Tuning Anionic Redox Activity and Reversibility for a High‐Capacity Li‐Rich Mn‐Based Oxide Cathode via an Integrated Strategy

Li, Qingyuan; Zhou, Dong; Zhang, Lijuan; Ning, De; Chen, Zhenhua; Xu, Zijian; Gao, Rui; Liu, Xinzhi; Xie, Donghao; Schumacher, G.; Liu, Xiangfeng

doi:10.1002/adfm.201806706

Cited by 143 publications

(115 citation statements)

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“…As a result, O-K sXAS pre-edge evolution has been used overwhelmingly in a large number of publications as the evidence of the so-called oxygen redox states in battery electrodes based on TM oxides. [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] On the contrary, as we pointed out directly in a recent review, 6 The importance of this debate stems from the fact that the oxygen activities in electrochemical systems hold both sides of the dilemma of stability and performance, 32 which are critical topics for materials across a wide range of energy applications, including batteries and catalytic systems. 33 Therefore, many fervent research topics on oxygen activities are in dire need of a correct interpretation of the O-K sXAS pre-edge.…”

Section: Introductionmentioning

confidence: 99%

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

Roychoudhury¹,

Qiao²,

Zhuo³

et al. 2020

Preprint

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<div>The pre-edges of oxygen-K X-ray absorption spectra have been ubiquitous in transition metal (TM) oxide studies in various fields, especially on the fervent topic of oxygen redox states in battery electrodes. However, critical debates remain on the use of the O-K pre-edge variations upon electrochemical cycling as evidences of oxygen redox reactions, which has been a popular practice in the battery field. This study presents an investigation of the O-K pre-edge of 55 oxides covering all 3d TMs with different elements, structures and electrochemical states through combined experimental and theoretical analyses. It is shown unambiguously that the O-K pre-edge variation in battery cathodes is dominated by changing TM-d states. Furthermore, the pre-edge enables a unique opportunity to project the lowest unoccupied TM-d states onto one common energy window, leading to a summary map of the relative energy positions of the low-lying TM states, with higher TM oxidation states at lower energies, corresponding to higher electrochemical potentials. The results naturally clarify some unusual redox reactions, such as Cr<sup>3+/6+</sup>. This work provides a critical clarification on O-K pre-edge interpretation and more importantly, a benchmark database of O-K pre-edge for characterizing redox reactions in batteries and other energy materials.</div>

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Section: Introductionmentioning

confidence: 99%

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

Roychoudhury¹,

Qiao²,

Zhuo³

et al. 2020

Preprint

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“…[1][2][3] Lithium-rich (Li-rich) materials, with the specific capacity over 260 mAh g −1 and energy density up to ≈1000 Wh kg −1 , [4] have attracted great interest in the past decades. To build the next generation LIBs with higher performances, high energy density materials are urgently pursued worldwide.…”

mentioning

confidence: 99%

Local Electric‐Field‐Driven Fast Li Diffusion Kinetics at the Piezoelectric LiTaO₃ Modified Li‐Rich Cathode–Electrolyte Interphase

et al. 2019

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HEVs (PHEVs), besides the traditional applications in portable devices. To build the next generation LIBs with higher performances, high energy density materials are urgently pursued worldwide. [1][2][3] Lithium-rich (Li-rich) materials, with the specific capacity over 260 mAh g −1 and energy density up to ≈1000 Wh kg −1 , [4] have attracted great interest in the past decades. It is reported that Li-rich materials are composed of two phases of Li 2 MnO 3 (C 2/m ) and LiMO 2 (R m 3 ) (M = Ni, Co, Mn, etc.). [5][6][7][8][9] Despite the above advantages, several concerns including structural instability and the resulted voltage degradation, as well as the poor diffusion kinetics at the interface have become the bottlenecks of Li-rich materials. [9][10][11][12][13] In this regard, multifarious modification approaches, such as doping and surface coating, have been intensively investigated. [14][15][16] Particularly, Li + diffusion at the cathode-electrolyte interphase (CEI) is widely regarded as the rate determining step in LIBs. [17][18][19] From this viewpoint, metal fluorides (FeF 3 , [20] MOF, [21,22] AlF 3 , [23,24] etc.), metal oxides (MgO, [25] Al 2 O 3 , [26,27] etc.), metal phosphates (AlPO 4 , [28] LaPO 4 , [29] Li 3 PO 4 , [30] FePO 4 /Li 3 PO 4 , [31] Li-Mn-PO 4 , [32] etc.), and those with similar structure of Li-rich Li 2 MnO 3 (Li 2 SiO 3 [33,34] and Li 2 SnO 3 , [35] ) have been widely applied to modify the surface of bulk Li-rich materials. Recently, fast lithium-ion conductors (LiVO 3 , [36] Li 2 ZrO 3 , [37] Li-La-Ti-O, [38,39] LiPON, [40] etc.) have also been proposed to decorate the surface of Li-rich cathodes to enhance the apparent diffusion coefficients. All the aforesaid surface modification materials, unexceptionally, have been proved to be effective in both stabilizing the structure and facilitating the Li + kinetics. Nevertheless, in general, the decoration layers themselves seem rather "passive" in promoting Li + diffusion. Assuming they are Li + conductive (e.g., solid electrolyte materials), fast Li + diffusion channels will be provided besides the general separation effect (in suppressing side reactions and inevitable TM dissolution). As for Li + insulators (e.g., metal fluorides), only the benefit of physical barriers could be exploited. Therefore, a more "initiative" function interface is imperative to be built to more effectively promote the Li + transport at the electrode-electrolyte interphase.It is noteworthy that piezoelectric material, as an important category in the energy-conversion community, works on the As one of the most promising cathodes for next-generation lithium ion batteries (LIBs), Li-rich materials have been extensively investigated for their high energy densities. However, the practical application of Li-rich cathodes is extremely retarded by the sluggish electrode-electrolyte interface kinetics and structure instability. In this context, piezoelectric LiTaO 3 is employed to functionalize the surface of Li 1.2 Ni 0.17 Mn 0.56 Co 0.07 O 2 (LNMCO), aiming to boost t...

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“…[16a,60-61] The doping of Sn 4 + is beneficial for enlarging the interplanar spacing because Sn 4 + has a large ion radius and pillar structure in the lattice, which can improve the mobility of Li-ion. [62] W doping tends to segregate on the surface of the electrode, which can reduce the ratio of Ni/Mn and alter the valence state on the surface. [63] In addition, the formed WÀ O bonds have strong covalent bond property, which is conducive to reducing the migration of transition metal ions and the loss of surface oxygen.…”

Section: Defective Materials On High-capacity Li-based Batteries 31mentioning

confidence: 99%

Function and Application of Defect Chemistry in High‐Capacity Electrode Materials for Li‐Based Batteries

Qiao

Lin

Yan

et al. 2020

Chemistry An Asian Journal

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Current commercial Li-based batteries are approaching their energy density limitation, yet still cannot satisfy the energy density demand of the high-end devices. Hence, it is critical to developing advanced electrode materials with high specific capacity. However, these electrode materials are facing challenges of severe structural degradation and fast capacity fading. Among various strategies, constructing defects in electrode materials holds great promise in addressing these issues. Herein, we summarize a series of significant defect engineering in the high-capacity electrode materials for Li-based batteries. The detailed retrospective on defects specification, function mechanism, and corresponding application achievements on these electrodes are discussed from the view of point, line, planar, volume defects. Defect engineering can not only stabilize the structure and enhance electric/ionic conductivity, but also act as active sites to improve the ionic storage and bonding ability of electrode materials to Li metal. We hope this review can spark more perspectives on evaluating high-energydensity Li-based batteries.

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Tuning Anionic Redox Activity and Reversibility for a High‐Capacity Li‐Rich Mn‐Based Oxide Cathode via an Integrated Strategy

Cited by 143 publications

References 68 publications

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

Local Electric‐Field‐Driven Fast Li Diffusion Kinetics at the Piezoelectric LiTaO₃ Modified Li‐Rich Cathode–Electrolyte Interphase

Function and Application of Defect Chemistry in High‐Capacity Electrode Materials for Li‐Based Batteries

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Tuning Anionic Redox Activity and Reversibility for a High‐Capacity Li‐Rich Mn‐Based Oxide Cathode via an Integrated Strategy

Cited by 143 publications

References 68 publications

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

Local Electric‐Field‐Driven Fast Li Diffusion Kinetics at the Piezoelectric LiTaO3 Modified Li‐Rich Cathode–Electrolyte Interphase

Function and Application of Defect Chemistry in High‐Capacity Electrode Materials for Li‐Based Batteries

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Local Electric‐Field‐Driven Fast Li Diffusion Kinetics at the Piezoelectric LiTaO₃ Modified Li‐Rich Cathode–Electrolyte Interphase