The increasing demand for wearable electronic devices necessitates flexible batteries with high stability and desirable energy density. Flexible lithium–sulfur batteries (FLSBs) have been increasingly studied due to their high theoretical energy density through the multielectron chemistry of low-cost sulfur. However, the implementation of FLSBs is challenged by several obstacles, including their low practical energy density, short life, and poor flexibility. Various graphene-based materials have been applied to address these issues. Graphene, with good conductivity and flexibility, exhibits synergistic effects with other active/catalytic/flexible materials to form multifunctional graphene-based materials, which play a pivotal role in FLSBs. This review summarizes the recent progress of graphene-based materials that have been used as various FLSB components, including cathodes, interlayers, and anodes. Particular attention is focused on the precise nanostructures, graphene efficacy, interfacial effects, and battery layout for realizing FLSBs with good flexibility, energy density, and cycling stability.

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The development of lithium−sulfur (Li−S) batteries with high-energy density, flexibility, and safety is very appealing for emerging implantable devices, biomonitoring, and roll-up displays. Nevertheless, the poor cycling stability and flexibility of the existing sulfur cathodes, flammable liquid electrolytes, and extremely reactive lithium anodes raise serious battery performance degradation and safety issues. Herein, a metallic 1T MoS 2 and rich oxygen vacancies Ti n O 2n−1 /MXene hierarchical bifunctional catalyst (Mo−Ti/Mx) anchored on a reduced graphene oxide-cellulose nanofiber (GN) host (Mo−Ti/Mx−GN) was proposed to address the above challenges. By applying a directional freezing process, the hierarchical architecture of a flexible GN scaffold composed of waved multiarch morphology with long-range alignment is achieved. The synergetic effects of 1T MoS 2 and Ti n O 2n−1 /MXene are beneficial to suppress the shuttling behavior of lithium polysulfides (LiPSs), expedite the redox kinetics of sulfur species, and promote the electrocatalytic reduction of LiPSs to Li 2 S. The electrode demonstrates improved electrochemical properties with high sulfur-mass loading (8.4 mg s cm −2 ) and lean electrolyte (7.6 μL mg s −1 ) operation. We also explored the feasibility of producing pouch cells with such flexible electrodes, gel polymer electrolytes, and a robust lithium anode, which exhibited reversible energy storage and output, wide temperature adaptability, and good safety against rigorous strikes, implying the potential for practical applications.

Lithium–sulfur batteries (Li‐S batteries) are promising next‐generation energy storage systems because of their high‐theoretical energy density. However, the commercialization of Li‐S batteries is still impeded by the aggregation of sulfur, low‐sulfur utilization, shuttling of dissolved polysulfides and sluggish reaction kinetics. Herein, we designed a hierarchically maple leaf‐like structured sulfur electrodes by in‐situ growth of ultrathin sulfur microcrystal on two‐dimensional MXene‐graphene‐cellulose nanofiber (MGN) matrice (denoted as IS‐MGN@S). The sulfur microcrystal as cathode can achieve improved kinetics than bulk sulfur due to its few layers of sulfur atoms, which is proved by the density functional theory calculations. The MXene not only confines polysulfides through strong chemisorption but also promotes the catalytic conversion of polysulfides. The introduction of graphene improves the conductivity and boosts the immobilization and conversion of polysulfides. As a result, the IS‐MGN@S cathode demonstrates remarkable electrochemical properties with a high‐initial capacity (1229 mAh g−1 at 0.2C), substantial improvement in rate capability (770 mAh g−1 at 2C), and stable long‐term cycling capacity. Moreover, the pouch cells with IS‐MGN@S cathode and gel electrolyte demonstrate excellent mechanical properties under mechanical damage (nail & cut tests, severe deformations), suggesting their promising applications for wearable electronic devices.

for the LIBs to develop advanced anode materials with high specific capacity and long-cycle life. Recently, transition metal oxides, [4][5][6] sulfides, [7][8][9] nitrides, [10][11] and phosphides [12][13][14][15] have attracted extensive attention by virtue of their high theoretical capacity. Among them, transition metal phosphides (TMPs) are more suitable as LIBs anode materials by having a lower potential for lithium insertion, smaller voltage lag, and higher theoretical capacity. [16][17][18] Additionally, the lithiation products (Li 3 P) of TMPs show higher Li ionic conductivity (10 −4 S cm −1 ) than Li 2 O (5 × 10 −8 S cm −1 ) and Li 2 S (10 −13 S cm −1 ) at room temperature, which is beneficial for reducing the polarization. [19,20] To date, various phosphides have been reported, such as FeP, [21] MoP, [22] and CoP. [23,24] Among these candidates, CoP shows great potential for practical applications as an anode material because of its high theoretical capacity (894 mAh g −1 ) and low lithiation potential (≈0.6 V vs Li/Li + ). [25,26] Nevertheless, CoP still face the challenges of low conductivity, large volume expansion, and serious agglomeration, which inevitably restrict its rate and cycling performance. [24,25,27] In addition, the presence of inactive binders in traditional rigid electrodes based on slurry coating causes many invalid interfaces and poor contact of active material with the current collector, which leads to exfoliation of the active material from the current collector and poor kinetics during charge/discharge. [28,29] To overcome these challenges, many strategies have been proposed to achieve high-performance CoP anodes. First, the nanoscale design of CoP should effectively reduce the electron/ ion transport paths, such as nanowires, [27] nanorods, [25,26,30] nanoparticles. [23,31] Second, directly growing these nanostructures on conductive substrates to construct a binder-free electrode can effectively improve the electrochemical performance of the anode. [32][33][34] For example, Yang et al. successfully prepared a CFC@Ni 5 P 4 electrode via directly synthesizing Ni 5 P 4 on the carbon fiber cloth (CFC), which exhibited the best electrochemical performance compared to P-Ni 5 P 4 electrodes based on slurry coating. [35] Such binder-free structural design has the following advantages: i) the direct contact between the conductive substrates and the active materials is conducive to improve Cobalt phosphide (CoP) is considered as one of the most promising candidates for anode in lithium-ion batteries (LIBs) owing to its low-cost, abundant availability, and high theoretical capacity. However, problems of low conductivity, heavy aggregation, and volume change of CoP, hinder its practical applicability. In this study, a binder-free electrode is successfully prepared by growing CoP nanosheets arrays directly on a carbon cloth (CC) via a facile one-step electrodeposition followed by an in situ phosphorization strategy. The CoP@CC anode exhibits good interfacial bonding between the CoP and CC, whi...