Facile Synthesis of Nanostructured MnO₂ as Anode Materials for Sodium‐Ion Batteries

Abstract

Nanostructured MnO2 (including nanorods and nanoflowers) has been synthesized by a simple two‐step hydrothermal method and thermal treatment. When employed as anode materials for sodium‐ion batteries, MnO2 nanorods and nanoflowers demonstrate high initial sodium ion storage capacities of 427.4 and 487.8 mA h g−1, respectively, at a current density of 50 mA g−1. Compared with MnO2 nanorods, MnO2 nanoflowers achieved a much better electrochemical performance including good rate capability (103.3 mA h g−1 at 800 mA g−1 after 100 cycles) and superior cyclability (133.6 mA h g−1 at 400 mA g−1 after 1000 cycles). The good performance can be ascribed to the nanocrystalline nature and the three‐dimensional hierarchical architecture of MnO2 nanoflowers, which promotes the contact between MnO2 and electrolyte and shortens the electronic sodium ion pathway in the charge and discharge processes.

Amorphous MnO2 as Cathode Material for Sodium‐ion Batteries

“…MnO 2 is one of the promising materials for energy storage due to its high theoretical specific capacity, low cost, natural abundance and environmentally benign nature. [24][25][26][27] Over the past several years, various MnO 2 nanostructures, such as nanoflakes, [28] nanosheets, [29,30] nanorods, [31][32][33] nanotubes, [34] and amorphous nature [20] have been synthesized and applied as electrodes for LIBs and supercapacitors. [35][36][37] What's more, MnO 2 materials with various nanostructures have been employed as cathode materials in Zn-MnO 2 system in recent years and all of the composites exhibit excellent storage capacities.…”

Boosting the Sodiation Capability and Stability of FeP by In Situ Anchoring on the Graphene Conductive Framework

“…Peak IV at 1.50–2.20 V was detected in following initial anodic scan, which correspond to a stepwise sodium ion extraction of Na 3 P to Na x P intermediates . In the subsequent CV curves, two major cathodic peaks (V and VI) shift to 1.2–0.6 and 0.2–0 V. The shift of peak position to higher potential is mainly owing to the structural reorganization ,,. Since the second cycle, all of curves overlap together, which indicates the excellent stability and reversibility.…”

“…As shown in Figure b, FeP@rGO coin cell shows a lower resistance Rct of 86.0 Ω after 100 cycles. The decrease of remarkable resistance after 100 cycles may be ascrilbed to the better electrochemical contact and surface activation after cycles ,. Compared with the Rct of 100 th cycle, the charge‐transfer resistance after the subsequent 500 cycles only increases a little to 136.9 Ω, indicating the well‐maintained electrical contact and a good stability of FeP@rGO electrode during discharge‐charge processes …”

“…To solve these problems, reducing the content of phosphorus in MPs is a promising approach, which often leads to metal‐rich phosphides (Cu 3 P, Ni 2 P, etc.). Another critical strategy is to design special microstructures for the electrode with the MPs, such as core‐shell or porous structure, nanowires and nanotubes,,, which can effectively buffer the volume change and also improve the interfacial contact between electrode/electrolyte. In addition, introducing carbonaceous materials in the electrode can relieve the aggregation of phosphides particles and enhance the conductivity.…”

In Situ Growth of a Feather‐like MnO2 Nanostructure on Carbon Paper for High‐Performance Rechargeable Sodium‐Ion Batteries

“…For instance, space‐confined MnO 2 nanocrystallites exhibited an initial discharge capacity of 567 mAh g −1 . Zhang et al reported that MnO 2 nanorods and nanoflowers could deliver an initial specific capacity of 427 and 488 mAh g −1 , respectively . Besides, binder additives also have a negative influence on the conductivity of electrode and further electrochemical performance.…”