Bidirectional Lithiophilic Gradients Modification of Ultralight 3D Carbon Nanofiber Host for Stable Lithium Metal Anode

A Slightly Expanded Graphite Anode with High Capacity Enabled By Stable Lithium-Ion/Metal Hybrid Storage

Integrating lithium-ion and metal storage mechanisms to improve the capacity of graphite anode holds the potential to boost the energy density of lithium-ion batteries. However, this approach, typically plating lithium metal onto traditional graphite anodes, faces challenges of safety risks of severe lithium dendrite growth and short circuits due to restricted lithium metal accommodation space and unstable lithium plating in commercial carbonate electrolytes. Herein, a slightly expanded spherical graphite anode is developed with a precisely adjustable expanded structure to accommodate metallic lithium, achieving a well-balanced state of high capacity and stable lithium-ion/metal storage in commercial carbonate electrolytes. This structure also enables fast kinetics of both Li intercalation/de-intercalation and plating/stripping. With a total anode capacity of 1.5 times higher (558 mAh g-1) than graphite, the full cell coupled with a high-loading LiNi0.8Co0.1Mn0.1O2 cathode (13 mg cm-2) under a low N/P ratio (≈1.15) achieves long-term cycling stability (75% of capacity after 200 cycles, in contrast to the fast battery failure after 50 cycles with spherical graphite anode). Furthermore, the capacity of the full cell also reaches a low capacity decay rate of 0.05% per cycle at 0.2 C under the low temperature of -20 °C.

Hybrid Dynamic Covalent Network-Based Protecting Layer for Stable Li-Metal Batteries

Metallic lithium (Li) is considered as the "Holy Grail" anode material for next-generation energy storage systems due to its extremely high theoretical capacity and low electrochemical potential. Before the commercialization of the Li electrode, dendritic Li growth and the unstable solid electrolyte interphase layer should be conquered. Herein, a hybrid covalent adaptable polymer network (HCAPN) is prepared via the random copolymerization of poly(ethylene glycol) methyl ether methacrylate and -acetoacetoxyethyl methacrylate, followed by chemical cross-linking with polyethylenimine (PEI) and amine-modified silicon dioxide (SiO2). Such a hybrid network, where PEI and amine-modified SiO2 formed a vinylogous urethane-based dynamic covalent bond with the copolymer, respectively, shows improved mechanical properties, solvent resistance, and excellent healability/recyclability. As the protecting layer on the Li electrode, the assembled HCAPN@Li||HCAPN@Li symmetric cell shows a long cycle life of 800 h with low overpotential at a current density of 1 mA cm-2, and superior electrochemical performance can be achieved in the HCAPN@Li||LiFePO4 full cell (capacity retention of 77% over 400 cycles at 1.5 C) and HCAPN@Li||NCM811 cell (capacity retention of 79% after 300 cycles). Surface morphology analysis is also performed for physical insight into their role as protecting layer. This work provides a new perspective for constructing a hybrid dynamic covalent network-based polymer protecting layer for inhibiting Li dendrite growth.

3D Lithiophilic CuZrAg Metallic Glass Based-Current Collector for High-Performance Lithium Metal Anode

Lithium metal anodes face several challenges in practical applications, such as dendrite growth, poor cycle efficiency, and volume variation. 3D hosts with lithiophilic surfaces have emerged as a promising design strategy for anodes. In this study, inspiration from the intrinsic isotropy, chemical heterogeneity, and wide tunability of metallic glass (MG) is drew to develop a 3D mesoporous host with a lithiophilic surface. The CuZrAg MG is prepared using the scalable melt-spinning technique and subsequently treated with a simple one-step chemical dealloying method. This resultes in the creation of a host with a homogeneously distributed abundance of lithium affinity sites on the surface. The excellent lithiophilic property and capability for uniform lithium deposition of the 3D CuZrAg electrode have been confirmed through theoretical calculations. Therefore, the 3D CuZrAg electrode displays excellent cyclic stability for over 400 cycles with 96% coulomb efficiency, and ultra-low overpotentials of 5 mV for over 2000 h at 1.0 mA cm-2 and 1.0 mAh cm-2 . Additionally, the full cells partied with either LiFePO4 or LiNi0.8 Co0.1 Mn0.1 O2 cathode deliver exceptional long-term cyclability and rate capability. This work demonstrates the great potential of metallic glass in lithium metal anode application.

Modulation of Si-O Structure in Uniformly Ultrasmall Silicon Oxycarbide for Superior Lifespan of Lithium Metal Anodes

Utilizing nanoseeds guiding homogeneous deposition of lithium is an effective strategy to inhibit disorderly growth of lithium, where silicon oxide has been attracting attention as a transform seed. However, the research on silicon-oxide-based seeds has concentrated more on utilizing their lithiophilicity but less on their Si-O structures, which could result in different failure mechanisms. In this study, various Si-O structures of silicon oxycarbide carbon nanofibers are prepared by adjusting the content of octa(aminopropylsilsesquioxane). According to XANES and experimental observations, the C-rich SiOC has an active Si-O-C structure but generates a larger volume variation during lithiation, while in the O-rich phase, the silica-oxygen tetrahedral structure can contribute to alleviate the volume expansion but has poor electrochemical activity. SiOC, which is dominated by SiO3C, has a suitable Si-O and silica-oxygen tetrahedral-structure distribution, which balances the electrochemical activity and volume expansion. This allows the host to demonstrate an excellent lifespan over 3740 h with a tiny voltage hysteresis (22 mV) at 2 mA cm-2, and it retains a favorable capacity of 97 mA h g-1 after 630 cycles with a high Coulombic efficiency of 99.7% in full cells. This study experiences the influence of various Si-O structures on lithium metal anodes.

Recent Advances in Structural Optimization and Surface Modification on Current Collectors for High-Performance Zinc Anode: Principles, Strategies, and Challenges

The last several years have witnessed the prosperous development of zinc-ion batteries (ZIBs), which are considered as a promising competitor of energy storage systems thanks to their low cost and high safety. However, the reversibility and availability of this system are blighted by problems such as uncontrollable dendritic growth, hydrogen evolution, and corrosion passivation on anode side. A functionally and structurally well-designed anode current collectors (CCs) is believed as a viable solution for those problems, with a lack of summarization according to its working mechanisms. Herein, this review focuses on the challenges of zinc anode and the mechanisms of modified anode CCs, which can be divided into zincophilic modification, structural design, and steering the preferred crystal facet orientation. The possible prospects and directions on zinc anode research and design are proposed at the end to hopefully promote the practical application of ZIBs.

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@1 mA cm^-2 with 1 mAh cm^-2 and 1000h@20 mA cm^-2 with 20 mAh cm^-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.

Advances in Nanofibrous Materials for Stable Lithium-Metal Anodes

Lithium metal is regarded as the most potential anode material for improving the energy density of batteries due to its high specific capacity and low electrode potential. However, the practical application of lithium-metal anodes (LMAs) still faces severe challenges such as uncontrollable dendrites growth and large volume expansion. The development of functional nanomaterials has brought opportunities for the revival of LMAs. Among them, nanofibrous materials show great application potential for LMAs protection due to their distinct functional and structural features. Here, the latest research progress in nanofibrous materials for LMAs is systematically outlined. First, the problems existing in the practical application of LMAs are analyzed. Then, prospective strategies and recent research progress toward stable LMAs based on nanofibrous materials are summarized from the aspects of artificial protective layers, three-dimensional frameworks, separators, and solid-state electrolytes. Finally, the future development of nanofibrous materials for the protection of lithium-metal batteries is summarized and prospected. This review establishes a close connection between nanofibrous materials and LMA modification and provides insight for the development of high-safety lithium-metal batteries.