Coral-Inspired Nanoengineering Design for Long-Cycle and Flexible Lithium-Ion Battery Anode

Abstract

Conversion reaction electrode materials (CREMs) have gained significant interest in lithium-ion batteries (LIBs) owing to their high theoretical gravimetric capacity. However, traditional CREMs-based electrodes, with large strain arising from Li(+) intercalation/deintercalation causes pulverization or electrical breakdown and cracking of the active materials which leads to structural collapse, limiting performance. Therefore, in order to construct electrodes with a strong tolerance to the strain incurred during the conversion reaction process, we design a coral-like three-dimensional (3D) hierarchical heterostructure by using cross-linked nanoflakes interspersed with nanoparticles (NPs) standing vertically on graphene foam (GF). The coral-like 3D hierarchical heterostructures can efficiently disperse the strain from both internal and external forces as well as increase the specific surface area for enhanced electrochemical reactions. These features lead to long-cycle stability and excellent flexibility in LIBs. Fe3O4 NPs and CoO NFs are utilized as a model system to demonstrate our strategy. The as-prepared coral-like hierarchical electrode is studied as an anode in LIBs for the first time and is shown to deliver a high reversible specific gravimetric capacity of ∼1200 mA h g(-1) at a rate of 0.5 A g(-1) for 400 cycles. In addition, our batteries can even power a green light-emitting diode when bent to high degrees confirming the excellent flexibility of the material.

Nano-SnO2/Carbon Nanotube Hairball Composite as a High-Capacity Anode Material for Lithium Ion Batteries

“…Moreover, this structure can facilitate electrolyte diffusion and penetration through the electrode and maintain good contact between the SnO 2 and the conductive CNTs, which will favor to the rapid transport of electrons and lithium ions. 3 The diffraction rings are observed in the SAED pattern of SnO 2 /CNTH (inset of Figure 4a), revealing the polycrystalline nature of the SnO 2 particles. As shown in Figure 4b, the SnO 2 crystallites (nanograins) are interspersed uniformly on the surface of cross-linked CNTs and are interconnected with each other.…”

“…The nanodispersed SnO 2 particles with the hierarchic structure would provide more electrochemical reaction sites and disperse the strain generated during the electrochemical reaction. Moreover, this structure can facilitate electrolyte diffusion and penetration through the electrode and maintain good contact between the SnO 2 and the conductive CNTs, which will favor to the rapid transport of electrons and lithium ions . The diffraction rings are observed in the SAED pattern of SnO 2 /CNTH (inset of Figure a), revealing the polycrystalline nature of the SnO 2 particles.…”

“…However, their applications in practical LIBs are severely hampered by the unsatisfactory cyclability resulting from their inherent low conductivity and large volume change. Thus, many attempts have been taken so that properties of conversion-type anode materials can be improved. − …”

Issues and Challenges Facing Flexible Lithium‐Ion Batteries for Practical Application

“…Recently, a variety of electrode morphologies such as nanostructure, porous structure, and twisted structure have been reported to reduce the stress of cells upon flexing. Yu and co‐workers reported self‐supported LTO nanotube arrays as anode materials .…”

Transition Metal Migration Can Facilitate Ionic Diffusion in Defect Garnet-Based Intercalation Electrodes

“…Structural transformations triggered by the transport of alkali ions through the solid state can strongly affect the performance of rechargeable Li-ion batteries. , Large changes in the unit-cell volume of active materials lead to the degradation of electrodes and can eventually fracture the film, creating electrically inaccessible regions within the cell. − Similarly, substantial atomic rearrangements can complicate Li-ion diffusion pathways and hinder conductivity . Hence, the performance of intercalation battery electrodes is intimately tied to processes that occur at the atomic length scale …”