MnWO4 nanoparticles as advanced anodes for lithium-ion batteries: F-doped enhanced lithiation/delithiation reversibility and Li-storage properties

Synergistically Boosting Li Storage Performance of MnWO4 Nanorods Anode via Carbon Coating and Additives

Polyanionic structures, (MO4)n-, can be beneficial to the transport of lithium ions by virtue of the open three-dimensional frame structure. However, an unstable interface suppresses the life of the (MO4)n--based anode. In this study, MnWO4@C nanorods with dense nanocavities have been synthesized through a hydrothermal route, followed by a chemical deposition method. As a result, the MnWO4@C anode exhibits better cycle and rate performance than MnWO4 as a Li-ion battery; the capacity is maintained at 718 mAh g-1 at 1000 mA g-1 after 400 cycles because the transport of lithium ions and the contribution of pseudo-capacitance are increased. Generally, benefiting from the carbon shell and electrolyte additive (e.g., FEC), the cycle performance of the MnWO4@C electrode is also effectively improved for lithium storage.

From spent alkaline batteries to active Zn||ZnxMn2O4 aqueous batteries: a mild process of cathode recycling and crystal engineering

A mild, efficient, and low-cost method was designed for recycling cathode materials from spent alkaline batteries into advanced aqueous zinc batteries.

In-situ self-assembled hollow urchins F-Co-MOF on rGO as advanced anodes for lithium-ion and sodium-ion batteries

To obtain MOFs materials with good electrochemical performance in both lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), a kind of hollow urchins Co-MOF with doping fluorine (F) was in-situ assembled on reduced graphene oxide (rGO) using a simple solvothermal reaction. According to XRD, XPS and EDS mapping analysis, the molecular structure should be Co₂[F_x(OH)_1-x]₂(C₈O₄H₄) (denoted as F-Co-MOF). When the composite material is used as active material to assemble LIBs, it not only presents the outstanding reversible capacity (1202.0 mA h g^-1 at 0.1 A g^-1), but also gives the excellent rate performance and cycle performance (771.5 mA h g^-1 at 2 A g^-1 after 550 repeated cycles). The remarkable lithium storage capacity of F-Co-MOF/rGO is also reflected in the full cell, where it can still maintain a high capacity of 165.2 mA h g^-1 after 300 cycles at 0.2 A g^-1. It benefits from the synergistic effect of F-Co-MOF and high conductive rGO networks, so that the reversibility of lithium and sodium storage can be improved. This kind of F doped solvothermal synthesis of MOFs is of great significance for the exploration of high performance materials.

Atomic-scale investigation of enhanced lithium, sodium and magnesium storage performance from defects in MoS2/graphene heterostructures

MoS₂ is of great interest as an anode material of batteries due to its high theoretical reversible capacity; in particular, a defective MoS₂/graphene heterostructure exhibits excellent cycling stability. However, very little is known about the diffusion and ion storage mechanism at the atomistic level. To provide insights into the issue, we have developed and used first principles calculations and an atom intercalation/deintercalation algorithm to model the adsorption, diffusion, insertion and removal of Li, Na and Mg in pristine and defective MoS₂/graphene systems. First, the adsorption of Li, Na and Mg is generally more stable in the defective MoS₂/graphene structure. Mg and Li prefer to diffuse in the structure with disulfide defects, while Na prefers to diffuse in the molybdenum defective structure. Next, we found that the atomic configurations of both pristine and defective MoS₂/graphene are not restored to their original states after the insertion and removal of Li, Na and Mg, which is related to the irreversible capacity loss of the system. Furthermore, by excluding the amount of lithium atoms related to the unrestored sulfur atoms, an algorithm was proposed to calculate the reversible capacity and it was verified by experimental results. We have also demonstrated that the introduction of defects leads to significant increase in the theoretical capacities of the Na and Mg systems, however, decreasing the capacity retention rate of Mg.

Crystal reconstruction of binary oxide hexagonal nanoplates: monocrystalline formation mechanism and high rate lithium-ion battery applications

Structural design and/or carbon modification are the most important strategies to improve the performance of materials in many applications, where metal (oxide)-based anode design attracts great attention in metal ion batteries due to their high capacities. However, achieving these two goals within one-step remains challenging due to the lower cost and higher efficiency needed to satisfy the demand in practical application. Herein, we report a new approach for the crystal reconstruction of metal oxides by acetylene treatment, in which a hierarchical binary oxide decorated with carbon (i.e., Mn2Mo3O8@C) is introduced. The mechanism of constructing unique monocrystalline hexagonal nanoplates and uniform carbon coating is discussed in detail. Benefiting from the uniqueness of structure and composition, the Mn2Mo3O8@C demonstrates an extremely high lithium storage capacity of 890 mA h g-1 and good rate capacities at 20 A g-1 over 1000 cycles. In addition, the high rate capabilities and long cycle lifespan are further confirmed when the Mn2Mo3O8@C anode is matched with the nickel-rich layered oxide cathode. This study not only introduces a new binary oxide anode with high performances in lithium (ion) batteries but also presents a convenient methodology to design more advanced functional materials.

Investigation of two-dimensional hf-based MXenes as the anode materials for li/na-ion batteries: A DFT study

Density functional theory calculations are performed to investigate electronic properties and Li/Na storage capability of Hf₃ C₂ and its derivatives (uniform passivated: Hf₃ C₂ T₂ [T = F, O, OH] and hybrid passivated: Hf₃ C₂ F_x O_2-x and Hf₃ C₂ O_x (OH)_2-x [x = 1.0, 1.5]). For Hf₃ C₂ monolayer, it has excellent performance, such as good conductivity, low diffusion energy barrier, low open circuit voltage, and high storage capacities (Li(1034.70 mAh g^-1 ), Na(444.90 mAh g^-1 )), providing the most prospective as anode material. However, due to the unsaturated dangling bonds of surface Hf, so it is easily passivated. For the uniform passivated ones, Hf₃ C₂ T₂ , show higher diffusion barriers and lower storage capacities than bare monolayer Hf₃ C₂ . Nevertheless, compared with uniform passivated ones, the hybrid passivated derivative, Hf₃ C₂ F_1.5 O_0.5 and Hf₃ C₂ OOH possess a lower energy barrier and a better storage capacity. Therefore, Hf₃ C₂ F_1.5 O_0.5 and Hf₃ C₂ OOH are deemed to be a suitable candidate as anode electrode material for Li-ion batteries. © 2019 Wiley Periodicals, Inc.

Formation of Mn–Cr mixed oxide nanosheets with enhanced lithium storage properties

Novel carbon-free Mn₂O₃/MnCr₂O₄ hybrid nanosheets are synthesized. As an anode for lithium-ion batteries, they deliver a wonderful electrochemical performance.