Well-dispersed Pt/RuO2-decorated mesoporous N-doped carbon as a hybrid electrocatalyst for Li–O2 batteries

Despite their high energy density, the poor cycling performance of lithium–oxygen (Li–O₂) batteries limits their practical application. Therefore, to improve cycling performance, considerable attention has been paid to the development of an efficient electrocatalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Catalysts that can more effectively reduce the overpotential and improve the cycling performance for the OER during charging are of particular interest. In this study, porous carbon derived from protein-based tofu was investigated as a catalyst support for the oxygen electrode (O₂-electrode) of Li–O₂ batteries, wherein ORR and OER occur. The porous carbon was synthesized using carbonization and KOH activation, and RuO₂ and Pt electrocatalysts were introduced to improve the electrical conductivity and catalytic performance. The well-dispersed Pt/RuO₂ electrocatalysts on the porous N-doped carbon support (Pt/RuO₂@ACT) showed excellent ORR and OER catalytic activity. When incorporated into a Li–O₂ battery, the Pt/RuO₂@ACT O₂-electrode exhibited a high specific discharge capacity (5724.1 mA h g⁻¹ at 100 mA g⁻¹), a low discharge–charge voltage gap (0.64 V at 2000 mA h g⁻¹), and excellent cycling stability (43 cycles with a limit capacity of 1000 mA h g⁻¹). We believe that the excellent performance of the Pt/RuO₂@ACT electrocatalyst is promising for accelerating the commercialization of Li–O₂ batteries.

The excellent performance of the Pt/RuO₂@ACT electrocatalyst is promising for accelerating the commercialization of Li–O₂ batteries.     

Transformation of ZIF-8 nanoparticles into 3D nitrogen-doped hierarchically porous carbon for Li–S batteries

Li–S batteries have been attracting increasing interest owing to their remarkable advantages of low cost, high theoretical capacity and high theoretical energy density. Nevertheless, the severe “shuttle effects” of lithium polysulfides have markedly limited the performance of the cells and further hindered their commercial applications. Herein, a novel scheme combining a transformation strategy with ammonia treatment was developed to fabricate ZIF-8-derived nitrogen-doped hierarchically porous carbon (NHPC/NH₃). When NHPC/NH₃ was used as a host of sulfur, the obtained S@NHPC/NH₃ cathode for Li–S cells presented an initial specific capacity of 1654 mA h g⁻¹ and an outstanding cycling stability with only 0.27% attenuation per cycle from the 30th cycle to 130th cycle. Together with the theoretical calculation, it was concluded that such excellent electrochemical performances should be attributed to the suppressed “shuttle effect” via both physical and chemical adsorption of lithium polysulfides in the optimized microporous structures with effective nitrogen doping sites as well as the improved kinetics owing to the abundant meso/macroporous structures.

A novel transformation strategy assisted with ammonia treatment was successfully developed to fabricate ZIF-8-derived nitrogen-doped hierarchically porous carbon (NHPC/NH₃).     

Polyvinylchloride-derived N,S co-doped carbon as an efficient sulfur host for high-performance Li–S batteries

The intrinsic polysulfide shuttle in lithium–sulfur (Li–S) batteries have significantly limited their practical applications. Conductive carbon materials with heteroatom doping and rich porosity is the most common strategy for the effective prevention of polysulfide shuttle, but are usually obtained with high costs and tedious procedures. Herein, we managed to obtain highly porous N, S-codoped carbon materials (NS-C) through treating waste plastic of polyvinylchloride (PVC) with KOH. The resulting NS-C was revealed to be highly efficient hosts for sulfur cathode, achieving large reversible capacities of 1205 mA h g⁻¹ and 836 mA h g⁻¹ at 0.1C and 1.0C, respectively, and remaining at 550 mA h g⁻¹ after 500 cycles at 1C rate, showing an outstanding cycling stability. The significantly enhanced cycling performance was mainly ascribed to both the hierarchically porous structure and heavy N, S co-dopants, which respectively provided physical blocks and chemical affinity for the efficient immobilization of intermediate lithium polysulfides. The results provide an effective paradigm in the surface chemistry and sulfur cathode materials design for high-performance Li–S batteries and a new application for recycled plastic waste.

The intrinsic polysulfide shuttle in lithium–sulfur (Li–S) batteries have significantly limited their practical applications.     

Post-synthetically modified metal–porphyrin framework GaTCPP for carbon dioxide adsorption and energy storage in Li–S batteries

Lithium–sulphur batteries attract increasing interest due to their high theoretical specific capacity, advantageous economy, and “eco-friendliness”. In this study, a metal–organic framework (MOF) GaTCPP containing a porphyrinic base ligand was used as a conductive additive for sulphur. GaTCPP was synthesized, characterized, and post-synthetically modified by the transition metal ions (Co²⁺/Ni²⁺). The doping of GaTCPP ensured an increase in the carbon dioxide adsorption capacities, which were measured under different conditions. Post-synthetic modification of GaTCPP with Co²⁺/Ni²⁺ ions has been shown to increase carbon dioxide storage capacity from 22.8 wt% for unmodified material to 23.1 wt% and 26.5 wt% at 0 °C and 1 bar for Co²⁺ and Ni²⁺-doped analogues, respectively. As a conductive part of cathode material, MOFs displayed successful sulphur capture and encapsulation proven by stable charge/discharge cycle performances, high-capacity retention, and coulombic efficiency. The electrodes with pristine GaTCPP showed a discharge capacity of 699 mA h g⁻¹ at 0.2C in the fiftieth cycle. However, the doping of GaTCPP by Ni²⁺ has a positive impact on the electrochemical properties, the capacity increased to 778 mA h g⁻¹ in the fiftieth cycle at 0.2C.

Metal–porphyrin framework GaTCPP was used for carbon dioxide adsorption and as a host for preparation of a Li–S battery cathode material.     

Metal–organic framework derived hollow porous CuO–CuCo2O4 dodecahedrons as a cathode catalyst for Li–O2 batteries

Herein, hollow porous CuO–CuCo₂O₄ dodecahedrons are synthesized by using a simple self-sacrificial metal–organic framework (MOF) template, which resulted in dodecahedron morphology with hierarchically porous architecture. When evaluated as a cathodic electrocatalyst in lithium–oxygen batteries, the CuO–CuCo₂O₄ composite exhibits a significantly enhanced electrochemical performance, delivering an initial capacity of 6844 mA h g⁻¹ with a remarkably decreased discharge/charge overpotential to 1.15 V (vs. Li/Li⁺) at a current density of 100 mA g⁻¹ and showing excellent cyclic stability up to 111 charge/discharge cycles under a cut-off capacity of 1000 mA h g⁻¹ at 400 mA g⁻¹. The outstanding electrochemical performance of CuO–CuCo₂O₄ composite can be owing to the intrinsic catalytic activity, unique porous structure and the presence of substantial electrocatalytic sites. The ex situ XRD and SEM are also carried out to reveal the charge/discharge behavior and demonstrate the excellent reversibility of the CuO–CuCo₂O₄ based electrode.

Metal–organic framework derived porous CuO–CuCo₂O₄ dodecahedrons as a cathode catalyst for Li–O₂ batteries with significantly enhanced rate and cyclic performance.     

Sb nanosheet modified separator for Li–S batteries with excellent electrochemical performance

An air-stable antimony (Sb) nanosheet modified separator (SbNs/separator) has been prepared by coating exfoliated Sb nanosheets (SbNs) successfully onto a pristine separator through a vacuum infiltration method. The as-prepared Li–S batteries using SbNs/separators exhibit much improved electrochemical performance compared to the ones using commercial separators. The coulombic efficiency (CE) of the Li–S battery using the SbNs/separator after the initial cycle is close to 100% at a current density of 0.1 A g⁻¹, and 660 mA h g⁻¹ capacity retained after 100 cycles. The rate capability of Li–S battery using SbNs/separator delivers a reversible capacity of 425 mA h g⁻¹ when the current density increases to 1 A g⁻¹. The improved electrochemical performance is mainly attributed to the following reasons. Firstly, the combination of physical adsorption and chemical bonding between SbNs and lithium polysulfides (LiPSs), which efficiently inhibits the shuttle phenomena of LiPSs. Secondly, the good electronic conductivity of SbNs improves the utilization of the adsorbed LiPSs, which benefits the capacity release of active materials. Lastly, the fast conversion kinetics of intermediate LiPSs caused by the catalytic effect from SbNs further suppresses the shuttle effect of LiPSs. The SbNs/separators exhibit a great potential for the future high-performance Li–S batteries.

Antimony nanosheet modified separator is prepared for high performance Li–S batteries for the first time.     

A new metallic π-conjugated carbon sheet used for the cathode of Li–S batteries

Lithium–sulfur (Li–S) batteries are considered as the most promising next generation high density energy storage devices. However, the commercialization of Li–S batteries is hindered by the shuttle effect of polysulfides, the low electronic conductivity of the sulfur cathode and a large volume expansion during lithiation. Herein, we predict a new two dimensional sp² hybridized carbon allotrope (PHE-graphene) and prove its thermodynamic and kinetic stability. If it is utilized to encapsulate the cathode of Li–S batteries, not only will the shuttle effect be avoided but also the electronic conductivity of the sulfur cathode will be improved significantly owing to its metallic electronic band structure. The thermal conductivity of PHE-graphene was found to be very high and even comparable with graphene, which is helpful for the heat dissipation of cathodes. In addition, PHE-graphene also exhibited superior mechanical properties including ideal tensile strength and in-plane stiffness.

A metallic carbon sheet was used for the cathode of Li–S batteries to eliminate the shuttle effect and improve cathode electric conductivity.     

Biomass-derived activated carbon/sulfur composites as cathode electrodes for Li–S batteries by reducing the oxygen content

Corncob-derived activated carbon/sulfur as the cathode electrode for lithium sulfur batteries shows a good electrochemical performance, but the capacity fades rapidly with increase of cycle time. The experimental results demonstrate that such capacity fading is closely related to oxygen content of the activated carbon matrix. To investigate the effect of oxygen content on capacity fading, four carbon matrices (CAC, OAC, HAC, NAC) with different oxygen contents but similar surface areas and pore textures were obtained through a two-step method, namely, CAC was firstly oxygenated by nitric acid and then was reduced by H₂ or NH₃ at high temperature. The oxygen content of CAC, OAC, HAC and NAC was about 9.49 wt%, 20.41 wt%, 4.98 wt% and 4.74 wt%, respectively. Electrodes HAC/50S (H₂-treated carbon/sulfur composite with 50% sulfur) and NAC/50S with low oxygen content show a big improvement compared to the CAC/50S electrode. The HAC/50S and NAC/50S electrode deliver a high initial discharge of 1443 and 1504 mA h g⁻¹ respectively, which remain at 756 and 799 mA h g⁻¹ after 200 cycles at 0.3C, demonstrating a good cycle capacity and stability. It is believed that the carbon matrix with low oxygen content can effectively trap the lithium polysulfides within the carbon framework, weakening the shuttle effect and thus slowing down the capacity fade to a certain degree. Therefore, one of the effective routes to improve the electrochemical performance of Li–S batteries is to reduce the oxygen content.

Carbon matrix with low oxygen content can effectively trap the lithium polysulfides within carbon framework, weakening the shuttle effect and slowing down capacity fade in certain degree, improve the electrochemical performance of Li–S batteries.     

N-Doped carbon nanoparticles on highly porous carbon nanofiber electrodes for sodium ion batteries

Nitrogen doped carbon nanoparticles on highly porous carbon nanofiber electrodes were successfully synthesized via combining centrifugal spinning, chemical polymerization of pyrrole and a two-step heat treatment. Nanoparticle-on-nanofiber morphology with highly porous carbon nanotube like channels were observed from SEM and TEM images. Nitrogen doped carbon nanoparticles on highly porous carbon nanofiber (N-PCNF) electrodes exhibited excellent cycling and C-rate performance with a high reversible capacity of around 280 mA h g⁻¹ in sodium ion batteries. Moreover, at 1000 mA g⁻¹, a high reversible capacity of 172 mA h g⁻¹ was observed after 300 cycles. The superior electrochemical properties were attributed to a highly porous structure with enlarged d-spacings, enriched defects and active sites due to nitrogen doping. The electrochemical results prove that N-PCNF electrodes are promising electrode materials for high performance sodium ion batteries.

Nitrogen doped carbon nanoparticles on highly porous carbon nanofiber electrodes were successfully synthesized via combining centrifugal spinning, chemical polymerization of pyrrole and a two-step heat treatment.     

Conducting polymer-coated MIL-101/S composite with scale-like shell structure for improving Li–S batteries

Lithium–sulfur batteries are regarded as a promising energy storage system. However, they are plagued by rapid capacity decay, low coulombic efficiency, a severe shuttle effect and low sulfur loading in cathodes. To address these problems, effective carriers are highly demanded to encapsulate sulfur in order to extend the cycle life. Herein, we introduced a doped-PEDOT:PSS-coated MIL-101/S multi-core–shell structured composite. The unique structure of MIL-101, large specific area and conductive shell ensure high dispersion of sulfur in the composite and minimize the loss of polysulfides to the electrolyte. The doped-PEDOT:PSS-coated sulfur electrodes exhibited an increase in initial capacity and an improvement in rate characteristics. After 192 cycles at the current density of 0.1C, a doped-PEDOT:PSS-coated MIL-101/S electrode maintained a capacity of 606.62 mA h g⁻¹, while the MIL-101/S@PEDOT:PSS electrode delivered a capacity of 456.69 mA h g⁻¹. The EIS measurement revealed that the surface modification with the conducting polymer provided a lower resistance to the sulfur electrode, which resulted in better electrochemical behaviors in Li–S battery applications. Test results indicate that the MIL-101/S@doped-PEDOT:PSS is a promising host material for the sulfur cathode in the lithium–sulfur battery applications.

Lithium–sulfur batteries are regarded as a promising energy storage system.     

Sulfur encapsulated in thermally reduced graphite oxide as a cathode for Li–S batteries

Rechargeable Li–S batteries are receiving ever-increasing attention due to their high theoretical energy density and inexpensive raw sulfur materials. However, their practical applications have been hindered by short cycle life and limited power density owing to the poor electronic conductivity of sulfur species, diffusion of soluble polysulfide intermediates (Li₂S_n, n = 4–8) and the large volume change of the S cathode during charge/discharge. Optimizing the carbon framework is considered as an effective approach for constructing high performance S/carbon cathodes because the microstructure of the carbon host plays an important role in stabilizing S and restricting the “shuttle reaction” of polysulfides in Li–S batteries. In this work, reduced graphite oxide (rGO) materials with different oxidation degree were investigated as the matrix to load the active material by an in situ thermally reducing graphite oxide (GO) and intercalation strategy under vacuum at 600 °C. It has been found that the loaded amount of S embedded in the rGO layer for the S/carbon cathode and its electrochemical performance strongly depended on the oxidation degree of GO. In particular, on undergoing CS₂ treatment, the rGO–S cathode exhibits extraordinary performances in Li–S batteries. For instance, at a current density of 0.2 A g⁻¹, the optimized rGO–S cathode shows a columbic efficiency close to 100% and retains a capacity of around 750 mA h g⁻¹ with progressive cycling up to over 250 cycles.

Reduced graphite oxide materials with different oxidation degree were investigated as the matrix to load sulfur by an in situ thermal-reduction and intercalation strategy. The C/S composite cathode exhibits a superior electrochemical properties.     

Reduced graphene oxide/TiO2(B) nanocomposite-modified separator as an efficient inhibitor of polysulfide shuttling in Li–S batteries

The shutting effect in lithium–sulfur (Li–S) batteries hinders their widespread application, which can be restrained effectively by a modified separator. In this work, a composite of reduced graphene oxide and beta-phase TiO₂ nanoparticles (RGO/TiO₂(B)) is designed as a separator modification material for improving the electrochemical behavior of Li–S batteries. The TiO₂(B) nanoparticles are in situ prepared and tightly adhere to the RGO layer. A series of examinations demonstrated that the RGO/TiO₂(B)-coated separator efficiently inhibits the polysulfide shuttling phenomenon by the cooperative effect of physical adsorption and chemical binding. Specifically, as modified separators, a comparison between TiO₂(B) and anatase TiO₂(A) each composited with RGO has been conducted. The TiO₂(B) sample not only exhibits a superior blocking character of migrating polysulfides, but also enhances battery electrochemical kinetics by fast Li ion diffusion.

Beta-phase TiO₂ nanoparticles were adhered onto RGO in situ to fabricate a multi-functional separator for high-performance lithium–sulfur (Li–S) batteries.     

Mesoporous TiO2 coating on carbon–sulfur cathode for high capacity Li–sulfur battery

In this paper, a meso-porous TiO₂ (titania) coating is shown to effectively protect a carbon–sulfur composite cathode from polysulfide dissolution. The cathode consisted of a sulfur impregnated carbon support coated with a few microns thick mesoporous titania layer. The carbon–sulfur cathode is made using activated carbon powder (ACP) derived from biomass. The mesoporous titania coated carbon–sulfur cathodes exhibit a retention capacity after 100 cycles at C/3 rate (433 mA g ⁻¹) and stabilized at a capacity around 980 mA h g⁻¹. The electrochemical impedance spectroscopy (EIS) of the sulfur cathodes suggests that the charge transfer resistance at the anode, (R_act) is stable for the titania coated sulfur electrode in comparison to a continuous increase in R_act for the uncoated electrode implying mitigation of polysulfide shuttling for the protected cathode. Stability in the cyclic voltammetry (CV) data for the first 5 cycles further confirms the polysulfide containment in the titania coated cathode while the uncoated sulfur electrode shows significant irreversibility in the CV with considerable shifting of the voltage peak positions. Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) studies confirm the adsorption of soluble polysulfides by mesoporous titania.

Mesoporous TiO₂ coating on carbon–sulfur cathode with simple electrical contact for high capacity Li–S battery.     

Nitrogen–sulfur dual-doped porous carbon spheres/sulfur composites for high-performance lithium–sulfur batteries

A nitrogen–sulfur dual-doped porous carbon spheres/sulfur composite (PCS-NS/S) sample was prepared by a simple hydrothermal method with starch and l-methionine as carbon and nitrogen–sulfur resources, respectively. XRD, XPS, and N₂ adsorption–desorption tests were used to characterize the crystal and pore structure of the PCS-NS/S sample. The morphology and weight ratio of sulfur were investigated by SEM, TEM, and TG analyses. The sample was used as the positive electrode for lithium–sulfur batteries and found to exhibit excellent electrochemical performance.

Simultaneously introduced nitrogen–sulfur through one reagent. The as-prepared PCS-NS/S composites exhibited excellent electrochemical performance as positive electrode for Li–S battery.     

Effect of Ti3C2Tx–PEDOT:PSS modified-separators on the electrochemical performance of Li–S batteries

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost. However, the practical application of Li–S batteries is impeded by a severe shuttle effect. Using polar and conductive materials to prepare a modified separator as the second collector is an effective strategy to solve the shuttle effect. Herein, a Ti₃C₂T_x–PEDOT:PSS hybrid for modifying PP separators is successfully fabricated. In this hybrid, PEDOT:PSS can effectively prevent Ti₃C₂T_x nanosheets from restacking and enhance the electrical conductivity of Li–S batteries, thereby promoting fast Li⁺/electron transport and improving the sulfur utilization. Meanwhile, the introduction of Ti₃C₂T_x–PEDOT:PSS makes Ti₃C₂T_x nanosheets effectively anchor polysulfide, thus inhibiting the shuttle effect. As a result, Li–S cells with Ti₃C₂T_x–PEDOT:PSS modified-separators exhibit superior performances, including a high discharge capacity of 1241.4 mA h g⁻¹ at 0.2C, a long cycling stability, and a low decay rate of 0.030% per cycle at 0.5C for 1000 cycles.

Lithium–sulfur (Li–S) batteries have attracted much attention due to their high theoretical energy density, environmental friendliness, and low cost.     

Facile synthesis of partially oxidized Mn3O4-functionalized carbon cathodes for rechargeable Li–O2 batteries

High charging overpotential (low energy efficiency) is one of the most important challenges preventing the use of current nonaqueous Li–O₂ batteries. This study demonstrates direct in situ-incorporation of metal oxides on carbon during synthesis and the associated application to nonaqueous Li–O₂ battery catalysts. The partially oxidized Mn₃O₄ (Mn₃O₄/Mn₅O₈)-incorporating carbon cathode shows an average overpotential reduction of ∼8% charge/discharge during 40 cycles in a rechargeable nonaqueous Li–O₂ cell. Here, we suggested the possibility that only a small amount of the oxide species (<5%) could show catalytic effects during charge in a rechargeable Li–O₂ cell.

Only a small amount of manganese oxide species (<5%) in carbon shows catalytic effects during charging in a rechargeable Li–O₂ cell.     

Ni3FeN functionalized carbon nanofibers boosting polysulfide conversion for Li–S chemistry

Limiting the shuttle effect of polysulfides is an important means to realizing high energy density lithium–sulfur batteries (Li–S). In this study, an efficient electrocatalyst (CNFs@Ni₃FeN) is synthesized by anchoring Ni₃FeN in the carbon nanofibers (CNFs). The CNFs@Ni₃FeN shows electrocatalytic activity and enhances the conversion of polysulfides. After assembling a battery, a high initial capacity (1452 mA h g⁻¹) and favorable long-time cycling stability (100 cycles) with a capacity retention rate of 83% are obtained by the electrocatalysis of Ni₃FeN. Compared with unmodified CNFs, the cycling stability of CNFs@Ni₃FeN can be greatly improved. The catalytic mechanism is further deduced by X-ray photoelectron spectroscopy (XPS). Our work will inspire the rational design of CNFs@support hybrids for various electrocatalysis applications.

Limiting the shuttle effect of polysulfides is an important means to realizing high energy density lithium–sulfur batteries (Li–S).     

Lychee-like TiO2@TiN dual-function composite material for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries are promising candidates for next generation rechargeable batteries because of their high energy density of 2600 W h kg⁻¹. However, the insulating nature of sulfur and Li₂S, the “shuttle effect” of lithium polysulfides (LiPSs), and the volumetric change of sulfur electrodes limit the practical application of Li–S batteries. Here, lychee-like TiO₂@TiN hollow spheres (LTTHS) have been developed that combine the advantages of high adsorption TiO₂ and high conductivity TiN to achieve smooth adsorption/spread/conversion of LiPSs and use them as a sulfur host material in Li–S batteries for the first time. The cathode exhibits an initial specific capacity of 1254 mA h g⁻¹ and a reversible capacity of 533 mA h g⁻¹ after 500 cycles at 0.2C, which corresponds to an average coulombic efficiency up to 99%. The cell with the LTTHS@S cathode achieved an extended lifespan of over 1000 cycles. Such good performance can be assigned to the good adsorption and catalysis of the dual-function TiO₂@TiN composite. This work proved that the TiO₂@TiN composite can be an attractive matrix for sulfur cathodes.

Lithium–sulfur (Li–S) batteries are promising candidates for next generation rechargeable batteries because of their high energy density of 2600 W h kg⁻¹.     

Material balance in the O2 electrode of Li–O2 cells with a porous carbon electrode and TEGDME-based electrolytes

This work figures out the material balance of the reactions occurring in the O₂ electrode of a Li–O₂ cell, where a Ketjenblack-based porous carbon electrode comes into contact with a tetraethylene glycol dimethyl ether (TEGDME)-based electrolyte under more practical conditions of less electrolyte amount and high areal capacity. The ratio of electrolyte weight to cell capacity (E/C, g A h⁻¹) is a good parameter to correlate with cycle life. Only 5 cycles were obtained at an areal capacity of 4 mA h cm⁻² (E/C = 10) and a discharge/charge current density of 0.4 mA cm⁻², which corresponds to the energy density of 170 W h kg⁻¹ at a complete cell level. When the areal capacity was decreased to half (E/C = 20) by setting a current density at 0.2 mA cm⁻², the cycle life was extended to 18 cycles. However, the total electric charge consumed for parasitic reactions was 35 and 59% at the first and the third cycle, respectively. This surprisingly large amount of parasitic reactions was suppressed by half using redox mediators at 0.4 mA cm⁻² while keeping a similar cycle life. Based on by-product distribution, we will propose possible mechanisms of TEGDME decomposition and report a water breathing behavior, where H₂O is produced during charge and consumed during discharge.

The material balance in the O₂ electrode of a Li–O₂ cell with a Ketjenblack-based porous carbon electrode and a tetraethylene glycol dimethyl ether-based electrolyte under more practical conditions of less electrolyte amount and high areal capacity.     

Binder-free SnO2–TiO2 composite anode with high durability for lithium-ion batteries

A SnO₂–TiO₂ electrode was prepared via anodization and subsequent anodic potential shock for a binder-free anode for lithium-ion battery applications. Perpendicularly oriented TiO₂ microcones are formed by anodization; SnO₂, originating in a Na₂SnO₃ precursor, is then deposited in the valleys between the microcones and in their hollow cores by anodic potential shock. This sequence is confirmed by SEM and TEM analyses and EDS element mapping. The SnO₂–TiO₂ binder-free anode is evaluated for its C-rate performance and long-term cyclability in a half-cell measurement apparatus. The SnO₂–TiO₂ anode exhibits a higher specific capacity than the one with pristine TiO₂ microcones and shows excellent capacity recovery during the rate capability test. The SnO₂–TiO₂ microcone structure shows no deterioration caused by the breakdown of electrode materials over 300 cycles. The charge/discharge capacity is at least double that of the TiO₂ microcone material in a long-term cycling evaluation.

A binder-free SnO₂–TiO₂ composite, where SnO₂ is encapsulated into hollow TiO₂, is designed for inhibiting performance degradation for a stable LIB anode.