small

Transcription

1 Communication Lithium Sulfur Batteries Functional Differentiation of Three Pores for Effective Sulfur Confinement in Li S Battery Qian Wang, Minghui Yang,* Zhen-Bo Wang,* Chao Li, and Da-Ming Gu Shuttle effect of the dissolved intermediates is regarded as the primary cause that leads to fast capacity degradation of Li S battery. Herein, a microporous carbon-coated sulfur composite with novel rambutan shape (R-S@MPC) is synthesized from microporous carbon-coated rambutan-like zinc sulfide (R-ZnS@MPC), via an in situ oxidation process. The R-ZnS is employed as both template and sulfur precursor. The carbon frame of R-S@MPC composite possesses three kinds of pores that are distinctly separated from each other in space and are endowed with the exclusive functions. The central macropore serves as buffer pool to accommodate the dissolved lithium polysulfides (LPSs) and volumetric variation during cycling. The marginal straight-through mesoporous, connected with the central macropore, takes the responsibility of sulfur storage. The micropores, evenly distributed in the outer carbon shell of the as-synthesized R-S@MPC, enable the blockage of LPSs. These pores are expected to perform their respective single function, and collaborate synergistically to suppress the sulfur loss. Therefore, it delivers an outstanding cycling stability, decay rate of 0.013% cycle 1 after 500 cycles at 1 C, when the sulfur loading is kept at 4 mg cm 2. Amid the burgeoning chemical energy storage systems, the lithium sulfur battery has received wide attention for its promising high energy density at low cost. Poor conductivity, volumetric exchange, and shuttle effect, as the primary challenges of Li S batteries, have been intensively investigated in the past decades. [1 5] Especially, the fundamental problem of the shuttle effect that is caused by the intermediates dissolution, leads to significant capacity decay with time. This is considered as the most crucial hindrance to the practical application process of Li S batteries. [6 9] The shuttle problem in category of space gives rise to capacity degradation in time concept. Therefore, aiming at exchanging space for time, researchers have devoted to suppress the capacity degradation, by creating barriers on Dr. Q. Wang, Prof. M. Yang Ningbo Institute of Industrial Technology Chinese Academy of Sciences No Zhongguan West Road, Zhenhai District, Ningbo , China myang@nimte.ac.cn Dr. Q. Wang, Prof. Z.-B. Wang, Dr. C. Li, Prof. D.-M. Gu School of Chemistry and Chemical Engineering Harbin Institute of Technology No. 92 West-Da Zhi Street, Harbin , China wangzhb@hit.edu.cn The ORCID identification number(s) for the author(s) of this article can be found under DOI: /smll the diffusion pathway of the dissolved intermediates. The barriers are mainly in forms of spatial obstacles [10 13] and chemical traps. [14 17] As the initial fortification, the cathode hosts are the first substances that the dissolved intermediates of lithium polysulfides (LPSs) come in contact with, due to the uniform distribution of sulfur into the porous host materials. [18 20] The various nonpolar carbon-based materials, [10 13,18 20] with controllable morphology, dimension, and even pore size distribution, are employed as the host materials to slow down the trend of the LPSs diffusion outwardly, [21 23] by space obstacles and capillary adsorbent. On the other hand, some polar substances, such as polar organic functional groups, [4,9] transition metal, [24] oxides, [25 27] sulfides, [28 30] nitrides, [31,32] etc., are selected to anchor the LPSs by forming chemical bonds, which also achieve good effect of slowing down the outward diffusion. To increase the restrictive effect for LPSs, the same concept is employed to fabricate the interlayers between the cathode and the separator, which enables the creation of second defense on the LPSs path toward the anode metal lithium. [33 37] The third countermeasure is lithium protection, which is meant for the separation of the metal lithium from the shuttled LPSs. This serves as the last defender for this issue. [38 41] Apparently, solving the problem from the origin is the comparatively optimal strategy. Hollow materials, as one of the promising hosts, have been studied a lot for the past few years, due to the presence of porous shell and internal cavity in their structures enable the blockage of LPSs and accommodation of the volumetric expansion, [42 47] respectively. However, in the ordinary porous shells, there are usually four kinds of pores which are: (i) passing pore, (ii) interconnected pore, (iii) dead end pore, and (iv) closed pore, respectively. The diagrammatical representation is shown in Figure 1a. The pores of type (iv) cannot be effectively utilized since there is disconnection with either inside or outside. In the traditional outside-in sulfur loading process, the hollow host can be impregnated with sulfur through the passing pores and interconnected pores, whereas, sulfur prefers to stay in the pores of type (i) and (ii) on the shell, for the capillary adsorption. Thus, the shell additionally shoulders the responsibility of sulfur storage, which should only be in charge of blocking the dissolved LPSs. When the sulfur is loaded into the pores of type (iii), the internal reservation space is wasted, due to their (1 of 8)

2 Figure 1. a) Schematic diagram of sulfur loading and confining of traditional hollow host. b) The preparation route, and c) sulfur confinement mechanism of disconnection with the internal cavity. Moreover, the sulfur stored in the open pores of type (i), (ii), and (iii) on the shell is easier to lose, compared with that loaded in the hollow cavity (Figure 1a). In this context, our research work is focused on the design of a cathode material with a novel hollow structure, in which different pores are assigned to perform their respective duties, and collaborate synergistically to achieve the goal of sulfur confinement. The preparation progress is schematically illustrated in Figure 1b. The ZnS nanorods grew vertically on the surface of the as-prepared ZnS sphere, through a facile solvothermal reaction, to obtain the rambutan-like ZnS (R-ZnS). The R-ZnS, as the sulfur source and template, was coated with the resorcinolformaldehyde (RF) resin and carbonized, to form a microporous carbon coated R-ZnS (R-ZnS@MPC) composite with core shell structure. The R-ZnS was subsequently in situ oxidized to sulfur inside the microporous carbon shell, using the iodine as the oxidation agent. [48,49] Owing to the characteristic adsorption of the iodine, the generated sulfur was oriented deposited on the inwall of the carbon frame, which meant the sulfur was almost loaded in the straight-through mesopores on the edge of the R-S@MPC. The rambutan-like microporous carbon-coated sulfur composite (R-S@MPC) was prepared. The preparation of the R-ZnS and oriented loading of sulfur in the straight-through mesopores were the two highlights in the synthesis process. R-S@MPC had great improvement in the structure, compared with the traditional hollow materials. [43 46] The carbon framework presented a hollow rambutan-shaped micromorphology, when the self-sacrificed template of R-ZnS disappeared. The carbon shell carbonized from the RF resin only possessed micropores distribution. The abundant straight-through holes, distributed on the edge of the R-S@MPC, were originated from the removal of the ZnS nanorod. They belonged to the category of mesopore. Additionally, the straight-through mesopores on the edge were connected with the hollow cavity, due to the special rambutan shape of the R-ZnS. The central hollow cavity belonged to macropore. Thus, the peculiarity of R-S@MPC in the structure was that three kinds of pores coexisted in the frame and were distinctly divided from each other in space. The unique structure led to the functional differentiation of the three kinds of pores. As mentioned earlier, in situ oxidation method guaranteed the generated sulfur to be almost stored in the straight-through mesopores. [48,49] At the first stage of discharge process (Figure 1c), the elemental sulfur was reduced to the LPSs that were subsequently dissolved in the ether-based electrolyte. [7,8] It was difficult for the LPSs to flow out, due to the blockage of the microporous carbon shell. The LPSs could only diffuse into the central macropore, driven by the concentration gradient of LPSs. The macropores, as a buffer pool, undertook the obligation of the LPSs accommodation. In the (2 of 8)

3 second phase of discharge, the LPSs were further reduced to Li 2 S, whose volume increased by 80% compared to the initial elemental sulfur. [9] This volumetric expansion was also accommodated by the hollow macropore. During the charging process, the end product of sulfur was finally re-deposited in the mesopores, following the reverse reaction path. Thereby, in the framework of R-S@MPC, the functions of three pores were precisely divided, central macropore for accommodation, marginal straight-through mesopores for storage, and micropores distributed on the outer carbon shell for blockage. They took their own responsibilities, as well as worked together as a team for effective sulfur confinement, aiming at extending the cycle life. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images (Figure 2a,b) display the morphologies of the obtained Rambutan-like ZnS, which has undergone self-assemblage from the ZnS sphere and nanorod (Figure S1, Supporting Information), following the principle of minimum surface energy. The annular with lighter color in Figure 2b is considered to be the ZnS nanorod, for the contrast difference of color. And the thickness of the annular is consistent with the length of the ZnS nanorod (Figure S1b, Supporting Information), suggesting that the ZnS nanorods are standing upright to the ZnS sphere. In addition, the stepwise zoom-in SEM images also exhibit that the ZnS nanorods grow vertically on the surface of the ZnS sphere (Figure S2, Supporting Information). The high-resolution TEM (HRTEM) image (Figure 2c) with the selected area of the R-ZnS exhibits lattice fringes with an interplanar d space of nm, exactly corresponding to that of (002) plane of wurtzite ZnS (JCPDS No ). This is consistent with the strongest diffraction peak of crystal face (002) in the X-ray diffraction (XRD) pattern, as shown in Figure S3 (Supporting Information). The microporous carbon-coated R-ZnS (R-ZnS@MPC) demonstrates the similar configuration with R-ZnS (Figure 2d,e). The only difference, as shown in the HRTEM image of Figure 2f, is that the R-ZnS is observed to be coated outside with a thin layer of carbon that has a uniform thickness of about 3 nm. The R-S@MPC composite obtained from in situ oxidization of the R-ZnS@MPC presents a rambutan appearance with hollow structure, inherited from the self-sacrificed template of ZnS (Figure 2g,h). The local enlarged image in Figure 2i shows intact shell of the one-end-closed holes distributed on the edge of the R-S@MPC composite. This is derived from the disappearance of the ZnS nanorod. These one-end-closed holes can be observed to be connected with the hollow cavity in the SEM image of a cracked sphere (Figure S4, Supporting Information), which indicates they are straight-through pores. More notably, no aggregated sulfur is observed in the TEM images of R-S@MPC (Figure 2h,i), with the fact that the sulfur content reaches up to 75 wt% (Figure 3b). Additionally, the thickness Figure 2. a) SEM, b) TEM, and c) HRTEM images of R-ZnS. d) SEM, e) TEM, and f) HRTEM images of R-ZnS@MPC. g) SEM, h) TEM, and i) HRTEM images of R-S@MPC (3 of 8)

4 NANO MICRO Figure 3. a) The pore size distribution of and R-C. b) TGA measurements of and control sample. c) STEM HAADF, EDX element mappings of d) carbon and e) sulfur of f h) HAADF, element mapping of carbon and sulfur of partial area of the carbon shell. The visual pictures during discharge of i) control sample and j) of the coating carbon layer is investigated to have an effect on the morphology of besides the sulfur content. The decreased thickness of carbon shell leads to the collapse of the structure. While, increased thickness of carbon results in the incomplete reaction during in situ oxidation process (Figure S5, Supporting Information). In the XRD pattern of Figure S6 (Supporting Information), there are no obvious characteristic peaks of sulfur but a wide peak of the amorphous carbon located at (4 of 8)

5 25, also indicating the homogenous distribution of the generated tiny sulfur particles. [50,51] In addition, the N 2 adsorption/desorption measurements of R-S@MPC and R-C are carried out to determine whether the three kinds of pores exist, and how they are distributed. R-C is the carbon frame (Figure S7, Supporting Information), which is obtained by removing the sulfur inside the R-S@MPC under high temperature and low pressure. The steep rises at p/p 0 = 0 in the isothermals (Figure S8, Supporting Information) and the dominate peaks of micropores (pore size 2 nm) in pore size distributions (Figure 3a) reveal the presence of micropores in both R-ZnS@MPC and R-C, indicating the distribution of the micropores on the outer carbon shell. Compared with the R-ZnS@MPC, there is an obvious wide peak of mesopores located at the range of 4 30 nm in the pore size distribution of R-C (Figure 3a), corresponding to the straight-through holes derived from the removal of the ZnS nanorod on the edge of R-ZnS. Combined the test results of the N 2 adsorption/ desorption measurements with the TEM image of the R-S@ MPC (Figure 2i), it was confirmed that R-S@MPC possesses (i) hollow macropore, (ii) the straight-through mesopores connected with the central macropore, and (iii) the micropores distributed on the carbon shell. In Figure S9 (Supporting Information), the micropore volume ( 2 nm) of 0.16 cm 3 g 1 guarantees sulfur blockage effect of microporous carbon shell. It can be calculated that the straight-through mesopore volume (10 50 nm) of 1.61 cm 3 g 1 can provide 1.1 times the volume 75 wt% sulfur needed (based on the sulfur density of 2.07 g cm 3 ), suggesting that the space provided by the mesopores is fully enough to store the sulfur. Similarly, it can be deduced that the internal pore volume can accommodate the generated Li 2 S during discharging, based on the total pore volume of 2.96 cm 3 g 1 and the Li 2 S density of 1.66 g cm 3. In Figure 3c e, the element mappings of R-S@MPC exhibit the similar distribution of sulfur with carbon, as well as the sulfur enrichment on the edge of R-S@MPC. And no obvious signal of Zn can be found in the element mappings of Figure S10 (Supporting Information), confirming that ZnS is completely oxidized to be sulfur in the R-S@MPC composite. We enlarge one tube in the selected area (Figure 3c), as shown in Figure 3f h. It can be clearly observed that the sulfur is mainly distributed inside the straight holes of the carbon tube, indicating the sulfur storage in mesopores. This is consistent with the relative lower surface sulfur atomic concentration of R-S@MPC in the XPS measurement, compared with the control sample that is prepared by melt-diffusion approach (Figure S11, Supporting Information). To investigate the restriction effect of micropores on LPSs, the off-line observable experiment is carried out (Figure 3i,j), simulating the actual discharge process in the battery. The photos of the control sample show that lots of generated LPSs dissolve in the electrolyte in the first few hours, accompanied by the electrolyte color changes into deep yellow gradually (Figure 3i). As discharge continues, part of the dissolved LPSs is further reduced to insoluble Li 2 S 2 or Li 2 S that are deposited on the carbon host, leading to the pale yellow color of the electrolyte. However, part of LPSs cannot be reduced, or eventually move back to the cathode, which causes the irreversible loss of the active sulfur. [27,37] That is why the color cannot disappear completely, at the end of discharge. In contrast, the electrolyte color of R-S@MPC, as shown in Figure 3j, has almost no change, suggesting that LPSs can hardly diffuse into the main electrolyte through the microporous carbon shell, and the dissolved LPSs are all accommodated in the hollow cavity of R-S@MPC. In addition, the thermogravimetric analysis (TGA) is executed, not only to get the sulfur contents of the composites, but also to observe the difficulty level of sulfur loss. In Figure 3b, the weight loss V s temperature of R-S@MPC is about 30 C later than that of the control sample, indicating that the sulfur loss of R-S@MPC is more difficult. This proves that the sulfur confinement within the microporous carbon shell is well established. [49,52,53] In Figure 3, using the following techniques, we verify: (i) the presence and the distribution of the three pores by N 2 adsorption/desorption measurements, (ii) sulfur storage of the marginal straight mesopores by EDX element mappings, and (iii) LPSs blockage of micropores and accommodation of macropores by visualization experiment, which are basically in line with the original material design. As an energy storage material, battery performances are the only criterion for testing it. We fabricate 2032 coin cell, employing R-S@MPC composite as the cathode material, to evaluate the electrochemical performance as shown in Figure 4. In the rate test (Figure 4a,b), the R-S@MPC composite delivers stable reversible capacities under every current rate except the initial 0.2 C, 928 mah g 1 under 0.4 C, 822 mah g 1 under 0.6 C, 733 mah g 1 under 0.8 C, and 657 mah g 1 under 1 C. And when the current reverts to 0.4 C, the discharge capacity gets back to 919 mah g 1, responding to a recovery ratio of 99%. Compared with the control sample, R-S@MPC demonstrates higher rate capacities and superior capacity retention. The discharge voltage plateau at 1 C remains above 1.9 V, even under the high sulfur loading of 3.5 mg cm 2 (Figure 4b). R-S@ MPC and control sample are also investigated under higher discharge current density and low sulfur loading (Figure S12, Supporting Information). R-S@MPC delivers the reversible capacities of 762, 562, and 263 mah g 1, respectively, at 2, 3, and 4 C rate, exhibiting obvious advantages compared with the control sample. However, the rate capacities at 5 C fall significantly. This is attributed to that the microporous carbon shell limited the transmission rate of Li-ion, besides the suppression of the LPSs diffusion, especially under higher current density (5 C means 8.85 ma cm 2 ). The cycling performances are, respectively, measured at 0.2 and 0.5 C, as demonstrated in Figure 4c. R-S@MPC delivers an initial capacity of 1397 mah g 1 at the first cycle (0.1 C) for activation, [54 57] corresponding to an areal capacity of 5.8 mah cm 2. The R-S@MPC composite exhibits satisfactory cycling stability with 100% Coulombic efficiency and a residual specific capacity of 736 mah g 1 after 250 cycles at 0.2 C. It also displays an initial specific capacity of 869 mah g 1 and corresponding capacity retention of 61% after 300 cycles at 0.5 C, which is much higher than that of the control sample. Based on the rate test results, the long-term cycling performance of R-S@MPC under 1 C rate is investigated (Figure 4e and Figure S13, Supporting Information). The initial peak capacity is 470 mah g 1, and 440 mah g 1 remains after 500 cycles. This is corresponded to an ultralow decay rate of 0.013% cycle 1 at the sulfur loading of 4 mg cm 2. Compared with some typical cathode materials (Table S1, Supporting Information), R-S@MPC (5 of 8)

6 Figure 4. a) Rate performance of and control sample at stepwise current rates, and b) charge/discharge voltage profiles in rate test. c) Cycling performance of and control sample at current rate of 0.2 and 0.5 C. d) The EIS of the fresh cell, the cell after 200 and 400 cycles, respectively. e) Cycling capacity and Coulombic efficiency of at 1 C, and the inset photos are the separator and anode lithium metal after 500 cycles. The sulfur loadings are, respectively, 3.5 mg cm 2 (R-S@MPC) and 3.4 mg cm 2 (control sample) in (a), 4.2 mg cm 2 (0.2 C) and 3.2 mg cm 2 (0.5 C) in (c), and 4 mg cm 2 in (e). exhibits higher long-term cycling stability, reflecting the advantages of our work. The extremely low decay rate is ascribed to the functional differentiation and synergistic cooperation of the three pores in carbon frame. At the first stage of discharge, the generated long-chain LPSs gradually dissolve, and quickly transfer to the hollow cavity through the straight-through hole without any obstacles. Owing to the strong electric field force, the LPSs have tendencies to spread out, leading to the LPSs gathering in the straight-through mesopores on the edge of the R-S@MPC. The microporous carbon shell plays its function of sulfur blockage at this time, which buys time for the conversion of LPSs to the insoluble short chain lithium sulfides (Li 2 S/ Li 2 S 2 ). As the reductive reaction continues, abundant active sites provided by the large specific surface area pave way for fast and homogeneous re-deposition of LPSs, which is also reflected by the significantly decreased charge transfer resistance (R ct ) after cycling (Figure 4d). To further substantiate the argument aforementioned, we disassemble the cell after 500 cycles at 1 C. The R-S@MPC composite is characterized by SEM, TEM, and element mapping, as shown in Figure S14 (Supporting Information), verifying the structural integrity after the long-term cycling. Moreover, only slightly corroded metal lithium anode is found, accompanied by the separator without apparent color change, as displayed in the inset of Figure 4e, suggesting that almost no dissolved LPSs diffuse to the bulk electrolyte, neither shuttle to the surface of metal Li. This phenomenon in turn demonstrates the superior sulfur confinement effect of the unique structure, which has great significance to the cycling (6 of 8)

7 stability and the lithium dendrite suppression. The steady concentration and viscosity of the bulk electrolyte ensure fast Li-ion transfer and depressed concentration polarization, which is consistent with the unchanged Warburg resistance between before and after cycling (Figure 4d). And it is accounted as another cause for the splendid cycling stability under high current rate and high loading. In summary, a rambutan-shaped microporous carboncoated sulfur composite with 75 wt% sulfur content has been designed and synthesized, through in situ oxidation of the improved ZnS precursor that is self-assembled by ZnS nanosphere and nanorod. N 2 adsorption/desorption measurement is employed to prove the existence of the hollow macropore, the marginal straight-through mesopores connected with the macropore, and the micropores distributed on the outer carbon shell. The element mappings are applied to confirm the sulfur storage in the straight-through mesopores. And finally, an off-line visualization experiment is adopted to verify the effect of LPSs blockage of micropores and accommodation of macropores. The three pores perform their own single function, and collaborate with each other to suppress the shuttle effect of LPSs. Therefore, a remarkable decay rate of 0.013% cycle 1 is obtained, after 500 cycle at 1 C under sulfur loading of 4 mg cm 2. The strategy applied in this research work demonstrates a new idea to promote the cycling performance of Li S batteries, and provides a facile method to prepare the heterostructured metal sulfides that can also be applied in the field of photocatalysis. Experimental Section Synthesis of R-ZnS Precursor: The preparation schematic diagram is shown in Figure 1. First, the spherical ZnS core was prepared by a solvothermal method as reported previously. [48,49] Element sulfur (Sigma-Aldrich) and Zn(NO 3 ) 2 6H 2 O (Aladdin) were dispersed in glycol to form a uniform suspension, followed by a solvothermal reaction at 150 C. Second, 0.2 g of as-obtained ZnS nanospheres were mixed with 0.4 g zinc diethyl dithiocarbamate (ZDEC) in a mixture of 60 ml 80 wt% hydrazine hydrate and 20 ml deionized water under ultrasonication for 30 min. Then, the solution was transferred to Teflon-lined autoclave, and reacted at 150 C for 48 h. The product of rambutan-like ZnS was collected by centrifugation, and dried at 80 C overnight. Synthesis of R-ZnS@MPC: 0.29 g R-ZnS and g resorcinol were ultrasonically dispersed in 160 ml ethanol. Then, 50 µl of wt% formaldehyde and 4 ml of 28 wt% ammonia aqueous solution were added to the mixture, and stirred for 24 h at 30 C. The solution was sealed in a Teflon-lined autoclave and maintained at 100 C for 24 h. The as-obtained suspension was filtered, washed with deionized water and dried, followed by a calcination process under Ar gas at 750 C for 2 h, at heating rate 2 C min 1. Synthesis of R-S@MPC: 0.4 g of FeSO 4, 0.6 g of Fe 2 (SO 4 ) 3, and 1.8 g of I 2 were dissolved in a mixture of 40 ml of deionized water and 40 ml of ethanol under magnetic stirring. Then, 0.2 g pre-prepared R-ZnS@ MPC was added to the solution, and vigorously stirred for 24 h at 25 C. The solid product of R-S@MPC was collected through filtration, washed with ethanol and dried at 60 C for 24 h. Synthesis of Control Sample: The obtained R-S@MPC was heated in the tube furnace at 500 C and low pressure, under the protection of Ar gas, to obtain the rambutan-shaped hollow carbon (R-C). Then, the R-C was mixed with sulfur, and heated at 155 C for 24 h, under Ar atmosphere, to obtain the S/R-C composite as the control sample. Material Characterization: XRD patterns were recorded on the D/max-RB diffractometer (Rigaku, Japan) with a Cu Kα radiation. TGA measurements were carried out by heating to 500 C at a scanning rate of 5 C min 1 under Ar atmosphere. SEM characterization and EDX analysis were conducted using JSM-7800F. TEM, STEM, HAADF, and EDX element mapping were characterized by FEI Tecnai G 2 F30 field emission scanning transmission electron microscope at 300 kev. A gas adsorption analyzer (ASAP-2020) was used for N 2 adsorption/ desorption measurement, and the specific surface areas and pore-size distribution were calculated using Brunauer Emmett Teller (BET) and density functional theory (DFT) methods, respectively. The XPS spectra were obtained by ESCALAB250 X-ray photoelectron spectrometer using monochromatic Al Kα ( ev) radiation. Electrochemical Measurement: The cathode slurry was prepared by mixing 90 wt% of S-S/MPC, 4 wt% carboxymethylcellulose sodium (CMC), and 6 wt% styrene butadiene rubber (SBR) in deionized water. The electrodes were produced by coating the slurry onto carbon-coated aluminium foil with the sulfur loading of about 3.5 mg cm 2, which were then dried and cut into round disk with a diameter of 12 mm. The 2032 coin cells were fabricated in an Ar-filled glove box and used for the evaluation of the electrochemical performance of the R-S@MPC composite as cathode materials, Li metal served as anode, and Celgard 2325 membrane used as separator. The electrolyte was composed of 1 m lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in a mixture of 1,3-dioxolane (DOL) and dimethoxymethane (DME) (1:1, v/v) with 5 wt% of LiNO 3 (GuoTaiHuaRong Co., Ltd.). The electrolyte/sulfur ratio of 20 µl mg 1 is adopted. Visualization experiment was performed in a sealed bottle, with R-S@MPC as cathode, and metal lithium as anode. Both electrodes were connected with external circuit, and discharged under 0.1 C-rate (based on the sulfur mass of the cathode). Discharge/ charge and cycling performances were evaluated with a Neware Battery Measurement System (Neware, China) in the voltage range of V (vs Li + /Li). The electrochemical impedance spectroscopy (EIS) of the cells was recorded with a CHI660E electrochemical workstation (ShangHai ChenHua Co., Ltd.) over the frequency range of 100 khz to 100 mhz. Supporting Information Supporting Information is available from the Wiley Online Library or from the author. Acknowledgements This work was supported by the National Natural Science Foundation of China through Grant No M.Y. would like to thank the National Thousand Youth Talents program of China. This research was also financially supported by the National Natural Science Foundation of China (Grant Nos and ), Harbin Technological Achievements Transformation Projects (2016DB4AG023), and HIT Environment and Ecology Innovation Special Funds (Grant No. HSCJ201620). Conflict of Interest The authors declare no conflict of interest. Keywords functional separation of three pores, high cyclic stability under high loading, in situ oxidation preparation, rambutan-shaped sulfur/carbon composites, self-assembled ZnS precursors Received: September 21, 2017 Revised: November 11, 2017 Published online: (7 of 8)

8 [1] L. Xiao, Y. Cao, J. Xiao, B. Schwenzer, M. H. Engelhard, L. V. Saraf, Z. Nie, G. J. Exarhos, J. Liu, Adv. Mater. 2012, 24, [2] Z. Ma, S. Dou, A. Shen, L. Tao, L. Dai, S. Wang, Angew. Chem., Int. Ed. 2015, 54, [3] R. Demir-Cakan, M. Morcrette, Gangulibabu, A. Gueguen, R. Dedryvere, J. M. Tarascon, Energy Environ. Sci. 2013, 6, 176. [4] L. Ji, M. Rao, H. Zheng, L. Zhang, Y. Li, W. Duan, J. Guo, E. J. Cairns, Y. Zhang, J. Am. Chem. Soc. 2011, 133, [5] X. Fang, H. S. Peng, Small 2015, 11, [6] Q. Pang, L. F. Nazar, ACS Nano 2016, 10, [7] X. Liang, Y. Rangom, C. Y. Kwok, Q. Pang, L. F. Nazar, Adv. Mater. 2017, 29, [8] T. Zhao, Y. S. Ye, C. Y. Lao, G. Divitini, P. Coxon, Xi. Y. Peng, X. He, H. K. Kim, K. Xi, C. Ducati, R.J. Chen, Y. J. Liu, S. Ramakrishna, R. V. Kumar, Small 2017, 13, [9] J. Liu, W. Li, L. Duan, X. Li, L. Ji, Z. Geng, K. Huang, L. Lu, L. Zhou, Z. Liu, W. Chen, L. Liu, S. Feng, Y. Zhang, Nano Lett. 2015, 15, [10] J. T. Lee, Y. Zhao, S. Thieme, H. Kim, M. Oschatz, L. Borchardt, A. Magasinski, W. I. Cho, S. Kaskel, G. Yushin, Adv. Mater. 2013, 25, [11] J. L. Shi, C. Tang, H. J. Peng, L. Zhu, X. B. Cheng, J. Q. Huang, W. C. Zhu, Q. Zhang, Small 2015, 11, [12] Z. Lyu, D. Xu, L. Yang, R. Che, R. Feng, J. Zhao, Y. Li, Q. Wu, X. Wang, Z. Hu, Nano Energy 2015, 12, 657. [13] H. Yao, G. Zheng, P.-C. Hsu, D. Kong, J. J. Cha, W. Li, Z. W. Seh, M. T. McDowell, K. Yan, Z. Liang, V. K. Narasimhan, Y. Cui, Nat. Commun. 2014, 5, [14] S. Rehman, T. Y. Tang, Z. S. Ali, X. X. Huang, Y. L. Hou, Small 2017, 13, [15] J. Zhang, H. Hu, Z. Li, X. W. Lou, Angew. Chem., Int. Ed. 2016, 55, [16] Z. W. Seh, W. Li, J. J. Cha, G. Zheng, Y. Yang, M. T. McDowell, P.-C. Hsu, Y. Cui, Nat. Commun. 2013, 4, [17] S. Rehman, S. Guo, Y. Hou, Adv. Mater. 2016, 28, [18] M. Q. Zhao, X.-F. Liu, Q. Zhang, G.-L. Tian, J.-Q. Huang, W. Zhu, F. Wei, ACS Nano 2012, 6, [19] C. Wang, X. Wang, Y. Wang, J. Chen, H. Zhou, Y. Huang, Nano Energy 2015, 11, 678. [20] H. Wang, Y. Yang, Y. Liang, J. T. Robinson, Y. Li, A. Jackson, Y. Cui, H. Dai, Nano Lett. 2011, 11, [21] H. Sohn, M. L. Gordin, T. Xu, S. Chen, D. Lv, J. Song, A. Manivannan, D. Wang, ACS Appl. Mater. Interfaces 2014, 6, [22] H.-J. Peng, J. Liang, L. Zhu, J.-Q. Huang, X.-B. Cheng, X. Guo, W. Ding, W. Zhu, Q. Zhang, ACS Nano 2014, 8, [23] F. Wu, J. T. Lee, N. Nitta, H. Kim, O. Borodin, G. Yushin, Adv. Mater. 2015, 27, 101. [24] T. Chen, B. R. Cheng, G. Y. Zhu, R. P. Chen, Y. Hu, L. B. Ma, H. L. Lv, Y. R. Wang, J. Liang, Z. X. Tie, Z. Jin, J. Liu, Nano Lett. 2017, 17, 437. [25] L. B. Ma, R. P. Chen, G. Y. Zhu, Y. Hu, Y. R. Wang, T. Chen, J. Liu, Z. Jin, ACS Nano 2017, 11, [26] X. Liang, C. Y. Kwok, F. Lodi-Marzano, Q. Pang, M. Cuisinier, H. Huang, C. J. Hart, D. Houtarde, K. Kaup, H. Sommer, T. Brezesinski, J. Janek, L. F. Nazar, Adv. Energy Mater. 2016, 6, [27] G. Zhou, Y. Zhao, C. Zu, A. Manthiram, Nano Energy 2015, 12, 240. [28] H. Wang, Q. Zhang, H. Yao, Z. Liang, H. W. Lee, P. C. Hsu, G. Zheng, Y. Cui, Nano Lett. 2014, 14, [29] T. Y. Lei, Y. M. Xie, X. F. Wang, S. Y. Miao, J. Xiong, C. L. Yan, Small 2017, [30] T. Chen, Z. W. Zhang, B. R. Cheng, R. P. Chen, Y. Hu, L. B. Ma, G. Y. Zhu, J. Liu, Z. Jin, J. Am. Chem. Soc. 2017, 139, [31] D. R. Deng, F. Xue, Y. J. Jia, J. C. Ye, C. D. Bai, M. S. Zheng, Q. F. Dong, ACS Nano 2017, 11, [32] D. R. Deng, T. H. An, Y. J. Li, Q. H. Wu, M. S. Zheng, Q. F. Dong, J. Mater. Chem. A 2016, 4, [33] Y. Zhao, M. Liu, W. Lv, Y. B. He, C. Wang, Q. B. Yun, B. H. Li, F. Y. Kang, Q. H. Yang, Nano Energy 2016, 30, 1. [34] C. Oh, N. Yoon, J. Choi, Y. Choi, S. Ahn, J. K. Lee, J. Mater. Chem. A 2017, 5, [35] Z. A. Ghazi, X. He, A. M. Khattak, N. A. Khan, B. Liang, A. Iqbal, J. X. Wang, H. Sin, L. S. Li, Z. Y. Tang, Adv. Mater. 2017, 29, [36] M. Liu, Q. Li, X. Y. Qin, G. M. Liang, W. J. Han, D. Zhou, Y. B. He, B. H. Li, F. Y. Kang, Small 2017, 13, [37] W. B. Kong, L. J. Yan, Y. F. Luo, D. T. Wang, K. L. Jiang, Q. Q. Li, S. S. Fan, J. P. Wang, Adv. Funct. Mater. 2017, 27, [38] D. C. Lin, Y. Y. Liu, W. Chen, G. M. Zhou, K. Liu, B. Dunn, Y. Cui, Nano Lett. 2017, 17, [39] S. Jin, S. Xin, L. J. Wang, Z. Z. Du, L. N. Cao, J. F. Chen, X. H. Kong, M. Gong, J. L. Lu, Y.W. Zhu, H. X. Ji, R. S. Ruoff, Adv. Mater. 2016, 28, [40] Q. Li, S. Zhu, Y. Y. Lu, Adv. Funct. Mater. 2017, 27, [41] H. K. Jing, L. L. Kong, S. Liu, G. R. Li, X. P. Gao, J. Mater. Chem. A 2015, 3, [42] G. He, S. Evers, X. Liang, M. Cuisinier, A. Garsuch, L. F. Nazar, ACS Nano 2013, 7, [43] Z. Li, Y. Jiang, L. Yuan, Z. Yi, C. Wu, Y. Liu, P. Strasser, Y. Huang, ACS Nano 2014, 8, [44] M. Li, Y. Zhang, X. Wang, W. Ahn, G. Jiang, K. Feng, G. Lui, Z. Chen, Adv. Funct. Mater. 2016, 26, [45] C. Zhang, H. B. Wu, C. Yuan, Z. Guo, X. W. Lou, Angew. Chem., Int. Ed. 2012, 51, [46] S.-H. Chung, C.-H. Chang, A. Manthiram, Energy Environ. Sci. 2016, 9, [47] Z. Li, H. B. Wu, X. W. Lou, Energy Environ. Sci. 2016, 9, [48] Q. Wang, Z. B. Wang, C. Li, D. M. Gu, J. Mater. Chem. A 2017, 5, [49] Q. Wang, Z. B. Wang, M. H. Yang, C. Li, D. M. Gu, J. Mater. Chem. A 2017, 5, [50] Z. Zhang, Q. Li, S. Jiang, K. Zhang, Y. Lai, J. Li, Chem. Eur. J. 2015, 21, [51] R. Chen, T. Zhao, J. Lu, F. Wu, L. Li, J. Chen, G. Tan, Y. Ye, K. Amine, Nano Lett. 2013, 13, [52] D. L. Wang, Y. C. Yu, W. D. Zhou, H. Chen, F. J. DiSalvo, D. A. Muller, H. D. Abruna, Phys. Chem. Chem. Phys. 2013, 15, [53] Y. Zhao, W. L. Wu, J. X. Li, Z. C. Xu, L. H. Guan, Adv. Mater. 2014, 26, [54] F. Pei, T. H. An, J. Zang, X. J. Zhao, X. L. Fang, M. S. Zheng, Q. F. Dong, N. F. Zheng, Adv. Energy Mater. 2016, 6, [55] C. Y. Chen, H. J. Peng, T. Z. Hou, P. Y. Zhai, B. Q. Li, C. Tang, W. C. Zhu, J. Q. Huang, Q. Zhang, Adv. Mater. 2017, 29, [56] T. Chen, L. B. Ma, B. R. Cheng, R. P. Chen, Y. Hu, G. Y. Zhu, Y. R. Wang, J. Liang, Z. X. Tie, J. Liu, Z. Jin, Nano Energy 2017, 38, 239. [57] X. Liang, L. F. Nazar, ACS Nano 2016, 10, (8 of 8)