Suppression of voltage-decay in Li2MnO3 cathode via reconstruction of layered-spinel coexisting phases

Wu, Jue; Cui, Zehao; Wu, Jinpeng; Xiang, Yuxuan; Liu, Haodong; Zheng, Shiyao; Yang, Wanli; Yang, Yong

doi:10.1039/d0ta05101b

Cited by 11 publications

(4 citation statements)

References 56 publications

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“…As shown in Figure 5c−f, the surface and inner structure of the cycled LMNO can be assigned to a rock-salt structure (space group Fm3̅ m), as verified by the FFT patterns, indicating that the LMNO material has suffered severe structural degradation caused by irreversible oxygen release and TM migration. 65,66 In contrast, as shown in Figure 5g−j, for LMNOC, a thin rock-salt layer (∼5 nm thick) can be observed on the surface after the same electrochemical cycles, indicating much less structural degradation in LMNOC. Furthermore, it is noted that the internal area of LMNOC remains a layered structure after 200 cycles (Figure 5h), indicating that Cl doping greatly inhibits the layered to rock-salt structural transformation caused by oxygen release and TM migration, which also ensures the excellent electrochemical performance of the LMNOC material.…”

Section: Resultsmentioning

confidence: 90%

Regulating Anion Redox and Cation Migration to Enhance the Structural Stability of Li-Rich Layered Oxides

Wang

Zhang

et al. 2021

ACS Appl. Mater. Interfaces

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Lithium-rich manganese-based layered oxide cathodes (LLOs) with oxygen redox reactions are considered to be potential candidates for the next generation of high-energy-density Li-ion batteries. However, the oxygen redox process that enables ultrahigh specific capacity usually leads to irreversible O 2 release and cation migration, which induce structure degradation and severe capacity/ voltage losses and thus limit the commercial application of LLOs. Herein, we successfully synthesized chlorine (Cl)-doped Co-free LLOs (Li 1.2 Mn 0.53 Ni 0.27 O 1.976 Cl 0.024 ) and analyzed the effect of anion doping on oxygen redox and structure stability of LLOs. Cl doping has been proven to decrease the irreversible lattice oxygen loss to enhance the redox reversibility of oxygen and inhibit the transition-metal migration during cycles, which substantially enhances the capacity and voltage retention and improves the rate capability during cycling. This work provides new insights for the development of high-performance TM oxide cathode materials with reversible oxygen redox.

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Section: Resultsmentioning

confidence: 90%

Regulating Anion Redox and Cation Migration to Enhance the Structural Stability of Li-Rich Layered Oxides

Wang

Zhang

et al. 2021

ACS Appl. Mater. Interfaces

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“…A large amount of CO 2 evolution was observed during the initial charge of both samples, which is strongly related to the electrolyte decomposition. [ 48,50 ] Interestingly, LMMO exhibited much lower O 2 emission compared with LMO, indicating an improvement in the structural stability through Mg substitution. In the low‐voltage region, during the discharge process, electrolyte decomposition and irreversible structural changes did not occur; thus, the gas emission of both samples was significantly reduced.…”

Section: Resultsmentioning

confidence: 99%

Li‐Rich Mn–Mg Layered Oxide as a Novel Ni‐/Co‐Free Cathode

Lee

Park

Cho

et al. 2022

Adv Funct Materials

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Although Li2MnO3 exhibits high capacity via anionic oxygen redox, it suffers from rapid capacity decay owing to structural disordering accompanying irreversible Mn migration and O2 release. To promote the reversibility of the anionic redox reaction, Li1.8Mg0.3Mn0.9O3 as a novel cathode material, prepared by partially substituting Li+ and Mn4+ of Li2MnO3 with the redox‐inactive Mg2+ as a structural stabilizer is proposed. Li1.8Mg0.3Mn0.9O3 delivers a high specific capacity and energy density of ≈310 mAh g−1 and ≈915 Wh kg−1, respectively. In particular, the power‐capability and cycle performance of Li1.8Mg0.3Mn0.9O3 greatly surpass those of Li2MnO3. Through first‐principles calculations and various experiments, it is revealed that Mg substitution effectively suppresses the Mn migration by stabilizing Mn cations in the original sites at the charged state. The energetically stabilized layered structure disfavors the distortion of the MnO6 octahedra, which induces the oxygen dimer (OO) formation through the metal–oxygen decoordination, thus mitigating oxygen release.

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“…So far, the state-of-the-art characterization techniques have provided multiscale structure and spectroscopy information to understand the structure evolution of LLOs. − It is now believed that a series of disordered structures generated, such as lattice distortion, dislocation, and stacking faults, disturb the structure stability. ,, Some unusual ways are proposed to suppress structures degradation effectively. Embedding the undesired disordered structures into pristine host structures is favored to promote the structure stability. − Our recent work further illustrates that subtle adjustments of the disordered structures from type/range/distribution are necessary to mobilize them as a modification method . The role of the embedded disordered structures is still inconclusive.…”

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confidence: 97%

Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

Zhou

Cui

Qiu

et al. 2021

ACS Materials Lett.

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Oxygen-redox-based Li-rich layered oxide cathode materials always suffer from severe voltage decay, because of progressively structural transformation. An initial consensus is that less utilization of oxygen redox in these cathodes would retard this process on cycling. In this work, we find sufficient oxygen redox in Li 1.26 Ni 0.0741 Co 0.0741 Mn 0.593 O 2 that contributes toward the available capacity of 80.5% can deliver a specific capacity of 280 mAh g −1 with the retentions of voltage and capacity of ∼96.7% and 97.1% after 50 cycles, respectively. The suppressed voltage decay with sufficient oxygen redox is originated from the stabilizing effect of vast disordered structures generated by the initial electrochemical activation. Based on a unique disorder−order transition induced by temperature, the degree of the concentration of the disordered structures is well-revealed through temperature-dependent in situ X-ray diffraction and Raman spectroscopy. The abundant disordered structures via sufficient oxygen redox activation are believed to act as an accommodator to promote structural stability.R echargeable lithium-ion batteries have dominated the market of electric energy storage devices for decades. Cathodes with high energy density have always been the pursuit of the goal to meet the ever-increasing demands. 1−4 At present, Li-rich layered oxides (LLOs) stand out among the others, because of its ultrahigh capacity. Exploiting oxygen redox has demonstrated a subsistent way to contribute to the considerable capacity. 5,6 Unfortunately, the activation of the oxygen redox also brings detrimental structural changes, resulting in structure degradation and, thus, the notorious voltage decay upon cycling. 7 So far, the state-of-the-art characterization techniques have provided multiscale structure and spectroscopy information to understand the structure evolution of LLOs. 8−12 It is now believed that a series of disordered structures generated, such as lattice distortion, dislocation, and stacking faults, disturb the structure stability. 10,11,13 Some unusual ways are proposed to suppress structures degradation effectively. Embedding the undesired disordered structures into pristine host structures is favored to promote the structure stability. 14−17 Our recent work further illustrates that subtle adjustments of the disordered structures from type/range/distribution are necessary to mobilize them as a modification method. 14 The role of

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Suppression of voltage-decay in Li₂MnO₃ cathode via reconstruction of layered-spinel coexisting phases

Abstract: Voltage decay, i.e., voltage decrease during electrochemical cycling is a decade-long challenge for lithium-ion battery. This issue not only leads to a substantial loss of the energy density, but also...

Cited by 11 publications

References 56 publications

Regulating Anion Redox and Cation Migration to Enhance the Structural Stability of Li-Rich Layered Oxides

Regulating Anion Redox and Cation Migration to Enhance the Structural Stability of Li-Rich Layered Oxides

Li‐Rich Mn–Mg Layered Oxide as a Novel Ni‐/Co‐Free Cathode

Sufficient Oxygen Redox Activation against Voltage Decay in Li-Rich Layered Oxide Cathode Materials

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