Petal-like Mn-doped α-Ni(OH)2 nanosheets for high-performance Li–S cathode material

Abstract

Lithium–sulphur (Li–S) batteries are high-energy-density and cost-effective batteries. Herein, petal-like Ni_1−xMn_x(OH)₂ (x ≈ 0.04) nanosheets were synthesised using a hydrothermal method and the electrical conductivity of Ni(OH)₂ was improved by applying the cathode functional materials in Li–S batteries. With up to 5 mg cm⁻² of S content in the cathode, the fabricated Ni_1−xMn_x(OH)₂ electrode exhibited specific discharge capacities up to 1375 and 1150 mA h g⁻¹ at 0.2 and 0.5C, and retained this capacity at 813 and 714 mA h g⁻¹ after 200 cycles, respectively. Electrochemical measurement results show that Ni_1−xMn_x(OH)₂ plays a critical role in Li–S batteries as it has a larger specific surface area than Ni(OH)₂, which has superior adsorption performance toward lithium polysulphides. Moreover, the conductivity performance of Ni_1−xMn_x(OH)₂ is significantly better than that of Ni(OH)₂, which improves the electrochemical reaction kinetics of the Li–S batteries.