Gradient three-dimensional current collector with lithiophilic nanolayer regulation for efficient lithium metal anode construction.

Metallic lithium (Li) is highly desirable for Li battery anodes due to its unique advantages. However, the growth of Li dendrites poses challenges for commercialization. To address this issue, researchers have proposed various three-dimensional (3D) current collectors. In this study, the selective modification of a 3D Cu foam scaffold with lithiophilic elements was explored to induce controlled Li deposition. The Cu foam was selectively modified with Ag and Sn to create uniform Cu foam (U-Cu) and gradient lithiophilic Cu foam (G-Cu) structures. Density Functional Theory (DFT) calculations revealed that Ag exhibited a stronger binding energy with Li compared to Sn, indicating superior Li induction capabilities. Electrochemical testing demonstrated that the half cell with the G-Cu@Ag electrode exhibited excellent cycling stability, maintaining 550 cycles with an average Coulombic efficiency (CE) of 97.35%. This performance surpassed that of both Cu foam and G-Cu@Sn. The gradient modification of the current collectors improved the utilization of the 3D scaffold and prevented Li accumulation at the top of the scaffold. Overall, the selective modification of the 3D Cu foam scaffold with lithiophilic elements, particularly Ag, offers promising prospects for mitigating Li dendrite growth and enhancing the performance of Li batteries.

Dendrite-Free Dual-Phase Li-Ba Alloy Anode Enabled by Ordered Array of Built-in Mixed Conducting Microchannels.

The development and application of lithium (Li) anode is hindered by volumetric variation, dendritic Li growth, and parasitic reactions. Herein, a dual-phase Li-barium (Ba) alloy with self-assembled microchannels array is synthesized through a one-step thermal fusion method to investigate the inhibition effect of lithiophilic composite porous array on Li dendrites. The Li-rich Li-Ba alloy (BaLi24) as composite Li electrode exhibits an ordered porous structure of BaLi4 intermetallic compound after delithiation, which acts as a built-in 3D current collector during Li plating/striping process. Furthermore, the lithiophilic BaLi4 alloy scaffold is a mixed conductor, featuring with Li+ ions diffusion capability, which can efficiently transport the reduced Li to the interior of the electrode structure. This unique top-down growth mode can effectively prohibit Li dendrites growth and improve the space utilization of 3D electrode structure. The spin-polarized density functional theory (DFT) calculations suggest that the absorption capability of BaLi4 benefits the deposition of Li metal. As a result, the cell performance with the dual-phase Li-Ba alloy anode is significantly improved.

Low-temperature fusion fabrication of Li-Cu alloy anode with in situ formed 3D framework of inert LiCux nanowires for excellent Li storage performance.

The commercialization of rechargeable Li metal batteries is hindered by dendrite growth and volumetric variation. Herein, we report a Li-rich dual-phase Li-Cu alloy with built-in 3D conductive skeleton to replace conventional planar Li anode. The Li-Cu alloy is simply prepared by fusion of Li and Cu metals at a relatively low-temperature of 500 °C, followed by a cooling process where phase-segregation leads to metallic Li phase distributed in the network of LiCux solid solution phase. Different from the common Li alloy, the electrochemical alloying reaction between Li and Cu metals is not observed. Therefore, the lithiophilic LiCux nanowires guides conformal plating of Li and the porous framework provides superior dimensional stability for the anode. This unique ferroconcrete-like structure of Li-Cu alloy enables dendrite-free Li plating for an expanded cycling lifetime. Constructing a new type of Li alloy with in situ formed electrochemically inactive framework is a promising and easily scaled-up strategy toward practical application of Li metal anodes.

Polymer Electrolyte Film as Robust and Deformable Artificial Protective Layer for High-Performance Lithium Metal Anode.

Lithium (Li) metal anode is a promising candidate for next-generation high capacity energy storage systems. Unfortunately, the uneven deposition/dissolution of Li metal hinders its wide applications. Herein, a robust and deformable polymer electrolyte film as the advanced protective layer on Li metal is developed by a simple tape-casting method, in which the polymer endows a comfortable interfacial contact as well as membrane flexibility to adapt the volume change, while the coordination between the polymer and Li salt provides fast Li+ ion diffusion channels. The modified Li metal anodes deliver a stable cycling over 1000 cycles under a high current density of 3 mA cm-2 in the ether-based electrolyte. The enhanced cycling performance at high current densities are mainly attributed to the Li plating occurred beneath the ion-conducting protective layer, which facilitates Li+ ion uniform distribution and further suppresses Li dendrite growth. Accordingly, constructing a polymer electrolyte protective film onto the Li metal anodes is a facile and low-cost methodology to drive the Li metal anode toward practical application.

Pretreatment of Lithium Surface by Using Iodic Acid (HIO3) To Improve Its Anode Performance in Lithium Batteries.

Iodic acid (HIO3) was exploited as the effective source to build an artificial solid-electrolyte interphase (SEI) on the surface of Li anode. On one hand, HIO3 is a weak solid-state acid and can be easily handled to remove most ion-insulating residues like Li2CO3 and/or LiOH from the pristine Li surface; on the other hand, both the products of LiI and LiIO3 resulted from the chemical reactions between Li metal and HIO3 are reported to be the ion-conductive components. As a result, the lower voltage polarization and impedance, longer cycling lifetime and higher Coulombic efficiency have been successfully achieved in the HIO3-treated Li-Li and Li-Cu cells. By further using the HIO3-treated Li anode into practical Li-S batteries, the impressive results also have been obtained, with average discharge capacities of 719 mAh g-1 for 200 cycles (0.2 C) and 506 mAh g-1 for 500 cycles (0.5 C), which were better than the Li-S batteries using the pristine Li anode (552 and 401 mAh g-1, respectively) under the same conditions.

Extremely Accessible Potassium Nitrate (KNO3) as the Highly Efficient Electrolyte Additive in Lithium Battery.

The systematic investigation of RNO3 salts (R = Li, Na, K, and Cs) as electrolyte additives was carried out for lithium-battery systems. For the first time, the abundant and extremely available KNO3 was proved to be an excellent alternative of LiNO3 for suppression of the lithium dendrites. The reason was ascribed to the possible synergetic effect of K(+) and NO3(-) ions: The positively charged K(+) ion could surround the lithium dendrites by electrostatic attraction and then delay their further growth, while simultaneously the oxidative NO3(-) ion could be reduced and subsequently profitable to the reinforcement of the solid-electrolyte interphase (SEI). By adding KNO3 into the practical Li-S battery, the discharging capacity was enhanced to average 687 mAh g(-1) from the case without KNO3 (528 mAh g(-1)) during 100 cycles, which was comparable to the one with the well-known LiNO3 additive (637 mAh g(-1)) under the same conditions.