As an alternative for lithium ion batteries, aqueous energy storage system has recently attracted tremendous attentions due to the low cost, non-flammable and non-toxic materials.^[1] Among various aqueous batteries, aqueous Zn ion batteries are particularly advantageous owing to a high-capacity Zn metal anode (819mAh/g).^[2] However, limited cathode materials have been explored for reversible Zn²⁺-ion intercalation, and most of which exhibit poor rate capabilities and inadequate cycling performance, or limited specific capacity. α-MoO₃, as a typical layered transition metal oxide, has been extensively studied as electrode material for lithium batteries due to the advantages of high capacity, low cost, abundant resources and non-toxic.^[3] Based on our research, we have found α-MoO₃ can be used as host material (cathode) for zinc ions as well owing to the large interlayer space. However, the capacity fading in the initial cycles is still significant and unavoidable. The reason for irreversible capacity fading of MoO₃ in the initial cycles can be attributed to its unstable structural prosperity. Recently, pre-intercalation has been demonstrated as an effective way to improve the electrochemical performance for zinc-ion batteries. For example, Linda et.al has reported vanadium oxide bronze pillared by interlayer Zn²⁺ ions and water can supply the remarkable performance.^[2] However, the related research of α-MoO₃ as electrode for zinc-ion is still blank.

For the first time, we have studied the electrochemical performance of zinc pre-intercalation α-MoO₃ as cathode material for zinc batteries and investigated the electrochemical mechanism during charging and discharging. The zinc pre-intercalation α-MoO₃ can supply the initial specific capacity as high as 300 mAh/g, exhibiting great potential for application as high-performance cathode material for zinc-ion batteries.

Reference

1. Pan, H.; Shao, Y.; Yan, P. F.; Cheng, Y. W.; Han, K. S.; Nie, Z. M., Wang, C. M., Yang, J. H.; Li, X. L.; Bhattacharya, P.; Mueller, K. T.; Reversible Aqueous Zinc/Manganese Oxide Energy Storage From Conversion Reactions. Nature Energy, 2016, 1, 16039.

2. Kundu, D.; Adams, B. D.; Duffort, V.; Vajargah, S. H.; Nazar, L. F.; A High-Capacity and Long-life Aqueous Rechargeable Zinc Battery Using a Metal Oxide Intercalation Cathode. Nature Energy. 2016,1,16119.

3. Dong, Y. F.; Xu, X. M.; Li, S., Han, C. H.; Zhao, K. N.; Zhang, L.; Niu, C. J.; Huang, Z.; Mai, L. Q.; Inhibiting Effect of Na⁺ Pre-Intercalation in MoO₃ Nanobelts with Enhanced Electrochemical Performance. Nano Energy. 2015, 15, 145.