Self‐Supporting 3D Lithiophilic and Flexible Carbon Nanofiber Film as a High‐Loading Li Host

Abstract

The ever-growing demands of rechargeable portable devices, electric vehicles, and large-scale grid energy storage have greatly accelerated the research of high-energy-density batteries. [1] Due to its high theoretical specific capacity (3860 mAh g À1 ) and low electrochemical potential (À3.04 V versus the standard hydrogen electrode), [2] lithium (Li) metal is regarded to be an important choice for battery system with high energy density. [3] However, there are some obstacles the Li anode has to remove before its application, including dendritic lithium formation, [4] unlimited volume change, [5] and unstable solid-electrolyte interface (SEI) layer. [6] Various strategies have been explored to achieve the Li anode protection, such as in situ protection by optimizing electrolyte, [7] ex situ protection by introducing an artificial SEI layer, [8] reasonable design of Li metal anode structure, [9] construction of novel solid electrolyte, [10] etc. Among these strategies, the construction of 3D current collectors or Li hosts seems to be a comprehensive solution. Researchers have chosen a series of metal elements, metal oxides, and heteroatoms as lithiophilic sites decorated on traditional 3D current collectors including copper foam, [11] nickel foam, [12] copper mesh, [13] etc. However, these current collectors are all metal based, and the large density makes them occupy too much weight of the whole battery.In view of this, 3D carbon skeletons with lightweight and high specific surface area would be ideal hosting materials for high-energy-density Li metal battery systems. [14] However, the common methods of lithiophilic layer construction for 3D carbon current collector are difficult for large-scale application, like chemical vapor deposition (CVD) [15] or atomic layer deposition (ALD). [16] Thus, developing feasible strategy of fabricating lithiophilic carbon framework is vital for the practical application of Li metal anode.Electrospinning is one of the most scalable techniques that produce nanofibrous membranes with highly porous structure, abundant active sites, and excellent mechanical properties. [17] If lithiophilic active sites and carbon precursor could be eletrospun simultaneously into uniformly hybrid membrane, then a 3D lithiophilic carbon Li host would be obtained. As a source of lithiophilic elemental Zn, [18] Zeolitic imidazolate framework-8 (ZIF-8) has been used to facilitate the Li-ion flow at the Li anode side for dendrite-free Li deposition. [19] As for the carbon source, polyacrylonitrile (PAN) is one of the most widely used polymers for electrospinning, [20] and it has been applied in Li batteries due

Assembly: A Key Enabler for the Construction of Superior Silicon‐Based Anodes

“…[ 25 , 26 , 27 ] The assembly can significantly enhance the comprehensive properties of the material compared with the primary structural units, thus the assembly strategy is widely used in the fields of optoelectronics, biological medicine, catalysis, energy storage and so on. [ 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ] As an anode material for lithium‐ion batteries, the assembled micron‐scale material has a lower interfacial area compared with the nanoparticles, which can effectively reduce the interparticle resistance at the nano‐size and mitigate the risk of side effects, thereby improving the energy density of the lithium‐ion battery. Moreover, under the same mass loading, the micron‐scale assembly can obtain a higher tap density, which makes the electrode thickness thinner and the electron transfer pathway shorter and increases the volumetric specific capacity of the whole cell.…”

Negatively Charged Holey Titania Nanosheets Added Electrolyte to Realize Dendrite‐Free Lithium Metal Battery

“…[26,27] The commonly applied methods include the building of 3D conductive host to decease the local current density and homogenize space charge distribution, and decorating the surface with lithiophilic sites to regulate the uniform lithium nucleation and growth. [28][29][30][31] However, either the electrolyte modulation or electrode design has its own advantages and disadvantages. Electrolyte modulation is simple, but not very effective to regulate the ion flux.…”