High-capacity and long-life lithium storage boosted by pseudocapacitance in three-dimensional MnO-Cu-CNT/graphene anodes

Interdiffusion and Intermetallic Compounds at Al/Cu Interfaces in Al-50vol.%Cu Composite Prepared by Solid-State Sintering

Al–Cu composites have attracted significant interest recently owing to their lightweight nature and remarkable thermal properties. Understanding the interdiffusion mechanism at the numerous Al/Cu interfaces is crucial to obtain Al–Cu composites with high thermal conductivities. The present study systematically investigates the interdiffusion mechanism at Al/Cu interfaces in relation to the process temperature. Al-50vol.%Cu composite powder, where Cu particles were encapsulated in a matrix of irregular Al particles, was prepared and then sintered at various temperatures from 340 to 500 °C. Intermetallic compounds (ICs) such as CuAl₂ and Cu₉Al₄ were formed at the Al/Cu interfaces during sintering. Microstructural analysis showed that the thickness of the interdiffusion layer, which comprised the CuAl₂ and Cu₉Al₄ ICs, drastically increased above 400 °C. The Vickers hardness of the Al-50vol.%Cu composite sintered at 380 °C was 79 HV, which was 1.5 times that of the value estimated by the rule of mixtures. A high thermal conductivity of 150 W∙m⁻¹∙K⁻¹ was simultaneously obtained. This result suggests that the Al-50vol.%Cu composite material with large number of Al/Cu interfaces, as well as good mechanical strength and heat conductance, can be prepared by solid-state sintering at a low temperature.

MOF-derived manganese monoxide nanosheet-assembled microflowers for enhanced lithium-ion storage

Achieving high energy density, power density and cycling performance is a great challenge for lithium-ion battery (LIB) anodes. To obtain favorable electrochemical properties, an effective approach for designing composite nanomaterials with good stability and large specific surface area has been reported here. In this work, metal-organic framework (MOF)-derived manganese monoxides with a stable macromolecular framework were synthesized by utilizing the template agent 1,2,3,4-butanetetracarboxylic acid (BTCA) and the organic salt manganese acetylacetone, which possess a compact microflower structure assembled by nanosheets. As a synergistic effect, not only the amorphous carbon derived from MOFs enhances the specific capacity and stability, but also the unique nanosheet exhibits a significant nano-effect and high areal capacity, which is in favour of an electrochemical reaction. For further enhancement of the electrochemical performance, reduced graphene oxide (rGO) was introduced. When tested as a LIB anode, the MnO@rGO composite displays superior reversible capacities (1716 mA h g-1 at 0.1 A g-1 and 930 mA h g-1 at 2 A g-1) and remarkable rate performances. The research results of the composite nanomaterials lay a foundation for the fabrication of high-capacity and stable anode materials in LIBs.

Pseudocapacitive Li-ion storage boosts high-capacity and long-life performance in multi-layer CoFe2O4/rGO/C composite

Due to the intrinsic low electrical conductivity and large volume expansion of the CoFe₂O₄ based active materials, designing more novel structures is still one of the most important challenges for its lithium ion battery application. In this work, the CoFe₂O₄/reduced graphene oxide/carbon (CFO/rGO/C) composite with integrated multi-layer structure has been synthesized through a facial two-step hydrothermal method. Benefiting from the introduction of the graphene network and amorphous carbon coating layer, as well as the accompanying synergistic effect, this composite can exhibit fast and reversible lithium intercalation/deintercalation reactions. With the aid of a surface-induced capacitive process, the CFO/rGO/C composite delivers a superior specific capacity (945 mA h g^-1 at 0.1 A g^-1) and excellent long-term cyclic stability (421 mA h g^-1 at 4 A g^-1 with closely 100% Coulombic efficiency after 2000 cycles). Significantly, at a high current density of 1 A g^-1, the reversible capacity exhibits a rapid increasing after 100 cycles and finally shows an ultra-high-capacity of 1430 mA h g^-1 over 500 cycles. This method could be generalized to the preparation of other similar transition metal oxide-based materials for the development of high-performance energy storage systems.

Carbonization/oxidation-mediated synthesis of MOF-derived hollow nanocages of ZnO/N-doped carbon interwoven by carbon nanotubes for lithium-ion battery anodes

Partial carbonization/oxidation-mediated treatment of ZIF-8 precursors generates hollow nanocages of ZnO/N-doped carbon for high performance lithium-ion battery anodes.

In situ synthesis of ultrasmall MnO nanoparticles encapsulated by a nitrogen-doped carbon matrix for high-performance lithium-ion batteries

Ultrasmall MnO nanoparticles encapsulated into the nitrogen-rich doped carbon matrix hybrids are synthesized by annealing Mn₂(EDTA) precursors and exhibit outstanding electrochemical performance as advanced anode material for lithium-ion batteries.

Highly durable and cycle-stable lithium storage based on MnO nanoparticle-decorated 3D interconnected CNT/graphene architecture

To accommodate huge volume change and boost the inferior electrochemical reaction kinetics of manganous oxide anodes for lithium-ion batteries, a unique 3D porous CNT/graphene-MnO architecture has been synthesized, with MnO nanoparticles homogeneously decorated on 3D interconnected CNT/graphene (3DCG) conductive networks. This porous 3DCG matrix with its abundant open pores and large surface area can provide efficient channels for fast charge transport and allow full contact between the electrode and electrolyte, leading to improved electrochemical activity. The robust 3D architecture offers abundant stress buffer space to tolerate volume expansion and ensures robust structural stability during the electrochemical processes. The synergistic effect between components endows the 3DCG/MnO electrodes with excellent electrochemical performance, retaining a high specific capacity of 526.7 mA h g-1 at 2.0 A g-1 with 98% capacity retention over 1400 cycles. This work provides a promising route for the practical application of fast and durable lithium-ion batteries and suggests insights for rational structural designs with other transition metal oxides.