Stable Lithium Metal Anode Research Articles

Highly stable lithium metal anode enabled by lithiophilic and spatial-confined spherical-covalent organic framework

Li metal anode (LMA) has been considered as the most gifted anode material endowed with unprecedented theoretical specific capacity and ultralow redox potential. Nevertheless, the inevitable Li dendrite growth and frangible solid electrolyte interphase (SEI) severely impede its commercial application. Herein, a facile strategy via constructing an artificial SEI configured with highly-crystalline spherical covalent organic framework (S-COF) was applied to regulate the interfacial stability of LMA. Benefiting from the well balance of precise geometric symmetry and methodical morphology within S-COF, the regular 3D-spherical spreading with ordered 1D channels can effectively promote homogeneous distribution of Li+ flux. Meanwhile, the functional lithiophilic coordination has been identified by solid-state nuclear magnetic resonance, Fourier-transform infrared spectra and density functional theory calculations. The energetical Li+ affinity towards S-COF skeleton is prone to facilitate ion-pair dissociation and Li+ uniform transfer. Furthermore, the rigid nanochannels with space-confinement effect can also retard the large-scale lithium nucleation and dendrite formation. Consequently, the derived LiF and Li2S2/Li2S-riched S-COF@Li layer exhibits extraordinary cycling stability in Li|Li symmetrical cell, Li|LiFePO4, and Li|S full cells operated at higher current densities. The aforementioned experimental and theoretical evidences provide a viable guidance for further design and implementation of 2D COF in high energy density batteries.

Amphiphilic-triblock-copolymer-derived protective layer for stable-cycling lithium metal anodes

Lithium metal batteries have shown great potential for the development of efficient energy storage devices. However, the uncontrollable growth of lithium metal dendrites results in poor cycling efficiency and severe safety concerns. In this study, amphiphilic triblock copolymers (P123) were used for the direct polymerization of silica precursors, resulting in a well-ordered mesoporous silica structure SBA-15 with a large surface area and excellent absorbent properties for the protective layer. The protective layer consisting of SBA-15 stores Li ions in a large number of pores as an electrolyte reservoir, which exhibits sufficient ionic conductivity. Furthermore, it ensures a spatially uniform Li-ion flux on the anode surface and plays an important role in the physical blocking of dendrite growth. As proof of concept, the SAB-15 protective layer anode demonstrates a high average Coulomb efficiency, rate capability, and cycle stability at 1 mA h cm−2 over 1200 cycles. Moreover, SAB-15 can be cycled stably for more than 750 cycles in symmetric cells. The results provide insights for implementing stable lithium metal anodes in next-generation batteries.

Polydimethylsiloxane functionalized separator for a stable and fast lithium metal anode

Lithium dendrite growth and sluggish Li+ desolvation can be alleviated using a polydimethylsiloxane functionalized separator, resulting in a fast and stable lithium metal anode.

3D hierarchical Cu@Ag nanostructure as a current collector for dendrite-free lithium metal anode.

Lithium metal is considered to be the best candidate for rechargeable batteries due to its unique advantages. But the instability and the uncontrollable dendrites of the lithium metal anode greatly limit its commercialization. In recent years, in order to obtain stable Li metal anodes, various three-dimensional (3D) current collectors have been proposed. However, for traditional 3D current collectors, its advantages in structure still need to be improved. Therefore, the 3D hierarchical Cu@Ag nanostructure consisting of Ag-decorated Cu nanowires grown on Cu foam as a current collector (denoted as 3D HCu@Ag) is well designed and successfully prepared. Cu nanowires were in situ grown on Cu foam to form a 3D hierarchical current collector to further increase the specific surface area and reduce the local current density, thus suppressing the formation of dendrites. Ag nanoparticles were in situ grown on the surface of Cu nanowires by displacement reaction, which can reduce the overpotential of lithium deposition. Under the synergistic effect of optimal structure and Ag surface modification, 3D HCu@Ag exhibits extremely excellent performance. As a result, the Li-3D HCu@Ag symmetrical cell exhibits a lifetime of 1500 h with a very low voltage hysteresis. More importantly, in practical application, the Li-3D HCu@Ag||LFP full cell can cycle stably for 200 cycles at 1C and maintain an extremely high-capacity retention rate of 78.5%. The experiment results show that this design provides a new idea for the lithiophilic 3D current collector for stable lithium metal anode.

Cations and Anions Regulation Through Hybrid Ionic Liquid Electrolytes Towards Stable Lithium Metal Anode

Cations and Anions Regulation Through Hybrid Ionic Liquid Electrolytes Towards Stable Lithium Metal Anode

Adjusting Ion Diffusion Kinetics of Li Deposition in Porous Melamine Sponge Coated with Silver for Stable Lithium Metal Anode

Adjusting Ion Diffusion Kinetics of Li Deposition in Porous Melamine Sponge Coated with Silver for Stable Lithium Metal Anode

Metal nitride heterostructures capsulated in carbon nanospheres to accommodate lithium metal for constructing a stable composite anode

Although various hosts have been proposed to accommodate the Lithium (Li) metal to solve the uneven Li deposition and infinite volume change, the pulverization of the host or lithiophilic modification layer easily leads to structural damage and the poor cycling stability of the composite anode. Herein, we design a host of metal nitrides (Mo2N and WN heterostructures) nanoparticles capsulated in the hollow carbon nanospheres, which can accommodate Li metal to form a stable composite anode. The lithiophilic Mo2N guides uniform infusion and reduces the nucleation barriers of Li metal during electrochemical process. Note that the rigid WN matrix is uniformly composited with Mo2N, which can suppress the pulverization of Mo2N during the repeat Li plating/stripping, ensuring the stability of regulated deposition during long cycling. High mechanical strength, uniform surface potential distribution and good electrolyte wettability of the Li metal-based composite anode guarantee the rapid Li plating/stripping kinetics. Thus, the obtained composite anode can stably cycle 1400 h at 1 mA cm-2 and 1 mA h cm-2 in the symmetric battery. The assembled full cells with LiNi0.8Mn0.1Co0.1O2 (NCM811) also deliver high capacity retention under the high loading (8.6 mg cm-2) or lean electrolyte (2 μL mg-1) condition. This work suggests a promising host structure design to construct a highly stable lithium metal anode for practical applications.

Constructing a Lithiophilic and Mixed Conductive Interphase Layer in Electrolyte with Dual-Anion Solvation Sheath for Stable Lithium Metal Anode

Constructing a Lithiophilic and Mixed Conductive Interphase Layer in Electrolyte with Dual-Anion Solvation Sheath for Stable Lithium Metal Anode

Phenylphosphonic acid as a grain-refinement additive for a stable lithium metal anode.

Phenylphosphonic acid (PPOA) has been proposed as a new additive for carbonate electrolytes, in which the complexation reaction between PPOA and Li+ reduces the nucleus size and boosts the nucleation quantity during the plating process. Thus, enhanced cycling stability is obtained in both symmetric cells and full cells.

Bi-doped carbon dots for a stable lithium metal anode.

Bi-doped carbon dots (Bi-CDs) with rich polar groups and good compatibility were employed as co-deposition electrolyte additives to homogenize Li+ flux for dendrite-free Li deposition. High coulombic efficiency (99.0%) and long-term stability (800 h) with reduced overpotential (∼15 mV) were achieved after introducing Bi-CDs in conventional electrolyte for high-performance Li-S batteries.

An amorphous ZnO and oxygen vacancy modified nitrogen-doped carbon skeleton with lithiophilicity and ionic conductivity for stable lithium metal anodes

The ZnO and oxygen vacancies modified nitrogen-doped 3D carbon skeleton with lithiophilicity and ionic conductivity can reduce local current density and show low ion concentration on the surface to induce uniform deposition of lithium.

A solid–solution-based Li–Mg alloy for highly stable lithium metal anodes

A facile method is reported to stabilize Li-metal anodes via constructing a solid–solution-based Li–Mg alloy.

Li(110) lattice plane evolution induced by a 3D MXene skeleton for stable lithium metal anodes.

The non-uniform plating-stripping behaviours of Li metal anodes hinder the application of Li metal batteries. Here, a stable 3D matrix is designed by coating a carbon skeleton with MXene, and the significant influence of the crystallographic texture of Li metal on electrochemical behaviour is investigated. The results demonstrate that the 3D MXene/carbon skeleton can effectively induce the evolution of advantageous Li(110) facets with a dendrite-free anode interface. Consequently, the modified Li metal anodes deliver stable plating-stripping behaviours.

Ultrahigh-capacity and dendrite-free lithium metal anodes enabled by lithiophilic bimetallic oxides

A new class of lithiophilic materials, bimetallic oxides, have been developed for stable lithium metal anodes, and the obtained Li-ZnMn2O4@CC exhibits stable stripping/plating behavior at a high areal capacity up to 20 mA h cm−2.

Constructing stable lithium metal anodes using a lithium adsorbent with a high Mn3+/Mn4+ ratio

Lithium (Li) metal batteries (LMBs) have emerged as the most prospective candidates for post-Li-ion batteries. However, the practical deployment of LMBs is frustrated by the notorious Li dendrite growth on hostless Li metal anodes. Herein, a protonated Li manganese (Mn) oxide with a high Mn3+/Mn4+ ratio is used as a Li adsorbent for constructing highly stable Li metal anodes. In addition to the Mn3+ sites with high Li affinity that afford an ultralow Li nucleation overpotential, the decrease in the average Mnn+ oxidation state also induces a disordered adsorbent structure via the Jahn-Teller effect, resulting in improved Li transfer kinetics with a significantly reduced Li electroplating overpotential. Based on the mutually improved Li diffusion and adsorption kinetics, the Li adsorbent is used as a versatile host to enable dendrite-free and stable Li metal anodes in LMBs. Consequently, a modified Li||LiNi0.8Mn0.1Co0.1O2 (NMC811) coin cell with a high NMC811 loading of 4.3 mAh cm-2 delivers a high Coulombic efficiency of 99.85% over 200 cycles and the modified Li||NMC811 pouch cell also achieves a remarkable improvement in electrochemical performance. This work demonstrates a novel approach for the preparation of highly efficient Li protection structures for safe LMBs with long lifespans.

N, P-Codoped Carbon Microspheres Modified Cu Foil as a Lithiophilic Current Collector for a Stable Lithium Metal Anode

N, P-Codoped Carbon Microspheres Modified Cu Foil as a Lithiophilic Current Collector for a Stable Lithium Metal Anode

Hierarchical porous structure construction for highly stable self-supporting lithium metal anode

Lithium (Li) metal, with extremely high specific capacity and low reduction potential, is considered one of the most promising anode candidates for next-generation batteries. However, uncontrolled growth of dendritic Li and extreme volume fluctuation during cycles hinder the broad application of Li metal anodes. Herein, Li dendrite growth can be effectively suppressed by constructing a unique hierarchical porous structure. ~300 nm rigid carbon nano-box contains abundant ~20 nm Cu3P/CoP heterostructural nanobubbles. Densely growth villiform carbon tubes tangled with ~50 µm carbon nanotubes cover the surface of the carbon nano-box. This flexible interlaced matrix (Cu3P/CoP@C/CNT) possessing 3D hierarchical porous interspace and structure can effectively confine metallic Li. More than physical confinement, strong chemical bonding between Cu3P/CoP heterostructures and Li atoms is also proved by DFT calculation to regulate Li plating behavior. The LiǀCu3P/CoP@C/CNT composite anode exhibits a high average efficiency of 94.6% over 220 cycles and a long-running lifespan for 400 h with an exceptionally low voltage hysteresis of 24 mV. LiFePO4|Li@Cu3P/CoP@C/CNT full cells can be cycled 300 times at a negligible capacity decay of 0.01% per cycle at 1 C. This work inspires a self-supporting and hollow heterostructured Li container design, promoting the development of Li metal host anodes.

Stable and Efficient Lithium Metal Anode Cycling through Understanding the Effects of Electrolyte Composition and Electrode Preconditioning

Stable metal anode cycling for high energy density batteries can be realized through modification of electrolyte composition and optimization of formation protocols, i.e., electrode interphase preconditioning conditions. However, the relationship between these and the electrochemical performance is still unclear due to a lack of molecular level understanding of electric double layer (EDL) changes with modification of these two parameters. Herein, we examine the impact of ionic liquid (IL) electrolyte composition (salt concentration and cosolvent) and preconditioning cycling conditions on Li anode performance through EDL changes affecting both the solid–electrolyte interphase (SEI) and deposition morphology. Each electrolyte composition results in a particular interfacial Li-ion solvation environment, which controls the reductive stability, Li deposition potential, and ultimately the composition of properties of the SEI. The latter is dependent on the EDL composition such as the IL cation/Li-anion ratio or the presence of other surface active additives. It is found that in a superconcentrated electrolyte, a high current density (≥10.0 mA cm–2/1.0 mAh cm–2) is beneficial during the metal anode preconditioning step, compared with the case of low Li salt-containing IL. This correlates with a predominance of Lix(anion)y (x > y) at a highly negatively charged interface, which is present when higher current densities are used for preconditioning, as suggested by molecular dynamics simulations. In contrast, for the lower viscosity superconcentrated electrolyte containing 20 wt % of ether cosolvent, a more moderate preconditioning step current density (6.0 mA cm–2/1.0 mAh cm–2) leads to an optimized deposition morphology and improved cycling performance. This is a consequence of the competing processes of ion transport at the interface, which controls the Li+ ion flux and the intrinsic reduction kinetics occurring at the more negative electrode.

Self-healing single-ion-conductive artificial polymeric solid electrolyte interphases for stable lithium metal anodes

Unstable solid-electrolyte interphase (SEI) layer, accompanied with detrimental Li dendrite growth, is the major challenge for realizing viable Li metal batteries. Herein, we report a self-healing and single-ion conductive artificial SEI (SS-ASEI) layer to stabilize Li metal anode, suppress the Li dendrite growth and promote the Li plating/stripping kinetics. The polymeric SS-ASEI layer is optimized to be dynamically cross-linked poly(dimethylsiloxane) filled with 7 wt% SiO2 nanoparticles. The modified Li symmetric cell achieves extremely stable plating/stripping cycling for 1340 h at 0.5 mA cm−2 and 1.0 mAh cm−2 cutting-off capacity. Superior rate capability and cycling stability of the modified anode are also demonstrated in cells with commercial NCM811 (LiNi0.8Co0.1Mn0.1O2) cathode. The self-healing ability, elastic deformation capability, selectively high Li-ion conductivity and low liquid electrolyte swelling rate of our SS-ASEI layer synergistically account for the superior performances of modified Li electrode over the bare Li electrode.

Free-Standing N, P Codoped Hollow Carbon Fibers as Efficient Hosts for Stable Lithium Metal Anodes

Free-Standing N, P Codoped Hollow Carbon Fibers as Efficient Hosts for Stable Lithium Metal Anodes