A Nonstoichiometric Niobium Oxide/Graphite Composite for Fast‐Charge Lithium‐Ion Batteries
Tongtong Li, Kuan-Ting Liu, Gyutae Nam, Min Gyu Kim, Yong Ding, Bote Zhao, Zheyu Luo, Zirui Wang, Weilin Zhang, Chenxi Zhao, Jeng‐Han Wang, Yan‐Yan Song, Meilin Liu
Abstract
Abstract Electrification of transportation has spurred the development of fast‐charge energy storage devices. High‐power lithium‐ion batteries require electrode materials that can store lithium quickly and reversibly. Herein, the design and construction of a Nb 2 O 5−δ /graphite composite electrode that demonstrates remarkable rate capability and durability are reported. The presence of graphite enables the formation of a dominant Nb 12 O 29 phase and a minor T‐Nb 2 O 5 phase. The high rate capability is attributed to the enhanced electronic conductivity and lower energy barriers for fast lithium diffusion in both Nb 12 O 29 and T‐Nb 2 O 5 , as unraveled by density functional theory calculations. The excellent durability or long cycling life is originated from the coherent redox behavior of Nb ions and high reversibility of lithium intercalation/deintercalation, as revealed by operando X‐ray absorption spectroscopy analysis. When tested in a half‐cell at high cycling rates, the composite electrode delivers a specific capability of 120 mAh g –1 at 80 C and retains over 150 mAh g –1 after 2000 cycles at 30 C, implying that it is a highly promising anode material for fast‐charging lithium‐ion batteries.