eScience

An interdisciplinary exploration of energy, electrochemistry, electronics, and environment

Chen Jun, Archer Lynden A., Li Jinghong, Ramakrishna Seeram, Wu Li-Zhu, Yu Shu-Hong, Zhang Jin

2021, 1(1): 1-2. doi: 10.1016/j.esci.2021.11.004

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Abstract:

Quasi-compensatory effect in emerging anode-free lithium batteries

Li Peng, Kim Hun, Ming Jun, Jung Hun-Gi, Belharouak Ilias, Sun Yang-Kook

2021, 1(1): 3-12. doi: 10.1016/j.esci.2021.10.002

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Abstract:
As electric vehicle (EV) sales grew approximately 50% year-over-year, surpassing 3.2 million units in 2020, the "roaring era" of EV is around the corner. To meet the increasing demand for low cost and high energy density batteries, anode-free configuration, with no heavy and voluminous host material on the current collector, has been proposed and further investigated. Nevertheless, it always suffers from several nonnegligible "bottlenecks", such as fragile solid electrolyte interface, deteriorated cycling reversibility, and uncontrolled dendrite formation. Inspired by the "compensatory effect" of some disabled people with other specific functions strengthened to make up for their inconvenience, corresponding quasi-compensatory measures after anode removal, involving dimensional compensation, SEI robustness compensation, lithiophilicity compensation, and lithium source compensation, have been carried out and achieved significant battery performance enhancement. In this review, the chemistry, challenges, and rationally designed "quasi-compensatory effect" associated with anode-free lithium-ion battery are systematically discussed with several possible R & D directions that may aid, direct, or facilitate future research on lithium storage in anode-free configuration essentially emphasized.

Spinel/Post-spinel engineering on layered oxide cathodes for sodium-ion batteries

Zhu Yan-Fang, Xiao Yao, Dou Shi-Xue, Kang Yong-Mook, Chou Shu-Lei

2021, 1(1): 13-27. doi: 10.1016/j.esci.2021.10.003

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Sodium-ion batteries (SIBs) have attracted much scientific interest for use in large-scale energy storage systems because sodium is cheaper than lithium. However, the large radius of Na⁺ and barriers to Na⁺ transport result in sluggish kinetics and complicated structural distortion, leading to unsatisfactory rate capability and poor cycling stability. It therefore is essential to develop an electrode with enhanced kinetics and a stable structure during cycling to improve SIB performance. Among the various layered oxide cathodes, those with a spinel-like structure could play an important role in boosting electron transport because of their excellent intrinsic conductivity, including by coordinating with Na ⁺ insertion/extraction. Moreover, thanks to the inherent high stability of the spinel-like phase, it could function as a stabilizer for host cathode structures. This review summarizes recent advances in spinel engineering on layered oxide cathodes to boost Na⁺ transport kinetics and provide structural stability to achieve high-performance SIBs, focusing particularly on post-spinel structures, layered oxide integrated spinel-like structures, and spinel transitions. The insights proposed in this review will be useful for guiding rational structural engineering and design to drive the development of new materials and chemistries in Na-based electrode materials.

Pillararene/Calixarene-based systems for battery and supercapacitor applications

Cao Shuai, Zhang Huacheng, Zhao Yuxin, Zhao Yanli

2021, 1(1): 28-43. doi: 10.1016/j.esci.2021.10.001

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Pillararene/calixarene-based functional materials have garnered significant attention for their unique topological/chemical structures and physicochemical properties, and their extended applications in electrochemistry have given rise to a promising area of research. This review details current advance in developing electrochemical energy materials based on pillararene/calixarene systems from the viewpoint of both fundamental theoretical simulations and research on practical applications. First, we discuss the underlying mechanisms of applying pillararene/calixarene-based systems for electrochemical energy applications. Second, we summarize simulation studies on pillarquinone and calixquinone with intrinsic structures for applications in batteries. In addition, state-of-the-art applications of pillararene/calixarene-based systems in electrochemical energy storage devices such as lithium/sodium-ion batteries and supercapacitors are highlighted. The diverse roles they play and the various design strategies that have been investigated for high-performance pillararene/calixarene-based batteries are analyzed. Finally, we discuss the prospects for further developments in this emerging field. This review not only describes recent advances in pillararene/calixarene-based batteries and supercapacitors but also lays a firm groundwork for their further application in electrochemical energy engineering.

Promoting the sulfur redox kinetics by mixed organodiselenides in high-energy-density lithium–sulfur batteries

Zhao Meng, Li Xi-Yao, Chen Xiang, Li Bo-Quan, Kaskel Stefan, Zhang Qiang, Huang Jia-Qi

2021, 1(1): 44-52. doi: 10.1016/j.esci.2021.08.001

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Lithium–sulfur (Li–S) batteries are considered as a highly promising energy storage system due to their ultrahigh theoretical energy density. However, the sluggish kinetics of the complex multi-electron sulfur redox reactions seriously hinders the actual battery performance especially under practical working conditions. Homogeneous redox mediation, through elaborately designing the additive molecules, is an effective approach to promote the sulfur redox kinetics. Herein a promoter of mixed organodiselenides (mixed-Se) is proposed to comprehensively improve the sulfur redox kinetics following the redox comediation principles. Concretely, diphenyl diselenide promotes the liquid–liquid conversion between polysulfides and the solid–liquid conversion regarding lithium sulfide oxidation to polysulfides, while dimethyl diselenide enhances the liquid–solid conversion regarding lithium sulfide deposition. Consequently, the mixed-Se promoter endows a high discharge capacity of 1002 mAh g⁻¹ with high sulfur loading of 4.0 mg cm⁻², a high capacity retention of 81.6% after 200 cycles at 0.5 C, and a high actual energy density of 384 Wh kg⁻¹ at 0.025 C in 1.5 Ah-level Li–S pouch cells. This work affords an effective kinetic promoter to construct high-energy-density Li–S batteries and inspires molecular design of kinetic promoters toward targeted energy-related redox reactions.

Smelting recrystallization of CsPbBrI₂ perovskites for indoor and outdoor photovoltaics

Wang Kai-Li, Yang Ying-Guo, Lou Yan-Hui, Li Meng, Igbari Femi, Cao Jun-Jie, Chen Jing, Yang Wen-Fan, Dong Chong, Li Lina, Tai Ren-Zhong, Wang Zhao-Kui

2021, 1(1): 53-59. doi: 10.1016/j.esci.2021.09.001

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A smelting multiple recrystallization strategy and its effects on the morphology, composition, and defects of CsPbBrI₂ film were investigated. An optimal number (n = 2) of recrystallization cycles improved the crystallinity and phase purity, minimized the grain boundaries, and optimized the crystal structure, yielding a high-quality perovskite film with significantly reduced defects density. The corresponding photovoltaic devices exhibited a champion efficiency of 16.02% under AM 1.5 G illumination and presented an even higher indoor efficiency of 33.50% under an LED (2956 K, P_in: 334.41 μW/cm²). This recrystallization method offers a promising strategy for developing high-performance indoor and outdoor photovoltaics. Direct recrystallization in the cells was also explored to achieve enhanced stability and longer lifetime in humid conditions.

A branched dihydrophenazine-based polymer as a cathode material to achieve dual-ion batteries with high energy and power density

Xu Shuaifei, Dai Huichao, Zhu Shaolong, Wu Yanchao, Sun Mingxuan, Chen Yuan, Fan Kun, Zhang Chenyang, Wang Chengliang, Hu Wenping

2021, 1(1): 60-68. doi: 10.1016/j.esci.2021.08.002

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Organic electrode materials have exhibited good electrochemical performance in batteries, but their voltages and rate capabilities still require improvement to meet the increasing demand for batteries with high energy and power density. Herein, we design and synthesize a branched dihydrophenazine-based polymer (p-TPPZ) as a cathode material for dual-ion batteries (DIBs) through delicate molecular design. Compared with the linear dihydrophenazine-based polymer (p-DPPZ, with a theoretical capacity of 209 mAh g^-1), p-TPPZ possessed a higher theoretical capacity of 233 mAh g^-1 and lower highest occupied molecular orbital energy levels, which resulted in a high actual capacity (169.3 mAh g^-1 at 0.5 C), an average discharge voltage of 3.65 V (vs. Li⁺/Li) and a high energy density (618.2 Wh kg^-1, based on the cathode materials). The branched structure of p-TPPZ led to a larger specific surface area than that of p-DPPZ, which was beneficial for the electrolyte infiltration and fast ionic transport, contributing to the high power density. Due to the fast reaction kinetics, even at a power density of 23, 725 W kg^-1 (40 C), the energy density still reached 474.5 Wh kg^-1. We also made a detailed investigation of the p-TPPZ cathode's charge storage mechanism. This work will stimulate the further molecular design to develop organic batteries with both high energy and power density.

Ni₂P/NiMoP heterostructure as a bifunctional electrocatalyst for energy-saving hydrogen production

Wang Tongzhou, Cao Xuejie, Jiao Lifang

2021, 1(1): 69-74. doi: 10.1016/j.esci.2021.09.002

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Electrochemical water splitting is a sustainable and feasible strategy for hydrogen production but is hampered by the sluggish anodic oxygen evolution reaction (OER). Herein, an effective approach is introduced to significantly decrease the cell voltage by replacing the anodic OER with a urea oxidation reaction (UOR). A Ni₂P/NiMoP nanosheet catalyst with a hierarchical architecture is uniformly grown on a nickel foam (NF) substrate through a simple hydrothermal and phosphorization method. The Ni₂P/NiMoP achieves impressive HER activity, with a low overpotential of only 22 mV at 10 mA cm^-2 and a low Tafel slope of 34.5 mV dec^-1. In addition, the oxidation voltage is significantly reduced from 1.49 V to 1.33 V after the introduction of 0.33 M urea. Notably, a two-electrode electrolyzer employing Ni₂P/NiMoP as a bifunctional catalyst exhibits a current density of 10 mA cm^-2 at a cell voltage of 1.35 V and excellent long-term durability after 80 h.

Integration of homogeneous and heterogeneous nucleation growth via 3D alloy framework for stable Na/K metal anode

Ye Shufen, Wang Lifeng, Liu Fanfan, Shi Pengcheng, Yu Yan

2021, 1(1): 75-82. doi: 10.1016/j.esci.2021.09.003

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Sodium/Potassium (Na/K) metal anodes have been considered as the promising anodes for next-generation Na/K secondary batteries owing to their ultrahigh specific capacity, low redox potential and low cost. However, their practical application is still hampered due to unstable solid electrolyte interphase, infinite volume change, and dendrite growth. Herein, we design a 3D-Na₃Bi/3D-K₃Bi alloy host which enables the homogeneous and heterogeneous nucleation growth of Na/K metal. The unique structure with periodic alternating of electron and ion conductivity improves the mass transfer kinetics and prevents the volume expansion during cycling. Meanwhile, the sodiophilicity of Na₃Bi/potassiophilicity of K₃Bi framework can avoid dendritic growth. Cycling lifespans over 700 h with 1 mAh cm^?2 for 3D-Na₃Bi@Na electrode and about 450 h with 1 mAh cm^?2 for 3D-K₃Bi@K electrode are achieved, respectively. 3D-Na₃Bi@Na||Na₃V₂(PO₄)₃ full battery shows sustainable cycle performance over 400 cycles. This design provides a simple but effective approach for achieving safety of sodium/potassium metal anodes.

Molecular crowding agents engineered to make bioinspired electrolytes for high-voltage aqueous supercapacitors

Peng Mengke, Wang Li, Li Longbin, Peng Zhongyou, Tang Xiannong, Hu Ting, Yuan Kai, Chen Yiwang

2021, 1(1): 83-90. doi: 10.1016/j.esci.2021.09.004

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The development of low-cost and eco-friendly aqueous electrolytes with a wide voltage window is the key to achieving safe high energy density supercapacitors (SCs). In this work, a molecular crowding electrolyte is prepared by simulating the crowded environment in living cells. Ion transport in the molecular crowding electrolyte can be effectively improved via reducing the molecular weight of the crowding agent, polyethylene glycol (PEG). The results show that PEG with a molecular weight of 200 (PEG200) can significantly improve ionic conductivity while maintaining a wide voltage window. These advantages enable commercial activated carbon-based SCs to work at 2.5 V with high energy density, outstanding rate performance and good stability for more than 10, 000 cycles. On this basis, three series of molecular crowding electrolytes using sodium perchlorate, lithium perchlorate, and sodium trifluoromethanesulfonate as salts are developed, demonstrating the versatility of PEG200 for wide-voltage aqueous electrolytes.

In situ growth of ultra-thin perovskitoid layer to stabilize and passivate MAPbI₃ for efficient and stable photovoltaics

Miao Yanfeng, Wang Xingtao, Zhang Haijuan, Zhang Taiyang, Wei Ning, Liu Xiaomin, Chen Yuetian, Chen Jie, Zhao Yixin

2021, 1(1): 91-97. doi: 10.1016/j.esci.2021.09.005

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The efficiency and stability of typical three-dimensional (3D) MAPbI₃ perovskite-based solar cells are highly restricted, due to the weak interaction between methylammonium (MA⁺) and [PbI₆]^4-octahedra in the 3D structure, which can cause the ion migration and the related defects. Here, we found that the in situ-grown perovskitoid TEAPbI₃ layer on 3D MAPbI₃ can inhibit the MA⁺ migration in a polar solvent, thus enhancing the thermal and moisture stability of perovskite films. The crystal structure and orientation of TEAPbI₃ are reported for the first time by single crystal and synchrotron radiation analysis. The ultra-thin perovskitoid layer can reduce the trap states and accelerate photo-carrier diffusion in perovskite solar cells, as confirmed by ultra-fast spectroscopy. The power conversion efficiency of TEAPbI₃-MAPbI₃ based solar cells increases from 18.87% to 21.79% with enhanced stability. This work suggests that passivation and stabilization by in situ-grown perovskitoid can be a promising strategy for efficient and stable perovskite solar cells.

2021 Vol. 1, No. 1