Transformed Akhtenskite MnO₂ from Mn₃O₄ as Cathode for a Rechargeable Aqueous Zinc Ion Battery

Abstract

Low cost, safety, and environmental benignity make rechargeable aqueous Zn/MnO2 batteries promising candidates for large-scale energy storage. However, the synthesis of MnO2 with excellent electrochemical performance is limited to the traditional hydrothermal method, which is difficult to scale up for mass production. Herein, a ball-milling approach is developed to rapidly obtain Mn3O4 nanoparticles in large quantity. As the cathode material of aqueous zinc ion battery, Mn3O4 gradually transforms to ε-MnO2 in 1 M ZnSO4 + 1 M MnSO4 aqueous electrolyte with increasing cycles. Benefiting from the unexpected phase transition from Mn3O4 to ε-MnO2, the cathode delivers a specific capacity of 221 mAh g–1 at a current density of 100 mA g–1 and a good long-term cyclic stability over 500 cycles with 92% capacity retention at a high rate of 500 mA g–1. The excellent battery performance combined with the cost-effective preparation procedure, the good safety of aqueous mild electrolyte, and the easy cell assembly are believed to promote the practical use of the Zn/MnO2 battery in large-scale energy storage.

Valence Engineering via In Situ Carbon Reduction on Octahedron Sites Mn3O4 for Ultra‐Long Cycle Life Aqueous Zn‐Ion Battery

“…The storage mechanism of O d ‐Mn 3 O 4 @C NA/CC in electrochemical processes has been difficult to determine. There are already three viewpoints, namely reversible transformation of MnO [ 18 ] and ion insertion after conversion to ε‐MnO 2 [ 34 ] or birnessite MnO 2 . [ 33 ] The ex situ XPS, XRD, EPR, and TEM are performed in the electrochemical process to reveal the storage mechanism of the O d ‐Mn 3 O 4 @C NA/CC cathode.…”

Recent Development of Mn‐based Oxides as Zinc‐Ion Battery Cathode

“…As reported, the battery could sustain 10000 cycles at high current density of 6.5 C with minimal capacity decline of 0.007 % as shown in Figure 10a. In 2018, Zheng and co‐workers noticed the urgency for large‐scale battery production [98] . For the small‐scale laboratory preparation methods (such as using traditional hydrothermal method,) it was deemed to be challenging towards large scale production.…”

Unravelling H+/Zn2+ Synergistic Intercalation in a Novel Phase of Manganese Oxide for High‐Performance Aqueous Rechargeable Battery

“…After longterm cycle, some inactive by-products (e.g., woodruffite ZnMn 3 O 7 [13] ) with low electrochemical activity will form, leading to a serious capacity fading. A single Zn 2+ intercalation mechanism has been revealed for layered δ-MnO 2 , [11,17] spineltype ZnMn 2 O 4 , [18,19] and Mn 3 O 4 , [20,21] and despite of excellent cyclability, their reversible capacity is much lower than that of the α-, β-, and γ-MnO 2 . The amorphous MnO 2 [22,23] obtained from electrodeposition shows an impressive electrochemistry, however, it is not clear whether it follows intercalation or conversion mechanism during discharge.…”