{ "sample": "07-elsevier-middle-pages", "threshold": 0.35, "cache_status": { "exists": true, "usable": true, "reason": "cache_page_count_ok", "expected_pdf_pages": 10, "cached_docling_pages": 10, "cached_docling_max_page": 10, "formula_enrichment_enabled": false, "formula_enrichment_scale": 3.0, "formula_nodes": 0, "recognized_formula_nodes": 0 }, "candidate_blocks": [ { "page": 1, "page_count": 10, "bbox": [ 36.85, 345.77, 503.12, 420.5 ], "text": "A mixed cathode material between Li2MnO3 and Li[Mn1/3Ni1/3Co1/3]O2 for high capacity lithium secondary batteries was introduced in this study. It was prepared using the sucrose combustion process because this is a simple process. The oxidation states of Mn, Co and Ni ions in the pristine Li[Li(1\u0002x)/3Mn(2\u0002x)/3Nix/3Cox/3]O2 compounds were confirmed to be tetravalent, trivalent and divalent, respectively, via XANES measurements. Electrochemical charge/discharge studies showed that the highest first discharge capacity of 224 mAh/g was obtained in composition of x = 0.5 at a 0.2 C rate. The oxidation state of the Co and Ni ions in the Li[Li1/6Mn1/2Ni1/6Co1/6]O2 changed to higher oxidation states, but that of the Mn ions did not change. # 2008 Elsevier Ltd. All rights reserved.", "category": "metadata", "coverage": 0.804, "words": 142 }, { "page": 2, "page_count": 10, "bbox": [ 41.16, 103.94, 507.46, 141.84 ], "text": "Theoretical capacity (mAh/g) 336.12 321.15 307.46 294.89 283.30 a (Å) 2.83700(14) 2.84947(3) 2.85330(1) 2.85806(0) 2.86248(0) c (Å) 14.24141(65) 14.22449(25) 14.22872(11) 14.23524(0) 14.23820(4) c/a 5.01988 4.99198 4.98676 4.98074 4.97408", "category": "scientific_body", "coverage": 0.0, "words": 58 }, { "page": 2, "page_count": 10, "bbox": [ 41.16, 290.64, 507.36, 348.4 ], "text": "3Co1/3Mn1/3]O2 were synthesized via a SCP (Sucrose Combustion Process) method. Compared with other synthetic methods, this method is very simple and involves less manufacturing time. The structural and electrochemical properties were investigated using X-ray diffraction, a charge–discharge method and XANES. In consequence, the most feasible composition of x in Li[Li1\u0002x/3Mn2\u0002x/3Nix/3Cox/3]O2 for the highest discharge capacity and the redox mechanism were formulated.", "category": "scientific_body", "coverage": 0.914, "words": 74 }, { "page": 2, "page_count": 10, "bbox": [ 41.16, 386.28, 507.41, 623.42 ], "text": "Mixed compounds Li[Li(1\u0002x)/3Mn(2\u0002x)/3Nix/3Cox/3]O2 composed of Li[Ni1/3Co1/3Mn1/3]O2 and Li2MnO3 were prepared by a SCP method from LiNO3, Mn(NO3)2\u00036H2O, Ni(NO3)2\u00036H2O and Co(NO3)2\u00036H2O as precursors. Initially, to make each Li[Ni1/3Co1/3Mn1/3]O2 and Li2MnO3 solution, stoichiometric amounts of source materials of Ni, Co, Mn and Li (molar ratio of Li:Ni:Co:Mn = 3:1:1:1 for Li[Ni1/3Co1/3Mn1/3]O2 and Li:Mn = 2:1 for Li2MnO3) were dissolved and mixed homogeneously in distilled water. The two solutions were mixed with ratios of 1:9, 3:7, 5:5, 7:3 and 9:1 (x = 0.1, 0.3, 0.5, 0.7 and 0.9, respectively). A powder, similar in appearance to gray ash, was produced through stirring the mixed solution continuously at 100 8C with 1 M ratio of sucrose, followed by gelation and combustion of mixed solution. The decomposed powder was ground and heated at 900 8C in a box type furnace for 12 h. It was then poured into liquid nitrogen and quenched. And the quenched powder was dried at 120 8C to evaporate the residual moisture. The synthesized particle size was measured with Malvern Mastersize S. X-ray diffraction experimental was performed using Automated Rigaku X-ray diffractometer in the 2u ranges from 108 to 708 with Cu Ka radiation. To prepare the positive electrode, the produced powder, carbon black (Vulcan XC-72) as conductor and PVdF were mixed in homogenizer at mass ratio of 84:8:8, respectively. And a viscous slurry was coated in aluminum foil using the doctor blade with uniform thickness of 20 mm. And the coated film was dried in vacuum oven at 100 8C. Then the 2032 type coin cell was assembled in glove box filled with Ar gas using cathode film, lithium foil (Foote Mineral Co.), separator (PP, Celgard Inc.) and electrolyte (1 M LiPF6 solution in a 1: 1 volume ratio of EC and DEC). Galvanostatic charge/discharge tests were performed using WBCS3000 system. The current density was 0.2 C-rate and cut off voltage was 2.0–4.8 V. The cyclic voltammograms tests were conducted from 2.0 to 4.8 Vat 0.1 mV/s scan rate. The X-ray absorption near-edge structure (XANES) analysis was carried out to examine oxidation state of Mn, Co and Ni ions and the change of their oxidation state during charge/discharge measurement.", "category": "scientific_body", "coverage": 0.86, "words": 425 }, { "page": 3, "page_count": 10, "bbox": [ 36.85, 266.62, 503.1, 301.6 ], "text": "layered structures showed a good splitting of the peaks assigned to (108, 110) with c/a values higher than 4.899 [10]. The clearly split (108, 110) pairs and the c/a ratio (when higher than 4.899) in all compositions of x indicate that the layered structure was synthesized successfully. The c/a values and lattice parameters of the Li[Li(1\u0002x)/3Mn(2\u0002x)/3Nix/", "category": "scientific_body", "coverage": 0.984, "words": 68 }, { "page": 4, "page_count": 10, "bbox": [ 41.16, 601.49, 507.38, 683.17 ], "text": "by itself, the Li2MnO3 inside a domain structure is active when the voltage is higher than 4.4 V. When charged, one Li2MnO3 loses one O2\u0002 ion and two Li+ ions in forms of Li2O at above 4.4 Vand becomes MnO2. When discharged, the MnO2 becomes LiMnO2 by gaining only one Li+ ion, which is a main reason of irreversible capacity loss on the initial cycle. Considering the results shown in Fig. 4(a) and (b), it was determined that the optimized composition is x = 0.5, as the compounds of x = 0.5 and Li[Li1/6Mn1/2Ni1/6Co1/6]O2 incorporate the advantages of both structural stability and coulomb efficiency.", "category": "scientific_body", "coverage": 0.891, "words": 114 }, { "page": 10, "page_count": 10, "bbox": [ 41.16, 75.44, 507.4, 169.08 ], "text": "6Co1/6]O2 during two cycles and after fifty cycles. It is shown in Fig. 9(a) that the entire edge of the Mn K-edge XANES spectra does not change strictly to higher energy value during two cycles and after fifty cycles. As a result, the valence state of the Mn ions in the Li[Li1/6Mn1/2Ni1/6Co1/6]O2 does not obviously change during the charge/discharge cycles. The shape of spectra after the first cycle (scan 4) differs from that of the fresh compound (pristine point, scan 0), it is similar, however, to that after fifty cycles. This indicates that the local structural changes of Mn ions are not clearly reversible during the first cycle, but that they are highly reversible after the first cycle. The redox behavior of the Co and Ni ions is clearly different from that of the Mn ions. As shown in Fig. 9(b) and (c), the oxidation states of the Co and Ni ions change reversibly as the cycles proceed. The valence state of the Co ions changes between Co3+ and Co3.5+", "category": "scientific_body", "coverage": 0.777, "words": 183 }, { "page": 10, "page_count": 10, "bbox": [ 41.16, 166.66, 507.34, 228.89 ], "text": "while that of the Ni ions changes between Ni2+ and Ni3+. Consequently, the redox behavior of the Co and Ni ions is highly reversible during the cycling process. Considering the XANES results, it can be concluded that the redox reactions of Ni (Ni2+$Ni3+) ions and Co (Co3+$Co3.5+) are dominant at a 4.1 V plateau during charge/discharge cycles, whereas the valence state of Mn ions does not change.", "category": "scientific_body", "coverage": 0.735, "words": 72 }, { "page": 10, "page_count": 10, "bbox": [ 41.16, 266.62, 507.38, 372.32 ], "text": "As an alternative cathode material to LiCoO2, Li[Li1\u0002x/3Mn2\u0002x/3Nix/3Cox/3]O2 powders (x = 0.1, 0.3, 0.5, 0.7 and 0.9) were investigated. The powders were synthesized easily using a sucrose combustion process. As a result of experiments using various compositions, the highest discharge capacity of 224 mAh/g was obtained at a composition of x = 0.5, as Li ions were used in place of heavy transition metal ions. When more Li2MnO3 exists compared to Li[Ni1/3Co1/3Mn1/3]O2, the discharge capacity is very low due to the electrochemically inactive Li2MnO3. Via XANES spectra measurements, the electrochemical reaction of Ni and Co ions at 4.1 Vions is reversible during charge/discharge cycling. The local environmental change of Mn ions is irreversible during the first cycle, but becomes reversible after the first charge. The oxidation state of the Mn ions remains tetravalent during the cycling process. It is possible that this cathode material can be utilized for high capacity Li ion batteries", "category": "scientific_body", "coverage": 0.876, "words": 173 } ], "low_coverage_blocks": [ { "page": 2, "page_count": 10, "bbox": [ 41.16, 103.94, 507.46, 141.84 ], "text": "Theoretical capacity (mAh/g) 336.12 321.15 307.46 294.89 283.30 a (Å) 2.83700(14) 2.84947(3) 2.85330(1) 2.85806(0) 2.86248(0) c (Å) 14.24141(65) 14.22449(25) 14.22872(11) 14.23524(0) 14.23820(4) c/a 5.01988 4.99198 4.98676 4.98074 4.97408", "category": "scientific_body", "coverage": 0.0, "words": 58 } ], "high_risk_body_missing_blocks": [ { "page": 2, "page_count": 10, "bbox": [ 41.16, 103.94, 507.46, 141.84 ], "text": "Theoretical capacity (mAh/g) 336.12 321.15 307.46 294.89 283.30 a (Å) 2.83700(14) 2.84947(3) 2.85330(1) 2.85806(0) 2.86248(0) c (Å) 14.24141(65) 14.22449(25) 14.22872(11) 14.23524(0) 14.23820(4) c/a 5.01988 4.99198 4.98676 4.98074 4.97408", "category": "scientific_body", "coverage": 0.0, "words": 58 } ], "front_summary_missing_blocks": [], "back_matter_low_overlap_blocks": [] }