Jin-Yi Li

Passivation of Lithium Metal Anode via Hybrid Ionic Liquid Electrolyte toward Stable Li Plating/Stripping

Hybrid electrolyte of ionic liquid and ethers is used to passivate the surface of Li metal surface via modification of the as‐formed solid electrolyte interphase with N‐propyl‐N‐methylpyrrolidinium bis(trifluoromethanesulfonyl)amide (Py13TFSI), thereby reducing the side reactions between the Li metal and electrolyte, leading to remarkably suppressed Li dendrite growth and mitigating Li metal corrosion.

Stable Li Metal Anodes via Regulating Lithium Plating/Stripping in Vertically Aligned Microchannels

Li anodes have been rapidly developed in recent years owing to the rising demand for higher-energy-density batteries. However, the safety issues induced by dendrites hinder the practical applications of Li anodes. Here, Li metal anodes stabilized by regulating lithium plating/stripping in vertically aligned microchannels are reported. The current density distribution and morphology evolution of the Li deposits on porous Cu current collectors are systematically analyzed. Based on simulations in COMSOL Multiphysics, the tip effect leads to preferential deposition on the microchannel walls, thus taking full advantage of the lightening rod theory of classical electromagnetism for restraining growth of Li dendrites. The Li anode with a porous Cu current collector achieves an enhanced cycle stability and a higher average Coulombic efficiency of 98.5% within 200 cycles. In addition, the resultant LiFePO4 /Li full battery demonstrates excellent rate capability and stable cycling performance, thus demonstrating promise as a current collector for high-energy-density, safe rechargeable Li batteries.

A Flexible Solid Electrolyte Interphase Layer for Long-Life Lithium Metal Anodes

Lithium (Li) metal is a promising anode material for high-energy density batteries. However, the unstable and static solid electrolyte interphase (SEI) can be destroyed by the dynamic Li plating/stripping behavior on the Li anode surface, leading to side reactions and Li dendrites growth. Herein, we design a smart Li polyacrylic acid (LiPAA) SEI layer high elasticity to address the dynamic Li plating/stripping processes by self-adapting interface regulation, which is demonstrated by in situ AFM. With the high binding ability and excellent stability of the LiPAA polymer, the smart SEI can significantly reduce the side reactions and improve battery safety markedly. Stable cycling of 700 h is achieved in the LiPAA-Li/LiPAA-Li symmetrical cell. The innovative strategy of self-adapting SEI design is broadly applicable, providing opportunities for use in Li metal anodes.

Research progress regarding Si-based anode materials towards practical application in high energy density Li-ion batteries

Silicon has been considered as one of the most promising high-capacity anode materials because of its environmentally friendly character, natural abundance, and attractive operating voltage. However, successful implementation of Si-based anodes in Li-ion batteries is seriously hindered by their huge volume variation and low electric conductivity. The rational design of Si and effective combination of nanosized Si with carbonaceous materials represent the most effective approaches to overcome the challenges towards practical application of Si-based anodes. In this review, the mechanisms of Li–Si alloying and cell failure are briefly analyzed to comprehend the inherent impediments of Si-based anodes. Furthermore, nano-structured Si materials are summarized and nano/micro-structured Si/C and SiOx/C composites with 3D conductive networks and stable interfaces are discussed in detail. Accessory battery components that influence electrochemical performance are also reviewed. As for practical application, full batteries with Si-based anodes are discussed. Finally, the key aspects of Si-based materials are emphasized and prospective strategies for promoting the practical applications of Si-based anodes in high energy density Li-ion batteries are proposed.

Uniform Lithium Nucleation/Growth Induced by Lightweight Nitrogen‐Doped Graphitic Carbon Foams for High‐Performance Lithium Metal Anodes

The lithium metal anode has attracted soaring attention as an ideal battery anode. Unfortunately, nonuniform Li nucleation results in uncontrollable growth of dendritic Li, which incurs serious safety issues and poor electrochemical performance, hindering its practical applications. Herein, this study shows that uniform Li nucleation/growth can be induced by an ultralight 3D current collector consisting of in situ nitrogen-doped graphitic carbon foams (NGCFs) to realize suppressing dendritic Li growth at the nucleating stage. The N-containing functional groups guide homogenous growth of Li nucleus nanoparticles and the initial Li nucleus seed layer regulates the following well-distributed Li growth. Benefiting from such favorable Li growth behavior, superior electrochemical performance can be achieved as evidenced by the high Coulombic efficiency (≈99.6% for 300 cycles), large capacity (10 mA h cm-2 , 3140 mA h g-1NGCF-Li ), and ultralong lifespan (>1200 h) together with low overpotential (<25 mV at 3 mA cm-2 ); even under a high current density up to 10 mA cm-2 , it still displays low overpotential of 62 mV.

Nano/Micro-Structured Si/C Anodes with High Initial Coulombic Efficiency in Li-Ion Batteries.

One of the major challenges for designing high-capacity anode materials is to combine both Coulombic efficiency and cycling stability. Herein, nano/micro-structured Si/C composites are designed and synthesized to address this challenge by decreasing the specific surface area and improving the tap density of Si/C materials. An ultrahigh initial Coulombic efficiency of 91.2 % could be achieved due to a proper particle size, low specific surface area, and optimized structure. The nano/micro-structured Si/C anodes exhibit excellent cycling stability with 96.5 % capacity retention after 100 cycles under a current density of 0.2 A g(-1) .

Gradiently Polymerized Solid Electrolyte Meets with Micro-/Nanostructured Cathode Array

The poor contact between the solid-state electrolyte and cathode materials leads to a high interfacial resistance, severely limiting the rate capability of solid Li metal batteries. Herein, an integrative battery design is introduced with a gradiently polymerized solid electrolyte (GPSE), a microchannel current collector array, and nanosized cathode particles. An in situ formed GPSE encapsulates cathode nanoparticles in the microchannel with ductile inclusions to lower the interfacial impedance, and the stiff surface layer of GPSE toward anode suppresses the Li dendrite growth. The Li metal batteries based on GPSE and the Li-free hydrogenated V2O5 (V2O5-H) cathode exhibit an outstanding high rate response of up to 5 C (the capacity ratio of 5 C/1 C is 90.3%) and an ultralow capacity fade rate of 0.07% per cycle over 300 cycles. The other Li-containing cathodes such as LiFePO4 and LiNi0.5Mn0.3Co0.2O2 can also operate effectively at the rates of 5 and 2 C, respectively. Such an ingenious design may provide new insights into other solid metal batteries through an interfacial engineering manipulation at the micro- and nanolevel.

Stable Sodium Storage of Red Phosphorus Anode Enabled by a Dual-Protection Strategy

Red phosphorus is appealing for anode use in sodium-ion batteries. However, the synthesis of electrochemically stable red P anodes remains challenging due to a notable volume variation upon (de)sodiation, and limited synthetic methods arising from the low ignition and sublimation temperatures. To address the above problems, we herein successfully develop an industrially adaptable process for scalable synthesis of affordable phosphorus/carbon (APC) anode materials with an excellent electrochemical performance at a significantly reduced cost. The key to our success is a delicately designed, self-organized, strongly interactive porous P/C structure filled with sodium alginate binder, which maintains the structural integrity of anode and enhances the electrical contact of red P upon its volume variation via a dual protection from porous structure and strong surface interactions. The APC anodes hence present ultrahigh initial Coulombic efficiency (86.2%), excellent cycling stability, and superior rate capability. The industrially adaptable process and excellent electrochemical performance endow the novel APC nano/microspheres with promising applications in high-performance Na-ion batteries.