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• W2054673905 abstract "Best of both worlds: A heterostructured material is synthesized that comprises a core of layered lithium-rich material and an outer layer of nanospinel material. This spinel/layered heterostructured material maximizes the inherent advantages of the 3D Li+ insertion/extraction framework of the spinel structure and the high Li+ storage capacity of the layered structure. The material exhibits super-high reversible capacities, outstanding rate capability and excellent cycling ability. High energy- and -power-density lithium-ion batteries (LIBs) are critically needed for applications in electric vehicles (EVs), and renewable energy storage in smart grids.1, 2 Lack of high-performance cathode materials has become a technological bottleneck for the commercial development of advanced LIBs.3 Layered lithium-rich materials,4-11 xLi2MnO3·(1–x)LiMO2 (0 < x < 1, M = Ni0.5Mn0.5, Mnx'Niy'Co1–x'–y', 0 < x', y' < 1), have attracted much attention due to their encouraging features such as high specific capacity (ca. 250 mAh g−1) and low cost. Despite these advantages, one major weakness of xLi2MnO3·(1–x)LiMO2 is their intrinsically poor rate capability, which has been recently verified to be associated with retarding mass transport of the rearranged surface after activating Li2MnO3 at above 4.5 V charge.12 This rearrangement causes a large capacity loss as well. In addition, these materials suffer from fragile surface properties at high potential, erosion from the electrolytes, and dissolution of transition-metal ions.7-12 Therefore, implementation of layered lithium-rich materials to achieve high and stable capacity at high rate has not really been feasible. Many efforts have been devoted to addressing these challenges. Reduction of the particle size to nanoscale levels can improve the rate performance of a material by shortening the lithium-diffusion pathways in it. However, this reduction will lower packing density and structural stability of the material.13 Surface modification has also been employed to reinforce the rate performance and cycling stability of layered lithium-rich materials.14-20 Coating lithium-rich materials with various oxides and phosphates could stabilize the surface structure of the materials,14-17 while AlF3 coating was reported to promote partially the transformation of bulk layered lithium-rich materials into spinel.18 Lithium-rich materials coated with Li+-conducting LiNiPO4 showed a reversible capacity of 200 mAh g−1 at 1 C rate.19, 20 However, it remains a challenge to apply these layered lithium-rich materials for high-power-density batteries. Currently, spinels LiNixMn2–xO4 (0 ≤ x ≤ 0.5) with three-dimensional (3D) Li+ diffusion channels exhibit great potential as high-power cathode materials for LIBs,21-25 because of their “high Li+ ionic and electronic conductivity”,26 high voltage, low cost, and low toxicity. However, the spinel cathode delivers a capacity of less than 150 mAh g−1 at above 3 V cycling. Up to now, there have been few reports that combine the merits of the layered and the spinel materials to render a material superior in kinetics, energetics, and stability.27-29 Herein, we report a reasonable design and synthesis of spinel/layered heterostructured material, by encapsulating a layered lithium-rich material with a nanospinel mixture LiNixMn2–xO4. This heterostructured material can maximize the inherent advantages of the 3D Li+ insertion/extraction framework of the spinel structure and high Li+ storage capacity of the layered structure. The pristine layered lithium-rich material (PL), Li1.2Mn0.6Ni0.2O2 (or 0.5Li2MnO3·0.5LiMn0.5Ni0.5O2) was prepared by a “mixed-oxalate” method (see the Supporting Information for details). Fabrication of the spinel/layered heterostructured material involves two key steps as illustrated in Scheme S1. Firstly, the particles of the lithium-rich material were coated with Mn(AC)2 by a “dip and dry” process to yield a good encapsulating layer. Then the coated material was heat-treated in air, which allowed the Mn2+ ions of the decomposed Mn(AC)2 and the Li+ and Ni2+ ions of the lithium-rich material to diffuse into each other to form the heterostructured material with spinel and layered phases. To optimize synthetic conditions, three temperatures (500, 750, and 900 °C) were applied in this step. The morphology and surface structure of these three materials were firstly characterized by using field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HRTEM; Figure 1). Similar to the PL particles (Figure S1), the micron-sized particles of the material heat-treated at 500 °C in Figure 1A are an assembled structure of submicron crystallites. The HRTEM image in Figure 1B shows that the material produced at 500 °C has an unstable amorphous outer layer with a trace amount of crystal phase. When a temperature of 750 °C is used, the particle size of the material (Figure 1C) presents negligible change in comparison with that at 500 °C. However, as illustrated in Figure 1D, the outer layer becomes well crystalized as a stable single crystal rather than randomly dispersed nanoparticles, which can be confirmed by its digitalized Fourier-transformed image (inset). By forming such a well-crystalized structure, this material is probably able to increase its stability. On further increase of the temperature to 900 °C, the particle size of the material exhibits dramatic increase due to the aggregation of material particles (Figure 1E), although it has a thick and well-crystalized outer layer (Figure 1F). Thus, the results clearly illustrate that 750 °C is the ideal temperature to obtain the heterostructure, and here we label the material heat-treated at 750 °C as the SLH (spinel/layered heterostructured material). FESEM and HRTEM images of materials heat-treated at A,B) 500 °C, C,D) 750 °C, and E,F) 900 °C; insets are the corresponding digitalized Fourier-transformed images of the white rectangles in HRTEM images; the inset in top left corner of F) is the corresponding TEM image. As suggested by the morphological characterizations, the materials heat-treated at different temperatures exhibit corresponding structural patterns (Figure S2). The structural characterization of the SLH material is as shown in Figure 2. For comparison, XRD patterns of phase-pure spinel LiNi0.5Mn1.5O4 and the PL material are indexed as well. Clearly, the XRD pattern of the SLH sample is composed of two sets of XRD patterns, that of the PL (R m symmetry) with weak superlattice reflections at 2θ = 20–25°, which corresponds to Li2MnO3 (C/2m symmetry),4, 5, 8, 11 and that of the spinel (Fd m symmetry), except for some shift of the reflections due to diffusion of the transition-metal atoms during material preparation. Consequently, we can conclude that the SLH sample is a composite of spinel and layered lithium-rich Li–Ni–Mn–O. Powder X-ray diffraction patterns of all the samples and some Miller indices of the main peaks. Detailed morphological characterizations were further performed to confirm the heterostructure of the SLH sample. Clearly structural differences were observed between the PL and the SLH materials under HRTEM. The PL sample shows a typical layered structure: its (003) fringes, with interlayer spacing of ca. 4.7 Å, are straight and uninterrupted until the edge of a particle (Figure 3A). On the other hand, a distinguishable interface is observed close to the edge of the SLH particles in Figure 3B. The magnified view near the interface exhibits the dense contact of the core and the outer layer. This phenomenon results from the metal-ion diffusion between both sides during heat treatment,30, 31 which is confirmed by the energy-dispersive X-ray (EDX) line-scanning results for the SLH and PL materials (Figure S3). The inner side of the interface shows clear and perfect (003) fringes, characteristic of the layered structure of a lithium-rich material. Outside of the core is a crystalline layer approximately 10 nm thick. As further characterized in Figure 3C, the outer nanostructure clearly presents fine lattice fringes. The interplanar spacings of the lattice fringes are measured to be 0.206 and 0.146 nm, which are well indexed to the [400] and [440] planes of cubic-spinel structure, respectively. This result is in good agreement with the selected-area diffraction (SAED) patterns of the PL and SLH samples (Figure S4). Thus, combined with XRD observation, this fourfold symmetry, which cannot be found in the space group R m of a layered lithium-rich material, explicitly confirms the spinel/layered heterostructure of the SLH material. HRTEM of A) PL and B) SLH, inset of (B) is the 2.5× magnified view of the black rectangle area; C) HRTEM of the outer nanostructure of the SLH; D) schematic diagram of the SLH materal. Due to structural compatibility between the cubic-close-packed spinel LiNixMn2–xO4 (0 < x ≤ 0.5) and layered lithium-metal oxides,6-8 this SLH material is expected to have high structural stability. The diffusion of metal ions leads to the formation of the spinel integrated into the layered structure in the SLH, so the interface between the layered core and the outer spinel should have good Li+ penetrability. In addition, the 3D Li+ diffusion channel of the spinel ensures rapid Li+ ion exchange with the electrolytes. Therefore, the thin outer nanospinel layer acts as a “expressway” for the Li+, transporting between the layered core and electrolytes as shown in Figure 3D. This feature will have a vital impact on the rate performance of the SLH. To explore the advantages of the heterostructured material as a cathode for LIBs, we firstly investigated its initial charge/discharge performance between 2.0 and 4.8 V at C/10 rate (25 mA g−1) as shown in Figure 4A. The PL sample was also tested for comparison. In Figure 4A, the PL shows a representative profile of lithium-rich cathode, comprising a sloping curve below 4.5 V and a plateau around 4.5 V in charge and continuous sloping curves in discharge.8, 11 As for the SLH sample, the curve shape exhibits differences at the beginning and the end of the charge/discharge cycle, compared with that of the PL sample. Surprisingly, the dQ/dV plots clearly illustrate that the electrochemical reactions emerging in the SLH sample consist of nearly all the redox couples in the PL and the spinel LiNi0.5Mn1.5O4 in the same charge/discharge voltage range (Figure S5). Furthermore, it is notable that the SLH delivers a discharge capacity of over 300 mAh g−1. This increase in discharge capacity has been obtained by leveraging the activity of the spinel mixture LiNixMn2–xO4 both at 4.7 V (due to Ni4+ being reduced to Ni2+) and 2.9 V (due to Mn4+ reduction to Mn3+), and maintaining lithium vacancies of the layered lithium-rich material in the core by the outer spinel around 3.5 V.14-18, 21-25 From the data obtained by structural and morphological characterizations and initial charge/discharge tests, we can undoubtedly conclude that the SLH unites structural configuration and electrochemical properties of the as-designed spinel and layered materials simultaneously. A) Initial charge/discharge characteristics of SLH and PL; B) cycling performance of half cells based on the SLH and PL materials between 2.0 – 4.8 V by applying constant currents of C/10, C/5 and C/2; high rate-discharge capability and capacity retention for the the SLH and PL materials; C) discharge curves of both samples at various C rates after charging at C/10 rate to 4.8 V, and D) the capacity retentions of both samples; E) 1C rate charge/discharge cycling performance of the SLH and PL materials; constant voltage at 4.8 V to C/10 current density was applied during charging. Figure 4B and Table S1 show that superhigh capacity at moderate rates can be achieved by the SLH between 2.0 and 4.8 V. The SLH sample exhibited much advantage over the PL sample both in capacity and cycling ability. The PL showed a discharge capacity of 283.5 mAh g−1 with acceptable capacity retention of 86.5% after 50 cycles at C/10 rate; it retained maximal capacity of only 220.6 and 170.0 mAh g−1 with modest capacity retention at C/5 and C/2 rate charge/discharge, respectively. However, the SLH yielded capacities above 270 mAh g−1 with excellent capacity retention at both C/10 and C/5 rate, and it maintained nearly 240 mAh g−1 after 80 cycles at C/2 rate after gradual activation, although structural transformation was suffered during cycling at these rates (Figure S6). The coulombic efficiency of the SLH was maintained close to 98% after several initial cycles at all these rates. Moreover, an aggressive test (rest for 30 days before being recycled at C/10 rate), was carried out to evaluate the stability and self-maintainence of the materials. The SLH nicely maintained its capacity of 275.9 mAh g−1 after a total of 100 cycles. In contrast, the capacity of the PL abruptly decreased and then remained at only 221.9 mAh g−1 by the 100th cycle. The poor rate performance of the layered lithium-rich material is one of the major barriers to their applications in EVs. Our work has provided evidence that high-rate discharge capacities could be achieved by the SLH material. Figure 4C, 4D, and Table S2 show the rate performance of the PL and SLH at 1C, 2C, 5C, and 10C after charging the materials to 4.8 V at C/10 rate (1C rate is equivalent to 250 mAh g−1 in our definition). Figure 4C shows that both samples exhibit similar curve shape to that at moderate rate in Figure 4A. Interestingly, the SLH maintains its capacity at around the 4.5 V plateau, which is probably associated with the high Li+ conductivity and electrochemical activity of the outer nanospinel. Figure 4D shows that the PL sample delievers maximal capacities of less than 190 mAh g−1 with extremely poor cycling ability from 1C to 10C. This serious capacity fade results from fast Li+ insertion/extraction damaging the fragile surface of the layered structure at high rates.6-8, 12 Conversely, the SLH sample yields high maximal discharge capacities of 274.6 mAh g−1 at 1C rate and 268.8 mAh g−1 at 2C rate. More surprisingly, the SLH sample delivers a maximal capacity of 218.9 mAh g−1 at 5C rate. In addition, the SLH obtains nice capacity retentions of over 94% for 30 cycles at all these rates. For the 10C rate, fully discharged to 1.5 V, the SLH delivers a maximal capacity of 189.5 mAh g−1 with retention of 90.9%, and it obtains stable capacity over 150 mAh g−1 discharged to 2.0 V (Figure S7). The SLH sample yields superior capacities at ultrahigh rates as well (Figure S8). Apart from high-rate discharging performance, the fast charge capability of the material is also of significance for practical application. For this reason, we further tested the rate-cycling ability of the SLH and PL samples at 1C rate charge/discharge, while constant potential charging to C/10 current density was applied to eliminate polarization. As shown in Figure 4E, a real capacity of ca. 250 mAh g−1 was obtained by the SLH, and it exhibited a maximal capacity of 264.8 mAh g−1 and capacity retention of 93.7% after 100 cycles in spite of structural transformation (Figure S9). To the best of our knowledge, this high capacity is among the highest values reported for the power performance of layered or spinel cathode materials at 1C rate charge/discharge. Nevertheless, the PL sample shows a maximal capacity of 181.7 mAh g−1 and capacity retention of less than 80% after the same cycles. The outstanding overall rate performance (both at moderate and high rate) of the SLH material can result from its reasonable design and feasible synthesis. The as-designed heterostructure can display the high Li+ conductivity of the spinel structure and the high Li+ storage capacity of the layered structure to the extreme. First, the stable spinel structure can protect the layered core from erosion of electrolytes and restrain the bulk active-mass loss. Second, the outer nanospinel has 3D Li+ diffusing channels, and it could facilitate fast Li+ ions diffusion from electrolytes to the core-layered structure. Finally, the compatibility and integration of the cubic-close-packed spinel and layered structure in the heterostructure endow this material with high structural stability. In summary, we have developed a high-capacity and high-rate heterostructured cathode material for LIBs. The spinel/layered heterostructure of the material has been confirmed by structural, morphological, and electrochemical characterization. This cathode material exhibits a remarkable rate capability, extremely high capacity, and excellent cycling ability and may eventually lead to advanced LIBs that meet the requirements of electric vehicles and renewable energy storage, although the voltage drop during cycling indicates that structural transformation still needs work to finally enable this material to fulfil such aims. We anticipate this novel insight into the design and synthesis of cathode materials should inspire the development of a wide range of other stable, high-rate, and high-capacity intercalation materials. Supporting Information is available from the Wiley Online Library or from the author. The authors acknowledge Prof. Zhao-Xiang Wang from Laboratory for Solid State Ionics, Institute of Physics, Chinese Academy of Sciences for helpful discussion. This work was funded by the Key National Basic Research and Development Program of China (2009CB220100), National Natural Science Foundation of China (51102018, 21103011) and National High-Tech Research and Development Program of China (2011AA11A235, SQ2010AA1123116001). Thanks to Beijing National Center for Electron Microscopy (Beijing, China) for the technology support in EDX line scanning. As a service to our authors and readers, this journal provides supporting information supplied by the authors. Such materials are peer reviewed and may be re-organized for online delivery, but are not copy-edited or typeset. Technical support issues arising from supporting information (other than missing files) should be addressed to the authors. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article." @default.
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• W2054673905 date "2013-06-06" @default.
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• W2054673905 title "Spinel/Layered Heterostructured Cathode Material for High-Capacity and High-Rate Li-Ion Batteries" @default.
• W2054673905 cites W1964815587 @default.
• W2054673905 cites W1970330754 @default.
• W2054673905 cites W1972718132 @default.
• W2054673905 cites W1982926166 @default.
• W2054673905 cites W1990457205 @default.
• W2054673905 cites W1990652323 @default.
• W2054673905 cites W1991087444 @default.
• W2054673905 cites W1997206245 @default.
• W2054673905 cites W2006318126 @default.
• W2054673905 cites W2008305658 @default.
• W2054673905 cites W2009994680 @default.
• W2054673905 cites W2018105634 @default.
• W2054673905 cites W2019903682 @default.
• W2054673905 cites W2029450706 @default.
• W2054673905 cites W2039530673 @default.
• W2054673905 cites W2058284086 @default.
• W2054673905 cites W2069419870 @default.
• W2054673905 cites W2073873501 @default.
• W2054673905 cites W2089525884 @default.
• W2054673905 cites W2097924219 @default.
• W2054673905 cites W2136230858 @default.
• W2054673905 cites W2142745319 @default.
• W2054673905 cites W2151121108 @default.
• W2054673905 cites W2151492763 @default.
• W2054673905 cites W2157194577 @default.
• W2054673905 cites W2161747741 @default.
• W2054673905 cites W2164158077 @default.
• W2054673905 cites W2232898241 @default.
• W2054673905 cites W2328713745 @default.
• W2054673905 cites W2332180492 @default.
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