Spontaneous Electrochemical Reconstruction of NiNb2O6@C for High-Rate Lithium-Ion Batteries

Abstract

16 Niobium oxides are widely active in the arena of lithium-ion batteries due to their 17 distinctive structure and rapid charging capability, nevertheless facing the serious 18 challenge from their inherently low electrical conductivity. Herein, a molten salt 19 method is proposed to prepare nickel niobate (NiNb2O6) anode materials for lithium-20 ion batteries, and a carbon coating derived from mesophase pitch is fabricated to 21 construct NiNb2O6@C composites. Importantly, NiNb2O6@C undergoes spontaneous 22 electrochemical reconstruction to generate metallic Ni and amorphous Nb2O5 during 23 the initial charge/discharge cycle. The presence of the outer carbon layer not only serves 24 as a uniform conductive coating to improve the conductivity and thereby deliver 25 superior rate performance, but also effectively inhibits the stripping of Ni 0 to guarantee 26 a great cycling stability. The synergistic effects of the dual conductive interfaces, 27 consisting of the carbon layer and the Mott-Schottky heterojunction between 28 amorphous Nb2O5 and metallic Ni, culminate in exceptional electrochemical 29 performance. Specifically, NiNb2O6@C-10% delivers impressive specific capacity of 30 436.3 mAh g-1 at 0.5 C and conspicuous cycling stability, maintaining 86.3% capacity 31 retention after 800 cycles at 10 C. This work underscores the substantial potential of 32 nickel niobate anode materials in advancing the development of next-generation 33 lithium-ion batteries. 34 35