Abundant nanoscale defects to eliminate voltage decay in Li-rich cathode materials

Guo, Huijuan; Wei, Zhen; Jia, Kai; Qiu, Bao; Yin, Chong; Meng, Fanqi; Zhang, Qinghua; Gu, Lin; Han, Shaojie; Liu, Yan; Zhao, Huahua; Jiang, Wei; Cui, Hui-Wang; Xia, Yonggao; Liu, Zhaoping

doi:10.1016/j.ensm.2018.05.022

Cited by 162 publications

(103 citation statements)

References 61 publications

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HEVs (PHEVs), besides the traditional applications in portable devices. [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. [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.

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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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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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“…CT‐LRM displays apparently shorter potential plateau than pristine sample, which can be ascribed to the inactive of magnesium ion and the strong binding energy of P−O. Although electrochemical activation of Li 2 MnO 3 is beneficial to the capacity utilization, it also leads to huge lattice oxygen release which deteriorates the initial structure integrity and triggers the phase‐transitions . Therefore, the shorter potential plateau also presents less oxygen release and undesirable structure‐rearrangements.…”

Section: Results and Discussmentioning

confidence: 99%

A Collaboration of Surface Protection and Bulk Doping for High‐performance Li‐rich Cathode Materials

Wang

Sun

et al. 2019

ChemistrySelect

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Li‐rich layered oxides (LLRO) are promising high energy‐density cathode, but always suffer from the oxygen loss in initial activation and gradual structure transformation during cycling, which leads to capacity degradation and potential decay. Here, we employ a simple strategy to achieve the collaboration of surface protection and bulk doping for improving the performance of Li‐rich material. Scanning electron microscope and transmission electron microscopy tests demonstrate that a nanoscale protective layer of magnesium pyrophosphate is uniformly coated on the Li‐rich material surface. X‐ray diffraction test indicates Mg2+ and P2O74− are incorporated into the crystal structure, which induces the larger lattice spacing and lower cation mixing. As a result, the resultant LLRO displays extremely high Coulombic efficiency of 91.8% and discharge capacity of 288.4 mAh g−1, showing prominent cycling stability of 89.2% after 200 cycles. Furthermore, our strategy also suppresses the attenuation of average voltage during cycling and the potential drop is only 0.56 mV per cycle from 25 th to 200 th cycle. The excellent electrochemical performance can be ascribed to the combined merits of surface protection and bulk doping. This strategy may provide some new insights into the design and synthesis of high‐performance electrode materials.

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“…The first narrow peak at about 430 cm −1 along with other weak peaks at about 330 cm −1 and 375 cm −1 are recognized as the vibration of Li 2 MnO 3 components. [55] Therefore, the as-prepared pristine-LMR samples keep a slightly better layered structure while the as-prepared Na/SDS-LMR electrode contains lots of nano-defects (like stacking faults which can provide a dramatically enhancement for electrochemical performance). [29,53] The spinel-like structure is identified by the peak at about 647 cm −1 in the fitted results of pristine-LMR, Na-LMR, and Na/SDS-LMR.…”

Section: Mechanisms Of Enhanced Performancementioning

confidence: 99%

Uniform Na⁺ Doping‐Induced Defects in Li‐ and Mn‐Rich Cathodes for High‐Performance Lithium‐Ion Batteries

Liu

et al. 2019

Advanced Science

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The corrosion of Li‐ and Mn‐rich (LMR) electrode materials occurring at the solid–liquid interface will lead to extra electrolyte consumption and transition metal ions dissolution, causing rapid voltage decay, capacity fading, and detrimental structure transformation. Herein, a novel strategy is introduced to suppress this corrosion by designing an Na + ‐doped LMR (Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 ) with abundant stacking faults, using sodium dodecyl sulfate as surfactant to ensure the uniform distribution of Na + in deep grain lattices—not just surface‐gathering or partially coated. The defective structure and deep distribution of Na + are verified by Raman spectrum and high‐resolution transmission electron microscopy of the as‐prepared electrodes before and after 200 cycles. As a result, the modified LMR material shows a high reversible discharge specific capacity of 221.5 mAh g −1 at 0.5C rate (1C = 200 mA g −1 ) after 200 cycles, and the capacity retention is as high as 93.1% which is better than that of pristine‐LMR (64.8%). This design of Na + is uniformly doped and the resultanting induced defective structure provides an effective strategy to enhance electrochemical performance which should be extended to prepare other advanced cathodes for high performance lithium‐ion batteries.

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Abundant nanoscale defects to eliminate voltage decay in Li-rich cathode materials

Cited by 162 publications

References 61 publications

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

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

A Collaboration of Surface Protection and Bulk Doping for High‐performance Li‐rich Cathode Materials

Uniform Na⁺ Doping‐Induced Defects in Li‐ and Mn‐Rich Cathodes for High‐Performance Lithium‐Ion Batteries

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Abundant nanoscale defects to eliminate voltage decay in Li-rich cathode materials

Cited by 162 publications

References 61 publications

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

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

A Collaboration of Surface Protection and Bulk Doping for High‐performance Li‐rich Cathode Materials

Uniform Na+ Doping‐Induced Defects in Li‐ and Mn‐Rich Cathodes for High‐Performance Lithium‐Ion Batteries

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Product

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

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

Uniform Na⁺ Doping‐Induced Defects in Li‐ and Mn‐Rich Cathodes for High‐Performance Lithium‐Ion Batteries