Effects of Mn(II) salt anions on MnO@C composites derived from manganese-based aerogels and their lithium storage properties

The anion of inorganic metal salts has a great influence on the epoxide-initiated sol–gel process and thus affects the morphology and structure of MnO@C composites derived from aerogels. Four inorganic Mn(II) salts with different anions (NO3−, Cl−, SO42−, CH3COO−) were used to prepare Mn-based aerogel. Only when Mn(NO3)2 or MnCl2 was used as an inorganic salt precursor, Mn-based aerogel could be successfully fabricated, which can be attributed to the diverse nucleophilicity of anions. After carbonization, two MnO@C composites were produced and showed individual microstructures. MnO@C-N composites obtained from nitrate exhibit homogeneous fine nanoparticles and a high BET surface area of 151.3 m2 g−1. When used as anodes for lithium-ion batteries, MnO@C-N electrode exhibits excellent lithium storage performance with a high reversible capacity of 1090 mAh g−1 at a current density of 0.2 A g−1, outstanding cycling stability of 96% capacity retained after 100 cycles and good rate capability of 413 mAh g−1 at 2 A g−1.