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1. Pd-Ru pair on Pt surface for promoting hydrogen oxidation and evolution in alkaline media.

Author

Cao, Longsheng, Soto, Fernando, Li, Dan, Deng, Tao, Hu, Enyuan, Lu, Xiner, Cullen, David, Eidson, Nico, Yang, Xiao-Qing, He, Kai, Balbuena, Perla, and Wang, Chunsheng

Abstract

Hydrogen oxidation reaction in alkaline media is critical for alkaline fuel cells and electrochemical ammonia compressors. The slow hydrogen oxidation reaction in alkaline electrolytes requires large amounts of scarce and expensive platinum catalysts. While transition metal decoration can enhance Pt catalysts activity, it often reduces the electrochemical active surface area, limiting the improvement in Pt mass activity. Here, we enhance Pt catalysts activity without losing surface-active sites by using a Pd-Ru pair. Utilizing a mildly catalytic thermal pyrolysis approach, Pd-Ru pairs are decorated on Pt, confirmed by extended X-ray absorption fine structure and high-angle annular dark-field scanning transmission electron microscopy. Density functional theory and ab-initio molecular dynamics simulations indicate preferred Pd and Ru dopant adsorption. The Pd-Ru decorated Pt catalyst exhibits a mass-based exchange current density of 1557 ± 85 A g-1metal for hydrogen oxidation reaction, demonstrating superior performance in an ammonia compressor.

Published
2024

4. Localized High-Concentration Electrolytes Get More Localized Through Micelle-Like Structures

Author

Efaw, Corey M., Wu, Qisheng, Gao, Ningshengjie, Zhang, Yugang, Zhou, Haoyu, Gering, Kevin, Hurley, Michael F., Xiong, Hui, Hu, Enyuan, Cao, Xia, Xu, Wu, Zhang, Ji-Guang, Dufek, Eric J., Xiao, Jie, Yang, Xiao-Qing, Liu, Jun, Qi, Yue, and Li, Bin

Subjects
Condensed Matter - Materials Science
Abstract

Liquid electrolytes in batteries are typically treated as macroscopically homogeneous ionic transport media despite having complex chemical composition and atomistic solvation structures, leaving a knowledge gap of microstructural characteristics. Here, we reveal a unique micelle-like structure in a localized high-concentration electrolyte (LHCE), in which the solvent acts as a surfactant between an insoluble salt in diluent. The miscibility of the solvent with the diluent and simultaneous solubility of the salt results in a micelle-like structure with a smeared interface and an increased salt concentration at the centre of the salt-solvent clusters that extends the salt solubility. These intermingling miscibility effects have temperature dependencies, wherein an exemplified LHCE peaks in localized cluster salt concentration near room temperature and is utilized to form a stable solid-electrolyte interphase (SEI) on Li-metal anode. These findings serve as a guide to predicting a stable ternary phase diagram and connecting the electrolyte microstructure with electrolyte formulation and formation protocols to form stable SEI for enhanced battery cyclability.

Published
2023

5. Simultaneous Single Crystal Growth and Segregation of Ni-Rich Cathode Enabled by Nanoscale Phase Separation for Advanced Lithium-Ion Batteries

Author

Bi, Yujing, Xu, Yaobin, Yi, Ran, Liu, Dianying, Zuo, Peng, Hu, Jiangtao, Li, Qiuyan, Wu, Jing, Wang, Chongmin, Tan, Sha, Hu, Enyuan, Li, Jingnan, Toole, Rebecca O, Luo, Liu, Hao, Xiaoguang, Venkatachalam, Subramanian, Rijssenbeek, Job, and Xiao, Jie

Subjects
Condensed Matter - Materials Science, Physics - Chemical Physics
Abstract

Synthesis of high-performance single crystal LiNi0.8Mn0.1Co0.1O2 (NMC811) in the absence of molten salt is challenging with no success yet. An innovative drop-in approach is discovered to synthesize single crystal NMC811 by controlling the morphology of transition metal hydroxide TM(OH)2 precursors followed by a simple decomposition step to form transition metal oxide (TMO) intermediates. Ni redistribution in TMO, as a result of the concurrent formation of mixed spinel and rock salt phases, helps deagglomerate the later formed NMC811 clusters of single crystals. As-prepared single crystal NMC811 is validated in a 2Ah pouch cell demonstrating 1000 stable cycling. The fundamentally new reaction mechanism of single crystal growth and segregation without molten salt provides a new direction towards cost-efficient manufacturing of single crystal NMC811 cathode for advanced lithium-based batteries., Comment: 13 pages, 5 figures

Published
2023

10. Healable and conductive sulfur iodide for solid-state Li–S batteries

Author

Zhou, Jianbin, Holekevi Chandrappa, Manas Likhit, Tan, Sha, Wang, Shen, Wu, Chaoshan, Nguyen, Howie, Wang, Canhui, Liu, Haodong, Yu, Sicen, Miller, Quin R. S., Hyun, Gayea, Holoubek, John, Hong, Junghwa, Xiao, Yuxuan, Soulen, Charles, Fan, Zheng, Fullerton, Eric E., Brooks, Christopher J., Wang, Chao, Clément, Raphaële J., Yao, Yan, Hu, Enyuan, Ong, Shyue Ping, and Liu, Ping

Published
2024
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11. Ligand-channel-enabled ultrafast Li-ion conduction

Author

Lu, Di, Li, Ruhong, Rahman, Muhammad Mominur, Yu, Pengyun, Lv, Ling, Yang, Sheng, Huang, Yiqiang, Sun, Chuangchao, Zhang, Shuoqing, Zhang, Haikuo, Zhang, Junbo, Xiao, Xuezhang, Deng, Tao, Fan, Liwu, Chen, Lixin, Wang, Jianping, Hu, Enyuan, Wang, Chunsheng, and Fan, Xiulin

Published
2024
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19. All-temperature zinc batteries with high-entropy aqueous electrolyte

Author

Yang, Chongyin, Xia, Jiale, Cui, Chunyu, Pollard, Travis P., Vatamanu, Jenel, Faraone, Antonio, Dura, Joseph A., Tyagi, Madhusudan, Kattan, Alex, Thimsen, Elijah, Xu, Jijian, Song, Wentao, Hu, Enyuan, Ji, Xiao, Hou, Singyuk, Zhang, Xiyue, Ding, Michael S., Hwang, Sooyeon, Su, Dong, Ren, Yang, Yang, Xiao-Qing, Wang, Howard, Borodin, Oleg, and Wang, Chunsheng

Published
2023
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25. Local structure adaptability through multi cations for oxygen redox accommodation in Li-Rich layered oxides

Author

Zhao, Enyue, Zhang, Minghao, Wang, Xuelong, Hu, Enyuan, Liu, Jue, Yu, Xiqian, Olguin, Marco, Wynn, Thomas A, Meng, Ying Shirley, Page, Katharine, Wang, Fangwei, Li, Hong, Yang, Xiao-Qing, Huang, Xuejie, and Chen, Liquan

Subjects
Affordable and Clean Energy, Lithium-ion battery, Lithium-rich cathode, Lattice oxygen redox, Pair distribution function, Local structure, Chemical Engineering, Electrical and Electronic Engineering
Abstract

Stable lattice oxygen redox (l-OR) is the key enabler for achieving attainable high energy density in Li-rich layered oxide cathode materials for Li-ion batteries. However, the unique local structure response to oxygen redox in these materials, resulting in energy inefficiency and hysteresis, still remains elusive, preventing their potential applications. By combining the state-of-the-art neutron pair distribution function with crystal orbital overlap analysis, we directly observe the distinct local structure adaption originated from the potential O–O chemical bonds. The structure adaptability is optimized based on the nature of multi transition metals in our model compound Li1.2Ni0.13Mn0.54Co0.13O2, which accommodates the oxygen redox and at the same time preserves the global layered structure. These findings not only advance the understanding of l-OR, but also provide new perspectives in the rational design of high-energy-density cathode materials with reversible and stable l-OR.

Published
2020

26. Lithium halide cathodes for Li metal batteries

Author

Xu, Jijian, Pollard, Travis P., Yang, Chongyin, Dandu, Naveen K., Tan, Sha, Zhou, Jigang, Wang, Jian, He, Xinzi, Zhang, Xiyue, Li, Ai-Min, Hu, Enyuan, Yang, Xiao-Qing, Ngo, Anh, Borodin, Oleg, and Wang, Chunsheng

Published
2023
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30. Surface-to-Bulk Redox Coupling through Thermally Driven Li Redistribution in Li- and Mn-Rich Layered Cathode Materials

Author

Li, Shaofeng, Lee, Sang-Jun, Wang, Xuelong, Yang, Wanli, Huang, Hai, Swetz, Daniel S, Doriese, William B, O’Neil, Galen C, Ullom, Joel N, Titus, Charles J, Irwin, Kent D, Lee, Han-Koo, Nordlund, Dennis, Pianetta, Piero, Yu, Chang, Qiu, Jieshan, Yu, Xiqian, Yang, Xiao-Qing, Hu, Enyuan, Lee, Jun-Sik, and Liu, Yijin

Subjects
Engineering, Materials Engineering, Chemical Sciences, Physical Chemistry, General Chemistry, Chemical sciences
Abstract

Li- and Mn-rich (LMR) layered cathode materials have demonstrated impressive capacity and specific energy density thanks to their intertwined redox centers including transition metal cations and oxygen anions. Although tremendous efforts have been devoted to the investigation of the electrochemically driven redox evolution in LMR cathode at ambient temperature, their behavior under a mildly elevated temperature (up to ∼100 °C), with or without electrochemical driving force, remains largely unexplored. Here we show a systematic study of the thermally driven surface-to-bulk redox coupling effect in charged Li1.2Ni0.15Co0.1Mn0.55O2. We for the first time observed a charge transfer between the bulk oxygen anions and the surface transition metal cations under ∼100 °C, which is attributed to the thermally driven redistribution of Li ions. This finding highlights the nonequilibrium state and dynamic nature of the LMR material at deeply delithiated state upon a mild temperature perturbation.

Published
2019

31. Trace doping of multiple elements enables stable battery cycling of LiCoO2 at 4.6 V

Author

Zhang, Jie-Nan, Li, Qinghao, Ouyang, Chuying, Yu, Xiqian, Ge, Mingyuan, Huang, Xiaojing, Hu, Enyuan, Ma, Chao, Li, Shaofeng, Xiao, Ruijuan, Yang, Wanli, Chu, Yong, Liu, Yijin, Yu, Huigen, Yang, Xiao-Qing, Huang, Xuejie, Chen, Liquan, and Li, Hong

Subjects
Electrical and Electronic Engineering, Environmental Engineering
Abstract

LiCoO2 is a dominant cathode material for lithium-ion (Li-ion) batteries due to its high volumetric energy density, which could potentially be further improved by charging to high voltages. However, practical adoption of high-voltage charging is hindered by LiCoO2’s structural instability at the deeply delithiated state and the associated safety concerns. Here, we achieve stable cycling of LiCoO2 at 4.6 V (versus Li/Li+) through trace Ti–Mg–Al co-doping. Using state-of-the-art synchrotron X-ray imaging and spectroscopic techniques, we report the incorporation of Mg and Al into the LiCoO2 lattice, which inhibits the undesired phase transition at voltages above 4.5 V. We also show that, even in trace amounts, Ti segregates significantly at grain boundaries and on the surface, modifying the microstructure of the particles while stabilizing the surface oxygen at high voltages. These dopants contribute through different mechanisms and synergistically promote the cycle stability of LiCoO2 at 4.6 V.

Published
2019

32. Anomalous metal segregation in lithium-rich material provides design rules for stable cathode in lithium-ion battery.

Author

Lin, Ruoqian, Hu, Enyuan, Liu, Mingjie, Wang, Yi, Cheng, Hao, Wu, Jinpeng, Zheng, Jin-Cheng, Wu, Qin, Bak, Seongmin, Tong, Xiao, Zhang, Rui, Yang, Wanli, Persson, Kristin A, Yu, Xiqian, Yang, Xiao-Qing, and Xin, Huolin L

Subjects
MD Multidisciplinary
Abstract

Despite the importance of studying the instability of delithiated cathode materials, it remains difficult to underpin the degradation mechanism of lithium-rich cathode materials due to the complication of combined chemical and structural evolutions. Herein, we use state-of-the-art electron microscopy tools, in conjunction with synchrotron X-ray techniques and first-principle calculations to study a 4d-element-containing compound, Li2Ru0.5Mn0.5O3. We find surprisingly, after cycling, ruthenium segregates out as metallic nanoclusters on the reconstructed surface. Our calculations show that the unexpected ruthenium metal segregation is due to its thermodynamic insolubility in the oxygen deprived surface. This insolubility can disrupt the reconstructed surface, which explains the formation of a porous structure in this material. This work reveals the importance of studying the thermodynamic stability of the reconstructed film on the cathode materials and offers a theoretical guidance for choosing manganese substituting elements in lithium-rich as well as stoichiometric layer-layer compounds for stabilizing the cathode surface.

Published
2019

37. Structure-Induced Reversible Anionic Redox Activity in Na Layered Oxide Cathode

Author

Rong, Xiaohui, Liu, Jue, Hu, Enyuan, Liu, Yijin, Wang, Yi, Wu, Jinpeng, Yu, Xiqian, Page, Katharine, Hu, Yong-Sheng, Yang, Wanli, Li, Hong, Yang, Xiao-Qing, Chen, Liquan, and Huang, Xuejie

Abstract

Anionic redox reaction (ARR) in lithium- and sodium-ion batteries is under hot discussion, mainly regarding how oxygen anion participates and to what extent oxygen can be reversibly oxidized and reduced. Here, a P3-type Na0.6[Li0.2Mn0.8]O2 with reversible capacity from pure ARR was studied. The interlayer O-O distance (peroxo-like O-O dimer, 2.506(3) Å), associated with oxidization of oxygen anions, was directly detected by using a neutron total scattering technique. Different from Li2RuO3 or Li2IrO3 with strong metal-oxygen (M-O) bonding, for P3-type Na0.6[Li0.2Mn0.8]O2 with relatively weak Mn-O covalent bonding, crystal structure factors might play an even more important role in stabilizing the oxidized species, as both Li and Mn ions are immobile in the structure and thus may inhibit the irreversible transformation of the oxidized species to O2 gas. Utilization of anionic redox reaction (ARR) on oxygen has been considered as an effective way to promote the charge-discharge capacity of the layered oxide cathodes for lithium- or sodium-ion batteries. The detailed mechanism of ARR, in particular how crystal structure affects and coordinates with the ARR, is not yet well understood. In the present work, a combination of X-ray and neutron total scattering measurements has been performed to study the structure of the prototype P3-type layered Na0.6[Li0.2Mn0.8]O2 with pure ARR. Unique structural characteristics, rather than prevailing knowledge of covalency of metal-oxygen, enable the stabilization of the crystal structure of Na0.6[Li0.2Mn0.8]O2 along with the ARR. This work suggests that reversible ARR can be manipulated by proper structure designs, thus to achieve high lithium or sodium storage in layered oxide cathodes. For P3-type Na0.6[Li0.2Mn0.8]O2 with relatively weak Mn-O covalent bonding, crystal structure factors play an important role in stabilizing the oxidized species, inhibiting the irreversible transformation of the oxidized species to O2 gas. The finding is important for better design of layered oxide positive materials with higher reversible capacity via the introduction of a reversible anionic redox reaction.

Published
2018

48. Visualizing non-equilibrium lithiation of spinel oxide via in situ transmission electron microscopy.

Author

He, Kai, Zhang, Sen, Li, Jing, Yu, Xiqian, Meng, Qingping, Zhu, Yizhou, Hu, Enyuan, Sun, Ke, Yun, Hongseok, Yang, Xiao-Qing, Zhu, Yimei, Gan, Hong, Mo, Yifei, Stach, Eric, Murray, Christopher, and Su, Dong

Abstract

Spinel transition metal oxides are important electrode materials for lithium-ion batteries, whose lithiation undergoes a two-step reaction, whereby intercalation and conversion occur in a sequential manner. These two reactions are known to have distinct reaction dynamics, but it is unclear how their kinetics affects the overall electrochemical response. Here we explore the lithiation of nanosized magnetite by employing a strain-sensitive, bright-field scanning transmission electron microscopy approach. This method allows direct, real-time, high-resolution visualization of how lithiation proceeds along specific reaction pathways. We find that the initial intercalation process follows a two-phase reaction sequence, whereas further lithiation leads to the coexistence of three distinct phases within single nanoparticles, which has not been previously reported to the best of our knowledge. We use phase-field theory to model and describe these non-equilibrium reaction pathways, and to directly correlate the observed phase evolution with the batterys discharge performance.

Published
2016

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