Urchin-like Co3O4 microspheres have been obtained through a two-step hydrothermal method followed by a post-calcination process and show a unique hollow structure with mesoporous nanosheets on their surface. Oxygen vacancies on the ultrathin nanosheets were introduced by annealing treatment, inducing a local built-in electric field to promote the migration of Li ions by Coulomb force during cycling and leading to a superior electrochemical performance for lithium-ion batteries. The electrodes containing urchin-like mesoporous hollow Co3O4 microspheres delivered a high discharge capacity of 2164.1 mA h g−1 at 0.05 A g−1 after 100 cycles. Even at a higher current density of 1.0 A g−1, a remarkable discharge capacity of 1307.9 mA h g−1 after 1000 cycles could still be achieved.

Oxygen vacancy derived local build-in electric field in mesoporous hollow Co3O4 microspheres promotes high-performance Li-ion batteries

Metal oxide-based nanomaterials are widely studied because of their high-energy densities as anode materials in lithium-ion batteries. However, the fast capacity degradation resulting from the large volume expansion upon lithiation hinders their practical application. In this work, the preparation of walnut-like multicore–shell MnO encapsulated nitrogen-rich carbon nanocapsules (MnO@NC) is reported via a facile and eco-friendly process for long-cycling Li-ion batteries. In this hybrid structure, MnO nanoparticles are uniformly dispersed inside carbon nanoshells, which can simultaneously act as a conductive framework and also a protective buffer layer to restrain the volume variation. The MnO@NC nanocapsules show remarkable electrochemical performances for lithium-ion batteries, exhibiting high reversible capability (762 mAh g−1 at 100 mA g−1) and stable cycling life (624 mAh g−1 after 1000 cycles at 1000 mA g−1). In addition, the soft-packed full batteries based on MnO@NC nanocapsules anodes and commercial LiFePO4 cathodes present good flexibility and cycling stability.

Walnut-Like Multicore–Shell MnO Encapsulated Nitrogen-Rich Carbon Nanocapsules as Anode Material for Long-Cycling and Soft-Packed Lithium-Ion Batteries

The development of inexpensive electrode materials with a high volumetric capacity and long cycle-life is a central issue for large-scale lithium-ion batteries. Here, we report a nanostructured porous Fe2N anode fully encapsulated in carbon microboxes (Fe2N@C) prepared through a facile confined anion conversion from polymer coated Fe2O3 microcubes. The resulting carbon microboxes could not only protect the air-sensitive Fe2N from oxidation but also retain thin and stable SEI layer. The appropriate internal voids in the Fe2N cubes help to release the volume expansion during lithiation/delithiation processes, and Fe2N is kept inside the carbon microboxes without breaking the shell, resulting in a very low electrode volume expansion (the electrode thickness variation upon lithiation is ∼9%). Therefore, the Fe2N@C electrodes maintain high volumetric capacity (1030 mA h cm–3 based on the lithiation-state electrode volume) comparable to silicon anodes, stable cycling performance (a capacity retention of over 91...

Air-Stable Porous Fe2N Encapsulated in Carbon Microboxes with High Volumetric Lithium Storage Capacity and a Long Cycle Life

Tin foil should have outstanding volumetric capacity as a Li-ion battery anode; however, it suffers from an unacceptable initial coulombic efficiency (ICE) of 10–20%, which is much poorer than that of Si or SnO2 nanoparticles. Herein, we demonstrate that bare Sn catalyzes liquid electrolyte decomposition at intermediate voltages to generate gas bubbles and Leidenfrost gas films, which hinder lithium-ion transport and erode the solid–electrolyte interphase (SEI) layer. By metallurgically pre-alloying Li to make LixSn foil, the lower initial anode potential simultaneously suppresses gassing and promotes the formation of an adherent passivating SEI. We developed a universally applicable roll-to-roll mechanical prelithiation method and successfully prelithiated Sn foil, Al foil and Si/C anodes. The as-prepared LixSn foil exhibited an increased ICE from 20% to 94% and achieved 200 stable cycles in LiFePO4//LixSn full cells at ∼2.65 mA h cm−2. Surprisingly, the LixSn foil also exhibited excellent air-stability, and its cycling performance sustained slight loss after 12 h exposure to moist air. In addition to LiFePO4, the LixSn foil cycled well against a lithium nickel cobalt manganese oxide (NMC) cathode (4.3 V and ∼4–5 mA h cm−2). The volumetric capacity of the LixSn alloy in the LFP//LixSn pouch cell was up to ∼650 mA h cm−3, which is significantly better than that of the graphite anode on a copper collector, with a rate capability as high as 3C.

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Roll-to-roll prelithiation of Sn foil anode suppresses gassing and enables stable full-cell cycling of lithium ion batteries

Silicon and lithium metal are considered as promising alternatives to state-of-the-art graphite anodes for higher energy density lithium batteries because of their high theoretical capacity. However, significant challenges such as short cycle life and low coulombic efficiency have seriously hindered their practical applications. In the past decades, various strategies have been proposed to address the major problems of Si and Li anodes. In this review, we summarize the understanding on Si and Li anodes, highlight the recent progress in the development and introduce advanced characterization techniques. We also indicate the remaining challenges of Si and Li anodes requiring more efforts for future widespread applications. We expect that this review provides an overall picture of the recent progress and inspires more efforts in the fundamental understanding and practical applications of Si and Li anodes.

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Towards high energy density lithium battery anodes: silicon and lithium

A novel design of hollow structured SnO2@Si nanospheres was presented, which not only demonstrates high volumetric capacity as anode of LIBs, but also prevents aggregation of Sn and confines solid electrolyte interphase thickening. An impressive volumetric specific capacity of 1030 mAh cm–3 was maintained after 500 cycles. The electrochemical impedance spectroscopy and differential scanning calorimetry indicated that solid electrolyte interphase can be confined in pores of as-prepared hollow structured SnO2@Si.

High Volumetric Capacity of Hollow Structured SnO2@Si Nanospheres for Lithium-Ion Batteries.

A design of coaxial hollow nanocables of carbon nanotubes and silicon composite (CNTs@Silicon) was presented, and the lithiation/delithiation behavior was investigated. The FIB-SEM studies demonstrated hollow structured silicon tends to expand inward and shrink outward during lithiation/delithiation, which reveal the mechanism of inhibitive effect of the excessive growth of solid–electrolyte interface by hollow structured silicon. The as-prepared coaxial hollow nanocables demonstrate an impressive reversible specific capacity of 1150 mAh g–1 over 500 cycles, giving an average Coulombic efficiency of >99.9%. The electrochemical impedance spectroscopy and differential scanning calorimetry confirmed the SEI film excessive growth is prevented.

Lithiation Behavior of Coaxial Hollow Nanocables of Carbon-Silicon Composite.

The invention provides a continuous and batch preparation method and a preparation device of nano-particle materials. The method comprises: performing preheating to allow a core material, a precursorof a shell material, and a fluidized gas reaches respective independent temperature; adding the preheated nuclear material into a reactor, continuously introducing the fluidized gas to enable the corematerial to be in a fluidized state, and heating the core material in the fluidized state to a fourth temperature higher than the reaction temperature of the precursor of the shell material; and thenintroducing the precursor of the shell material to ensure the core material is fully and uniformly dispersed in the precursor of the shell material so as to react to generate a coated material. In the method disclosed by the invention, the core material is in a flowing state, the utilization rate of reactants is high, the reaction is sufficient, and the obtained nano-product is uniform and controllable. The reaction device is designed with a plurality of temperature control zones, so that the reaction process can be effectively regulated and controlled. According to the fluidized bed reactor,the nano coated material and a nano hollow material can be produced in a large scale in a large scale industrial production standard.

Continuous and batch preparation method and preparation device of nano-particle materials

The invention relates to a preparation method and a preparation device of a coated material or hollow material. In the method disclosed by the invention, only the temperature of a precursor of a shellmaterial which is in contact with a core material is above reaction temperature, so that the shell material can be controllably generated on the surface of the core material; moreover, in the dispersion process of the core material in the precursor, the core material is not easy to agglomerate, so that an uniform and fine coated material can be obtained. The invention also discloses application in the lithium battery field and specific negative electrode hollow silicon, raw material sources are rich, silane utilization rate is high, large-batch continuous production can be carried out, and the method has very high industrial value.

Wenguang Zhang

Papers

High Volumetric Capacity of Hollow Structured SnO2@Si Nanospheres for Lithium-Ion Batteries.

Lithiation Behavior of Coaxial Hollow Nanocables of Carbon-Silicon Composite.

Continuous and batch preparation method and preparation device of nano-particle materials

Preparation method and preparation device of coated material or hollow material