Renewable agaric-based hierarchically porous cocoon-like MnO/Carbon composites enable high-energy and high-rate Li-ion batteries

Fabrication of a Biomass-Derived Activated Carbon-Based Anode for High-Performance Li-Ion Batteries

Porous carbons are highly attractive and demanding materials which could be prepared using biomass waste; thus, they are promising for enhanced electrochemical capacitive performance in capacitors and cycling efficiency in Li-ion batteries. Herein, biomass (rice husk)-derived activated carbon was synthesized via a facile chemical route and used as anode materials for Li-ion batteries. Various characterization techniques were used to study the structural and morphological properties of the prepared activated carbon. The prepared activated carbon possessed a carbon structure with a certain degree of amorphousness. The morphology of the activated carbon was of spherical shape with a particle size of ~40-90 nm. Raman studies revealed the characteristic peaks of carbon present in the prepared activated carbon. The electrochemical studies evaluated for the fabricated coin cell with the activated carbon anode showed that the cell delivered a discharge capacity of ~321 mAhg^-1 at a current density of 100 mAg^-1 for the first cycle, and maintained a capacity of ~253 mAhg^-1 for 400 cycles. The capacity retention was found to be higher (~81%) with 92.3% coulombic efficiency even after 400 cycles, which showed excellent cyclic reversibility and stability compared to commercial activated carbon. These results allow the waste biomass-derived anode to overcome the problem of cyclic stability and capacity performance. This study provides an insight for the fabrication of anodes from the rice husk which can be redirected into creating valuable renewable energy storage devices in the future, and the product could be a socially and ethically acceptable product.

Rational design of nano-Fe3O4encapsulated in 3D honeycomb biochar for enhanced lithium storage performance

Developing green materials applied in lithium-ion batteries is of significant importance for the present-day society. Herein, a feasible strategy to construct Fe₃O₄nanoparticles (NPs) embedded in three-dimensional (3D) honeycomb biochar derived from pleurotus eryngii was proposed. The obtained material consists of Fe₃O₄NPs (35-85 nm) encapsulated in 3D honeycomb biochar possesses a high specific capacity of 723 mAh g^-1at 1.5 A g^-1after 1000 cycles. The effectively enhanced cycling life of Fe₃O₄@C nanocomposites can be ascribed to the small Fe₃O₄NPs provide lower degree of cracking and high specific capacity, while the honeycomb biochar function like a cage to inhibit huge volume change of Fe₃O₄NPs during the charge-discharge process.

Binary-Metal Mn2SnO4 Nanoparticles and Sn Confined in a Cubic Frame with N-Doped Carbon for Enhanced Lithium and Sodium Storage

Sn-based materials have been popularly researched as anodes for energy storage due to their high theoretical capacity. However, the sluggish reaction kinetics and unsatisfied cycling stability caused by poor conductivity and dramatic volume expansion are still pivotal barriers for the development of Sn-based materials as anodes. In this work, the binary-metal Mn₂SnO₄ nanoparticles and Sn encapsulated in N-doped carbon (Sn@Mn₂SnO₄-NC) were fabricated by multistep reactions and employed as the anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The coexistence of binary metals (Sn and Mn) can improve intrinsic conductivity. Simultaneously, hollow architecture along with carbon relieves internal stress and prevents structural collapse. A Sn@Mn₂SnO₄-NC anode delivers an appealing capacity of 1039.5 mAh g^-1 for 100 cycles at 100 mA g^-1 and 823.8 mAh g^-1 for 600 cycles at 1000 mA g^-1 in LIBs. When evaluated as an anode in SIBs, the Sn@Mn₂SnO₄-NC anode tolerates up to 7000 cycles at 2000 mA g^-1 and maintains a capacity of 185.8 mAh g^-1. Quantified kinetic investigations demonstrate the high contribution of pseudocapacitive effects during the cycle process. Furthermore, density functional theory (DFT) calculations further verify that introduction of the second metal (Mn) improves the conductivity of the material, which is favorable for charge transport. This work is expected to provide a feasible preparation strategy for binary-metal materials to enhance the performance of lithium- and sodium-ion batteries.

Guiding uniform Zn deposition by cocoons for long-life Zn metal batteries

The interlaced carbon membranes are prepared using silk cocoons via high-temperature sintering processes and has been assembled in symmetric zinc batteries to successfully inhibit the dendrite growth.

3D Lamellar Structure of Biomass-Based Porous Carbon Derived from Towel Gourd toward Phase Change Composites with Thermal Management and Protection

The practical application of shape-stable phase change composites (PCCs) is beneficial to thermal energy management and energy conservation due to their superior properties. A shape-stable PCC was fabricated by incorporating poly(ethylene glycol) (PEG) with biomass-based porous carbon that was produced via freeze-drying and carbonization using a low-cost and environmentally friendly fresh towel gourd. The towel gourd derived porous carbon with the characteristics of porosity, unique three-dimensional (3D) lamellar structure, and high specific surface area allowed a high encapsulation capacity (up to 94.5 wt %) for PEG. Structural morphologies, as well as the properties of latent heat storage, thermal reliability, thermal energy management, and thermal protection ability of the fabricated shape-stable PCC, were investigated. The micromorphologies revealed that PEG molecular chains were arranged in a 3D lamellar tissue structure. The shape-stable PCC demonstrated excellent thermal reliability and a high melting latent heat of ∼164.3 J/g. The analysis of infrared thermal images indicated that the shape-stable PCC exhibited remarkable strengths in thermal energy management. The result of the thermal insulation simulation experiment proved that the shape-stable PCC had superior thermal protection ability. This study provided an innovative strategy for the design and development of shape-stable PCCs for great potential in heat-insulating protective textiles, solar thermal energy storage, energy-saving buildings, and infrared stealth of military targets.

Interfacial Superassembly of Grape-Like MnO-Ni@C Frameworks for Superior Lithium Storage

Despite the excellent electrochemical performance of MnO-based electrodes, a large capacity increase cannot be avoided during long-life cycling, which makes it difficult to seek out appropriate cathode materials to match for commercial applications. In this work, a grape-like MnO-Ni@C framework from interfacial superassembly with remarkable electrochemical properties was fabricated as anode materials for lithium-ion batteries. Electrochemical analysis indicates that the introduction of Ni not only contributes to the excellent rate capability and high specific capacity but also prevents further oxidation of MnO to the higher valence states for ultrastable long-life cycling performance. Furthermore, thermodynamic calculation proves that the ultrastable long cycling life of the Ni-Mn-O system originated from a buffer composition region to stabilize the MnO structure. Because of the unique grape-like structure and performance of the Ni-Mn-O system, the MnO-Ni@C electrode displayed an invertible specific capacity of 706 mA h g^-1 after 200 cycles at a current density of 0.1 A g^-1 and excellent cycling stability maintained a capacity of 476.8 mA h g^-1 after 2100 cycles at 1.0 A g^-1 without obvious capacity change. This new nanocomposite material could offer a novel fabrication strategy and insight for MnO-based materials and other metal oxides as anodes for improved electrochemical performance.

Novel agaric-derived olive-like yolk–shell structured MnO@C composites for superior lithium storage

An ingenious and effective biomass strategy has been designed to prepare unique hierarchical olive-like yolk–shell structured MnO@C composites, which realized outstanding electrochemical performances for lithium storage.