Neat Design for the Structure of Electrode To Optimize the Lithium-Ion Battery Performance

Abstract

The appearance of mechanical cracks originated from anisotropic expansion and shrinkage of electrode particles during Li de/intercalation is a major cause of the capacity fading in Li-ion batteries. Well-designed and controlled nanostructures of electrodes have shown a prominent prospect for solving this obstacle. Here, we report a novel and convenient strategy for the preparation of graphene nanoscroll wrapping NbO nanoparticles (denoted as T-NbO/G). First, high energy ball milling is conducted to acquire softly agglomerated T-NbO nanoparticles owing to its spontaneous reduction of surface energy among these single particles. Then freeze-drying leads to the formation of graphene nanoscroll, which easily realizes the in situ wrapping over softly agglomerated T-NbO nanoparticles. Extended cycling tests demonstrate that such T-NbO/G yields a high reversible specific capacity of 222 mA h g over 700 cycles at 1C. The dominated surface capacitive insertion processes possessing favorable kinetics enable T-NbO/G to exhibit excellent rate performance, which achieve a capacity of 110 mA h g at 10C. A combined ex situ X-ray diffraction, scanning electron microscopy, and transmission electron microscopy investigation reveal that the long-term cycling stability of T-NbO/G is attributed to the excellent structural stability of the electrode, in which the synergistic effect between the softly agglomerated T-NbO nanoparticles and graphene nanoscroll prevents the formation of mechanical cracks.

Three Electron Reversible Redox Reaction in Sodium Vanadium Chromium Phosphate as a High‐Energy‐Density Cathode for Sodium‐Ion Batteries

“…The kinetic behavior of sodium storage in Na 3 V 1.5 Cr 0.5 (PO 4 ) 3 was studied via CV analysis with different scan rates (Figure e). Metal‐ion electrochemical storage can be divided into two processes, a diffusion reaction and a pseudocapacitance process . The diffusion reaction process usually plays the dominant role in sodium‐ion storage; the pseudocapacitance behavior is beneficial for rate capability and extended cycling life.…”

Advantageous Functional Integration of Adsorption‐Intercalation‐Conversion Hybrid Mechanisms in 3D Flexible Nb2O5@Hard Carbon@MoS2@Soft Carbon Fiber Paper Anodes for Ultrafast and Super‐Stable Sodium Storage

“…This phenomenon indicates that the sodium storage mechanism of Nb 2 O 5 @MoS 2 @C CNFs is mainly derived from surface‐controlled pseudocapacitive reaction, which can bring the fast Na‐ion insertion/extraction behavior. In addition, on the basis of the relationship between i and v , i can be divided into two parts at a fixed potential (V), which can be expressed as: i ( V ) = k 1 v + k 2 v 1/2 , where k 1 v and k 2 v 1/2 represent surface‐controlled capacitance and diffusion‐controlled intercalation reactions, respectively . The values of k 1 and k 2 can be calculated by plotting i / v 1/2 versus v 1/2 at a fixed V ‐value with various scan rates.…”

Niobium‐Based Oxides Toward Advanced Electrochemical Energy Storage: Recent Advances and Challenges

“…As increasing the current density from 0.2 to 5 A g −1 , the film electrode still maintains a high capacity retention of 60%. Graphene nanoscroll wrapping T‐Nb 2 O 5 compound have been successfully prepared by Zhao et al with the aid of freeze‐drying method . This electrode exhibits high reversible specific capacities of 222 and 110 mA h g −1 at 1 and 10C rate, respectively.…”