Performance Of Lithium-sulfur Batteries Research Articles

Tuning of electrolyte solvation structure for low-temperature operation of lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) can be good candidates for low-temperature batteries owing to the use of solvents with low freezing points. However, the clustering of lithium polysulfides (LiPSs) and inhomogeneous lithium deposition hinder the successful operation of LSBs at low temperatures. Herein, we demonstrate that changing the solvation state of solvents and polysulfides (PSs) in an electrolyte via a high-donor number (DN) salt anion (NO3−) enables operation at low temperatures; NO3− relieves LiPS clustering by strongly coordinating to lithium ions, thereby improving the kinetics and diffusion process of LiPSs at −20 °C. Furthermore, the NO3−-coordinated lithium ion solvation structure facilitates the desolvation process of lithium ions and mitigates solvent decomposition at the lithium metal electrode, which results in excellent cycling stability at −20 °C. A pouch cell with a LiNO3-rich electrolyte provides 76% of its room-temperature discharge capacity and operates stably for 100 cycles at −20 °C. The results of this study broaden our knowledge about the factors determining the low-temperature performance of LSBs. Moreover, they imply that controlling the electrolyte solvation structure can result in high-performance LSBs for operation at low temperatures.

Brominated flame retardants coated separators for high-safety lithium-sulfur batteries

Lithium-sulfur batteries (LSBs) have become highly promising next-generation secondary lithium batteries owing to their high theoretical energy density and abundance of sulfur. Nevertheless, the large-scale application of LSBs is still restricted by the shuttle effect of lithium polysulfide (LiPSs) and the potential fire hazard caused by flammable electrolytes. Herein, three electrolyte-insoluble brominated flame retardants (BFRs) are selected and coated on both sides of commercial polypropylene separators by a facile slurry coating method. The effects of the three BFRs on the safety and electrochemical properties of LSBs are characterized and compared. The coating modification separators greatly improves the flame retardancy of LSBs through radical elimination mechanism. The self-extinguishing time of the electrolyte is reduced from 0.66 s/mg to 0.20 s/mg. Moreover, it is demonstrated that the oxygen (O)-containing BFRs exert a significant adsorption capacity and are more advantageous than O-free BFRs in LSBs. In addition, octabromoether (BDDP) coated separator is more effective in trapping LiPSs than decabromodiphenyl ether (DBDPO) due to higher O content, which can mitigate the shuttle effect and enhance the cycle and rate performance of LSBs. This simple coating strategy for separators with BFRs offers a strongly competitive option for the large-scale production of high-safety LSBs.

Designing a Stable Solid Electrolyte Interphase on Lithium Metal Anodes by Tailoring a Mg Atom Center and the Inner Helmholtz Plane for Lithium–Sulfur Batteries

Arising from the extraordinary theoretical energy density, rechargeable lithium-sulfur (Li-S) batteries have been reputed as one of the most appealing options for next-generation high-performance energy storage and conversion devices. Unfortunately, their industrial implementation has been strongly governed by the formation of Li dendrites caused by the unstable solid electrolyte interphase (SEI) film. Herein, we report a novel electrolyte by introducing the Mg(NO3)2 additive to suppress the growth of Li dendrites, further improving the cycling lifetime of Li-S batteries. On the one hand, Mg2+ can rapidly react with Li atoms to generate Mg atoms, replacing the Li atoms on the top surface of Li metal and forming the Mg center simultaneously. On the other hand, NO3- can be adsorbed in the inner Helmholtz plane and reduced as an inorganic-rich SEI film for stabilizing the Li metal anode when the electrolyte comes in contact with Li metal, effectively mitigating the formation of Li dendrites. Combining the experimental results and theoretical calculations, we confirm that the Mg atom center and the inorganic-rich SEI film are both beneficial for enhancing the electrochemical performance of Li-S batteries. This work provides a new insight into the electrolyte additive and a possible alternative for the design of high-performance Li-S batteries beyond the LiNO3 additive.

Establishing highly efficient absorptive and catalytic network for depolarized high-stability lithium-sulfur batteries

Practical operation of lithium-sulfur (Li-S) batteries with high sulfur loading and efficient/stable sulfur conversion requires the suppression of the lithium polysulfides (LiPSs) shuttling and the facilitation of ion and electron transfer on the electrode material surface. Herein, a multifunctional current collector, composed of Ag@polypyrrole (PPy) coated electrospun carbon nanofibers (CNF) framework, was rationally designed to construct a highly efficient catalytic/absorptive/conductive network to improve the performance of Li-S batteries under practical operation condition. At the molecular scale, the Ag@PPy molecular not only effectively inhibits LiPSs shuttle effect, but also achieves the fast sulfur catalysis and depolarization during charge transfer due to the high conductivity of Ag nanoparticles. At the electrode scale, the three-dimensional (3D) robust fibrous nanostructure provides abundant physical space to realize high sulfur loading, maintains electrode integrity during large volume change of active sulfur and under mechanical abuse condition, as well as enables the high-flux Li+ diffusion and electrolyte flow. Consequently, Li-S batteries with the CNF/Ag@PPy current collector delivered excellent cycling stability (capacity fading of 0.048% per cycle over 500cycles at 1.0C) and high energy density (234.2 Wh kgcell-1 under high sulfur loading of 9.77 mg cm−2). Flexible Li-S batteries are also fabricated indicating the feasibility of the CNF/Ag@PPy current collector in flexible devices.

Co-Ni Bimetallic Sulfides Functionalized Interlayer with Efficient Catalytic Conversion for Li-S Batteries

Tardive practical development of lithium-sulfur (Li-S) batteries faces two fatal nuisances, the grievous shuttle effect of sulfur electrodes as well as rock-ribbed Li dendrites, which results in undesired cycling lifespan and the potential safety hazard. Diversified electrocatalytic materials are employed to enhance polysulfides conversion kinetics and subsequently restrain shuttle effect. Here, pyrite-type cation regulation strategy is applied to motivate the electrochemical catalysis capability of bimetallic sulfide by regulating the cation ratio of Co and Ni ions. The reformative bimetallic sulfide with Co to Ni ratio near 2:1 shows stronger chemical adsorption capability towards lithium polysulfides in contrast to pristine NiS₂, which resulted from the strong contribution of metal oxide layer. The comparable electrochemical kinetics and electrochemical performances of Li-S batteries with CNS-2/CP interlayer show in the aspects of low polarization voltage, high lithium ion diffusion rate, high discharge capacity, as well as better rate performances. These results demonstrate cation regulation could be an efficient strategy for material design to optimize the surface physicochemical properties of iron pyrite for boosting the cycle durability of Li-S batteries.

Metal Coordinated Polymer as Three-Dimensional Network Binder for High Sulfur Loading Cathode of Lithium-Sulfur Battery.

The construction of high sulfur (S) loading cathode is one of the critical parameters to obtain lithium-sulfur (Li-S) batteries with high energy density, but the slow redox reaction rate of high S loading cathode limits the development process. In this paper, a metal coordinated polymer-based three-dimensional network binder, which can improve the reaction rate and stability of S electrode. Compared with traditional linear polymer binders, the metal coordinated polymer binder can not only increase the load amount of S through the three-dimensional cross-linking, but also promote the interconversion reactions between S and lithium sulfide (Li2 S), avoiding the passivation of electrode and improving the stability of the positive electrode. At an S load of 4-5mg cm-2 and an E/S ratio of 5.5µL mg-1 , the discharged voltage in the second platform is 2.04V and the initial capacity is 938 mA h g-1 with metal coordinated polymer binder. Moreover, the capacity retention rate approaches 87% after 100 cycles. In comparison, the discharged voltage in the second platform is lost and the initial capacity is 347 mA h g-1 with PVDF binder. It demonstrates the advanced properties of metal-coordinated polymer binders for improving the performance of Li-S batteries.

Selenium defects of 2D VSe2/CNTs composite as an efficient sulfur host for high-performance Li-S batteries

Introducing defects into two-dimensional materials can increase the ligand-unsaturated sites, thereby enhancing the redox catalysis of polysulphides. In this study, the selenium defects in the two-dimensional material VSe2 can effectively improve the electrochemical performance of lithium-sulfur batteries. Compared with VSe2, VSe2−x could strongly adsorb polysulfides, catalyze the conversion and accelerate the redox reactions of polysulfides. S/VSe2−x/CNTs cathode with an initial discharge specific capacity of 1457 mAh g−1 at 0.1 C current density and capacity decay rate per cycle of only 0.039% after 800 cycles at 0.5 C, showing excellent cycling stability. In addition, a high areal capacity of 4.35 mAh cm−2 and a reversible capacity of 4.106 mAh cm−2 after 100 cycles at 0.1 C can be achieved with the S/VSe2−x/CNTs cathode with a high areal sulfur loading of 4.5 mg cm−2. The results show that the shuttle effect is effectively suppressed by introducing defects in the two-dimensional transition metal dihalide compounds. Thus, the electrochemical performance of the sulfur electrode for lithium-sulfur batteries is improved. This work is expected to provide a new perspective for the rational design of sulfur host materials for high-performance lithium-sulfur batteries.

Perovskite lead zirconate titanate (PbZr0.52Ti0.48O3) nanofibers for inhibiting polysulfide shuttle effect in lithium-sulfur batteries

Rapid capacity fade and untimely failure caused by the infamous “shuttle effect” prevents the commercialization of Lithium-sulfur batteries (LSB). In this work, lead zirconate titanate (PZT) nanofibers have been employed as polysulfide immobilizer in LSB. Ferroelectric materials possess a unique domain structure where each individual domain carries a dipole moment. The dipole-dipole interaction between the domains of the ferroelectric PZT nanofibers and polysulfides inhibits the diffusion of polysulfides from the cathode. In addition to electrostatic interactions, the 1-dimensional nanofibers with large specific surface area are accompanied by lithiophilic and sulfiphilic heteroatoms which act as anchoring points for chemically binding the polysulfides. Moreover, the enhanced wettability of the electrode arising from the favorable affinity of PZT nanofibers towards the electrolyte along with lithiophilic heteroatoms aids the diffusion of Lithium-ions. Briefly, the synergy of physical and chemical interaction of PZT nanofibers towards the polysulfide species is found to mitigate the shuttle effect and improve electrochemical performance of LSB. Further, a promising long-term cycling over 200 cycles for LSB cell with PZT interlayer is observed with 98% Coulombic efficiency and slow fade rate of 0.08% per cycle.

Deciphering the electrocatalysis essence of cobalt diselenide in lithium-sulfur electrochemistry from crystal-phase engineering

Polysulfide shuttle effect and sluggish sulfur reaction kinetics severely impede the cycling stability and sulfur utilization of lithium-sulfur (Li-S) batteries. Precisely designing effective electrocatalysts to accelerate sulfur conversion kinetics and suppress polysulfide migration is urgently needed. Generally, electrocatalytic activity is highly dependent on the electronic structures of catalysts, while the crystal phases play a pivotal role in governing the electronic structures. However, the “crystal phase - electronic structure - catalytic capability” relation chain of Li-S batteries catalysts usually lacks clear elucidation. Herein, crystal-phase engineering is reported by regulating phases of CoSe2 to enhance the electrochemical performance of Li-S batteries. Experimental investigations and atomic level analyses reveal that the orthorhombic CoSe2 can trap and accelerate the conversion of sulfur species more effectively than cubic one. Electronic structure analysis further demonstrates that the superior electrocatalytic activity is originated from the strong Jahn-Teller distortion. As a result, the Li-S batteries with orthorhombic CoSe2 modified separator exhibit a high initial capacity of 1390.7 mAh g−1 at 0.1C and outstanding rate performance with a specific capacity of 738.4 mAh g−1 at 3C. Moreover, even at a high sulfur loading of 10.09 mg cm−2, a favorable initial areal capacity of 12.0 mAh cm−2 is achieved at 0.05C, and the battery still maintains at 7.9 mAh cm−2 over 50 cycles under 0.1C. This work may provide a new strategy for effective catalyst design in Li-S batteries.

Vanadium nitride nanocrystals decorated ultrathin, N-rich and hierarchically porous carbon nanosheets as superior polysulfides mediator for stable lithium-sulfur batteries

The diligent exploitation of high-efficiency polysulfides mediators have exhibited enormous prospects to promote the cycling performance of lithium-sulfur (Li–S) batteries with desirable sulfur loading and high sulfur utilization efficiency. Herein, we craft an elaborated catalyst of ultrafine vanadium nitride nanocrystals confined hierarchically porous, ultrathin nitrogen-doped carbon nanosheets (denoted as VN@NC) via a simple approach. Owing to the highly conductive porous carbon framework integrated with enriched V–N–C active sites, well-heterostructured VN@NC can actively favor the entrapping–adsorption–catalytic conversion of the polysulfides intermediates for boosted surface redox kinetics. As the separator interlayer, VN@NC dedicates to high-performance Li–S batteries with high discharge capacities (1594.8 mAh g−1 at 0.1 C), excellent rate capabilities (766.5 mAh g−1 at 5.0 C) and exceptional cyclic durability by a slight decay of 0.067% per cycle upon 500 cycles at 1.0 C. Interestingly, two cycled Li–S batteries after 100 cycles at 0.5 C can be connected to charge a daily smartphone. Even under elevated sulfur loading of 4.5 mg cm−2 and lean electrolyte of 8 μL mg−1, the assembled Li–S battery still maintains a stable cycling performance. The cost-effective VN@NC catalyst could offer a viable avenue to construct applicable sulfur catalysts for advanced Li–S batteries.

Zwitterionic Separator Featured with Superdesolvating Properties for High Performance Lithium-Sulfur Batteries.

Lithium-sulfur chemistry has greatly expanded the boundaries of lithium batteries, but the persistent parasitic reaction of soluble sulfur intermediates with lithium anode remains a primary challenge. Understanding and regulating the solvation structures of lithium ions (Li+) and polysulfides (LiPSs) are critical to addressing the above issues. Herein, inspired by the natural superhydrophilic resistance to contamination, we developed a zwitterionic nanoparticles (ZWP) separator capable of modulating the solvated of Li+ and LiPSs. The dense solvated layer induced by ZWP effectively prevents the movement of LiPSs without compromising Li+ transport. Moreover, the high electrolyte affinity of the ZWP effectively results in minimizing the deposition of LiPSs on the separator. Furthermore, the structure of the solvated Li+ and LiPSs is also unveiled by molecular simulation and nuclear magnetic resonance (NMR). In addition, in situ UV setup proved the ZWP separator can effectively suppress the shuttle of LiPSs. The restricted space formed by the tightly packed ZWP stabilizes the lithium deposition and regulates dendrite growth. Consequently, the performance of lithium-sulfur batteries is significantly improved and good cycle stability is maintained even at high sulfur loadings (5 mg cm-2). This contribution provides a new insight into the rational design of lithium-sulfur battery separators.

Surface‐Dependent Electrocatalytic Activity of CoSe2 for Lithium Sulfur Battery

AbstractElectrocatalysts play key roles in improving the performance of lithium sulfur (Li‐S) batteries. Here, the electrocatalytic activity of different CoSe2 surfaces for the polysulfide redox reactions in Li‐S batteries, by means of first‐principle calculations is considered. The authors demonstrate that there are obvious differences in surface energy (0.7–2.34 J m−2), adsorption energy for lithium polysulfides (LiPSs) (1.2–3.5 eV), Gibbs free energy of sulfur reduction reaction (SRR) (0.37–1.16 eV), and Li2S decomposition barrier (0.15–0.94 eV) among different CoSe2 surfaces, and thus lead to the different electrocatalytic activity for different CoSe2 surface. The stoichiometric CoSe2 surface with high surface energy, such as the (001) surface, tends to have stronger adsorption energy and larger SRR Gibbs free energy for LiPSs. The surface electron states are mainly dominated by p–d hybridization orbitals and the p‐band center is vital for the surface electrocatalytic properties. Such surface‐dependent mechanism may shed light on the design of sulfur host materials for high‐performance Li‐S batteries.

Nickel single atom overcoordinated active sites to accelerate the electrochemical reaction kinetics for Li-S cathode

Porous 2D N-doped carbon electrocatalyst consisting of atomically disperse Ni active centers with Ni-N 4 -O coordinated structure which act as efficient polysulfides traps and highly LiPSs conversion catalysts. Lithium-sulfur (Li-S) batteries with high theoretical energy density are promising advanced energy storage devices. However, shuttling of dissolute lithium polysulfide (LiPSs) and sluggish conversion kinetics impede their applications. Herein, single nickel (Ni) atoms on two-dimensional (2D) nitrogen(N)-doped carbon with Ni-N 4 -O overcoordinated structure (SANi-N 4 -O/NC) are prepared and firstly used as a sulfur host of Li-S batteries. Due to the efficient polysulfides traps and highly LiPSs conversion effect of SANi-N 4 -O/NC, the electrochemical performance of Li-S batteries obviously improved. The batteries can well operate even under high sulfur loading (5.8 mg·cm -2 ) and lean electrolyte (6.1 μL·mg -1 ) condition. Meanwhile, density functional theory (DFT) calculations demonstrate that Ni single atom’s active sites decrease the energy barriers of conversion reactions from Li 2 S 8 to Li 2 S due to the strong interaction between SANi-N 4 -O/NC and LiPSs. Thus, the kinetic conversion of LiPSs was accelerated and the shuttle effect is suppressed on SANi-N 4 -O/NC host. This study provides a new design strategy for a 2D structure with single-atom overcoordinated active sites to facilitate the fast kinetic conversion of LiPSs for Li-S cathode.

Molten salt etched Ti3C2Tx MXene for ameliorated electrochemical performances of lithium-sulfur batteries

Molten salt etched Ti3C2Tx MXene for ameliorated electrochemical performances of lithium-sulfur batteries

Conductive metal–metal phase and built-in electric field of 1T-VSe2-MXene hetero-structure to accelerate dual-directional sulfur conversion for high-performance Li-S batteries

The shuttle effect and tardy redox kinetics of lithium-polysulfides (LiPSs) seriously restrict the electrochemical performance of lithium-sulfur batteries (LSBs). Here, 1T-VSe2-MXene hetero-structure catalysts with conductive metal–metal phase and built-in electric field (BIEF) as sulfur hosts are developed to accelerate the catalytic conversion of sulfur species. Theoretical and experimental analysis verify that because the difference of energy-level structure between conductive MXene and 1T-VSe2 drives the electron flow through the hetero-interface to construct the interfacial BIEF of metal–metal phase. In the effect of interfacial BIEF, more electrons are accumulated on Se surface sites, so enhancing Li-Se bonding for strong adsorption with LiPSs/Li2S. Meanwhile, the strengthened Li-Se bonding weakens the competing Li-S bonds in LiPSs/Li2S captured on the heterostructure, thus accelerating the dissociation of Li-S bonds yet reducing Li2S nucleation/decomposition energy barrier. Furthermore, abundant Li+ are quickly propelled at the BIEF of the hetero-interface with metal–metal phase, thereby offering a rapid Li+ transfer and boosting the redox kinetics of sulfur species. As expected, the S/1T-VSe2-MXene cathode displays a high reversible capacity of 1321 mAh g−1 at 0.1C, a superb long cyclic stability with a capacity decay of 0.058% per cycle for over 550 cycles at 0.5C, and a high initials areal capacity of 6.42 mAh cm−2 (sulfur loading: 6.9 mg cm−2) at 0.2C. This work reveals its absorption and catalytic conversion mechanism and offers an effective way to design conductively dual-directional Li-S catalysts for high-performance LSBs.

Tuning the structure characteristic of the flexible covalent organic framework (COF) meets a high performance for lithium-sulfur batteries

Rigid-based covalent organic frameworks (COFs) are always employed as sulfur-redox/confined host for adapting its varied states upon cycling of highly effective Li-S batteries. Restricted by the unalterable structure frameworks of rigid COFs, flexible COFs are considered to reserve greater capability in coping with active sulfur to meet higher energy demands, while no flexible COF host has been employed currently. In this work, flexible-based COFs with triazine-ring organic macromolecule blocks (COF-TPT(OH) and COF-TPT) are designed and developed as the host materials of Li-S batteries. The structural diversity of flexible-based COF could provoke the phenomenon of capacity increase, which endows the COF-TPT(OH)@S electrode with a high reversible capacity of 1100 mAh g-1 after 80 cycles at 0.1 C. Even after 1000 cycles at 0.5 C, it can still deliver 732 mAh g−1 with a low decay rate of 0.045 % per cycle. Moreover, the introduction of hydroxyl groups (-OH) equips COF-TPT(OH) with the characteristics of both rigid- and flexible- COFs, contributing to the enhanced abilities of the polysulfides conversion and limitation. Our findings will provide a new idea for the selection of host materials for Li-S batteries.

Recent Progress in Framework Materials for High-Performance Lithium-Sulfur Batteries.

Lithium-Sulfur batteries (LSBs) have been considered as a promising candidate for the next generation of energy storage systems due to their high theoretical capacity. However, there are still lots of pending scientific and technological issues to be solved. Framework materials show great potential to address the above-mentioned issues due to the highly ordered distribution of pore sizes, effective catalytic activity, and periodically arranged aperture. In addition, good tunability gives framework materials unlimited possibilities to achieve satisfying performance for LSBs. In this review, the recent advances in pristine framework materials, their derivatives, and composites have been summarized. And a short conclusion and outlook regard to future prospects for guiding the development of framework materials and LSBs.

MXene derivative Ta4C3-Ta2O5 heterostructure as bi-functional barrier for Li-S batteries

The shuttle effect of polysulfides during the charging and discharging of lithium-sulfur (Li-S) batteries and the growth of Li dendrites are crucial obstacles to hinder the commercialization of Li-S batteries. Heterostructure engineering is an effective strategy to accelerate catalytic conversion and suppress the dissolution of polysulfides. Herein, we report a Ta4C3-Ta2O5 heterostructure composite as a bi-functional modified separator that not only achieves effective protection for lithium metal but also accelerates the polysulfides redox kinetics process. This heterostructure possesses efficient chemical anchoring and abundant active sites to immobilize polysulfides by synergistic effect, which endows a stable long cycling performance for Li-S batteries. This corresponds to an initial high capacity of 801.9 mAh g–1 at 1 C with a decay rate of 0.086% for 500 cycles. Due to its high Young's modulus (up to 384 GPa), Ta4C3 contributes to forming a protective layer on the Li metal surface to inhibit the growth of Li dendrites. Accordingly, the symmetrical cell has a stable overpotential for 700 cycles at 20 mA cm–2/20 mAh cm–2. So, this “one stone two birds” design affords a novel perspective for high-energy Li-S battery storage system design and Li metal protection.

Dual-Mediation pathways promote redox kinetics for High-Loading Lithium–Sulfur batteries under lean electrolyte

The high energy density (2500 Wh kg−1) makes that lithium–sulfur batteries (LSBs) have a great potential in energy storages. However, the practical application of LSBs is severely hampered by several inherent problems, including the sluggish sulfur redox kinetics, the shuttling of lithium polysulfides (LiPSs) and poor electronic conductivity. Although heterogeneous or homogeneous mediators could improve the cycling performance of LSBs to a certain extent, single mediators could not completely promote sulfur conversions, especially under high sulfur loading and lean electrolyte. Herein, dual-mediator systems consist of heterogeneous and homogeneous mediators that are introduced to address the above issues. Density functional theory (DFT) calculations and electrochemical analysis indicate that CoSe nanoparticles embedded in urchin-like nitrogen-doped porous carbon with in-situ growth of CNTs (CoSe@CNTs) as heterogeneous mediators and soluble CoCp2 as homogeneous mediators could effectively accelerate the bidirectional conversion kinetics of liquid LiPSs ↔ solid Li2S through the synergistic effect. As a consequence, the cell with dual-mediators delivers a high initial specific capacity of 1005 mAh/g with a low attenuation rate of 0.045 % per cycle at a current density of 1.0C under sulfur loading of 2.8 mg cm−2 after 800cycles. Importantly, it still maintains a high areal capacity of 6.53 mAh cm−2 under lower electrolyte/sulfur ratio (E/S, 4.2 µL mg−1) and higher sulfur loading of 7.3 mg cm−2 over 100cycles at 0.1C.

Lithiophilic vanadium oxide coated three-dimensional carbon network design towards stable lithium metal anode

The uncontrollable lithium dendrite growth and large volume changes during battery charge/discharge process lead to safety issues and performance degradation problems in lithium metal-based anode. To tackle these issues, an effective solution is to achieve uniform lithium deposition with buffering structure design of the anode. Herein, a high-performance Li host anode composite is developed by coating lithiophilic vanadium oxide onto three-dimensionally structured N-doped CNT rooted on carbon nanotube film (VO2-CNT/CNF). The porous structure of CNT/CNF provides a good buffering effect for the volume change of lithium metal anode during charging and discharging process. At the same time, the N-doped CNTs rooted on CNF fibers provide sufficient lithium nucleation sites for lithium deposition that reduce the regional current density preventing the growth of lithium dendrites. Attributed to these beneficial features, the VO2-CNT/CNF@Li anode exhibits a dendrite-free morphology and excellent cycling performance in lithium-sulfur batteries. The S/C || VO2-CNT/CNF@Li battery also shows good cycling stability at 1 C, and the capacity decay rate per cycle after 500 cycles is less than 0.05%.