posted on 2024-02-02, 04:04authored byQing Ji, Weiheng Chen, Xiaoping Chen, Xiaoyan Wang, Qingyu Dong, Shanshan Yin, Yanbin Shen, Peter Müller-Buschbaum, Ya-Jun Cheng, Yonggao Xia
Niobium
pentoxides (Nb2O5) present great
potential as next-generation anode candidates due to exceptional lithium-ion
intercalation kinetics, considerably high capacity, and reasonable
redox potential. Although four phases of Nb2O5 including hexagonal, orthorhombic, tetragonal, and monoclinic polymorphs
show diverse characteristics in electrochemical performance, stable
lifetime, high specific capacity, and fast intercalation properties
cannot be delivered simultaneously with a single phase. Herein, this
issue is addressed by generating a homogeneous mixture of orthorhombic
and monoclinic crystals at the nanoscale. Reversible lithium-ion intercalation/deintercalation
of the monoclinic phase is achieved, and exceptional lithium storage
sites are created at the interface of the two phases. As a result,
electrochemical features of stable lifetime from the orthorhombic
phase and high specific performance from the monoclinic phase are
harmoniously combined. This dual-phase Nb2O5/C nanohybrids deliver as high as 380 mA h g–1 (0.01–3.0
V) and 184 mA h g–1 (1.0–3.0 V) after 200
cycles. The essential principle of property enhancement is further
confirmed through in situ XRD measurements and DFT
calculations. The dual-phase concept can be further applied on electrodes
with multiphases to achieve high electrochemical performance.