Facile preparation of [Bi6O4] (OH)4(NO3)6•4H2O, [Bi6O4](OH)4(NO3)6• H2O and [Bi6O4](OH)4(NO3)6•H2O/C as novel high capacity anode materials for rechargeable lithium-ion batteries

[Bi6O4](OH)(4)(NO3)(6)center dot 4H(2)O, [Bi6O4](OH)(4)(NO3)(6)center dot H2O and [Bi6O4](OH)(4)(NO3)(6)center dot H2O/C, derivated from Bi(NO3)(3)center dot 5H(2)0, are firstly investigated for the electrochemical activity as anode materials for lithium-ion batteries. Electrochemical results show that [Bi6O4](OH)(4)(NO3)(6 center dot)4H(2)O can deliver a higher initial discharge specific capacity (2792.9 mAh g(-1)) than that of [Bi6O4](OH)(4)(NO3)(6)center dot H2O (832.2 mAh g(-1)) and [Bi6O4](OH)(4)(NO3)(6)center dot H2O/C (1169.3 mAh g(-)1). However, the capacity retention (60.3%) and reversible specific capacity (365.5 mAh g(-1)) of [Bi6O4](OH)(4)(NO3)(6 center dot)H2O/C are much higher than those of [Bi6O4](OH)(4)(NO3)(6)center dot H2O (4.75% and 39.6 mAh g(-1)) and [Bi6O4](OH)(4)center dot H2O (15.9% and 289.4 mAh g(-1)) in the first 30 cycles. The improved electrochemical properties are attributed to the decrease of crystal water in the structure and the introduction of carbon black as conductive additive and volume change buffer. The reaction mechanism of [Bi6O4](OH)(4)(NO3)(6)center dot H2O/C with Li is also studied in detail by using various ex-situ and in-situ techniques during the initial charge-discharge cycle. It can be found that the electrochemical reaction of [Bi6O4](OH)(4)(NO3)(6)center dot H2O with Li leads to the preliminary formation of metal Bi, LiNO3, LiOH, Li2O and H2O and then the alloying reaction to form Li-Bi alloys. (C) 2014 Elsevier B.V. All rights reserved.