Aqueous zinc-ion batteries have been regarded as a promising alternative to large-scale energy storage

due to associated low-cost

improved safety and environmental friendliness. However

a high-performance cathode material for both rate capability and specific capacity is still a challenge. One kind of the more promising candidates are sodium manganese oxide (NMO) materials

although they suffer from individual issues and need to be further improved. Herein

we present a novel mixed phase NMO material composed of nearly equal amounts of Na

0.55

Mn

2

O

4

and Na

0.7

MnO

2.05

. The structured configuration with particle size of 200-500 nm is found to be beneficial towards improving the ion diffusion rate during the charge/discharge process. Compared with Na

0.7

MnO

2.05

and Na

0.55

Mn

2

O

4

the mixed phase NMO demonstrates an enhanced rate capability and excellent long-term cycling stability with a capacity retention of 83% after 800 cycles. More importantly

the system also delivers an impressive energy density and power density

as 378 W·h·kg

-1

at 68.7 W·kg

-1

or 172 W·h·kg

-1

at 17

05 W·kg

-1

. The superior electrochemical performance is ascribed to the fast Zn

2+

diffusion rate because of a large ratio of capacitive contribution (63.9% at 0.9 mV·s

-1

). Thus

the mixed phase route provides a novel strategy to enhance electrochemical performance

enabling mixed phase NMO as very promising material towards large-scale energy-storage applications.