摘要: We discuss recent advances in the control and design of carbon hosts/carriers based on their dimensionality (0D, 1D, 2D and 3D) for achieving high performance Li metal anodes. Representative modification strategies for these different carbons for studying their lithium affinity and their influence on the anode performance are highlighted and discussed. Prospects for the design of carbon hosts/carriers for practical rechargeable LMBs are discussed.
摘要: This review highlights several recent models of Li dendrite formation that have been proposed. Based on the comprehensive understanding and insight gained from these models, carbon materials have been developed to prevent the formation of Li dendrites by virtue of their exceptional electrical conductivity, electrochemical stability, mechanical properties and mouldability. A comprehensive review of the advantages of using carbon materials, such as graphene, carbon nanotubes, carbon fibers and hollow carbons, to deal with the formation of Li dendrites in recent years is provided. Finally, the limitations of carbon materials and future research directions for inhibiting Li dendrite formation are summarized as a reference for the development of new carbon materials for high-performance Li metal anodes.
摘要: To address the issues of non-uniform Li plating/stripping and the large volume fluctuations during their repeated cycling, Li metal anodes, a composite Li anode with a three-dimensional (3D) host has been proposed as a promising strategy to improve the uniformity of Li plating/stripping and relieve volume fluctuations. One key strategy in this area is to develop 3D carbon hosts with gradients of lithiophilicity and conductivity to guide Li deposition from bottom to top, thus maximizing the positive effect of this composite Li anode. Such anodes have recently received significant attention due to the flexibility, adjustability, (electro)chemical stability and light weight of the carbon hosts. This review summarizes recent advances in these anodes, categorizing them into those that have hosts with a lithiophilicity gradient, hosts with a conductivity gradient, and those that have both. Latest research findings are discussed and these different anode categories are reviewed. Prospects for the design of such anodes to promote the use of Li metal anodes in high-energy-density rechargeable batteries are presented.
摘要: To solve the problems of large volume changes and the formation of lithium dendrites in lithium metal batteries, the incorporation of carbon into the lithium metal anodes has gained considerable attention due to its excellent chemical and electrochemical stability, as well as its exceptional mechanical strength that allows repeated cycling. This review provides a comprehensive overview of the formation of lithiated graphite (LiC6) and its role in both bulk and electrode-electrolyte interface regions during lithium plating and stripping. In bulk form, LiC6 has excellent lithiophilic properties, reducing the overpotential for lithium nucleation and promoting uniform lithium deposition. Additionally, when LiC6 is introduced at the electrode-electrolyte interfaces, it improves contact between the electrode and electrolyte by acting as a buffering layer, thereby reducing interfacial impedance. Finally, prospects and challenges for the development of Li/C composite anodes are discussed.
摘要: To tackle the issues of rapid electrode degradation and severe safety issues caused by the uncontrollable growth of lithium dendrites in Li metal anodes (LMAs), two-dimensional transition metal carbides/nitrides (MXenes) with a high electrical conductivity, excellent mechanical properties, and abundant surface functional groups have been used as hosts to induce uniform Li nucleation and alleviate the volume changes, eventually inhibiting the formation of Li dendrites. Recent advances in the use of MXene-based nanomaterials in LMAs are summarized. The problems with using LMAs are first considered, and the ways of using MXene-based nanomaterials for suppressing Li dendrite growth and constructing stable LMAs are then summarized. These include the use of MXenes, MXene-metal hybrids, MXene-carbon hybrids, and MXene derivatives as hosts for the anodes and as additives to modify the electrolyte compositions to increase ionic conductivity and inhibit polymer crystallization. Finally, the challenges and prospects for using MXene-based nanomaterials in next-generation LMAs are briefly discussed.
摘要: A brief overview of recent developments in the formation, detection, and suppression of lithium dendrites in carbon-based lithium-ion batteries is presented. The electrochemical processes that result in the formation of lithium dendrites on the anode surface are reviewed, and various detection methods, including the essential operando technique for understanding the complex mechanism, are then introduced. Methods for suppressing lithium dendrite formation are discussed and prospects for future research and development are presented.
摘要: Compositing lithium metal anodes (LMAs) with carbon-based materials has been given much attention because of the latter’s low density, high mechanical strength, stable electrochemical properties, and large specific surface area. Such a composite LMA stands out because of its ability to reduce the volume expansion, lower the local current density, and provide active nucleation sites for uniform Li+ plating. Recent research advances in carbon-based materials as scaffolds to make composite anodes are reviewed, including composites with pure metals and their alloys, and compositing strategies to improve anode stability.
摘要: Severe dendritic growth and volume expansion are easily induced during the cycling process when lithium metal is used as an anode electrode directly. These problems cause the solid electrolyte interface (SEI) layer to break and re-form, which consumes the active lithium metal and electrolyte, thereby reducing the Coulomb efficiency and rapid capacity. Designing a host matrix with rapid mass transfer and enough storage space to promote lithium homogeneous deposition, hence reducing the repeated SEI growth and the formation of dead lithium, is an effective method to address the concerns mentioned above issues. MXenes with two-dimensional layered structures have been regarded as feasible hosts for stabilizing lithium due to their superior electrical conductivity, sizeable interlayer space, abundant lithiophilic surface functional groups, and excellent mechanical properties. In this review, we first summarized the multiple synthesis methods of MXenes, including etching the precursor MAX phase, chemical vapor deposition, UV-induced etching, and mechanochemical et al. Various synthesis methods would induce different surface termination and lamellar structures, affecting lithium metal nucleation and growth behavior. Subsequently, pure MXene, MXene-carbon and MXene-non carbon hybrid compounds applied for lithium metal anode hosts were introduced, focusing on alleviating noticeable volume changes and inhibiting lithium dendrite growth. Finally, some modification strategies and potential research prospects were summarized and prospected.
摘要: We report the fabrication of vulcanized cross-linked polystyrene grafted on carbon nanotubes (CNTs) for use as an advanced three-dimensional Li host. First, polystyrene was grafted from Br-modified CNTs to form brush-like structure by surface-initiated atom-transfer radical polymerization. Polystyrene grafted on carbon nanotubes was then cross-linked using a Friedel-Crafts reaction and finally vulcanized with sulfur. Vulcanized cross-linked polystyrene grafted on carbon nanotubes was used as a support for the Li metal, and its macro-, meso- and microporous structure increased Li ion transport, buffered the volume changes of the Li anode, and provided a high specific surface area to reduce local current density, which assisted rapid and uniform Li plating/stripping. At the same time, the homogenously distributed sulfur in the support reacted with Li to produce a Li2S-containing SEI layer, while the CNTs provided conductive pathways for the rapid transmission of electrons. As a result, a Li|Li symmetric cell using this anode material and a Cu current collector had a stable cycling performance of more than 500 h at a current density of 1 mA cm−2. When LiFePO4 was used as the cathode, a full cell had a high discharge capacity of 101 mAh g−1 with a capacity retention of 77% after 600 cycles at 1 C.
摘要: 超薄锂金属（≤50 μm）是下一代高比能锂金属电池负极选择。然而纯锂质软、易脆，机械加工性较差，导致超薄锂箔的制备工艺复杂、成本高昂；此外相比于较厚的锂金属负极，超薄锂金属负极常呈现更差的电化学循环性能。本文提出一种“自下而上”的策略制备10~50 μm厚度可控的超薄还原氧化石墨烯/锂金属（rGO/Li）复合箔材，其结构由大量无序随机的rGO片层非平行排列并均匀分散在锂金属内。首先将还原氧化石墨烯（rGO）粉片与熔融锂金属在200 °C下搅拌复合，获得微米级的还原氧化石墨烯/锂复合粉片，之后将复合粉片作为原材料进一步通过反复辊压制备出结构均匀、超薄的复合箔材，该方法具有一定的规模化潜力。不同于其他所报道的rGO层状薄膜结构，在复合箔材中rGO片层随机无序分散形成三维网络，有利于实现锂的均匀沉积/剥离。所制50 μm超薄无序结构rGO/Li复合箔材负极在对称电池中以1 mA cm−2、1 mAh cm−2条件在醚基电解液中可稳定循环1600 h以上，在与硫化聚丙烯腈（SPAN）正极组配全电池以0.2 C倍率循环220次后比容量高达~675 mAh g−1，优于使用同厚度纯锂负极的电池。
摘要: We report the fabrication of a lithiophilic Ti3C2Tx MXene-modified carbon foam (Ti3C2Tx-MX@CF) for the production of highly-stable LMBs that regulates Li nucleation behavior and reduces the volume change of a lithium metal anode (LMA). The 3D CF skeleton with a high specific surface area not only reduces the local current density to avoiding concentrated polarization, but also provides enough space to absorb the volume expansion during cycling. The excellent lithiophilicity of Ti3C2Tx-MX produced by its abundant functional groups reduces the Li nucleation overpotential, guides uniform Li deposition without the formation of Li dendrites, and maintains a stable SEI on the anode surface. Consequently, a Li infiltrated Ti3C2Tx-MX@CF symmetrical cell has an excellent cycling stability for more than 2 400 h with a low overpotential of 9 mV at a current density of 4 mA cm−2 and has a capacity of 1 mA h cm−2. Furthermore, a Li- Ti3C2Tx-MX@CF||NCM111 full cell has a capacity of 129.6 mA h g−1 even after 330 cycles at 1 C, demonstrating the advantage of this method in constructing stable LMAs.
摘要: Structured carbon-based hosts for the Li anode both improve the transport of Li-ions and reduce the electron transfer rate and have proven to be an effective way to suppress dendrite growth in lithium metal anodes. An in-depth understanding of these effects is needed to clarify the intrinsic electrochemical mechanism involved. We used the finite element method to simulate the two crucial processes controlling Li-ion behavior, electron transfer and Li-ion transport, and visualized the local deposition rate, the overpotential, and the Li-ion concentration in a three-dimensional (3D) Li//electrolyte//Li cell. Our analysis showed a competitive relationship between the rates of Li-ion transport and electron transfer. When the electron transfer rate is relatively slow, there are sufficient Li-ions available near the anode surface and the deposition behavior is controlled by electron transfer. However, when the number of Li-ions is low, Li-ion transport dominates the deposition process because it is unable to keep up with electron transfer, and this causes dendrite formation. Therefore, reducing the reactivity of the Li anode and accelerating Li-ion transport are the two key factors to produce uniform Li metal deposition on the anode, particularly under fast charging conditions and in practical use.