Triple Conductive Wiring by Electron Doping, Chelation Coating and Electrochemical Conversion in Fluffy Nb₂O₅ Anodes for Fast‐Charging Li‐Ion Batteries

Abstract

High‐rate anode material is the kernel of developing fast‐charging lithium ion batteries (LIBs). T–Nb2O5, well‐known for its “room and pillar” structure and bulk pseudocapacitive effect, is expected to enable the fast lithium (de)intercalation. But this property is still limited by the low electronic conductivity or insufficient wiring manner. Herein, a strategy of triple conductive wiring through electron doping, chelation coating, and electrochemical conversion inside the microsized porous spheres consisting of dendrite‐like T–Nb2O5 primary particles is proposed to achieve the fast‐charging and durable anodes for LIBs. The penetrative implanting of conformal carbon coating (derivative from polydopamine chelate) and NbO domains (induced by excess discharging) reinforces the global supply of electronically conductive wires, apart from those from Co/Mn heteroatom or O vacancy doping. The polydopamine etching on T–Nb2O5 spheres promotes their evolution into fluffy morphology with better electrolyte infiltration. The synergic electron and ion wiring at different scales endow the modified T–Nb2O5 anode with ultralong cycling life (143 mAh g−1 at 1 A g−1 after 8500 cycles) and high‐rate performance (144.1 mAh g−1 at 10.0 A g−1). The permeation of multiple electron wires also enables a high mass loading of T–Nb2O5 (4.5 mg cm−2) with a high areal capacity of 0.668 mAh cm−2 even after 150 cycles.

Modulating the Stoichiometry and Lithium Content to Boost the Electrochemical Performance of Li2ZnTi3O8 via High Valence Nb5+ Dopants

“…[39] The O 1s spectrum can be detected to two peaks of 528.70 and 530.45 eV in Figure 4f, which are due to the lattice oxygen in Ti-O bond and the adsorbed oxygen in Nb-O species. [40,41] In the voltage range of 0.01-3.0 V, the galvanostatic chargedischarge (GCD) curves of LZTO and LZTNO samples at 0.1 C (1 C = 229 mA g −1 ) are tested and shown in Figure 5. All samples have two discharge platforms at about 0.5 and 1.5 V. It was reported that the former is originated both from the intercalation reaction and the pseudocapacitance, while the latter is mainly attributed to the pseudocapacitance.…”

Designing strategies of advanced electrode materials for high-rate rechargeable batteries

“…The coating layer not only strengthens the charge transport pathways, but also shows abundant specific surfaces and provides more reactive active sites. 162…”

Achieving structural stability and enhanced electrochemical performance through Nb-doping into Li- and Mn-rich layered cathode for lithium-ion batteries

“…40 The excellent electrochemical properties of the Nb-based layered oxide mean that the Nb ion is a key element for improving structural and electrochemical properties. 41,42 In addition, recent research has proved that Nb ions are one of the most promising doping elements because they can enhance the structural stability and electrical conductivity of conventional layered cathode materials. [43][44][45][46] Nb doping of Ni-rich layered oxides can reduce the charge-transfer resistance and improve the rate capability.…”