Multiscale Understanding of Surface Structural Effects on High‐Temperature Operational Resiliency of Layered Oxide Cathodes

Liu, Xiang; Zhou, Xinwei; Liu, Qiang; Diao, Jiecheng; Zhao, Chen; Li, Luxi; Liu, Yuzi; Xu, Wenqian; Daali, Amine; Harder, Ross; Robinson, Ian; Dahbi, Mouad; Alami, Jones; Chen, Guohua; Xu, Gui‐Liang; Amine, Khalil

doi:10.1002/adma.202107326

Cited by 26 publications

(27 citation statements)

References 46 publications

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“…Our previous studies have established the oxidative chemical vapor deposition (oCVD) technique for a conformal poly(3,4-ethylenedioxythiophene) (PEDOT) coating on both secondary and primary particles, which significantly enhanced the cyclability of polycrystal NMC at high-voltage and high-temperature conditions. , It is revealed that the conformal PEDOT coating can effectively scavenge HF, suppress metal dissolution, and inhibit the phase transition and intergranular cracking under harsh conditions (high cutoff voltage and elevated temperature) and therefore is an ideal coating material for high-voltage cathode materials. Inspired by the performance improvement, we further conducted conformal PEDOT coating on the single-crystal LiNi 0.83 Mn 0.1 Co 0.07 O 2 (SC-NMC83) cathodes, particularly aiming to improve the cycling stability under harsh operating conditions.…”

Section: Introductionmentioning

confidence: 99%

Conformal PEDOT Coating Enables Ultra-High-Voltage and High-Temperature Operation for Single-Crystal Ni-Rich Cathodes

Liu

Zhao

et al. 2022

ACS Nano

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Single-crystal Ni-rich Li[Ni x MnyCo1–x–y ]O2 (SC-NMC) cathodes represent a promising approach to mitigate the cracking issue of conventional polycrystalline cathodes. However, many reported SC-NMC cathodes still suffer from unsatisfactory cycling stability, particularly under high charge cutoff voltage and/or elevated temperature. Herein, we report an ultraconformal and durable poly(3,4-ethylenedioxythiophene) (PEDOT) coating for SC-NMC cathodes using an oxidative chemical vapor deposition (oCVD) technique, which significantly improves their high-voltage (4.6 V) and high-temperature operation resiliency. The PEDOT coated SC LiNi0.83Mn0.1Co0.07O2 (SC-NMC83) delivers an impressive capacity retention rate of 96.7% and 89.5% after 100 and 200 cycles, respectively. Significantly, even after calendar aging at 45 °C and 4.6 V, the coated cathode can still retain 85.3% (in comparison with 59.6% for the bare one) of the initial capacity after 100 cycles at a 0.5 C rate. Synchrotron X-ray experiments and interface characterization collectively reveal that the conformal PEDOT coating not only effectively stabilizes the crystallographic structure and maintains the integrity of the particles but also significantly suppresses the electrolyte’s corrosion, resulting in improved electrochemical/thermal stability. Our findings highlight the promise of an oCVD PEDOT coating for single-crystal Ni-rich cathodes to meet the grand challenge of high-energy batteries under extreme conditions.

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Section: Introductionmentioning

confidence: 99%

Conformal PEDOT Coating Enables Ultra-High-Voltage and High-Temperature Operation for Single-Crystal Ni-Rich Cathodes

Liu

Zhao

et al. 2022

ACS Nano

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“…Moreover, these dissociated particles surrounded by the CEI may lose their electrochemical activity, resulting in fast capacity fading and eventual battery failure. [ 34 ] In contrast, these cracking characteristics did not emerge in the PR‐ co ‐PAA‐coated particles (Figure 3h,i). The underlying reason for this result may be due to the high toughness and fast self‐healing of the PR‐ co ‐PAA nanolayer, which can help disperse stress and repair cracks inside the secondary particles.…”

Section: Resultsmentioning

confidence: 94%

Building a Self‐Adaptive Protective Layer on Ni‐Rich Layered Cathodes to Enhance the Cycle Stability of Lithium‐Ion Batteries

et al. 2022

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Layered Ni‐rich lithium transition metal oxides are promising battery cathodes due to their high specific capacity, but their poor cycling stability due to intergranular cracks in secondary particles restricts their practical applications. Surface engineering is an effective strategy for improving a cathode's cycling stability, but most reported surface coatings cannot adapt to the dynamic volume changes of cathodes. Herein, a self‐adaptive polymer (polyrotaxane‐co‐poly(acrylic acid)) interfacial layer is built on LiNi0.6Co0.2Mn0.2O2. The polymer layer with a slide‐ring structure exhibits high toughness and can withstand the stress caused by particle volume changes, which can prevent the cracking of particles. In addition, the slide‐ring polymer acts as a physicochemical barrier that suppresses surface side reactions and alleviates the dissolution of transition metallic ions, which ensures stable cycling performance. Thus, the as‐prepared cathode shows significantly improved long‐term cycling stability in situations in which cracks may easily occur, especially under high‐rate, high‐voltage, and high‐temperature conditions.

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“…[ 7 ] So far, a plethora of mitigation strategies were implemented to insulate the direct contact of the oxide particles with the electrolyte, for instance the exquisite coatings with the inorganic or polymeric artificial layers. [ 8–10 ] Additionally, the additives with electron donating groups were introduced into the electrolyte to scavenge the HF species. [ 11,12 ] Unfortunately, the pre‐oxidized additives easily deposit as a resistive layer, thereby impeding the ionic diffusion pathway.…”

Section: Introductionmentioning

confidence: 99%

“…To satisfy the burgeoning markets of transportation electrification, high-end electronics, and distributed energy storage the inorganic or polymeric artificial layers. [8][9][10] Additionally, the additives with electron donating groups were introduced into the electrolyte to scavenge the HF species. [11,12] Unfortunately, the pre-oxidized additives easily deposit as a resistive layer, thereby impeding the ionic diffusion pathway.…”

Section: Introductionmentioning

confidence: 99%

Boosting the Temperature Adaptability of Lithium Metal Batteries via a Moisture/Acid‐Purified, Ion‐Diffusion Accelerated Separator

Zhang

Liu

Gan

et al. 2022

Advanced Energy Materials

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solutions, explorative studies of the electro-redox couples, with the concurrent high retrievable capacity, enlarged nominal voltage gap, and rapid reaction kinetics, hold the key to promote the energy-dense battery construction at the extreme power output. [1] For the lithium ion batteries, the energy densities of traditional formats (LiCoO 2 /LiFePO 4 cathodes and graphite anodes) have approached their theoretical limits. [2] Alternatively, the unit cell prototyping of the high-capacity Li metal anode with the nickel-rich cathode can achieve the enhanced level of energy densities at the device level. [3,4] When soaking this electrode couples in the conventional carbonate-based electrolytes, however, the Fermi-energy incompatibility at the multiscale interface would cause the uncontrollable dendrite growth on the metallic foil and cathode structure collapse upon the high-voltage cycling. [5] Therefore, the reliable operation of the energy-dense battery necessitates the harmony balance of the enlarged voltage gap and the interfacial stability at multiple scales, yet still remains challenging.As the most attractive cathode type of the practical relevance, nickel-rich (Ni content >0.8) layered oxides exhibit the merits of the large specific capacity (>200 mAh g −1 ), environmental benignity and relative lower cost as compared to the LiCoO 2 cathode. Despite of the dominant nickel occupancy in the layered oxides for elevating the Li storage sites, the increased nickel ratio adversely deteriorates the cycle performance. The transition metal (TM) layer of the oxide structure at the highvoltage charged states would oxidize the carbonate solvents in the presence of moisture, leading to serious self-discharge rates upon the high-temperature storage. [6] Additionally, the hydrofluoric acid (HF) formed by the decomposition of the lithium hexafluorophosphate (LiPF 6 ) salt aggravates the TM ions (Co 2+ , Ni 2+ , and Mn 2+ ) dissolution and structural collapse of the layered cathode, meanwhile the TM species would deposit on the anode surface and degrade the solid electrolyte interface (SEI). [7] So far, a plethora of mitigation strategies were implemented to insulate the direct contact of the oxide particles with the electrolyte, for instance the exquisite coatings with The reliable operation of Li metal batteries suffers from cathode collapse due to high-voltage cycling, interfacial reactivity of the Li deposits, self-discharge at the elevated temperatures, as well as the power output deterioration in low-temperature scenarios. In contrast to the individual electrode optimization, herein, a hetero-layered separator with an asymmetric functional coating on polyethylene is proposed in response to the aforementioned issues: On the face-to-cathode side, the hybrid layer of the molecular sieve and sulfonated melamine formaldehyde can scavenge the hydrofluoric acid and moisture residues from the carbonate electrolyte, maintaining the cathode robustness in both the high-voltage cycling or high-temperature storage scenarios; while...

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Multiscale Understanding of Surface Structural Effects on High‐Temperature Operational Resiliency of Layered Oxide Cathodes

Cited by 26 publications

References 46 publications

Conformal PEDOT Coating Enables Ultra-High-Voltage and High-Temperature Operation for Single-Crystal Ni-Rich Cathodes

Conformal PEDOT Coating Enables Ultra-High-Voltage and High-Temperature Operation for Single-Crystal Ni-Rich Cathodes

Building a Self‐Adaptive Protective Layer on Ni‐Rich Layered Cathodes to Enhance the Cycle Stability of Lithium‐Ion Batteries

Boosting the Temperature Adaptability of Lithium Metal Batteries via a Moisture/Acid‐Purified, Ion‐Diffusion Accelerated Separator

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