Ammonium ion pre‐intercalated manganese dioxide with hydrogen bond for high‐rate and stable zinc‐ion batteries

Abstract

The low-cost and high-safety zinc-ion batteries (ZIBs) are expected to be promising alternatives of lithium-ion batteries (LIBs). Nevertheless, sluggish kinetics and unstable structure of cathode lead to the low-rate capability and poor cycling stability of ZIBs, which severely hinder their commercial application. Herein, a (NH 4 ) x MnO 2 cathode with ammonium ions (NH 4 + ) preintercalation is reported. The NH 4 + ions with small molar mass expand the layer spacing, accelerating ion diffusion and act as "structural pillars", preventing structural collapse. Moreover, hydrogen bond between NH 4 + and MnO 2 promotes the charge transfer and further stabilize the layered structure. Therefore, the (NH 4 ) x MnO 2 cathode delivers a high specific capacity (228.7 mAh g À1 at 0.3 A g À1 ), a superior high-rate performance (122.5 mAh g À1 at 3.0 A g À1 ),and an outstanding long-term cycling stability without obvious capacity fading after 1500 cycles at 2.0 A g À1 . This work provides a new perspective for future development of high-performance ZIBs.

Structural Engineering of Vanadium Oxide Cathodes by Mn2+ Preintercalation for High-Performance Aqueous Zinc-Ion Batteries

“…Furthermore, the two reduction peaks of MnVO shift to higher potentials, and the oxidation peak at 0.65 V shifts to lower potentials compared to the redox peaks of VO 2 . Thus, the overpotential gaps between the two pairs of redox peaks of the VO 2 electrode are 0.23 and 0.15 V, respectively, while the overpotential gaps of the two pairs of peaks for MnVO are both 0.08 V. This indicates that the incorporation of Mn 2+ guest ions improves the electrochemical reactivity of the MnVO electrode material. ,, The MnVO nanoribbon cathode delivers a reversible specific capacity of 462.5 mA h g –1 at a current density of 0.1 A g –1 and remains at 312 mA h g –1 after 100 cycles, which is higher than the 262 mA h g –1 of the VO 2 cathode after cycling (Figure c). Furthermore, the galvanostatic charge/discharge (GCD) curves under different cycles at a current density of 0.1 A g –1 agree well with the CV results (Figure d).…”

Pre‐intercalation of Ammonium Ions in Layered δ‐MnO2 Nanosheets for High‐Performance Aqueous Zinc‐Ion Batteries

“…Fourier transform infrared (FTIR) spectrum of AMO reveals two prominent peaks located at 1419 and 1625 cm −1 , which can be ascribed to coordination of ammonium ions to the surface MnO 6 groups via the hydrogen bonding (Figure 3d). [30] The survey X‐ray photoelectron spectroscopy (XPS) spectra in Figure 3e indicate that the weak peaks related to K species in KMO can hardly be identified in AMO, proving the evolution of interlayer species. The high‐resolution Mn 2p spectra further uncover the change of Mn species after the ion exchange (Figure 3f).…”

Challenges and Strategies in the Development of Zinc‐Ion Batteries

“…Preintercalation has been reported to be effective in widening the interlayer separation to lower the energy barrier and hence improve the transport kinetics. [217] Moreover, the preintercalated ions are able to strengthen the cathode by acting as "structural pillars", [218] protecting them against collapse for cycling stability. One example would be the preintercalation of metallic ions into the cathode material, demonstrated by Xie et al where monovalent alkali ions were chosen for preintercalation into 𝛿-MnO 2 , forming different interlayer spacings.…”