Initial Discharge Specific Capacity Research Articles

Borate-containing triblock copolymer electrolytes for improved lithium-ion transference number and interface stability

The electrolytes with high lithium-ion transference number (tLi+) can reduce the formation of concentration polarization during charge/discharge process and improve the electrochemical performance of lithium-ion batteries (LIBs). Herein, we report triblock copolymer electrolytes (PBOEE) containing borate. The sp2 hybridized boron atoms acting as Lewis acids can anchor the anions of lithium salts, enabling PBOEE to achieve high tLi+ of up to 0.53. Also, the borate groups can promote the formation of stable organic-rich solid electrolyte interphase (SEI) film, which enables the Li symmetric cell to cycle stably at 0.1 mA cm−2/0.1 mAh cm−2 for more than 3100 h with a low overpotential of 0.08 V under 50 °C. The optimized PBOEE_24 has an ionic conductivity of 1.41 × 10−4 S cm−1 and electrochemical stability window of 4.8 V vs. Li+/Li at 50 °C. Combining these advantages, the LiFePO4/PBOEE_24/Li cell exhibits an initial discharge specific capacity of 157.3 mA h g−1 at 0.5C with a capacity retention of 85 % after 600 cycles under 50 °C. At a higher current density of 1C, the discharge capacity maintains at 128.0 mA h g−1 after 400 cycles with a capacity retention of 84.88 %. These results suggest that block copolymer containing sp2 hybridized boron atoms is a promising all-solid-state polymer electrolyte.

Regulating Polysulfide Transformation and Stabilizing Lithium Anode Using [PMo12O40]3− Cluster@Carbon Nanotube‐Modified Separator for Lithium‐Sulfur Batteries

AbstractLithium‐sulfur (Li−S) batteries emerge as compelling contenders for next‐generation energy‐storage devices, boasting a noteworthy mass‐specific energy of 2600 Wh kg−1. However, the cycle stability and commercialization of Li−S batteries encounter challenges because of polysulfide shuttle and uncontrolled lithium dendrite growth. In this study, we present a polyoxometalates‐based dual‐function [PMo12O40]3− cluster@carbon nanotube modified polypropylene (PP) separator (PMo12@CNT/PP) to regulate polysulfide transformation and safeguard the lithium anode in Li−S batteries. Leveraging its multi‐electron redox properties and stable cluster structure, the PMo12 cluster acts as a polysulfide mediator, effectively capturing and promoting electrochemical polysulfide transformation. The incorporation of CNT fosters consistent Li‐ion nucleation, stabilizes the lithium anode, and impedes dendrite formation throughout cycling. Hence, Li−S cells equipped with the PMo12@CNT/PP separator display higher capacity and better stability (675 mAh g−1 at 3.0 C and 0.02 % capacity decay per cycle over 700 cycles). The pouch cells with a sulfur loading 4.5 mg cm−2 exhibit an initial discharge specific capacity of 925 mAh g−1 at 0.1 C, and remain 849 mAh g−1 after 40 cycles, underscoring the significant potential for practical applications of Li−S batteries.

Micro Area Interface Wetting Structure with Tailored Li+-Solvation and Fast Transport Properties in Composite Polymer Electrolytes for Enhanced Performance in Solid-State Lithium Batteries.

To satisfy the demand for high safety and energy density in energy storage devices, all-solid-state lithium metal batteries with solid polymer electrolytes (SPE) replacing traditional liquid electrolytes and separators have been proposed and are increasingly regarded as one of the most promising candidates as next-generation energy storage systems. In this study, poly(vinylidene fluoride)-hexafluoropropylene/lignosulfonic acid (PVDF-HFP/LSA) composite polymer electrolyte (CPE) membranes with a micro area interface wetting structure were successfully prepared by incorporating LSA into the PVDF-HFP polymer matrix. The enhanced interaction between the polar functional group in LSA and the C═O in N-methylpyrrolidone (NMP) hinders the evaporation of solvent NMP, thus creating a micro area wetting structure, which offers a flexible region for the chain segment movement and enlarging the area of the amorphous zone in PVDF-HFP. From the results of IR and Raman spectroscopy, it was found that the presence of LSA induced unique ion transport channels created by the massive aggregated ion pair (AGG) and contact ion pair (CIP) of ion cluster structures composed of Li+ and multiple TFSI- and, at the same time, effectively reduced the crystallinity of the polymer electrolyte, hence further contributing to the Li+ diffusion. As a result, at a rate of 2 C, the Li|CPE-15|LiFePO4 solid-state battery delivers an initial discharge-specific capacity of 134.9 mAh g-1 and maintains stability with a retention of 84% during 400 charge-discharge cycles while the Li|CPE-0|LiFePO4 battery fails after only a few cycles at the same rate.

Nano-flower spherical SnS2 combined with a special lithium storage mechanism as a multifunctional separator for lithium-sulfur batteries contributes to ultra-high initial discharge specific capacity

Nano-flower spherical SnS2 combined with a special lithium storage mechanism as a multifunctional separator for lithium-sulfur batteries contributes to ultra-high initial discharge specific capacity

Cubic CoSe2@carbon as polysulfides adsorption-catalytic mediator for fast redox kinetics and advanced stability lithium-sulfur batteries

Although lithium-sulfur batteries (LSBs) are an attractive next-generation rechargeable battery with high theoretical energy density (2600 Wh kg−1) and specific capacity (1675 mA h g−1), the shuttle of soluble lithium polysulfides (LiPSs) is still the protruding obstacle to accelerate the redox reaction of LSBs. Here, cubic cobalt diselenide@carbon (CoSe2@C) derived from zeolite imidazole framework-67 (ZIF-67) was employed as the functional coating of polypropylene (PP) separator to efficiently adsorb and catalyze polysulfides, inhibit “shuttle effect” and improve the electrochemical reaction kinetics of LSBs. The CoSe2@C offers larger mesopore proportion of 77.19 % and abundant active sites to ensure space as a secondary reaction region, and infiltration of electrolyte and rapid transport of Li+. The involved adsorption and catalysis effect are discussed by static adsorption experiment, XPS, and Li2S nucleation kinetics analysis. The results show that CoSe2@C exhibits strong adsorption effect and catalytic activity on LiPSs, and CoSe2@C/PP cells display fast Li+ diffusion and improved redox kinetics (high Li2S nucleation peak current of 0.27 mA and deposition capacity of 148.46 mA h g−1). Ascribe to these advantages, the CoSe2@C/PP cell provides an initial discharge specific capacity of 1335.01 mA h g−1 at 0.1 C and a fine reversible capacity at 5.0 C, and achieves stable and durable lifespan with an average capacity decay rate of 0.12 % over 400 cycles at 0.5 C. This work could promote the practical application of metal selenides in the key components and devices for LSBs.

Interfacial polymerization achieved integration of pore size adjustment, electrostatic repulsion and physical adsorption into one to inhibit polysulfide shuttle for enhanced lithium–sulfur battery

The application of lithium-sulfur battery is seriously hindered by the shuttle of dissolved polysulfide between sulfur cathode and lithium anode, by which is not selectively inhibited by the conventional separator. Developing functional separator is considered as a preferred solution for this issue, but it is always challenged by the tedious preparation process. Herein, interfacial polymerization (IP) is employed to modify the surface property of ZrO2 nanoparticles embedded polyetherimide (PZ) based separator, and the integration of pore size adjustment, electrostatic repulsion and physical adsorption into one is facilely achieved to effectively inhibit the polysulfide shuttle. Consequently, the optimized PZ separator presents a high lithium-ion transference number (0.55) and diffusion coefficient (2.16 × 10−8 cm s−1). Compared with the pristine one, the electrochemical performance of the assembled lithium-sulfur battery is obviously enhanced, and an initial discharge specific capacity of 1242 mAh g−1 and a capacity retention of 68 % after 200 cycles are obtained.

In situ reduction growth Sn-MoS2 on CNFs as advanced separator coating for improved-performance lithium sulfur batteries

Separator modification is a promising strategy to solve the issues of terrible “shuttle effect” and sluggish conversion of lithium polysulfides (LiPSs) in Lithium-sulfur batteries (LSBs). Herein, we fabricated an intriguing architecture of tin-molybdenum disulfide (Sn-MoS2) heterostructure uniformly distributed on carbon nanofibers (Sn-MoS2/CNFs) by the incorporation of electrospinning technology and the in-situ reduction methods to modify the separator for LSBs. The Sn reduced from tin oxide (SnO2) in carbon nanofiber can not only facilitate the rapid ion and electron migration but also promote the porous structure obtained by the reduction collapse process. Furthermore, the heterostructure of MoS2 and Sn uniformly and stably dispersed on the carbon nanofiber and effectively served as both chemical adsorption carriers and electrocatalysts to enhance the LiPSs anchoring and the conversion reaction kinetics. In result, the initial discharge specific capacity at 0.2 C can achieve 1332.8 mAh g−1, while the capacity remains at 579.3 mAh·g−1 after 200 cycles for the LSBs with the Sn-MoS2/CNFs separators. We believe that the experimental results offer a feasible method to design high-performance separators for LSBs.

Suppressing the P2–O2 phase transition of P2-type Ni/Mn-based layered oxide by synergistic effect of Zn/Ti co-doping for advanced sodium-ion batteries

P2-type Ni/Mn-based layered oxides are regarded to be promising cathode materials for advanced sodium-ion batteries (SIBs) owing to their rapid sodium ion diffusion kinetics, high working voltage, and high theoretical capacity. However, P2-type Ni/Mn-based layered oxides are prone to phase transition during charging and discharging processes, resulting in serious capacity fading. Here, introduction of Zn and Ti into transition-metal layers of P2-type layered Na0.66Ni0.33Mn0.67O2 can effectively inhibit P2–O2 phase transition at high voltage, leading to the improved cycling endurance. When being used as cathode materials for SIBs, Na0.66Ni0.27Zn0.06Mn0.61Ti0.06O2 (NNZMT) can deliver a discharge specific capacity of 106.6 mAh g−1, with 95.17% capacity retention after the 100th cycle at 100 mA g−1 within 2.1–4.3 V, which are much higher than those (58.4 mAh g−1 and 45.2%) of Zn/Ti-undoped Na0.66Ni0.33Mn0.67O2 (NNM). Besides, NNZMT displays a much better rate capability compared to the NNM sample. The full cell, based on P2-type layered NNZMT as cathode material and hard carbon as anode material, can provide an initial discharge specific capacity of 94.1 mAh g–1, with a capacity retention of 75.6% after 100 cycles at 100 mA g–1 within 1.0–4.2 V. This research work confirms that low-lost Zn/Ti co-doping strategy is an effective approach for designing and preparing cathode materials for advanced SIBs.

Constructing novel hydrated metal molten salt with high self-healing as the anode material for lithium-ion batteries.

Lithium-ion batteries (LIBs) are greatly limited in their practical application because of their poor cycle performance, low conductivity and volume expansion. Herein, molten salts (MSs) FeCl3·6H2O-NMP with low temperature via simple preparation are used as the anode material of LIBs for the first time to break through the bottleneck of LIBs. The good fluidity and high self-healing of FeCl3·6H2O-NMP effectively avoid the collapse and breakage of the structure. Based on this feature, the initial discharge specific capacity reached 770.28 mA h g-1, which was more than twice that of the commercial graphite anode. After 200 cycles at a current density of 100 mA g-1, the specific capacity did not decrease rather it was found to be higher than the initial discharge specific capacity, reaching 867.24 mA h g-1. Besides, the good conductivity of MSs provides convenience for the removal and intercalation of Li+. The active H sites that can combine with lithium ions form LiH and provide capacity for LIBs. Density functional theory (DFT) calculation also provided theoretical proof for the mechanism of LIBs.

SO3-COF@Al2O3 modified cathode electrode materials enhance the cycling ability of lithium sulfur batteries.

Herein, a covalent organic framework (SO3-COF) containing sulfonic acid groups has been developed on the surface of alumina by a one-step method, labeled as SO3-COF@Al2O3. The experimental results show that SO3-COF@Al2O3 can effectively inhibit the shuttle effect of soluble lithium polysulfide (LiPSs) in LSBs after loading the active material sulfur, and exhibits better cycling behavior than the initial polymer SO3-COF. The initial discharge specific capacity of this electrode material at 0.05C is as high as 1141 mA h g-1, and the capacity can be maintained at 466 mA h g-1 after 500 cycles with a capacity decay rate of 0.08% per cycle.

Valence state of V combined with D-tartaric acid and heat treatment affect sodium storage performance of NASICON-type multiphase composite

The polyanionic compound Na3V2(PO4)3 (NVP) and Na3V2(PO4)2F3 (NVPF) are promising cathode materials for sodium-ion batteries, but their poor electronic conductivity affects the electrochemical performance and the output energy density. The easy interconversion between V4+ and V5+ in the solution appears due to the weak bonds of D-tartaric acid, which lowers the energy barrier for further transition to V3+ and results in an excess V3+ in the product. A small amount of NVPF/C is converted to NVP/C due to the volatility of fluorine after heat treatment. D-tartaric acid as a carbon source forms a 3D network structure after calcination, thresholds the growth of NVP or NVPF and hinders the volume expansion during sodium storage. The initial discharge specific capacity of NVPF/C-650 is 85 mAh g−1 at 5C, and remains 59.2 mAh g−1 after 1000 cycles, which is related to the low charge transfer resistance, rapid Na+ ion diffusion and the pseudocapacitance effect. The binding of V and the carbon source in the solution affects the content of V3+/V4+ content, and the annealing temperature affects the formation and composition of the conducting carbon, both of which influence the electrochemical performance. This result provides a concept for possible screening of the carbon source for sodium storage materials with excellent performance.

Achieving Dendrite-Free Solid-State Lithium-Metal Batteries via In Situ Construction of Li3P/LiCl Interfacial Layers.

Hybrid solid electrolyte (HSE) exhibits potential as a solid electrolyte due to its satisfactory Li+ conductivity, superior flexibility, and optimal interface compatibility. However, the inadequate wettability of the Li/HSE interface leads to significant contact impedance, thus fostering the formation of Li dendrites and limiting their practical applicability. Here, a straightforward strategy to enhance the interfacial wettability between Li and HSE and promote the uniform migration of Li+ by in situ construction of a multifunctional interface consisting of Li3P/LiCl (PCl@Li) was created. The Li3P component acts as a Li+ channel, banishing Li+ diffusion obstacles within the interface layer, while the electronically insulating LiCl component acts as an electron-blocking shield at the Li/HSE interface, promoting uniform Li+ deposition and preventing the formation of Li dendrites. The interface impedance of the symmetric PCl@Li|HSE|PCl@Li battery decreases markedly from 230.2 to 47.4 Ω cm-2. Additionally, the battery demonstrates superb cycling stability for over 1300 h at 0.1 mA cm-2 and maintains a minimal overpotential of 32 mV at 30 °C. The PCl@Li|HSE|LiFePO4 battery shows an initial discharge-specific capacity of 135.6 mA h g-1 at 1 C, with a notable capacity retention of 87.0% (118.0 mA h g-1) after 500 cycles. This work provides a new facile strategy for all-solid-state batteries to address interface issues between Li electrodes and HSE.

A Facile Molten Salt Method for Diverse TiC/C Hybrid as Effective Polysulfide Confinement toward Stable Lithium–Sulfur Batteries

Traditional carbon materials suffer from weak adsorption of lithium polysulfides and excessive consumption of electrolyte. A simple and feasible molten salt method is applied for constructing an active nanocrystalline TiC shell on the surface of porous carbon. The highly active TiC nanoshells endow the core–shell composite with efficient chemical–physical synergistic adsorption, which can effectively confine and convert polysulfides, thereby improving the electrochemical performance of lithium–sulfur batteries. The lithium–sulfur batteries assembled with modified separator deliver a high initial discharge specific capacity of 1396 mAh g−1 at a discharge rate of 0.5 C and a high capacity retention of 747.1 mAh g−1 after 500 cycles, with a high coulombic efficiency of 98% during cycling. Besides, this molten salt method can be applied to modify the porous carbon materials of various composite sulfur cathodes such as graphene, carbon nanotubes, and 3D nonwoven carbon fabrics.

Efficient Sodium-Ion Storage Using MoS2@rGO Nanocomposite Anode: Exploring Na-Ion Diffusion in Metallic Phase

Sodium-ion batteries (SIBs) are gaining attention as a better and more economical option than lithium-ion batteries, owing to the abundance and low cost of sodium in comparison to lithium. The anode component of rechargeable batteries plays a vital role in obtaining superior energy and power density. Consequently, the investigation of novel materials for SIBs with enhanced performance is imperative. Transition metal chalcogenides (TMDs) are found to be promising contenders for this purpose, particularly MoS2 due to their two-dimensional open framework, structural tunability, and high theoretical specific capacity as an anode material in sodium ion storage. In this regard, we conducted a facile strategy to synthesize MoS2 and aluminium-doped MoS2 incorporated into reduced graphene oxide (rGO) using the hydrothermal method. The structural and morphological properties of the samples have been explored through X-ray diffraction (XRD), Raman spectroscopy, field-emission scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) measurements which revealed that the addition of aluminium increased the interlayer spacing of the (002) plane of MoS2 nanosheets and stabilized it in metallic 1T phase. The enhanced interlayer distance and improved conductivity of the electrode material displayed a significantly higher initial discharge specific capacity of around 750 mAhg−1 which is stabilized around 380 mAhg−1 at the current rate of 50 mAg−1 after 10 cycles as investigated through galvanostatic charge-discharge measurement. The long cycling test for 200 cycles revealed the capacity retention of ~65% and ~55 % at the current density of 100 and 300 mAg-1, respectively. The kinetic behavior of the Na-ion is studied employing cyclic voltammetry (CV), galvanostatic intermittent titration technique (GITT), and electrochemical impedance spectroscopy (EIS), and the diffusion coefficient of Na-ion in the bulk of the electrode was found to be in the range of 10-10 to 10-12 cm2s-1. Additionally, in-situ EIS analysis demonstrates the electrode's electrochemical kinetics at different charge-discharge states by showing variations in charge transfer resistance. Ex-situ XRD and X-ray photoemission spectroscopy (XPS) demonstrated the coexistence of 1T and 2H phases, and field-emission SEM validated the stable morphology after cycling. Keywords: Sodium-ion batteries, Transition metal chalcogenides (TMDs), Anode material, MoS2

Polydopamine-Induced Metal-Organic Framework Network-Enhanced High-Performance Composite Solid-State Electrolytes for Dendrite-Free Lithium Metal Batteries.

Due to the high safety, flexibility, and excellent compatibility with lithium metals, composite solid-state electrolytes (CSEs) are the best candidates for next-generation lithium metal batteries, and the construction of fast and uniform Li+ transport is a critical part of the development of CSEs. In this paper, a stable three-dimensional metal-organic framework (MOF) network was obtained using polydopamine as a medium, and a high-performance CSE reinforced by the three-dimensional MOF network was constructed, which not only provides a continuous channel for Li+ transport but also restricts large anions and releases more mobile Li+ through a Lewis acid-base interaction. This strategy endows our CSEs with an ionic conductivity (7.1 × 10-4 S cm-1 at 60 °C), a wide electrochemical window (5.0 V), and a higher Li+ transfer number (0.54). At the same time, the lithium symmetric batteries can be stably cycled for 2000 h at 0.1 mA cm-2, exhibiting excellent electrochemical stability. The LiFePO4/Li cells have a high initial discharge specific capacity of 153.9 mAh g-1 at 1C, with a capacity retention of 80% after 915 cycles. This paper proposes an approach for constructing three-dimensional MOF network-enhanced CSEs, which provides insights into the design and development of MOFs for the positive effects of high-performance CSEs.

Effective reinforcement on the structural stability and electrochemical performances of ultra-high nickel cobalt free cathode material by co-doping

Ultra-high nickel ternary cathode material with high energy density is a very important material to meet the long driving range of new energy vehicles. However, cobalt has high toxicity, high price and supply chain risks, so the material is being developed in the direction of low cobalt or no cobalt. For ultra-high nickel cobalt free cathode material with high theoretical capacity (LiNi0.9Mn0.1O2, NM90), the lattice collapse and particle fragmentation caused by microcracks during long cycle will lead to inferior rate performance and cycle life. At present, the effect of different cobalt content on structure and electrochemical properties of cobalt-free cathode material is rarely reported. Therefore, based on cobalt-free precursors, the effects of proper Co doping on structure and electrochemical properties of NM90 material are studied in depth. It showed that proper Co doping can effectively reduce cationic mixing and improve Li+ diffusion rate of NM90 material. The NM90–1.5%Co material exhibits discharge specific capacity of 167.1 mA h g−1 after 100 cycles at 1C and 121.2 mA h g−1 after 200 cycles at 5C, respectively. Furthermore, NM90–1.5%Co material shows an initial discharge specific capacity of 144.1 mA h g−1 at 10C. Therefore, Co doping provides a feasible way to improve the structural stability and electrochemical performances of ultra-high nickel cobalt free cathode material.

Concentration-gradient of Li-rich Mn-based cathode materials with enhanced cycling retention

Lithium-rich layered Mn-based materials have attracted much attention because of their high specific capacity and high energy density, but they have the characteristics of irreversible capacity loss, low initial coulombic efficiency, and poor cycling performance. In this study, a core-shell structure, including Mn0.75Ni0.25C2O4 precursor as core and Li-rich Mn-based oxides (LRMO, Li1.2Mn0.54Ni0.13Co0.13O2) as shell layer respectively, was synthesized by co-precipitation and sol-gel method. After sintering at high temperatures, the element concentration-gradient oxides material (LRMO-G) was formed. The material was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) and its electrochemical performance was investigated by various electrochemical methods. The LRMO-G material exhibits a high initial discharge specific capacity of 268 mAh/g at 0.1 C, and extremely superior capacity retention (95.4 %) after 100 cycles at 1 C. The initial coulomb efficiency of the LRMO-G material increases to 85 %, which is 12 % higher than that of LRMO.

Interfacial engineering of LiCoO2/Li10GeP2S12 with electron-ion mixed conductor Li7.5La3Zr1.5Co0.5O12 for high stable all-solid-state batteries

The space charge layer and interfacial side reactions between cathode and solid electrolyte seriously limit the electrochemical performances of sulfide electrolyte-based all-solid-state lithium batteries (ASSLIBs). In addition, the periodic strain of the cathode material during the charging-discharging process causes the cathode particles cracking and detachment from the electrolyte. Surface coating is an effective approach to improve electrochemical performances, and the coating material should have high ion and electron conductivity to ensure ion and electron conduction. Ionic-electronic mixed conductor Li7.5La3Zr1.5Co0.5O12 (LLZCO) is chosen as the coating material, and coated on the surface of LiCoO2 (LCO) by co-precipitation method. The pristine and coated LCO are assembled into LCO|Li10GeP2S12|InLi ASSLIBs. The buffering layer can reduce the space charge layer and maintain the stability of the cathode particles. The initial discharge specific capacity of the coated sample is 121.0 mAh g−1 (1.9–3.6 V, 0.2C, RT), with a capacity retention rate of 96.0 % after 100 cycles.

The Origin of Strain Effects on Sulfur Redox Electrocatalyst for Lithium Sulfur Batteries

AbstractIntroducing strain is considered an effective strategy to enhance the catalytic activity of host material in lithium‐sulfur batteries (LSB). However, the introduction of strain through chemical methods often inevitably leads to changes in chemical composition and phase structure, making it difficult to truly reveal the essence and root cause of catalytic activity enhancement. In this paper, strain into MoS2 is introduced through a simple heat treatment and quenching. Experimental research and theoretical analysis show that the strain raises parts of antibonding orbitals in Mo─S bonds above the Fermi level and weakens Li─S and S─S bonds, resulting in tight anchoring and accelerating the conversion for lithium polysulfides (LiPSs). The cells based on the MoS2 with high strain delivers an initial discharge specific capacity as high as 1265 mAh g−1 under 0.2 C and a low average capacity fading of 0.041% per cycle during 1500 cycles under 1 C. This research work deeply reveals the origin of strain effects in the reaction process of LSB, providing important design principles and references for the rational design of high‐performance catalytic materials in the future.

Rational Design of TiO2@g-C3N4/CNT Composite Separator for High Performance Lithium-Sulfur Batteries to Promote the Redox Kinetics of Polysulfide.

Lithium-sulfur batteries (LSB) show excellent potential as future energy storage devices with high energy density, but their slow redox kinetics and the shuttle effect seriously hinder their commercial application. Herein, a 0D@2D composite was obtained by anchoring polar nano-TiO2 onto a 2D layered g-C3N4 surface in situ, and a functional separator was prepared using multi-walled carbon nanotubes as a conductive substrate. Due to their long-range conductivity, multi-walled carbon nanotubes make up for the low conductivity of TiO2@g-C3N4 to some extent. A lithium-sulfur battery prepared with a modified separator exhibited excellent long-term cycle performance, a good lithium ion diffusion rate, and rapid redox kinetics. The initial specific discharge capacity of the composite was 1316 mAh g-1 at 1 C, and a high specific discharge capacity of 569.9 mAh g-1 was maintained after 800 cycles (the capacity decay rate per cycle was only 0.07%). Even at the high current density of 5 C, a specific capacity of 784 mAh g-1 was achieved. After 60 cycles at 0.5 C, the modified separator retained the discharge capacity of 718 mAh g-1 under a sulfur load of 2.58 mg cm-2. In summary, the construction of a heterojunction significantly improved the overall cycle stability of the battery and the utilization rate of active substances. Therefore, this study provides a simple and effective strategy for further improving the overall performance and commercial application of lithium-sulfur batteries.