Enhanced Elastic Migration of Magnesium Cations in alpha‐Manganese Dioxide Tunnels Locally Tuned by Aluminium Substitution

Abstract

The harsh conditions of large hydrated ion radius of Mg 2+ cations and the strong electrostatic interaction with the host material put forward higher requirements for high-performance aqueous magnesium ion (Mg 2+ ) energy storage devices. Herein, substituted aluminium ions (Al 3+ ) doped α-MnO 2 materials are prepared. The introduction of Al 3+ cations adjust the local chemical environment inside the tunnel structure of α-MnO 2 and precisely regulates the diffusion behavior of inserted Mg 2+ cations. The shortened oxygens' distance and abundant oxygen defects result in a substantially enhanced elastic migration pattern of Mg 2+ cations driven by strengthened electrostatic attraction, which brings the lower diffusion energy barrier, improved reaction kinetics, and adaptive volume expansion as evidenced by Climbing Image-Nudged Elastic Band density function theory calculations coupled with experimental confirmation in X-ray photoelectron spectroscopy, electron paramagnetic resonance, and galvanostatic intermittent titration technique. As a result, this rationally designed cathode exhibits a high reversible capacity of 197.02 mAh g -1 at 0.1 A g -1 and stable cycle performance of 2500 cycles with 82% retention. These parameters are among the best of Mg-ion capacitors reported to date. This study offers a detailed insight into the local tunnel structure tunning effect and opens up a new path of modification for tunnel-type structural materials.

Flexible Electronic Systems via Electrohydrodynamic Jet Printing: A MnSe@rGO Cathode for Aqueous Zinc-Ion Batteries

“…Generally, the current response changes with the power of the sweep rate (eqs and , the definitions of specific parameters are listed in Table S1). , i = a v b log ( i ) = b log ( v ) + log ( a ) …”

“…10 Therefore, aqueous rechargeable metalion batteries (e.g., Li + , Na + , K + , and Zn 2+ batteries) are becoming a more preferred solution. 11 Among the emerging aqueous metal-ion batteries, zinc-ion batteries (ZIBs) are particularly interesting because of the abundant crystal reserves of Zn (70 ppm), the relatively small ionic radius of Zn 2+ (0.74 Å), and weak reactivity of Zn toward air and water. 12 Flexible ZIBs can be fabricated in an atmospheric environment because of the air stability of the aqueous ZIB system, thereby considerably simplifying the fabrication process.…”

“…Additionally, in a large-scale depletion scenario, the use of organic solvents poses a huge environmental threat and simultaneously hampers cost-effective recycling . Therefore, aqueous rechargeable metal-ion batteries (e.g., Li + , Na + , K + , and Zn 2+ batteries) are becoming a more preferred solution …”

Accelerated redox conversion of an advanced Zn//Fe–Co3O4 battery by heteroatom doping

“…Moreover, the Fe-O bond length is shorter than the Co-O bonds, resulting in a wider diffraction peak. 15 The Fe ion is smaller than the Co ion, and thus, the volume of the material shrinks, and the grain size becomes smaller (the diffraction peak is wider), which further proves the substitution of Co ions with Fe ions. 16 To further explore the changes induced by Fe doping, X-ray photoelectron spectra (XPS) were applied for Co 3 O 4 and Fe-Co 3 O 4 (Fig.…”

Improving the intrinsic conductivity of δ-MnO2 by indium doping for high-performance neutral aqueous sodium-ion supercapacitors with commercial-level mass-loading

“…17,18 Manganese dioxide is an attractive material for energy storage due to the low cost and high natural abundance of manganese. 19,20 Among the different forms of manganese dioxide, delta phase manganese dioxide (d-MnO 2 ) has been extensively studied over the past few decades because of its twodimensional (2D) layered structure beneting ion diffusion. [21][22][23][24] Two main issues limit the practical application of d-MnO 2 based aqueous supercapacitors, including inferior structural stability and the drastic fading of gravimetric capacitance when the mass loading is higher than 0.5 mg cm −2 .…”