Biphase Cobalt–Manganese Oxide with High Capacity and Rate Performance for Aqueous Sodium‐Ion Electrochemical Energy Storage

Abstract

Manganese-based metal oxide electrode materials are of great importance in electrochemical energy storage for their favorable redox behavior, low cost, and environmental friendliness. However, their storage capacity and cycle life in aqueous Na-ion electrolytes is not satisfactory. Herein, the development of a biphase cobalt-manganese oxide (CoMnO) nanostructured electrode material is reported, comprised of a layered MnO 2 ⋅H 2 O birnessite phase and a (Co 0.83 Mn 0.13 Va 0.04 ) tetra (Co 0.38 Mn 1.62 ) octa O 3.72 (Va: vacancy; tetra: tetrahedral sites; octa: octahedral sites) spinel phase, verified by neutron total scattering and pair distribution function analyses. The biphase CoMnO material demonstrates an excellent storage capacity toward Na-ions in an aqueous electrolyte (121 mA h g −1 at a scan rate of 1 mV s −1 in the half-cell and 81 mA h g −1 at a current density of 2 A g −1 after 5000 cycles in full-cells), as well as high rate performance (57 mA h g −1 a rate of 360 C). Electrokinetic analysis and in situ X-ray diffraction measurements further confirm that the synergistic interaction between the spinel and layered phases, as well as the vacancy of the tetrahedral sites of spinel phase, contribute to the improved capacity and rate performance of the CoMnO material by facilitating both diffusion-limited redox and capacitive charge storage processes.

A review on mechanistic understanding of MnO2in aqueous electrolyte for electrical energy storage systems

“…The Na ions located in S-shape tunnels can reversibly intercalate, projecting a theoretical capacity of ∼50 mAh g −1 (Figure 14(a)) [195]. This crystal structure greatly facilitates Na + ion mobility while stabilising Na + ions to prevent crystal phase transition to the spinel phase [196][197][198].…”

Ultrafast Aqueous Potassium‐Ion Batteries Cathode for Stable Intermittent Grid‐Scale Energy Storage

“…Aqueous alkali‐ion battery chemistries have aroused increasing attention in recent years owing to the high ionic conductivity, environmental friendliness, and low cost of aqueous electrolytes . Nevertheless, aqueous LIBs generally exhibit substandard cycling stability, and aqueous sodium‐ion batteries are known to suffer from low‐capacity issues .…”

Dual-phase nanostructuring of layered metal oxides for high-performance aqueous rechargeable potassium ion microbatteries

“…4c). This exceptional rate performance enlists the V-Mn AR-PIMBs to outperform some of the best rechargeable aqueous metal-ion batteries reported previously: such as aqueous K + -ion batteries with carbon-encapsulated Fe 3 O 4 nanorod array anode and carbon nanotube film cathode in 3 M KOH electrolyte (Fe–C PIBs) 56 , Li + -ion batteries with Bi 2 O 3 anode, and LiMn 2 O 4 cathode in a mixed electrolyte of Li 2 SO 4 and LiCl (Bi–Mn LIBs) 57 , as well as symmetric Na + -ion batteries of biphase cobalt–manganese oxide nanosheets in 0.1 M Na 2 SO 4 (CoMn–CoMn SIBs) 21 . Meanwhile, the V-Mn AR-PIMBs displays very low self-discharge, with less than 3.6 mV h −1 , much better than LIBs assembled with Mo 6 S 8 anode and LiFePO 4 cathode (Mo-Fe LIBs) in Li-TFSI: H 2 O = 1 (21.1 mV h −1 ), Bi–Mn LIBs (58.9 mV h −1 ) 58 , and Zn 2+ -ion batteries with Zn anode and polyaniline film cathode (Zn–PANI ZIBs) in 1 M ZnCl 2 (12.7 mV h −1 ) (Fig.…”

“…Voltage window is extended to 1.6 V in aqueous electrolyte of 0.5 M K 2 SO 4 . c Stack capacity of aqueous V-Mn AR-PIMBs at various scan rates, comparing with previously reported rechargeable aqueous alkaline-metal-ion batteries, such as K + -ion batteries with carbon-encapsulated Fe 3 O 4 nanorod array anode and carbon nanotube film cathode in 3 M KOH electrolyte (Fe–C PIBs) 56 , Li + -ion batteries with Bi 2 O 3 anode, and LiMn 2 O 4 cathode in a mixed electrolyte of Li 2 SO 4 and LiCl (Bi–Mn LIBs) 57 , and symmetric Na + -ion batteries of biphase cobalt–manganese oxide nanosheets in 0.1 M Na 2 SO 4 (CoMn–CoMn SIBs) 21 . d Comparison of self-discharge performance for aqueous V-Mn AR-PIMBs with aqueous Bi–Mn LIBs 57 , LiFePO 4 //Mo 6 S 8 (Fe–Mo) LIB, and Zn//polyaniline Zn 2+ -ion battery (Zn–PANI ZIB) 58 .…”