Towards excellent electrical conductivity and high-rate capability: A degenerate superlattice Ni3(S)1.1(S2)0.9 micropyramids electrode
作者:Yuanhao Gao、Wensong Zhou、Wei Li、Tuo Cai、Yan Lei、Helin Niu、Pinjiang Li、Hongwei Yue、Zhongjun Li
DOI:10.1016/j.jallcom.2020.155590
日期:2020.12
Degenerate semiconductor is very highly desired in energy conversion and storage technologies due to its metal-like conduction behaviors. This is the first time the doping S-2 in Ni3S2 lattice into chemically homogeneous Ni-3(S)(1.1)(S-2)(0.9) superlattice structure is proposed to induce a degenerate characteristic towards excellent electrical conductivity and high-rate capability. In this study, a series of the chemically homogeneous S-2-doped Ni-3(S)(1.8)(S-2)(0.2), Ni-3(S)(1.6)(S-2)(0.4), Ni-3(S)(1.3)(S-2)(0.7), and Ni-3(S)(1.1)(S-2)(0.9) micropyramid arrays on Ni foam were synthesized by reacting the Ni foam and alkaline sulfur aqueous solution in different S-2(2-) concentrations. The perfect Ni-3(S)(1.1)(S-2)(0.9) superlattice structure corresponds to the periodic S-Ni-S-2 atom arrangements in whole crystal lattice, which endows a degenerate characteristic of metal-like electrical conductivity to significantly improve the electrochemical performance. The bulk series resistance (R-s) value is only 0.62 Omega, while the charge-transfer resistance (R-ct) is nearly 0 Omega in the superlattice Ni-3(S)(1.1)(S-2)(0.9) electrode. As a cathode material for application in lithium ion batteries (LIBs), a very high specific capacity of 874 mAh g(-1) is achieved at current density of 200 mA g(-1). Remarkably, it still holds a high capacity of 565 mAh g(-1) at current density of 500 mA g(-1), indicating its superior high-rate capability. This study reveals that the periodic S-Ni-S-2 atom arrangements in crystal lattice is a key factor in determining the superlattice structure, high specific capacity, and the dynamic behaviors of electron/ion transport. (C) 2020 Elsevier B.V. All rights reserved.