posted on 2019-10-29, 14:34authored byJing Guo, Jun Ming, Yongjiu Lei, Wenli Zhang, Chuan Xia, Yi Cui, Husam N. Alshareef
Vanadium-based
compounds have been widely used as electrode materials
in aqueous zinc ion batteries (ZIBs) due to the multiple oxidation
states of vanadium and their open framework structure. However, the
solubility of vanadium in aqueous electrolytes and the formation of
byproducts during the charge/discharge process cause severe capacity
fading and limit cycle life. Here, we report an ultrathin HfO2 film as an artificial solid electrolyte interphase (SEI)
that is uniformly and conformally deposited by atomic layer deposition
(ALD). The inactive hafnium(IV) oxide (HfO2) film not only
decreases byproduct (Zn4SO4(OH)6·xH2O) formation on the surface of Zn3V2O7(OH)2·2H2O (ZVO)
but also suppresses the ZVO cathode dissolution in the electrolyte.
As a result, the obtained HfO2-coated ZVO cathodes deliver
higher capacity and better cycle life (227 mAh g–1@100 mA g–1, 90% retention over 100 cycles) compared
with pristine ZVO (170 mAh g–1@100 mA g–1, 45% retention over 100 cycles). A mechanistic investigation of
the role of HfO2 is presented, along with data showing
that our method constitutes a general strategy for other cathodes
to enhance their performance in aqueous ZIBs.