Novel Bake-in-Salt Method for the Synthesis of Mesoporous Mn3O4@C Networks with Superior Cycling Stability and Rate Performance

Deciphering the storage mechanism of biochar anchored with different morphology Mn3O4 as advanced anode material for lithium-ion batteries

Biochar is regarded as a promising lithium-ion batteries anode material, owing to its high cost-effectiveness. However, the poor specific capacity and cycling stability have limited its practical applications. A straightforward and cost-efficient solvothermal method is presented for synthesizing Mn3O4/biochar composites in this study. By adjusting solvothermal temperatures, Mn3O4 with different morphology is prepared and anchored on the biochar surface (MKAC-T) to improve the electrochemical performance. Due to the morphological effect of nanospherical Mn3O4 on the biochar surface, the MKAC-180 anode material demonstrates outstanding reversible capacity (992.5 mAh/g at 0.2 A/g), significant initial coulombic efficiency (61.1 %), stable cycling life (605.3 mAh/g at 1.0 A/g after 1000 cycles), and excellent rate performance (385.8 mAh/g at 1.6 A/g). Moreover, electro-kinetic analysis and ex-situ physicochemical characterizations are employed to illustrate the charge storage mechanisms of MKAC-180 anode. This study provides valuable insights into the "structure-activity relationship" between Mn3O4 microstructure and electrochemical performance for the Mn3O4/biochar composites, illuminating the industrial utilization of biomass carbon anode materials.

Microwave-Assisted Rational Designed CNT-Mn3 O4 /CoWO4 Hybrid Nanocomposites for High Performance Battery-Supercapacitor Hybrid Device

Extensive research interest in hybrid battery-supercapacitor (BSH) devices have led to the development of cathode materials with excellent comprehensive electrochemical properties. In this work, carbon nanotube (CNT)-Mn3 O4 /CoWO4 triple-segment hybrid electrode is synthesized by using a two-step microwave-assisted hydrothermal route. Systematic physical characterization revealed that, with the assistance of microwave, granular Mn3 O4 and spheroid-like CoWO4 with preferred orientation, and oxygen vacancies are stacked or arranged on CNTs skeletons to construct a rational designed hybrid nanocomposite with abundant heterointerfaces and interfacial chemical bonds. Electrochemical evaluations show that the synergistic cooperation in CNT-Mn3 O4 /CoWO4 resulted in an ultra-high specific capacity (1907.5 C g-1 /529.8 mA h g-1 at 1 A g-1 ), a wide operating voltage window (1.15 V), the satisfactory rate capability (capacity maintained at 1016.5 C g-1 /282.3 mA h g-1 at 15 A g-1 ), and excellent cycling stability (117.2% initial capacity retention after 13000 cycles at 15 A g-1 ). In addition, the assembled CNT-Mn3 O4 /CoWO4 //N doped porous carbon (NC) BSH device delivered a stable working voltage of 2.05 V and superior energy density of 67.5 Wh kg-1 at power density of 1025 W kg-1 , as well as excellent stability (92.2% capacity retained at 5 A g-1 for 12600 cycles). This work provides a new and feasible tactic to develop high-performance transition metal oxide-based cathodes for advanced BSH devices.

SnO2 Anchored in S and N Co-Doped Carbon as the Anode for Long-Life Lithium-Ion Batteries

Tin dioxide (SnO2) has been the focus of attention in recent years owing to its high theoretical capacity (1494 mAh g−1). However, the application of SnO2 has been greatly restricted because of the huge volume change during charge/discharge process and poor electrical conductivity. In this paper, a composite material composed of SnO2 and S, N co-doped carbon (SnO2@SNC) was prepared by a simple solid-state reaction. The as-prepared SnO2@SNC composite structures show enhanced lithium storage capacity as compared to pristine SnO2. Even after cycling for 1000 times, the as-synthesized SnO2@SNC can still deliver a discharge capacity of 600 mAh g−1 (current density: 2 A g−1). The improved electrochemical performance could be attributed to the enhanced electric conductivity of the electrode. The introduction of carbon could effectively improve the reversibility of the reaction, which will suppress the capacity fading resulting from the conversion process.

Rational design of 3D net-like carbon based Mn3O4 anode materials with enhanced lithium storage performance

A three-dimensional net-like Mn3O4/carbon paper composite was realized, which delivers a remarkably enhanced rate performance and excellent cycling stability for lithium-ion storage.

One-pot thermal decomposition of commercial organometallic salt to Fe2O3@C-N and MnO@C-N for lithium storage

Iron oxide (Fe2O3) nanoparticles encapsulated in the N-doped carbon framework (Fe2O3@C-N) were synthesized via a one-step thermal decomposition reaction of commercial C10H12FeN2NaO8 (ethylenediaminetetraacetic acid monosodium ferric salt), which can serve as the source of Fe, O, C, and N. As an anode material for lithium storage, the Fe2O3@C-N sample exhibits a reversible capacity of 1072 mA h g-1 after 200 cycles at 0.2 A g-1 and 553 mA h g-1 after 500 cycles at 0.5 A g-1. Furthermore, the synthetic strategy can be simply extended to prepare other similar products, e.g. MnO@C-N and ZnO@C-N. The MnO@C-N anode also shows good cycling performances (915 mA h g-1 after 200 cycles at 0.2 A g-1 and 768 mA h g-1 after 500 cycles at 0.5 A g-1).

Effects of Carbon Content and Current Density on the Li+ Storage Performance for MnO@C Nanocomposite Derived from Mn-Based Complexes

In this study, a simple method was adopted for the synthesis of MnO@C nanocomposites by combining in-situ reduction and carbonization of the Mn₃O₄ precursor. The carbon content, which was controlled by altering the annealing time in the C₂H₂/Ar atmosphere, was proved to have great influences on the electrochemical performances of the samples. The relationships between the carbon contents and electrochemical performances of the samples were systematically investigated using the cyclic voltammetry (CV) as well as the electrochemical impedance spectroscopy (EIS) method. The results clearly indicated that the carbon content could influence the electrochemical performances of the samples by altering the Li⁺ diffusion rate, electrical conductivity, polarization, and the electrochemical mechanism. When being used as the anode materials in lithium-ion batteries, the capacity retention rate of the resulting MnO@C after 300 cycles could reach 94% (593 mAh g⁻¹, the specific energy of 182 mWh g⁻¹) under a current density of 1.0 A g⁻¹ (1.32 C charge/discharge rate). Meanwhile, this method could be easily scaled up, making the rational design and large-scale application of MnO@C possible.

Electrospinning-based construction of porous Mn3O4/CNFs as anodes for high-performance lithium-ion batteries

Porous one-dimensional Mn₃O₄/CNFs composites are fabricated and used as anode materials for Li-ion batteries; they exhibit excellent electrochemical performance.

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.

Highly Porous Mn3 O4 Micro/Nanocuboids with In Situ Coated Carbon as Advanced Anode Material for Lithium-Ion Batteries

The electrochemical performance of most transition metal oxides based on the conversion mechanism is greatly restricted by inferior cycling stability, rate capability, high overpotential induced by the serious irreversible reactions, low electrical conductivity, and poor ion diffusivity. To mitigate these problems, highly porous Mn₃ O₄ micro/nanocuboids with in situ formed carbon matrix (denoted as Mn₃ O₄ @C micro/nanocuboids) are designed and synthesized via a one-pot hydrothermal method, in which glucose plays the roles of a reductive agent and a carbon source simultaneously. The carbon content, particle size, and pore structure in the composite can be facilely controlled, resulting in continuous carbon matrix with abundant pores in the cuboids. The as-fabricated Mn₃ O₄ @C micro/nanocuboids exhibit large reversible specific capacity (879 mAh g^-1 at the current density of 100 mA g^-1 ) as well as outstanding cycling stability (86% capacity retention after 500 cycles) and rate capability, making it a potential candidate as anode material for lithium-ion batteries. Moreover, this facile and effective synthetic strategy can be further explored as a universal approach for the synthesis of other hierarchical transition metal oxides and carbon hybrids with subtle structure engineering.

Large-Scale Fabrication of Core-Shell Structured C/SnO2 Hollow Spheres as Anode Materials with Improved Lithium Storage Performance

Due to the high theoretical capacity as high as 1494 mAh g^-1 , SnO₂ is considered as a potential anode material for high-capacity lithium-ion batteries (LIBs). Therefore, the simple but effective method focused on fabrication of SnO₂ is imperative. To meet this, a facile and efficient strategy to fabricate core-shell structured C/SnO₂ hollow spheres by a solvothermal method is reported. Herein, the solid and hollow structure as well as the carbon content can be controlled. Very importantly, high-yield C/SnO₂ spheres can be produced by this method, which suggest potential business applications in LIBs field. Owing to the dual buffer effect of the carbon layer and hollow structures, the core-shell structured C/SnO₂ hollow spheres deliver a high reversible discharge capacity of 1007 mAh g^-1 at a current density of 100 mA g^-1 after 300 cycles and a superior discharge capacity of 915 mAh g^-1 at 500 mA g^-1 after 500 cycles. Even at a high current density of 1 and 2 A g^-1 , the core-shell structured C/SnO₂ hollow spheres electrode still exhibits excellent discharge capacity in the long life cycles. Consideration of the superior performance and high yield, the core-shell structured C/SnO₂ hollow spheres are of great interest for the next-generation LIBs.