Layered Ca_0.28MnO₂·0.5H₂O as a High Performance Cathode for Aqueous Zinc‐Ion Battery

Abstract

Aqueous zinc‐ion batteries are promising candidates for grid‐scale energy storage because of their intrinsic safety, low cost, and high energy intensity. However, lack of suitable cathode materials with both excellent rate performance and cycling stability hinders further practical application of aqueous zinc‐ion batteries. Here, a nanoflake‐self‐assembled nanorod structure of Ca0.28MnO2·0.5H2O as Zn‐insertion cathode material is designed. The Ca0.28MnO2·0.5H2O exhibits a reversible capacity of 298 mAh g−1 at 175 mA g−1 and long‐term cycling stability over 5000 cycles with no obvious capacity fading, which indicates that the per‐insertion of Ca ions and water can significantly improve reversible insertion/extraction stability of Zn2+ in Mn‐based layered type material. Further, its charge storage mechanism, especially hydrogen ions, is elucidated. A comprehensive study suggests that the intercalation of hydrogen ions in the first discharge plat is controled by both pH value and type of anion of electrolyte. Further, it can stabilize the Ca0.28MnO2·0.5H2O cathode and facilitate the following insertion of Zn2+ in 1 m ZnSO4/0.1 m MnSO4 electrolyte. This work can enlighten and promote the development of high‐performance rechargeable aqueous zinc‐ion batteries.

Hybridizing δ-Type MnO2 With Lignin-Derived Porous Carbon as a Stable Cathode Material for Aqueous Zn–MnO2 Batteries

“…As shown in the insert of Figure 1A, in the crystal structure of δ-MnO 2 , K + ions and H 2 O molecules reside in the interlayer space of MnO 6 layers. The pre-intercalated K + ions and H 2 O molecules can act as pillars to expand the interlayer distance and improve the structural stability (Wang et al, 2019b;Sun et al, 2020). The detailed valence states of Mn and C elements were investigated through XPS analysis.…”

Defect Engineering in Manganese‐Based Oxides for Aqueous Rechargeable Zinc‐Ion Batteries: A Review

“…f) Structural illustration of the as‐prepared Ca 0.28 MnO 2 ·0.5H 2 O. Reproduced with permission. [ 85 ] Copyright 2020, Wiley‐VCH.…”

“…Sun and co‐workers preinserted Ca 2+ and water into layered δ‐MnO 2 to act as pillars. [ 85 ] It was reported that the incorporation of hydrated Ca 2+ could expand the interlayer spacing and stabilize the layered structure of Ca 0.28 MnO 2 ·0.5H 2 O. As such, this resulted in a significantly improved reversible insertion/extraction stability of Zn 2+ .…”

“…[ 75 ] Similarly, Sun et al prepared Ca 2+ and water stabilized Ca 0.28 MnO 2 ·0.5H 2 O using a simple one step hydrothermal method. [ 85 ] Recently, Ce‐doped MnO 2 nanorod was fabricated though a one‐step hydrothermal route and applied as ZIBs cathode. [ 88 ] Also, the different polymorphs of MnO 2 nanostructures (α, β, γ, and δ) with copper doping could also be achieved by hydrothermal methods via tuning the reaction time, temperature, and reactants.…”

“…Sun et al reported a Ca 2+ ions and water‐stabilized δ‐MnO 2 (Ca 0.28 MnO 2 ·0.5H 2 O) cathode for aqueous ZIB. [ 85 ] Ca ion and H 2 O as pillars preinserting into layered δ‐MnO 2 could significantly improve the reversibility of Zn 2+ insertion/extraction behavior in Mn‐based layered material. Also, the preintercalation of Ca 2+ ions and H 2 O in δ‐MnO 2 could offer more cushion to relieve the strain from the Zn 2+ /H + insertion/extraction along with rapid reaction and high ion diffusion kinetics.…”