Development and enhancement strategy of MoSe2 based anodes for aqueous Li-ion battery

Durability and capacity of electrode materials, especially the anodes, are the main challenges for aqueous Li-ion batteries. In this work, MoSe 2 micron flowers have been synthesized and investigated as anodes for Li + storage in LiCl aqueous-based electrolytes. In the LiCl solution, the working potential of the MoSe 2 anode can reach −1.0 V (vs Ag/AgCl). Yet, its reversible capacity is only ∼14 mAh g −1 (50 C g −1 ), owing to the absence of Faradaic reactions and the fast deformation of MoSe 2 . After gelation of the LiCl solution using poly vinyl alcohol (PVA), the activity of water is largely inhibited, and the operating potential is broadened to −1.2 V. In this gel system, the Faradaic reaction of the MoSe 2 anode is triggered, and hence its capacity is largely enhanced. With a suitable amount of PVA (LiCl/PVA-20), the MoSe 2 electrode can deliver reversible capacities of high as 157 mAh g −1 at 1 A g −1 , and 139 mAh g −1 at 2 A g −1 , and still high as 100 mAh g −1 after 50 cycles, indicating relative good stability. Using commercial LiMn 2 O 4 as cathode, a full aqueous Li-ion battery was assembled, and a high discharge voltage of ∼1.8 V can be achieved. It is found that not only the activity of water but also the morphology change of the MoSe 2 during cycling is inhibited in the gel electrolyte.