Homogeneous Li⁺ Flux Distribution Enables Highly Stable and Temperature‐Tolerant Lithium Anode

Abstract

3D carbon hosts can enable low‐stress Li metal anodes (LMAs) with improved structural and interfacial stability. However, the uneven Li+ flux and large concentration polarization, resulting from intrinsically poor Li affinity and limited porosity of carbon scaffolds, make the precise control of Li plating/stripping still one the key challenges facing advanced LMAs. Here it is demonstrated that a lightweight carbon scaffold, featuring parallel‐aligned porous fibers, can work well for homogeneous Li+ flux distribution and reduced concentration gradient to form a stable solid electrolyte interphase, and then synergistically guide smooth Li nucleation/growth even at low temperatures. As a result, the obtained LMAs delivers a high areal capacity up to 15 mAh cm−2, ultralong lifespan (4800 cycles at 4 mA cm−2) with very low voltage hysteresis of ≈21 mV, a high practically available specific capacity of 863.9 mAh g−1 after 1000 cycles, and a long‐term stable behavior at low‐temperature operation. As coupling with the commercial LiNi1/3Co1/3Mn1/3O2 cathodes and common carbonate‐based electrolyte, the corresponding practical cells also possess an ultralong lifespan and outstanding low‐temperature functionality. This study not only presents an advanced carbon host candidate but also sheds new light on crucial design principles of carbon scaffolds for practically feasible rechargeable metal batteries.

A MOF‐Derivative Decorated Hierarchical Porous Host Enabling Ultrahigh Rates and Superior Long‐Term Cycling of Dendrite‐Free Zn Metal Anodes

“…The conductive porous 3D host with a high surface area can make the Zn 2+ ion flux uniform by reducing the local current density, and alleviate partial volume changes during the cycle. [21][22][23][24][25] In addition, the heterogeneous Zn nucleation barrier can be reduced by the zincophilic framework and the uniform Zn growth morphology can be controlled by the initial homogeneous Zn nuclear seed layer. [26][27][28] For a desirable 3D Zn metal composite anode that can achieve excellent long-term cycling performance at ultrahigh current density, optimized material design, and advanced nanotechnology should be combined to simultaneously meet the following basic requirements: 1) evenly distributed zincophilic nucleation sites and low nucleation overpotential with metallic Zn for guiding and regulating uniform Zn nucleation and deposition within the whole framework; [27,28] 2) intrinsically high electrical conductivity concomitant with a continuous conductive network, ensuring rapid electron charge transfer and uniform local electric field distribution for homogeneous Zn deposition and inhibiting formation of dendrites; [21] 3) large specific surface area and high porosity with short ion diffusion length ensuring fast ion transmission and uniform concentration distribution; [18] 4) high hydrogen evolution overpotential for suppressing the undesired side reactions and promoting high coulomb efficiency of plating/stripping; [29,30] 5) outstanding mechanical strength and toughness for relieving huge internal stress fluctuation and substantially avoiding electrode disintegration or collapse during rapid and repeated Zn plating/stripping processes.…”

In Situ Formed Lithiophilic LixNbyO in a Carbon Nanofiber Network for Dendrite-Free Li-Metal Anodes

“…The result shows an even and rapid infiltration of molten Li into the Nb 2 O 5 -CNF composite membrane to form a fully coated Li@Nb 2 O 5 -CNF, and the whole procedure was completed within 34 s. This experimental phenomenon strongly demonstrates the significantly improved lithiophilicity of the Nb 2 O 5 -CNF composite membrane. The cross-sectional image indicates that Li metal can be fully infiltrated into the whole Nb 2 O 5 -CNF network to form a compact structure. − On the contrary, the molten Li cannot effectively enter the pure CNFs, as indicated by the detached sandwich-structure Li-CNF-Li in Figure c. This result confirms the role of Nb 2 O 5 on the improved wettability of molten Li.…”

Electronic Localization Derived Excellent Stability of Li Metal Anode with Ultrathin Alloy

“…[ 13 , 14 , 15 , 16 ] Another effective strategy is to promote the uniform deposition of Li + ions by inducing the Li + electroplating using active sites or nanostructures, [ 17 , 18 , 19 ] reducing the heterogeneous nuclear barrier utilizing lithiophilic groups, [ 20 , 21 ] or decreasing current density via 3D current collectors with high specific surface area. [ 22 , 23 , 24 ] Unfortunately, up to now, fabricating stable Li metal anode beyond 3 mAh cm −2 is still an unfulfilled goal with extreme difficulty. The main reason is that all methods mentioned above only focus on the nucleation of Li or the initial period of Li growth, thus they cannot ensure a large amount of subsequent Li + to deposit uniformly due to the tip effect.…”