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Atomic Origin of Chemomechanical Failure of Layered Cathodes in All-Solid-State Batteries

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The ever-increasing demand for safety has thrust all-solid-state batteries (ASSBs) into the forefront of next-generation energy storage technologies. However, the atomic mechanisms underlying the failure of layered cathodes in ASSBs, as opposed to their counterparts in liquid electrolyte-based lithium-ion batteries (LIBs), have remained elusive. Here, leveraging artificial intelligence-enhanced super-resolution electron microscopy, we unravel the atomic origins dictating the chemomechanical degradation of technologically crucial high-Ni layered oxide cathodes in ASSBs. We reveal that the coupling of surface frustration and interlayer-shear-induced phase transformation exacerbates the chemomechanical breakdown of layered cathodes. Surface frustration, a phenomenon previously unobserved in liquid electrolyte-based LIBs, emerges through electrochemical processes involving surface nanocrystallization coupled with rock salt transformation. Simultaneously, delithiation-induced interlayer shear yields the formation of chunky O1 phases and intricate interfaces/transition motifs, distinct from scenarios observed in liquid electrolyte-based LIBs. Bridging the knowledge gap between the failure mechanisms of layered cathodes in solid-state electrolytes and conventional liquid electrolytes, our study provides unprecedented atomic-scale insights into the degradation pathways of layered cathodes in ASSBs.
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The pressing demand in electrical vehicle (EV) markets for high-energy-density lithium-ion batteries (LIBs) requires further increasing the Ni content in high-Ni and low-Co cathodes. However, the commercialization of high-Ni cathodes is hindered by their intrinsic chemomechanical instabilities and fast capacity fade. The emerging single-crystalline strategy offers a promising solution, yet the operation and degradation mechanism of single-crystalline cathodes remain elusive, especially in the extremely challenging ultrahigh-Ni (Ni > 90%) regime whereby the phase transformation, oxygen loss, and mechanical instability are exacerbated with increased Ni content. Herein, we decipher the atomic-scale stabilization mechanism controlling the enhanced cycling performance of an ultrahigh-Ni single-crystalline cathode. We find that the charge/discharge inhomogeneity, the intergranular cracking, and oxygen-loss-related phase degradations that are prominent in ultrahigh-Ni polycrystalline cathodes are considerably suppressed in their single-crystalline counterparts, leading to improved chemomechanical and cycling stabilities of the single-crystalline cathodes. Our work offers important guidance for designing next-generation single-crystalline cathodes for high-capacity, long-life LIBs.
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Layered Li(Ni1−x−yCoxMny)O2 (NCM, with Ni ≥ 0.8) cathode materials are essential in achieving high energy densities in the next generation of lithium-ion batteries. To extend the materials' lifetime, it is necessary to understand the role played by crystal defects in the degradation during electrochemical cycling. In this study, NCM851005 (85% Ni) is investigated in the pristine state and after 100 and 200 cycles using scanning transmission electron microscopy, with the focus on the defects in the material. The formation of antiphase boundaries (APBs) from a dislocation in a pristine sample is proven. After 100 cycles, the APBs' length and width are enlarged compared with the pristine state. After 200 cycles, APBs further evolve into an intragranular rock-salt-like phase, distorting the nearby layered structure. It is suggested that the behavior of APBs plays a critical role in determining the performance of this cathode material with prolonged electrochemical cycling.
Article
All-solid-state batteries (ASSBs) offer great promise as a next-generation energy storage technology with higher energy density, wider operating temperature range, and improved safety for electric vehicles. ASSBs employing lithium metal anodes (Li), sulfide-based solid-state electrolytes (SSE), and Ni-rich layered transition metal oxide cathodes (LiMO2, M = Ni, Mn, Co, Al) are particularly promising due to its superior electrochemical performance compared to other solid-electrolyte systems. However, the battery cycle life at high cathode mass loading and high current is still limited because the failure mechanism is not fully understood. Lithium dendrite growth at the anode or inside a solid electrolyte still represents as a serious risk of cell failure. Interfacial resistance increases attributed to electrolyte decomposition and interfacial void formation at both cathode−electrolyte and anode−electrolyte interfaces lead to gradual capacity fading. In this Review, we present the fundamental challenges and recent scientific understandings of each component in ASSBs. The novel diagnostic tools for these components, especially the interfaces buried under the surface that are often hard for characterization are mainly examined. Finally, we offer a perspective for future research directions. We hope this Review will provide a timely snapshot of state-of-the-art research progress in ASSBs to accelerate the development of ASSBs.
Article
LiNiO2 and cobalt-free ultrahigh-Ni content cathodes suffer from rapid capacity loss and severe chemomechanical degradation, especially when operated at high voltages. Here, by cycling LiNiO2 up to 4.7 V, we report the atomic-scale observation of O1 faulted phase-induced deactivation of LiNiO2. We find that, although a thin layer of the O3 phase forms on the particle surface by reversible O3 → O1 transformation during discharge, the bulk interior still maintains the O1 faulted phase, leading to rapid capacity loss of LiNiO2. Moreover, the atomic configuration of the O1/O3 interface is investigated comprehensively. We reveal that the misfit along the c axes of the O1 and O3 phases results in the formation of misfit dislocations, whereby cation mixing is promoted at the dislocation cores. A transition zone with continuous shear along the a−b plane is uncovered between the O1 and O3 phases for the first time. Besides, severe oxygen loss-induced pore formation and concurrent rock salt transformation are also identified.
Article
Cathode interface instability is a significant obstacle for the practical application of sulfide-based all-solid-state lithium-ion batteries (ASSLIBs). However, the origin of cathode interface degradation is lack of comprehensive understanding. In this paper, X-ray characterizations combined with electrochemical analysis are adopted to investigate the underlying degradation mechanism at cathode interface. The results indicate that residual lithium compounds on the surface of Ni-rich LiNi0.8Mn0.1Co0.1O2 (NMC811) are the main reason that triggering the oxidation of sulfide solid-state electrolytes (SSEs), therefore inducing severe side-reactions at cathode interface and structural degradation of NMC811. The degradation of the cathode interface can be significantly suppressed when the cathode surface is cleaned. As a result, the surface cleaned NMC811 without coating demonstrates significantly improved electrochemical performance in both Li5.5PS4.5Cl1.5 (LPSCl) and Li10GeP2S12 (LGPS) based ASSLIBs, proving the universal application of this strategy.
Article
All-solid-state lithium-ion batteries (ASSLIBs) are expected as safe and high-performance alternatives to replace the conventional liquid-based lithium-ion batteries. However, the incompatible interface between the most cathode materials and sulfide-based solid electrolytes is still challenging the stable delivery of electrochemical performance for ASSLIBs. Herein, a dual-functional Li3PO4 (LPO) modification is designed for Ni-rich layered oxide cathodes in sulfide-based ASSLIBs to realize the high performance. The modified cathode demonstrates a significantly improved initial capacity of 170.6 mAh g⁻¹ at 0.1C, better rate capability, and reduced polarization compared to the bare cathode. More importantly, a stable long-term cycling is achieved with a low capacity degradation rate of 0.22 mAh g⁻¹ per cycle for 300 cycles at 0.2C. The detailed surface chemical and structural evolutions are studied via X-ray absorption near edge spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The results indicate that the LPO modification not only significantly suppresses the side-reactions with sulfide electrolyte but also helps to alleviate the deterioration of the microstructural cracks during the electrochemical reactions. This work provides an ideal and controllable interfacial design for realizing high performance sulfide-based ASSLIBs, which is readily applicable to other solid-state battery systems.
Article
Solid-state batteries (SSBs) using a solid electrolyte show potential for providing improved safety as well as higher energy and power density compared with conventional Li-ion batteries. However, two critical bottlenecks remain: the development of solid electrolytes with ionic conductivities comparable to or higher than those of conventional liquid electrolytes and the creation of stable interfaces between SSB components, including the active material, solid electrolyte and conductive additives. Although the first goal has been achieved in several solid ionic conductors, the high impedance at various solid/solid interfaces remains a challenge. Recently, computational models based on ab initio calculations have successfully predicted the stability of solid electrolytes in various systems. In addition, a large amount of experimental data has been accumulated for different interfaces in SSBs. In this Review, we summarize the experimental findings for various classes of solid electrolytes and relate them to computational predictions, with the aim of providing a deeper understanding of the interfacial reactions and insight for the future design and engineering of interfaces in SSBs. We find that, in general, the electrochemical stability and interfacial reaction products can be captured with a small set of chemical and physical principles.
Article
Solid-state batteries have been attracting wide attention for next generation energy storage devices due to the probability to realize higher energy density and superior safety performance compared with the state-of-the-art lithium ion batteries. However, there are still intimidating challenges for developing low cost and industrially scalable solid-state batteries with high energy density and stable cycling life for large-scale energy storage and electric vehicle applications. This review presents an overview on the scientific challenges, fundamental mechanisms, and design strategies for solid-state batteries, specifically focusing on the stability issues of solid-state electrolytes and the associated interfaces with both cathode and anode electrodes. First, we give a brief overview on the history of solid-state battery technologies, followed by introduction and discussion on different types of solid-state electrolytes. Then, the associated stability issues, from phenomena to fundamental understandings, are intensively discussed, including chemical, electrochemical, mechanical, and thermal stability issues; effective optimization strategies are also summarized. State-of-the-art characterization techniques and in situ and operando measurement methods deployed and developed to study the aforementioned issues are summarized as well. Following the obtained insights, perspectives are given in the end on how to design practically accessible solid-state batteries in the future.
) cathodes with robust outside-in structures
  • L Wang
  • A Mukherjee
  • C Y Kuo
  • S Chakrabarty
  • R Yemini
  • A A Dameron
  • J W Dumont
  • S H Akella
  • A Saha
  • S Taragin
  • H Aviv
  • D Naveh
  • D Sharon
  • T S Chan
  • H J Lin
  • J F Lee
  • C T Chen
  • B Liu
  • X Gao
  • S Basu
  • Z Hu
  • D Aurbach
  • P Bruce
Wang, L.; Mukherjee, A.; Kuo, C. Y.; Chakrabarty, S.; Yemini, R.; Dameron, A. A.; DuMont, J. W.; Akella, S. H.; Saha, A.; Taragin, S.; Aviv, H.; Naveh, D.; Sharon, D.; Chan, T. S.; Lin, H. J.; Lee, J. F.; Chen, C. T.; Liu, B.; Gao, X.; Basu, S.; Hu, Z.; Aurbach, D.; Bruce, P. G.; Noked, M. High-energy all-solid-state lithium batteries enabled by Co-free LiNiO(2) cathodes with robust outside-in structures. Nat. Nanotechnol. 2024, 19, 208−218.