Lithium Metal Anodes For Batteries Research Articles

Advancing anode-less lithium metal batteries: ZnF2 modification and in situ structural regulation for enhanced performance

A novel LiF@LiZn10/Li composite foil was developed as an effective anode for lithium metal batteries. The uniform lithiophilic substrate and the LiF-rich SEI optimize Li+ deposition.

(Battery Division Research Award) Advanced Characterization of Electrochemical Interfaces and Systems for Next-Generation Batteries

Lithium (Li) metal has been considered as an ideal anode for high-energy rechargeable Li batteries while Li nucleation and growth at the nano scale remains mysterious as to achieving reversible stripping and deposition. A few decades of research have been dedicated to this topic and we have seen breakthroughs in novel electrolytes in the last few years, where the efficiency of lithium deposition is exceeding 99.6%. Here, cryogenic-transmission electron microscopy (Cryo-TEM/Cryo-FIB) was used to reveal the evolving nanostructure of Li deposits at various transient states in the nucleation and growth process, in which a disorder-order phase transition was observed as a function of current density and deposition time. More importantly, the complementary techniques such as titration gas chromatography (TGC) reveals the important insights about the phase fraction of solid electrolyte interphases (SEI) and electrochemical deposited Li (EDLi). While cryo-EM has made significant contributions to enabling lithium metal anodes for batteries, its applications in the area of electrochemical interphases such as those in all solid state batteries, beyond lithium batteries are still in the infancy, therefore, I will discuss a few new perspectives about how future advanced imaging and spectroscopic techniques can help to accelerate the innovation of novel energy storage materials and architectures.

Nanoarray Architecture of Ultra-Lithiophilic Metal Nitrides for Stable Lithium Metal Anodes.

Lithium metal anode (LMA) is puzzled by the serious issues corresponding to infinite volume change and notorious lithium dendrite during long-term stripping/plating process. Herein, the transition metal nitrides array with outstanding lithiophilicity, including CoN, VN, and Ni3 N, are decorated onto carbon framework as "nests" to uniform Li nucleation and guide Li metal deposition. These transition metal nitrides with excellent conductivity can guarantee the fast electron transport, therefore maintain a stable interface for Li reduction. In addition, the designed multi-dimensional structure of metal nitride array decorated carbon framework can effectively regulate the growth of Li metal during the stripping/plating process. Of note, attributing to the lattice-matching between CoN and Li metal, the composite Li/CoN@CF anode exhibits ultra-stable cycling performance in symmetrical cells (over 4000 h@1mAcm-2 with 1mAhcm-2 and 1000h@20mAcm-2 with 20mAhcm-2 ). The assembled full cells based on Li/CoN@CF composite anode, LiFePO4 or S as cathodes, deliver excellent cycling stability and rate capability. This strategy provides an effective approach to develop a stable lithium metal anode for lithium metal batteries.

Highly defective Ti3CNTx-MXene-based fiber membrane anode for lithium metal batteries

Lithium metal batteries (LMBs) have attracted increasing attention owing to their high theoretical capacity and low reduction potential. However, safety concerns and their low coulombic efficiencies (CE) arising from the nonuniform and irreversible formation of Li dendrites on their anodes hinder their practical application. Here, we demonstrate that a highly defective titanium-carbonitride (Ti3CNTx)-MXene-based fiber membrane can function as a dendrite-free anode substrate for LMBs. The Ti3CNTx fiber membrane electrodes, prepared via the electrostatic self-assembly of Ti3CNTx flakes onto a glass-fiber membrane substrate, had a high surface area (∼276 m2 g−1), leading to a high CE of ∼99.1%, excellent cycling stability of more than 1000 cycles in a Li half-cell test, and high energy density (581.78 W h kg−1) and high power density (3008 W kg−1) in a Li-MXene-fiber/NCM622 full-battery test. This excellent cell performance is attributed to the strong lithiophilicity and high density of Ti vacancy defects in the Ti3CNTx MXenes, as well as the high surface area of the fiber membrane electrode. The lithiophilicity and defect structure of Ti3CNTx MXenes in LMB operation were elucidated by DFT calculations.

Optimization of Magnesium-Doped Lithium Metal Anode for Lithium Metal Batteries: Simulation and Experiment

To further improve the energy density of the current lithium ion batteries, tremendous effort has been made on the development of anode materials with higher capacities than the widely commercialized graphite. Lithium metal is considered as the most attractive anode candidate for lithium batteries because of its ultrahigh specific capacity (3860 mAh g-1) and extremely low redox potential (-3.040 V vs. standard hydrogen electrode). While the uncontrolled lithium dendrite growth and the interfacial instability, leading to low Coulombic efficiency, are two big problems for pure lithium metal anodes. Lithium-magnesium alloy has been considered as a potential alternative anode material. There have been some studies of magnesium amount on lithium-magnesium alloy anode with a wide range. It is found that even a marginal amount of magnesium can improve the battery performance. However, the optimum content of magnesium in lithium-magnesium alloy anode and the mechanism on cell performance are still not well understood. Quantum chemistry and molecular dynamics simulation methods have been widely used in advanced electrode materials design to accelerate the material discovery and development. Computational and experimental approaches are combined to optimize the amount of magnesium in lithium-magnesium alloy anode materials and investigate the cell performance. This work focuses on lithium-magnesium alloy with limited magnesium amount. The density functional theory calculation is employed to investigate the effect of doping magnesium amount in lithium-magnesium alloy anode. Simulation results show that the additional magnesium atom in lithium-magnesium alloy can control the plating/stripping of lithium atoms on the alloy anode surface. Moreover, an optimum ratio of magnesium in lithium-magnesium alloy is found when calculating the absorption energy of lithium atom on lithium-magnesium alloy surface. Electrochemical experiments further demonstrate that the alloy anode material with the optimal ratio of magnesium exhibits the best cycling stability in lithium metal batteries with high nickel layered oxide cathode. This work provides an effective approach to identify optimal alloying-type lithium metal anodes for improving long-term cycling stability of high-energy-density lithium metal batteries. More details will be discussed at the presentation.

ZnF2 doped porous carbon nanofibers as separator coating for stable lithium-metal batteries

In this work, the ZnF2 doped three-dimensional (3D) porous carbon nanofibers (ZnF2-PCNFs) were prepared via the electro-blow spinning (EBS) and carbonization strategy. And its applications as promising interlayer to hybridize with metal Li as composite anode for lithium metal batteries (LMBs) were systematically investigated and researched. The 3D interconnected porous skeleton with a high electrical conductivity and large surface area could reduce the local current density and endow the significantly enhanced interfacial compatibility between the interlayer and lithium electrode including a high lithium-loading capacity. Moreover, the lithiophilic ZnF2 nanoparticles formed in-situ during carbonization process could provide more active sites to trigger an analogous alloying reaction with Li to guide the Li plating/stripping more homogeneous. For the assembled Li||LiFePO4 (LFP) batteries with ZnF2-PCNFs, the optimal initial discharge capacity and capacity retention after 500 cycles at 1C were 142.70 mAh g−1 and 96.42%, respectively. The symmetric Li||Li batteries further showed that the ZnF2-PCNFs coating interlayer could hinder Li dendrite growth and improve the cycling stability. In addition, the obtained Li||S battery with ZnF2-PCNFs also delivered the outstanding cycle performance among the various samples based on the convenient transport channels of Li ions and the strong adsorption or captured ability of ZnF2-PCNFs to species. These facts demonstrated that the prepared ZnF2-PCNFs coating acting as interlayer between separator and anode could effectively enhance safety and electrochemical performance of LMBs.

Porosity controlled carbon-based 3D anode for lithium metal batteries by a slurry based process

A carbon-based porous electrode was fabricated by a facile slurry based process using polymethyl methacrylate (PMMA) as a pore-forming agent. It exhibited the reversible reaction of Li into the inner pores of the as-synthesized electrode without dendritic Li growth, which resulted in showing the outstanding cycle performances for lithium metal batteries.

Cu coated soft fabric as anode for lithium metal batteries

Lithium dendrite related problems form a major barrier that limits the application of lithium metal anode for Li-ion batteries. Here a copper coated 3D soft fabric anode was developed to show superior battery performance under an optimized mechanical stress for the lithium metal anode application. A scalable two-step dip-coating method was applied to coat Cu onto various insulating cloth fabrics, making them electrically conductive. In our battery tests, the 3D soft conductive fabric contributes to a more uniform lithium deposition during the battery cycling, which works for more than 1000 h. The mechanism for suppressing lithium dendrite growth by the mechanical interaction with 3D Cu-fabric was also revealed by a combination of microscopy characterization, electrochemical test and theoretical modeling, which provides the design principle for their future applications in lithium metal anode batteries.

Uniform lithium electrodeposition for stable lithium-metal batteries

A lithium-metal composite is proposed, which includes a carbon-nitrogen modified stainless steel mesh (CNSSM) favoring homogeneous lithium-metal nucleation and growth of fresh and dense lithium deposits when employed as anode for lithium-metal batteries. This novel approach is able to overcome the usual drawbacks linked to the preexisting passivation layer at the surface of lithium. Instead, a favorable interphase with low resistivity is formed with the electrolyte, and the CNSSM modified lithium-metal composite (CNSSM-Li) results in low-voltage hysteresis (±24 mV) and allows stable and dendrite-free lithium electrodeposition. The performance of lithium-metal batteries demonstrates the outstanding capabilities of the novel CNSSM-Li electrode in promoting cell energy density and cycling stability. In addition, advanced X-ray nano-tomography is employed to characterize the composition and morphology changes of this electrode upon plating.

A safe quasi-solid electrolyte based on a nanoporous ceramic membrane for high-energy, lithium metal batteries

The use of lithium metal as the anode for Lithium Metal Batteries (LMB) requires having solid or quasi-solid electrolytes able to block dendrites formation during cell cycling. Here we reported on a hybrid electrolyte membrane based on nanostructured yttria-stabilized-zirconia, sintered by means of High Pressure-Field Assisted Sintering Technique (HP-FAST) in order to retain proper nano-porosity, and activated with a standard LiPF6-EC-DMC solution. By a thorough physico-chemical and functional characterization, we demonstrated that the liquid is effectively nano-confined in the ceramic membrane, and the resulting quasi-solid electrolyte is non-flammable. A remarkable conductivity value of 0.91 mS cm−1 was observed at room temperature, with activation energy of 0.2 eV, and cation transference number, t+ = 0.55, substantially higher than that of the pure liquid electrolyte. The hybrid electrolyte showed electrochemical stability up to 5.5 V vs. Li+/Li, and excellent resistance to dendrite formation for more than 350 cycles in a Li/electrolyte/Li symmetrical cell. A full cell Li/electrolyte/LiMn2O4 showed more than 90 mAh g−1 at 2C for more than 120 cycles. These very promising results indicated that nano-porous ceramic hybrid electrolytes may be conveniently used in LMB.