Reversible anionic redox chemistry in layered Li4/7[?1/7Mn6/7]O2 enabled by stable Li–O-vacancy configuration

•Design the Li–O-vacancy configuration to trigger oxygen redox reactions•Restrain irreversible release by means of stable Mn vacancy•Quantify approximate capacity distributions anionic/cationic reactions High-energy-density cathode materials for Li-ion batteries are developed along avenue transition from conventional Li–O-transition metal (TM) typical Li–O–Li. It achieved a great increase in energy density because anionic activities can provide additional capacities. However, utilization chemistry based on Li–O–Li always suffers inherent issues such as serious and induced structural distortion, further resulting rapid decay upon cycling. To address these problems, new configurations should be designed achieve restrain release, which is significant commercialization high-energy-density Li-rich materials. Besides, discovery will undoubtedly excite immediate interest wide audience scientists develop various advanced The combination cationic within breaks through traditional limitation achieves batteries. leads detrimental lattice accelerates distortion electrochemical performance deterioration. In contrast layered oxides, not only behaviors triggered Li4/7[?1/7Mn6/7]O2 (?: vacancy) with configuration, but loss effectively suppressed. Upon Li+ (de)intercalations, vacancy TM layer also enables reversible evolution Li migration processes, boosting high output long-term cycling stability. irreversible/reversible clearly unraveled, their roughly quantified Overall, our findings demonstrate that introduction provides promising high-capacity candidates next-generation Rechargeable lithium-ion regarded efficient devices store relatively high-energy long-cycling life.1Xie J. Lu Y.C. A retrospective batteries.Nat. 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J.-G. al.Formation spinel composite used batteries.ACS Nano. 7: 760-767Crossref (730) complex, hinders clarification charge compensation mechanisms (de)intercalation.13Ben Thus, pivotal stabilize oxygen-related quantify corresponding contributions, beneficial developing Li–O-TM (first-generation design, Figure 1). capacities, Li-rich/excess second-generation design proposed first time (Figure this study, we oxides restrained processes. Herein, novel Co/Ni-free cathode, Li4/7[?1/7Mn6/7]O2, grafting vacancies Na2Mn3O7. Coupling activities, harvests 312 g?1 970 Wh Kg?1. Benefiting layer, exhibits process, foundation (de)intercalation, limited (0.076% per cycle 500 cycles) oxygen-centered Mn-based comprehensively assigned situ/ex situ characterizations, unraveling aid theory calculation, indicates strong Mn–O interactions suppressing Li2MnO3, facilitating reversibility via chemical ion-exchange method Na2Mn3O7 (Na4/7[?1/7Mn6/7]O2). precursor prepared solid-state reaction, displayed ordered vacancy/Mn arrangement plateaus hysteresis.16Mortemard Scholar,24Tsuchimoto X.M. Kawai Mortemard De Nonpolarizing O-O dimerization Na2Mn3O7.Nat. 12: 631Crossref (38) Scholar,25Abate I.I. Pemmaraju C.D. S.Y. Hsu K.H. Sainio Moritz Vinson Toney M.F. Gent W.E. al.Coulombically-stabilized hole polarons enable fully redox.Energy 14: 4858-4867Crossref XRD pattern its Rietveld refinement S1A; Table S1) elemental analysis inductively coupled plasma (ICP) (Table S2) verified space group triclinic P1¯.26Adamczyk Pralong V. Na2Mn3O7: suitable electrode Na-ion batteries?.Chem. 29: 4645-4648Crossref (64) coordination prismatic or octahedral depending site AM Mn-vacancy ordering S1B).27Song Tang Hu Borkiewicz O.J. Wiaderek K.M. Phillip N.D. Liu Shadike C. al.Understanding low hysteresis Na2Mn3O7.Chem. 31: 3756-3765Crossref (91) scanning electron microscopy (SEM) S2A) transmission (TEM) S2B) images show morphology Na2Mn3O7, secondary particle constructed primary nanoparticles, irregular. 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Syntheses, structures, preliminary electrochemistry manganese (IV).Chem. 2001; 4618-4623Crossref all absent detection conditions. Instead, synchrotron 0.457944 characterized detect any fine demonstrating has three characteristic peaks, groups R3¯m, monoclinic C2/m P1¯, respectively 2C). possesses Li[Li0.2Ni0.2Mn0.6]O2.30Lei C.H. Bareño Wen Petrov Abraham D.P. Local composition Li1.2Ni0.2Mn0.6O2 analytical microscopy.J. 2008; 178: 422-433Crossref (142) trace amount P1¯ detected due residual Na+ after consistent ICP result residue S4). content neglected Li/Mn ratio (1:1.48) approaches stoichiometric value (1:1.5). By employment 7Li nuclear magnetic resonance (ssNMR), environments identified 2D).31Li Feng Hung Rose Chien P.-H. Gan Y.-Y. Lithiation delithiation dynamics different sites operando resonance.Chem. 8282-8291Crossref (36) At frequency conditions (25 30 KHz), ssNMR spectra suggest reside layers, signal layers detected. And projection magic-angle turning phase-adjusted sideband separation (pjMATPASS) spectrum individual located absence suggesting originate layer. Altogether, demonstrates shows ?/Mn were indicating generation direction. investigated both SEM S5A) S5B) proving exchange effective prepare structures.28Cao microscope (STEM) reveal about 0.48 (003) plane, successfully (Figures S5C S5D). inherited precursor. behavior galvanostatic mode window 2.0–4.8 10 mA/g 2E). profile long high-voltage plateau 4.65 (versus Li/Li+), delivering initial 123 (corresponds deintercalation 0.38 mol ions). attributed purely centered ligands Mn4+ oxidized structure. Li[Li1/3Mn2/3]O2 process.32Robertson A.D. Bruce P.G. Mechanism Li2MnO3.Chem. 2003; 15: 1984-1992Crossref (470) discharge, 0.8 inserted into formal Li0.99Mn0.857O2, corresponds reduction intercalation process. When recharged 4.8 V, two occurred 3.05 313 0.97 Li0.99Mn0.857O2 ?0.97 insertion second vacancies. Notably, kg?1 harvested 252 even 20 current mA 2.0 2E, insert). dQ/dV profiles S6). drastic downshift observed cycles. cycling, plagues applications On contrary, outstanding retention rearrangement Raman 100 presented S7), results. 300 g?1, drop 0.076% 2F), capacities 175 111 5 cycles, respectively. delivered 95 700 S8). dissolution S9). These favorable superior conducted evaluate delithiation/lithiation processes 3).33Cao Cabana Stabilizing Li-deficient pristine state.Adv. 33: e2004280Crossref (52) Because similarity LiMnO2 C2/m, patterns analyzed fitted unit cell convenience. shifts (101) concomitant (de)intercalation 3 S10). charging, peak gradually shifted angle, almost no change position, Li[Li1/3Mn2/3]O2.34Kan Ren Sun C.-J. Heald S.M. Bloom Formation probes.J. 266: 341-346Crossref (20) remained constant stage then angle. higher location charge, exserted After locations back same cycle, realized contour figures S11) evolutions (003), (104), (201¯), (204¯) results, clarify a-lattice, c-lattice, volume refinement. a-lattice parameter kept rapidly end discharging. contrast, c-lattice beginning charging slight until discharged increased display analogous lithiation delithiat