Oxide@Graphene Nanosheets for High‐Performance Sodium‐/Potassium‐Ion Full Batteries

Abstract

Nanoscale surface‐engineering plays an important role in improving the performance of battery electrodes. Nb2O5 is one typical model anode material with promising high‐rate lithium storage. However, its modest reaction kinetics and low electrical conductivity obstruct the efficient storage of larger ions of sodium or potassium. In this work, partially surface‐amorphized and defect‐rich black niobium oxide@graphene (black Nb2O5−x@rGO) nanosheets are designed to overcome the above Na/K storage problems. The black Nb2O5−x@rGO nanosheets electrodes deliver a high‐rate Na and K storage capacity (123 and 73 mAh g−1, respectively at 3 A g−1) with long‐term cycling stability. Besides, both Na‐ion and K‐ion full batteries based on black Nb2O5−x@rGO nanosheets anodes and vanadate‐based cathodes (Na0.33V2O5 and K0.5V2O5 for Na‐ion and K‐ion full batteries, respectively) demonstrate promising rate and cycling performance. Notably, the K‐ion full battery delivers higher energy and power densities (172 Wh Kg−1 and 430 W Kg−1), comparable to those reported in state‐of‐the‐art K‐ion full batteries, accompanying with a capacity retention of ≈81.3% over 270 cycles. This result on Na‐/K‐ion batteries may pave the way to next‐generation post‐lithium batteries.

Tailored Redox Kinetics, Electronic Structures and Electrode/Electrolyte Interfaces for Fast and High Energy‐Density Potassium‐Organic Battery

“…According to the equation i = k 1 v + k 2 v 1/2 , current response i during CV measurement can be separated into capacitive ( k 1 v ) and diffusion‐controlled ( k 2 v 1/2 ) contributions . As exhibited in Figure c,d and Figure S6 in the Supporting Information, at 0.2 mV s −1 , the capacitive contribution increases along with the interconnecting alkyl chain length.…”

Polymer blend directed anisotropic self-assembly toward mesoporous inorganic bowls and nanosheets

“…Notably, bm-Nb 2 O 5 /C exhibits the highest rate capability among the previously reported metal oxide anodes ( fig. S20A and table S4) (46)(47)(48)(49)(50)(51)(52)(53)(54)(55)(56)(57). After galvanostatic cycles, the specific capacity could be recovered to 201 mA•hour g −1 when the current density was reset to 50 mA g −1 .…”

Optimization Design and Application of Niobium‐Based Materials in Electrochemical Energy Storage

“…[67] In addition, its fast pseudo-capacitive response ensures excellent rate capability, which has been demonstrated in Li/Na batteries. [68][69][70] Therefore, it has the potential to be applied in KIBs. Tang and co-workers [70] first report hierarchical urchin-like Nb 2 O 5 nanomaterial assembled by nanowires as KIB anode, and detailed intercalation-pseudocapacitive behavior of the T-Nb 2 O 5 material was also explored.…”