Ti-Doped Tunnel-Type Na₄Mn₉O₁₈ Nanoparticles as Novel Anode Materials for High-Performance Supercapacitors

Abstract

Nanomaterials with tunnel structures are extremely attractive to be used for electrode materials in electrochemical energy storage devices. Tunnel-structured Ti-doped Na4Mn9O18 nanoparticles (TNMO-NPs) were synthesized by a facile and high-production method of the solid-state reaction with a high-energy ball-milling process. As electrode materials in the supercapacitor cell, the as-synthesized TNMO-NPs exhibit a high specific capacity of 284.93 mA h g–1 (0.57 mA h cm–2/1025.75 F g–1). A superior rate capability with a decay of 36% is achieved by increasing the scan rates from 2 to 25 mV s–1. To further explore the storage mechanism of Ti-doped Na4Mn9O18 materials, density functional theory (DFT) calculations were used to calculate the activation energy for the ion immigration in the electrode, and the results show that the minimum ion diffusion barrier energy is 0.272 eV, indicating that the sodium ions could insert into the system easily. Through the scan-rate-dependent cyclic voltammetry analysis, the capacity value indicates a mixed charge storage of capacitive behavior and Na+ intercalation progress. A maximum energy density of 77.81 W h kg–1 at a power density of 125 W kg–1 is achieved, and a high energy density of 54.79 W h kg–1 is maintained even at an ultrahigh power density of 3750 W kg–1. The TNMO-NP supercapacitors show excellent flexibility at various bent (0–180°) states. The capacitive performance of the TNMO-NPs makes them promising cathode materials for flexible supercapacitors with high specific capacities and high energy densities.

Molten-salt assisted synthesis of a high-performance oxide cathode for sodium-ion batteries: Na0.44MnO2as a case

“…4f shows the contribution ratio of surface-controlled and diffusion-controlled reactions of NMO-8002, and the contribution ratios of the diffusion component are only 4.8% and 14.1% at a scanning rate of 1 m V s À1 and 0.1 m V s À1 , respectively. These are lower than the related results of most other literature studies, 28,29,57,58 indicating that most of the capacity of NMO-8002 is attributed to surface-controlled reactions. With the increase in scan rate, it is difficult for more Na + to diffuse into the deeper interior of the material and they can only be stored on the material surface.…”

“…When charging, the position of the diffraction peak (3 5 0) gradually shifts to a high angle due to the extraction of Na + . 57 During discharging, the lattice spacing becomes larger, and the diffraction peak position gradually shifts back to a low angle. When discharged to about 3 V, the diffraction peak returns to the initial position, illustrating the good reversibility of the NMO-8002 structure during the charge–discharge process.…”

“…27,56 However, the Na + in the small tunnel is almost inactive because its Na + migration barrier energy is significantly higher. 9,57,58 It is worth noting that the NMO calcined at 750 1C shows an impurity peak of Na 0.7 MnO 2.05 (JCPDS No. 27-0751) at 15.81 and a diffraction peak of Na-birnessite (JCPDS No.…”

Zn induced NiCo composites modified by carbon materials as a battery-type electrode material for high-performance supercapacitors

“…According to the above analysis result about the CV curves, it can be inferred that the electrochemical process not only consists of double-layer but also pseudocapacitance process. Due to the introduction of carbon, which accelerates the dynamic process of the material's surface, it is interesting to quantify the capacity contribution from surface and diffusion control in this process by analyzing the data from CV curves in figures S5(a)-(d) based on the following equations [25,35,36].…”

AgxMn8O16 Cathode Enables High-Performance Aqueous Li-Ion Hybrid Supercapacitors

“…Recently, non-renewable energy has been gradually consumed to meet the demand for energy and brought serious environmental pollution. Therefore, it is necessary to develop renewable energy and establish a stable, efficient, and sustainable clean energy storage and conversion system to solve the above problems. − As a facile energy storage device, hybrid supercapacitors (HSCs) have been expected to realize high energy density and high power density at the same time using asymmetric electrodes with different energy storage mechanisms. , This hybrid device makes it possible to make full use of the capacitive characteristics of asymmetric electrodes over different voltage ranges . Although HSCs have been explored and developed for years, the performance, especially the power density, is far from satisfactory. , From the perspective of the energy storage mechanism, the battery-type electrode controlled by the diffusion process shows sluggish kinetics .…”