metals Article
Mn3O4 Octahedral Microparticles Prepared by Facile Dealloying Process as Efficient Sulfur Hosts for Lithium/Sulfur Batteries Yan Zhao 1 , Yuan Tian 1 , Xiaomin Zhang 1 , Zhifeng Wang 1, * and Yichao Wang 4 ID 1
2 3 4
*
ID
, Taizhe Tan 2 , Zhihong Chen 3, *
School of Materials Science and Engineering, Research Institute for Energy Equipment Materials, Hebei University of Technology, Tianjin 300130, China;
[email protected] (Y.Z.);
[email protected] (Y.T.);
[email protected] (X.Z.) Synergy Innovation Institute of GDUT, Heyuan 517000, China;
[email protected] Shenyang Institute of Automation, Chinese Academy of Sciences, Guangzhou 511458, China School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC 3216, Australia;
[email protected] Correspondence:
[email protected] (Z.W.);
[email protected] (Z.C.)
Received: 30 May 2018; Accepted: 3 July 2018; Published: 4 July 2018
Abstract: A facile and industry-accepted dealloying method was used to synthesize Mn3 O4 particles, which were then employed to prepare sulfur/Mn3 O4 (S/Mn3 O4 ) composites as cathode materials for lithium-sulfur batteries. The composites delivered initial discharge capacity reaching up 1184 mAh·g−1 at 0.1 C with capacity retention of 679 mAh·g−1 after 150 cycles. In addition, even at 2 C, the lithium/sulfur battery with S/Mn3 O4 cathode delivered high reversible discharge capacity of 540 mAh g−1 , demonstrating excellent rate capability. Keywords: dealloying; Mn3 O4 ; microparticles; lithium/sulfur batteries
1. Introduction Rechargeable lithium-ion batteries (LIBs) have gained increasing attention during the past decades as they become widely used as promising power sources in portable electronic devices including cameras, laptops and mobile phones. However, the requirements in terms of specific capacity and rate capability of hybrid electric vehicles, power tools and the power grid must be enhanced [1,2]. Due to their high theoretical capacity of 1672 mAh·g−1 and superior theoretical energy density of 2600 Wh·kg−1 , lithium/sulfur (Li/S) batteries become one of the most promising candidates in LIBs [3]. Moreover, sulfur is non-toxic, naturally abundant, low-cost and environmentally friendly [4]. However, despite the advantages of Li/S batteries, several issues still require solutions for better practical applications [5]. In particular, their low conductivities limit the electron transport in the cathode and leads to low active material utilization. Also, the volume expansion (up to 80%) of S to Li2 S leads to pulverization and collapse. Hence, the resulting soluble intermediate products lithium polysulfide (Li2 Sn , 4 < n < 8) contribute to low coulombic efficiency and active material loss [6,7]. Many means have been attempted to solve these problems, such as introduction of conductive carbon materials like carbon nanotubes [8–10], carbon spheres [11] and graphene [12–14], in an effort to improve the electronic conductivity of sulfur and accommodate the volume expansion during charge/discharge processes due to their porous structures and large specific surface areas. Recently, some studies have focused on using metal oxides as additives or complexes in sulfur cathodes instead of carbon materials. Examples include Al2 O3 [15], ZnO [16], Mg0.6 Ni0.4 O [17], TiO2 [18] and La2 O3 [19]. These metal oxides may provide superior electrochemical performances to Metals 2018, 8, 515; doi:10.3390/met8070515
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carbon-sulfur cathode materials. In particular, they can improve the performance of Li/S batteries over cycling, such as capacity, cycle stability and rate capability. This is because metal oxides could act as adsorbents and catalysts in lithium polysulfides. On the other hand, MnO is a promising sulfur host material due to its good structural stability and strong chemical anchoring effect towards Metals 2018, 8, x FOR PEER REVIEW 2 of 8 soluble lithium polysulfides, which can suppress the shuttle effect. In previous reports, MnO was synthesized by co-precipitation or In template. methods generally complex and hard to carbon-sulfur cathode materials. particular,These they can improve are the performance of Li/S batteries such asthe capacity, and rate capability. Thistheir is because metal oxides could anode control,over thuscycling, increasing cost ofcycle thestability final products and restrict applications as green act as adsorbents and catalysts in lithium polysulfides. On the other hand, MnO is a promising sulfur materials of LIBs. Recently, it is found that dealloying is a simple method to produce metal oxides, host material due to its good structural stability and strong chemical anchoring effect towards soluble which attracts considerable interest. Wada’s group [20] has prepared three-dimensional nanoporous lithium polysulfides, which can suppress the shuttle effect. In previous reports, MnO was silicon material by dealloying in metallic melt and applicated on the LIBs. They also synthesized synthesized by co-precipitation or template. These methods are generally complex and hard to bulk nanoporous by dealloying method for presenting high cyclability ofasLIBs [21]. Chen and control, thussilicon increasing the cost of the final products and restrict their applications green anode Sieradzki examined theRecently, formation bicontinuous nanostructures during of oxides, Li from Li-Sn materials of LIBs. it isof found that dealloying is a simple method to dealloying produce metal which attracts considerable Wada’s group [20] has prepared and three-dimensional nanoporous alloys, which contributes to theinterest. development of both dealloying LIBs fields [22]. The obvious silicon material by dealloying in metallic melt and applicated on the LIBs. They also synthesized bulk renders advantages of dealloying in terms of simple processing, short time consumption and low-cost, nanoporous silicon by dealloying method for presenting high cyclability of LIBs [21]. Chen and the method conducive to industrialization [23,24]. Sieradzki examined the formation of bicontinuous nanostructures during dealloying of Li from LiIn this work, Mn O4 microparticles with strong adsorption capabilities to soluble polysulfides and Sn alloys, which3contributes to the development of both dealloying and LIBs fields [22]. The obvious high sulfur loading (67 wt. %) were first The sulfur microparticles then anchored advantages of dealloying in terms of synthesized. simple processing, short time consumption were and low-cost, on Mn3renders O4 microparticles matrix, toasindustrialization cathodes of Li/S batteries. The structures, compositions and the method conducive [23,24]. In this work, Mn3O4 microparticles withcomposites strong adsorption electrochemical performances of the resulting were capabilities evaluated.to soluble polysulfides and high sulfur loading (67 wt. %) were first synthesized. The sulfur microparticles were then anchored Mn3O4 microparticles matrix, as cathodes of Li/S batteries. The structures, compositions 2. Materials andonMethods and electrochemical performances of the resulting composites were evaluated.
2.1. Preparation of Mn3 O4 Microparticles 2. Materials and Methods
Firstly, Al95 Mn5 alloy melts (at. %) were obtained by melting pure Al (99.99 wt. %) and pure Mn 2.1.%). Preparation of Mnwere 3O4 Microparticles (99.99 wt. The melts then transferred to a holding furnace until gravity pouring the melts Al95roller Mn5 alloy melts (at.speed %) were by melting Al (99.99 wt. %)ribbons. and pureDealloying Mn onto a singleFirstly, copper at rotating ofobtained 2000 r/min. This pure produced Al-Mn (99.99 wt. %). The melts werewas thentreated transferred holdingaqueous furnace until gravitywith pouring thebath meltsat 25 ◦ C of the melt-spun Al-Mn ribbons in 2 to MaNaOH solution water a single copper roller at rotating speed of 2000 r/min. This produced Al-Mn ribbons. Dealloying for 36 h.onto After dealloying, the Al atoms were selectively dissolved. The residual Mn atoms carried out of the melt-spun Al-Mn ribbons was treated in 2 M NaOH aqueous solution with water bath at 25 °C self-assembling and were oxidized into Mn3 O4 microparticles. The dealloying products were washed for 36 h. After dealloying, the Al atoms were selectively dissolved. The residual Mn atoms carried several out times with deionized water and collected by centrifuge machine. The Mn 3 O4 samples self-assembling and were oxidized into Mn3O4 microparticles. The dealloying products were were ◦ finally obtained after times drying for 24 h at 60 Cand in vacuum drying chamber. washed several with deionized water collected by centrifuge machine. The Mn3O4 samples were finally obtained after drying for 24 h at 60 °C in vacuum drying chamber.
2.2. Preparation of S/Mn3 O4 Microparticles 2.2. Preparation of S/Mn3O4 Microparticles
The preparation of Mn3 O4 microparticles was typically carried out by mixing the Mn3 O4 and The preparation of Mn3O4 microparticles was typically carried out by mixing the Mn3O4 and elemental sulfur at 1:3 mass ratio followed by grinding of the mixture for nearly 30 min to create elemental sulfur at 1:3 mass ratio followed by grinding of the mixture for nearly 30 min to create a uniform a uniform powder. Next, the was mixture was transferred into aautoclave stainless-steel autoclave and at powder. Next, the mixture transferred into a stainless-steel and heated at 155 °C for 12 heated h. ◦ 155 C for 12 cooling h. After cooling down to room temperature, the S/Mn3 Owere were obtained, After down to room temperature, the S/Mn3O4 microparticles obtained, with sulfur 4 microparticles content estimated by chemical analysis toanalysis 67 wt. %.to To67 better theunderstand fabrication process of with sulfur content estimated by chemical wt. understand %. To better the fabrication structure, the schematic representation is providedisinprovided Scheme 1. in Scheme 1. process this of this structure, the schematic representation
Scheme 1. The schematic fabrication ofS/Mn S/Mn Scheme 1. The schematic fabrication of 3O3 4O microparticles. 4 microparticles.
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2.3. Structural and Physical Characterization 2.3. Structural and Physical Characterization The structures and phase compositions of the samples were determined by scanning electron The structures and phase compositions of the samples were determined by scanning electron microscopy (SEM, JSM-6700F, JEOL, Tokyo, Japan) at 1 nm and 15 kV, X-ray diffraction (XRD, D8 microscopy (SEM, JSM-6700F, JEOL, Tokyo, Japan) at 1 nm and 15 kV, X-ray diffraction (XRD, D8 Discover, Bruker, Karlsruhe, Germany), transmission electron microscopy (HRTEM, JEM-2100F, Discover, Bruker, Karlsruhe, Germany), transmission electron microscopy (HRTEM, JEM-2100F, JEOL, JEOL, Tokyo, Japan) and X-ray photoelectron spectroscopy (XPS, Ulvac-Phi, Kanagawa, Japan). Tokyo, Japan) and X-ray photoelectron spectroscopy (XPS, Ulvac-Phi, Kanagawa, Japan). 2.4. Electrochemical 2.4. Electrochemical Measurements Measurements The S/Mn 3O4 electrodes were prepared by mixing 80 wt. % of the as-prepared S/Mn3O4 microparticle The S/Mn 3 O4 electrodes were prepared by mixing 80 wt. % of the as-prepared S/Mn3 O4 powders, 10 wt. % polyvinylidene fluoride (PVDF, Kynar, HSV900, France) asFrance) a binder microparticle powders, 10 wt. % polyvinylidene fluoride (PVDF, Kynar,Colombes, HSV900, Colombes, as 10 wt. % 10 Super-p conducting agent in 1-methyl-2-pyrrolidinone (NMP, Sigma-Aldrich, St. Louis, aand binder and wt. %as Super-p as conducting agent in 1-methyl-2-pyrrolidinone (NMP, Sigma-Aldrich, MO, USA,MO, 99.5% purity). The resultant wasslurry then well-proportionally spread onto Al foils using St. Louis, USA, 99.5% purity). Theslurry resultant was then well-proportionally spread onto Al ◦ a doctor blade and dried at 60 °C for 12 h. foils using a doctor blade and dried at 60 C for 12 h. The S/Mn S/Mn33OO4 4deposited circular The depositedfilms filmswere wereused usedto to prepare prepare the the electrodes electrodes through through punching punching circular disks with 1.5 cm in diameter. The active material loading in each electrode was estimated to about disks with 1.5 cm in diameter. The active material loading in each electrode was estimated to about −2 − 2 2 mg·cm . The coin cells were assembled in an Ar (99.9995%) filled MBraun glove box and tested 2 mg·cm . The coin cells were assembled in an Ar (99.9995%) filled MBraun glove box and tested galvanostatically on galvanostatically on aa multichannel multichannel battery battery tester tester (BT-2000, (BT-2000, Arbin Arbin Instruments, Instruments, College College Station, Station, TX, TX, + electrode and current densities + USA). The cut-off potential window was set to 1.5–3.0 V versus Li/Li USA). The cut-off potential window was set to 1.5–3.0 V versus Li/Li electrode and current densities were varied. varied. All All electrochemical electrochemical measurements measurements were were performed performed at at 25 25 ◦°C. were C. 3. Results and Discussion 3O34O microparticles were characterized by by XThe crystallographic crystallographic structures structures of of Mn Mn33OO4 4and andS/Mn S/Mn were characterized 4 microparticles ray diffraction (XRD) X-ray diffraction (XRD)spectroscopy spectroscopyand andthe theresults resultsare areshown shownin inFigure Figure 1. 1. All All main main X-ray X-ray diffraction can readily readily be be assigned assigned to to Mn Mn33O44 phase (JCPDS No. 18-0838) and the peaks appeared sharp, which can sulfur, indicating indicating the the successful successful synthesis synthesis of ofS/Mn S/Mn33O other peaks are ascribed to sulfur, O44[25]. [25].
Figure1.1.XRD XRDpatterns patternsof ofS/Mn S/Mn33O Figure O44. .
The detected peaks of Mn 2p, O 1s and S 2p could be seen in the survey spectrum from XPS The detected peaks of Mn 2p, O 1s and S 2p could be seen in the survey spectrum from XPS (Figure 2a), demonstrating the existence of Mn, O and S elements. The spectrum in Figure 2b (Figure 2a), demonstrating the existence of Mn, O and S elements. The spectrum in Figure 2b presented presented two peaks of oxidized Mn at 641.6 eV and 653.5 eV, corresponding to Mn 2p3/2 and Mn two peaks of oxidized Mn at 641.6 eV and 653.5 eV, corresponding to Mn 2p3/2 and Mn 2p1/2, 2p1/2, respectively [26,27]. Figure 2c depicts the spectrum of O 1s, where two peaks attributed to respectively [26,27]. Figure 2c depicts the spectrum of O 1s, where two peaks attributed to bonds of bonds of OH coming from residual NaOH corrodent at 533.3 eV and Mn-O appeared at 531 eV, OH coming from residual NaOH corrodent at 533.3 eV and Mn-O appeared at 531 eV, respectively. respectively. Figure 2d indicates a series of characteristic peaks at 162.5 eV, 164.4eV, 168.3 eV and Figure 2d indicates a series of characteristic peaks at 162.5 eV, 164.4eV, 168.3 eV and 170.5 eV, consistent 170.5 eV, consistent with S2p. with S2p.
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Figure 2. 2. (a) (a) The The survey survey spectra spectra of of S/Mn S/Mn3O Figure O4; ;(b) (b)Mn Mn2p; 2p;(c) (c)OO1s 1sand and(d) (d)SS2p. 2p. Figure 2. (a) The survey spectra of S/Mn33O44; (b) Mn 2p; (c) O 1s and (d) S 2p.
The SEM images of Mn3O4 microparticles are illustrated in Figure 3. Octahedral microparticles microparticles are are illustrated illustrated in Figure 3. Octahedral microparticles The SEM images of Mn3O44 microparticles with edge lengths of about 450 nm were homogeneously dispersed in Figure 3a. The surfaces of the with edge edge lengths lengths of ofabout about450 450nm nmwere werehomogeneously homogeneously dispersed Figure surfaces of dispersed in in Figure 3a.3a. TheThe surfaces of the octahedral microparticles looked highly faceted. The detailed structures of Mn3O4 octahedral the octahedral microparticles looked highly faceted.The Thedetailed detailedstructures structures of of Mn octahedral microparticles looked highly faceted. Mn33O44 octahedral octahedral microparticles were further monitored by high magnification SEM imaging and the data are presented microparticles were further monitored by high magnification SEM imaging and the data are presented in Figure 3b. in Figure 3b.
Figure 3. (a) SEM image and (b) high magnification SEM image of Mn3O4 microparticles. Figure 3. 3. (a) SEM image image and and (b) (b) high high magnification magnification SEM SEM image image of of Mn Mn3O 4 microparticles. Figure (a) SEM 3 O4 microparticles.
The morphology of S/Mn3O4 is illustrated in Figure 4a. Numerous empty space left between The morphology of S/Mn3O4 is illustrated in Figure 4a. Numerous empty space left between particles could be observed, a 3D conductive In-depth profiling of S/Mn 3O4 The morphology of S/Mnforming in Figurestructure. 4a. Numerous empty space left between 3 O4 is illustrated particles could be observed, forming a 3D conductive structure. In-depth profiling of S/Mn3O4 microparticle was further monitored by TEM imaging. As shown in Figure 4b, sulfur and Mn 3 O4 particles could be observed, forming a 3D conductive structure. In-depth profiling of S/Mn O microparticle was further monitored by TEM imaging. As shown in Figure 4b, sulfur and Mn33O44 microparticles were mixedmonitored uniformly.byInTEM the imaging. inset of Figure 4b, the corresponding microparticle was further As shown in Figure 4b, sulfurselected and Mnarea 3 O4 microparticles were mixed uniformly. In the inset of Figure 4b, the corresponding selected area electron diffraction (SAED) pattern confirmed the polycrystalline diffraction ring of the sample microparticles were mixed uniformly. In the inset of Figure 4b, the corresponding selected area electron diffraction (SAED) pattern confirmed the polycrystalline diffraction ring of the sample corresponding to both Mn3Opattern 4 and S confirmed phases. This indicated that S/Mn3O4ring microparticle was electron diffraction (SAED) thealso polycrystalline diffraction of the sample corresponding to both Mn3O4 and S phases. This also indicated that S/Mn3O4 microparticle was successfully synthesized. corresponding to both Mn O and S phases. This also indicated that S/Mn3 O4 microparticle was successfully synthesized. 3 4 successfully synthesized.
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Figure 4. (a) SEM image and (b) high magnification TEM image and corresponding SAED patterns Figure 4. (a) SEM image and (b) high magnification TEM image and corresponding SAED patterns (inset) of S/Mn3O4. (inset) of S/Mn3 O4 . Figure 4. (a) SEM image and (b) high magnification TEM image and corresponding SAED patterns
. S/Mn3O4 microparticle were demonstrated through the electrochemical (inset) of S/Mn3O4of The advantages 4. (a) SEM image and (b) high magnification TEM image and corresponding SAED patterns The Figure advantages of S/Mn microparticle the electrochemical 3 O4 batteries, performance evaluations of Li/S whichwere weredemonstrated first tested bythrough galvanostatic charge and (inset) of S/Mn3O4. Thecycling. advantages ofofS/Mn 3O4batteries, microparticle were demonstrated performance evaluations Li/S which were first tested by galvanostatic charge and discharge As presented in Figure 5, two main plateaus were through visible inthe theelectrochemical initial discharge performance evaluations of Li/S batteries, which were first tested by galvanostatic charge and discharge cycling. As presented in Figure 5, two main plateaus were visible in the initial discharge curves,The corresponding of high-orderwere lithium polysulfides (Li2Sn, the 4 ≤ nelectrochemical ≤ 8) at 2.4 V, as advantages to of formation S/Mn3O4 microparticle demonstrated through discharge cycling. As presented in Figure 5, two main plateaus were visible in the initial discharge curves, corresponding to formation high-order polysulfides (Li n ≤ 8) and at 2.4 V, well as further reduction toofLiLi/S 2S2/Li 2of S at 2.1 V [28].lithium The S/Mn 3tested O4 cathode exhibited initial performance evaluations batteries, which were first by galvanostatic charge 2 Sn , 4 ≤elevated curves, corresponding to formation of high-order lithium polysulfides (Li2Sn, 4 ≤ n ≤ 8) at 2.4 V,−1 as capacity and excellent discharge of about after as discharge well as further reduction to Li2 S2in /Li V [28]. S/Mnwere O4 cathode elevated initial discharge cycling. As maintained presented Figure 5,reversible two mainThe plateaus visible inexhibited the 1000 initialmAh·g discharge 2 S at 2.1 3capacity well as further reduction to Li 2S2/Li2S at 2.1 V [28]. The S/Mn3O4 cathode exhibited elevated initial − 1 after thecurves, 3rd cycle. No and obvious change in the position waspolysulfides detected in (Li subsequent indicating corresponding to formation ofplateau high-order lithium 2Sn,about 4 ≤ n 1000 ≤cycles, 8) atmAh 2.4 V, as discharge capacity maintained excellent reversible discharge capacity of · g discharge capacity and maintained excellent reversible discharge capacity of about 1000 mAh·g−1 after well as further reduction to and Li2in S2stability. /Li2Splateau at 2.1 V [28]. Thewas S/Mn 3O4 cathode exhibited elevated initial excellent cellobvious reversibility thethe 3rd No change detected subsequent cycles, indicating thecycle. 3rd cycle. No obvious change inthe the plateau position position was detected in in subsequent cycles, indicating −1 after discharge capacity and maintained excellent reversible discharge capacity of about 1000 mAh·g the excellent cell reversibility and stability. the excellent cell reversibility and stability.
2.53
Voltage/ V Voltage/ V
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3 the plateau position was detected in subsequent cycles, indicating the 3rd cycle. No obvious change in the excellent cell reversibility and stability. 1st cycle 3
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1st cycle 2nd cycle 3rd cycle 1st cycle 2nd cycle 3rd cycle
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1.5 Figure 5. Charge curves 3O4 cathode. 0 and discharge 500 1000 of S/Mn1500 -1
Figure 5. Charge and discharge Capacity/ curves mAh g of S/Mn3O4 cathode. Figure 5. Charge and discharge curves of S/Mn3 O4 cathode.
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The cells were then assembled to verify their cycling and rate capabilities (Figures 5. Charge and discharge curvesperformances of S/Mn3O4 cathode. The cells were thenFigure assembled to verify their cycling performances and rate capabilities 6 and 7). At 0.1 C, the cell presented an initial discharge capacity of about 1184 mAh·g−1 and(Figures delivered −1 and delivered The were then to an verify their cycling performances capabilities (Figures 6 6 andcells 7). At 0.1 C, the assembled cell presented initial discharge capacity of about and 1184 rate mAh·g −1 after a capacity about mAh·g 150 cycles. The coulombic efficiency remained almost at 100% Theof cells were679 then assembled to verify their cycling performances and rate capabilities (Figures − 1 −1 a capacity of the about mAh·g after 150 cycles. The coulombic efficiency remained at 100% and 7). At 0.1 C, cell679 presented an initial discharge capacity of about 1184 mAh−1almost ·g and delivered during charge cycling, indicating thecapacity high stability of 1184 S/MnmAh·g 3O4 microparticle in the 6 andthe 7). At 0.1 C,and the discharge cell presented an initial discharge of about and delivered −1 after duringofthe charge and discharge cycling, indicating the high stability of S/Mn 3O 4 microparticle in the a capacity about 679 mAh · g 150 cycles. The coulombic efficiency remained almost at 100% −1 after 150 cycles. The coulombic efficiency remained almost at 100% a capacity aboutcontrol 679 mAh·g cathode and of perfect of the shuttle effect. cathode and perfect control of cycling, the shuttle effect. during the charge and discharge indicating the high stability of S/Mn O microparticle 4 during the charge and discharge cycling, indicating the high stability of S/Mn3O43microparticle in thein the cathode and and perfect control of of the1500 shuttle cathode perfect control the shuttleeffect. effect. 1500
Figure6.6.Cycling Cyclingperformance performance of Cycle number Figure of S/Mn S/Mn33O O44cathode cathodeatat0.1 0.1C.C. Figure 6. Cycling performance of S/Mn3O4 cathode at 0.1 C.
Figure 6. Cycling performance of S/Mn3 O4 cathode at 0.1 C.
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Figure7.7.Rate Rateperformance performanceof ofS/Mn S/Mn3O 4 cathode. Figure 3 O4 cathode.
As depicted in Figure 7, the cell subjected to various rates at 0.5 C, 1 C, 1.5 C and 2 C showed As depicted in Figure 7, the cell subjected to various rates at 0.5 C, 1 C, 1.5 C and 2 C showed average discharge capacities of 930, 793, 683 and 540 mAh·g−−11, respectively. After recovering to 0.5 C, average discharge capacities of 930, 793, 683 and 540 mAh·g , respectively. After recovering to 0.5 C, the electrodes almost recovered the initial capacity of 789 mAh·g−1. This excellent rate performance the electrodes almost recovered the initial capacity of 789 mAh·g−1 . This excellent rate performance of S/Mn3O4 cathodes could be ascribed to the unique microparticle structures, which did not only of S/Mn3 O4 cathodes could be ascribed to the unique microparticle structures, which did not only provide pathways for electrolyte and Li-ion transport but also suppress the shuttle effect and provide pathways for electrolyte and Li-ion transport but also suppress the shuttle effect and enhanced enhanced the activity of the composite. the activity of the composite. 4. Conclusions 4. Conclusions Mn3O4 octahedral microparticles were successfully synthesized by facile dealloying method. Mn3 O4 octahedral microparticles were successfully synthesized by facile dealloying method. S/Mn3O4 composites were then prepared by using the Mn3O4 microparticles. When used as cathode S/Mn3 O4 composites were then prepared by using the Mn3 O4 microparticles. When used as cathode materials for Li/S batteries, the S/Mn3O4 composites exhibited high initial discharge capacities materials for Li/S batteries, the S/Mn3 O4 composites exhibited high initial discharge capacities reaching up 1184 mAh·g−1. At cycling rates of 0.5 C, 1 C, 1.5 C and 2 C, the S/Mn3O4 cathodes delivered reaching up 1184 mAh·g−1 . At cycling rates of 0.5 C, 1 C, 1.5 C and 2 C, the S/Mn3 O4 cathodes high discharge capacities of 930, 793, 683 and 540 mAh g−1, respectively. After 150 cycles, the delivered high discharge capacities of 930, 793, 683 and 540 mAh g−1 , respectively. After 150 cycles, capacities of S/Mn3O4 cathodes reached 679 mAh·g−1. These excellent electrochemical performances the capacities of S/Mn3 O4 cathodes reached 679 mAh·g−1 . These excellent electrochemical can be ascribed to structures of S/Mn3O4 microparticles, which suppressed shuttle effect. performances can be ascribed to structures of S/Mn3 O4 microparticles, which suppressed shuttle effect. Author Contributions: Contributions: Formal Investigation, Y.T., X.Z.; Project Project administration, administration, Z.W. Z.W. Author Formal analysis, analysis, Y.Z., Y.Z., X.Z. X.Z. and and T.T.; T.T.; Investigation, Y.T., X.Z.; Y.Z.;Supervision, Supervision,Z.W. Z.W.and andZ.C.; Z.C.;Writing-original Writing-original draft, Y.Z. and Z.W.; Writing-review & editing, and and Y.Z.; draft, Y.Z. and Z.W.; Writing-review & editing, Y.W.Y.W. and Z.C. Z.C. Funding: This work is financially supported by China Postdoctoral Science Foundation (2016M600190), Key Project Science & Technology Research of Higher Education Hebei Province, China Funding: Thisofwork is financially supported by China Postdoctoral ScienceInstitutions Foundation of (2016M600190), Key Project (ZD2018059), Innovation & Entrepreneurship Training Program of Hebei University of Technology (201710080052), of Science & Technology Research of Higher Education Institutions of Hebei Province, China (ZD2018059), Innovation Guangdong Provincial Science and Technology Project (2017A050506009). & Entrepreneurship Training Program of Hebei University of Technology (201710080052), Guangdong Provincial Conflicts of Interest: TheProject authors declare no conflict of interest. Science and Technology (2017A050506009). Conflicts of Interest: The authors declare no conflict of interest. References 1. Kang, B.; Ceder, G. Battery materials for ultrafast charging and discharging. Nature 2009, 458, 190–193. References [CrossRef] [PubMed] 1. Kang, B.; Ceder, G. Battery materials for ultrafast charging and discharging. Nature 2009, 458, 190–193. 2. Li, H.P.; Wei, Y.Q.; Zhang, Y.G.; Zhang, C.W.; Wang, G.K.; Zhao, Y.; Yin, F.X.; Bakenov, Z. In situ sol-gel 2. Li, H.P.; Wei, Y.Q.; Zhang, Y.G.; Zhang, C.W.; Wang, G.K.; Zhao, Y.; Yin, F.X.; Bakenov, Z. In situ sol-gel synthesis of ultrafine ZnO nanocrystals anchored on graphene as anode material for lithium-ion batteries. synthesis of ultrafine ZnO nanocrystals anchored on graphene as anode material for lithium-ion batteries. Ceram. Int. 2016, 42, 12371–12377. [CrossRef] Ceram. Int. 2016, 42, 12371–12377. Kaiser, M.R.; Wang, J.; Liang, X.; Liu, H.K.; Dou, S.X. A systematic approach to high and stable discharge 3. 3. Kaiser, M.R.; Wang, J.; Liang, X.; Liu, H.K.; Dou, S.X. A systematic approach to high and stable discharge capacity for scaling up the lithium-sulfur battery. J. Power Sources 2015, 279, 231–237. [CrossRef] capacity for scaling up the lithium-sulfur battery. J. Power Sources 2015, 279, 231–237. 4. Zhang, Y.G.; Zhao, Y.; Konarov, A.; Li, Z.; Chen, P. Effect of mesoporous carbon microtube prepared by 4. Zhang, Y.G.; Zhao, Y.; Konarov, A.; Li, Z.; Chen, P. Effect of mesoporous carbon microtube prepared by carbonizing the poplar catkin on sulfur cathode performance in Li/S batteries. J. Alloy Compd. 2015, 619, carbonizing the poplar catkin on sulfur cathode performance in Li/S batteries. J. Alloy Compd. 2015, 619, 298–302. [CrossRef] 298–302. 5. Manthiram, A.; Fu, Y.; Su, Y.S. Challenges and prospects of lithium-sulfur batteries. Acc. Chem. Res. 2013, 46, 5. Manthiram,[CrossRef] A.; Fu, Y.;[PubMed] Su, Y.S. Challenges and prospects of lithium-sulfur batteries. Acc. Chem. Res. 2013, 1125–1134. 46, 1125–1134. 6. Yin, F.X.; Liu, N.; Zhang, Y.G.; Zhao, Y.; Menbayeva, A.; Bakenov, Z.; Wang, X. 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