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, MoSe2 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 MoSe2 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 MoSe2. 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 MoSe2 anode is triggered, and hence its capacity is largely enhanced. With a suitable amount of PVA (LiCl/PVA-20), the MoSe2 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 LiMn2O4 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 MoSe2 during cycling is inhibited in the gel electrolyte.