Membranes of MnO Beading in Carbon Nanofibers as Flexible Anodes for High-Performance Lithium-Ion Batteries

Redox-Active High-Performance Polyimides as Versatile Electrode Materials for Organic Lithium- and Sodium-Ion Batteries

Organic electrode materials for rechargeable batteries show great promise for improving the storage capacity, reducing production costs, and minimizing environmental impact toward sustainability. In this study, we report a series of newly synthesized arylamine-based polyimides, TPPA-PIs, with three different bridge functionalizations on the imide rings and isomeric constituents that can work as versatile battery electrodes. As a lithium-ion battery cathode, a maximum energy density of 248 Wh kg-1 with high voltage operation up to 4.0 V can be achieved. As a lithium-ion battery anode, the TPPA-PIs showed a reversible storage capacity of 806 mA h g-1 at 100 mA g-1 current density with good rate capability up to a current density of 2000 mA g-1. Moreover, when applied as sodium-ion battery anodes, TPPA-PIs delivered an optimum specific capacity of up to 218 mA h g-1 after 50 cycles at a 50 mA g-1 current density and revealed a long cycling stability up to 1000 cycles under a high current density of 1000 mA g-1. More importantly, these electrochemical performances of TPPA-PIs are among the best compared with other reported polymer-based electrodes. The mechanistic studies show that both bridge functionalization on the imide units and isomerism impact the electrochemical performance by regulating their intrinsic properties such as charge storage behavior, ion diffusivity, and activation energy. We believe that such a detailed study of the structural design to electrochemical performance of these polymeric electrodes will offer insights into materials development and optimization for next-generation multifunctional energy storage devices in a wide range of applications.

Review on carbonaceous materials and metal composites in deformable electrodes for flexible lithium-ion batteries

With the rapid propagation of flexible electronic devices, flexible lithium-ion batteries (FLIBs) are emerging as the most promising energy supplier among all of the energy storage devices owing to their high energy and power densities with good cycling stability. As a key component of FLIBs, to date, researchers have tried to develop newly designed high-performance electrochemically and mechanically stable pliable electrodes. To synthesize better quality flexible electrodes, based on high conductivity and mechanical strength of carbonaceous materials and metals, several research studies have been conducted. Despite both materials-based electrodes demonstrating excellent electrochemical and mechanical performances in the laboratory experimental process, they cannot meet the expected demands of stable flexible electrodes with high energy density. After all, various significant issues associated with them need to be overcome, for instance, poor electrochemical performance, the rapid decay of the electrode architecture during deformation, and complicated as well as costly production processes thus limiting their expansive applications. Herein, the recent progression in the exploration of carbonaceous materials and metals based flexible electrode materials are summarized and discussed, with special focus on determining their relative electrochemical performance and structural stability based on recent advancement. Major factors for the future advancement of FLIBs in this field are also discussed.

A "non-dynamical" way of describing room-temperature paramagnetic manganese oxide

We present a new approach based on static density functional theory (DFT) to describe paramagnetic manganese oxides, representative paramagnetic Mott insulators. We appended spin noncollinearity and a canonical ensemble to the magnetic sampling method (MSM), which is one of the supercell approaches based on the disordered local moment model. The combination of the noncollinear MSM (NCMSM) with DFT+U represents a highly favorable computational method called NCMSM+U to accurately determine the paramagnetic properties of MnO with moderate numerical cost. The effects of electron correlations and spin noncollinearity on the properties of MnO were also investigated. We found that the spin noncollinearity plays an important role in determining the detailed electronic profile and precise energetics of paramagnetic MnO. Our results illustrate that the NCMSM+U approach may be used for insulating materials as an alternative to the ab initio framework of dynamic mean field theory based on DFT in the simulation of the room-temperature paramagnetic properties.

In Situ Synthesis of Mn3 O4 Nanoparticles on Hollow Carbon Nanofiber as High-Performance Lithium-Ion Battery Anode

The practical applications of Mn₃ O₄ in lithium-ion batteries are greatly hindered by fast capacity decay and poor rate performance as a result of significant volume changes and low electrical conductivity. It is believed that the synthesis of nanoscale Mn₃ O₄ combined with carbonaceous matrix will lead to a better electrochemical performance. Herein, a convenient route for the synthesis of Mn₃ O₄ nanoparticles grown in situ on hollow carbon nanofiber (denoted as HCF/Mn₃ O₄ ) is reported. The small size of Mn₃ O₄ particles combined with HCF can significantly alleviate volume changes and electrical conductivity; the strong chemical interactions between HCF and Mn₃ O₄ would improve the reversibility of the conversion reaction for MnO into Mn₃ O₄ and accelerate charge transfer. These features endow the HCF/Mn₃ O₄ composite with superior cycling stability and rate performance if used as the anode for lithium-ion batteries. The composite delivers a high discharge capacity of 835 mA h g^-1 after 100 cycles at 200 mA g^-1 , and 652 mA h g^-1 after 240 cycles at 1000 mA g^-1 . Even at 2000 mA g^-1 , it still shows a high capacity of 528 mA h g^-1 . The facile synthetic method and outstanding electrochemical performance of the as-prepared HCF/Mn₃ O₄ composite make it a promising candidate for a potential anode material for lithium-ion batteries.

3D Interconnected Binder-Free Electrospun MnO@C Nanofibers for Supercapacitor Devices

Rational design of binder-free materials with high cyclic stability and high conductivity is a great need for high performance supercapacitors. We demonstrate a facile one-step synthesis method of binder-free MnO@C nanofibers as electrodes for supercapacitor applications. The topology of the fabricated nanofibers was investigated using FESEM and HRTEM. The X-ray photoelectron spectroscopy (XPS) and the X-ray diffraction (XRD) analyses confirm the formation of the MnO structure. The electrospun MnO@C electrodes achieve high specific capacitance of 578 F/g at 1 A/g with an outstanding cycling performance. The electrodes also show 127% capacity increasing after 3000 cycles. An asymmetric supercapacitor composed of activated carbon as the negative electrode and MnO@C as the positive electrode shows an ultrahigh energy density of 35.5 Wh/kg with a power density of 1000 W/kg. The device shows a superior columbic efficiency, cycle life, and capacity retention.

Chemical vapor deposition-assisted fabrication of a graphene-wrapped MnO/carbon nanofibers membrane as a high-rate and long-life anode for lithium ion batteries

Novel MnO/CNFs@G membrane by electrospinning and APCVD; this anode with high specific capacity and longest cycling life is of great interest to high energy thin film or flexible Li-ion battery.

A facile electrospinning and electrospraying synchronization technique for preparation of high performance MnO/C@rGO composite anodes for lithium storage

A facile electrospinning and electrospraying synchronization technique is used to assemble 1D nanowires with 2D graphene sheets to build as 3D MnO/C@rGO composite thin film. The raw material MnO₂powder was recovered from spent Zn/MnO₂batteries.

Improved lithium-ion battery anode capacity with a network of easily fabricated spindle-like carbon nanofibers

A novel network of spindle-like carbon nanofibers was fabricated via a simplified synthesis involving electrospinning followed by preoxidation in air and postcarbonization in Ar. Not only was the as-obtained carbon network comprised of beads of spindle-like nanofibers but the cubic MnO phase and N elements were successfully anchored into the amorphous carbon matrix. When directly used as a binder-free anode for lithium-ion batteries, the network showed excellent electrochemical performance with high capacity, good rate capacity and reliable cycling stability. Under a current density of 0.2 A g^-1, it delivered a high reversible capacity of 875.5 mAh g^-1 after 200 cycles and 1005.5 mAh g^-1 after 250 cycles with a significant coulombic efficiency of 99.5%.