posted on 2022-12-29, 08:15authored byZhen Wang, Kun Han, Qi Wan, Yixing Fang, Xuanhui Qu, Ping Li
Although manganese-based oxides possess
high voltage
and low cost,
the sluggish reaction kinetics and poor structural stability hinder
their applications in aqueous rechargeable Zn-ion batteries (ZIBs).
Herein, a molybdenum (Mo) pre-intercalation strategy is proposed to
solve the above issues of δ-MnO2. The pre-intercalated
Mo dopants, acting as the interlayer pillars, can not only expand
the interlayer spacing but also reinforce the layered structure of
δ-MnO2, finally achieving enhanced reaction kinetics
and superb cycling stability during carrier (de)intercalation. Moreover,
oxygen defects, introduced due to Mo-pre-intercalation, play a critical
role in the fast reaction kinetics and capacity improvement of the
Mo-pre-intercalated δ-MnO2 (Mo-MnO2) cathode.
Therefore, the Mo-MnO2 cathode displays a high energy density
of 451 Wh kg–1 (based on cathode mass), excellent
rate capability, and admirable long-term cycling performance with
a high capacity of 159 mAhg–1 at 1.0 A g–1 after 1000 cycles. In addition, the energy storage mechanism of
Zn2+/H+ stepwise reversible (de)intercalation
is also revealed by ex situ experiments. This work provides an insightful
guide for boosting the electrochemical performance of Mn-based oxide
cathodes for ZIBs.