eScience

Advanced polymer-based electrolytes in zinc–air batteries

Liu Qingqing, Liu Ruiting, He Chaohui, Xia Chenfeng, Guo Wei, Xu Zheng-Long, Xia Bao Yu

2022, 2(5): 453-466. doi: 10.1016/j.esci.2022.08.004

Abstract(87) HTML (35) PDF(11)

Abstract:
Zinc–air batteries (ZABs) are expected to be some of the most promising power sources for wearable and portable electronic devices and have received widespread research interest. As an ion conductor connecting anodes and cathodes, the electrolyte is critical for the overall performance of ZABs (e.g., energy density, rechargeability, and operating voltage). Compared with liquid electrolytes, polymer-based electrolytes have superior characteristics for ZABs, such as negligible electrolyte leakage, three-phase interface stabilization, and dendrite suppression. In this perspective, we focus on recent progress in polymer-based electrolytes for ZABs. After a brief introduction to ZABs and electrolytes, we emphasize the development of polymer-based electrolytes in terms of their intrinsic properties and interfacial chemistry. Finally, challenges and viable strategies are proposed for polymer-based electrolytes in ZABs. We hope that this work will provide useful guidance to spur the development of high-performance ZABs based on advanced polymer-based electrolytes.

Phase engineering of metal nanocatalysts for electrochemical CO₂ reduction

Zhai Yanjie, Han Peng, Yun Qinbai, Ge Yiyao, Zhang Xiao, Chen Ye, Zhang Hua

2022, 2(5): 467-485. doi: 10.1016/j.esci.2022.09.002

Abstract(55) HTML (25) PDF(6)

Abstract:
The electrochemical CO₂ reduction reaction (CO₂RR) offers a green and sustainable process to convert CO₂ into valuable chemical stocks and fuels. Metal is one of the most promising types of catalysts to drive an efficient and selective CO₂RR. The catalytic performance of metal nanocatalysts is strongly dependent on their structural features. Recently, phase engineering of nanomaterials (PEN) has emerged as a prominent tactic to regulate the catalytic performance of metal nanocatalysts for the CO₂RR. A broad range of metal nanocatalysts with conventional and unconventional crystal phases has been developed, and remarkable achievements have been made. This review summarizes the most recent developments in phase engineering of metal nanocatalysts for the electrochemical CO₂RR. We first introduce the different crystal phases of metal nanocatalysts used in the CO₂RR and then discuss various synthetic strategies for unconventional phases of metal nanocatalysts. After that, detailed discussions of metal nanocatalysts with conventional and unconventional phases, including amorphous phases, are presented. Finally, the challenges and perspectives in this emerging area are discussed.

Trimethoxyboroxine as an electrolyte additive to enhance the 4.5 V cycling performance of a Ni-rich layered oxide cathode

Gu Wei, Xue Guoyong, Dong Qingyu, Yi Ruowei, Mao Yayun, Zheng Lei, Zhang Haikuo, Fan Xiulin, Shen Yanbin, Chen Liwei

2022, 2(5): 486-493. doi: 10.1016/j.esci.2022.05.003

Abstract(146) HTML (57) PDF(19)

Abstract:
Ni-rich layered oxides are attractive cathode materials for advanced lithium-ion batteries (LIBs) due to their high energy density. However, their large-scale application is seriously hindered by their interfacial instability, especially at a high cut-off potential. Here, we demonstrate that trimethoxyboroxine (TMOBX) is an effective film-forming additive to address the interfacial instability of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) material at a high cut-off voltage of 4.5 V. We find that TMOBX decomposes before carbonate solvent and forms a thin cathode electrolyte interphase (CEI) layer on the surface of the NCM811 material. This TMOBX-formed CEI significantly suppresses electrolyte decomposition at a high potential and inhibits the dissolution of transition metals from NCM811 during cycling. In addition, electron-deficient borate compounds coordinate with anions (, F⁻, etc.) and H₂O in the battery, further improving the battery's stability. As a result, adding 1.0 wt% of TMOBX boosts the capacity retention of a Li||NCM811 cell from 68.72% to 86.60% after 200 cycles at 0.5C in the range of 2.8–4.5 V.

Biodegradable composite polymer as advanced gel electrolyte for quasi-solid-state lithium-metal battery

Chai Simin, Zhang Yangpu, Wang Yijiang, He Qiong, Zhou Shuang, Pan Anqiang

2022, 2(5): 494-508. doi: 10.1016/j.esci.2022.04.007

Abstract(116) HTML (49) PDF(13)

Abstract:
The development of low-cost and eco-friendly gel polymer electrolytes (GPEs) with a wide window, ideal compatibility, and structural stability is an effective measure to achieve safe high-energy-density lithium-metal batteries. Herein, a biodegradable composite polyacrylonitrile/poly-L-lactic acid nanofiber membrane (PAL) is synthesized and used as a robust skeleton for GPEs. The 3D nanofiber membrane (PAL-3-C12) prepared with an adjusted weight ratio of polyacrylonitrile (PAN)/poly-L-lactic acid (PLLA) and spinning solution concentration delivers decent thermal stability, biodegradability, and liquid electrolyte absorbability. The "passivation effect" of PAN upon lithium metal is effectively alleviated by hydrogen bonds formed in the PAL chains. These advantages enable PAL GPEs to work stably to 5.17 V while maintaining high ionic conductivity as well as excellent corrosion resistance and dielectric properties. The interfacial compatibility of optimized GPEs promotes the stable operation of a Li||PAL-3-C12 GPEs||Li symmetric battery for 1000 h at 0.15 mA cm^-2/0.15 mA h cm^-2, and the LiFePO₄ full cell retains capacity retention of 97.63% after 140 cycles at 1C.

Toward dendrite-free and anti-corrosion Zn anodes by regulating a bismuth-based energizer

Wang Mingming, Meng Yahan, Li Ke, Ahmad Touqeer, Chen Na, Xu Yan, Sun Jifei, Chuai Mingyan, Zheng Xinhua, Yuan Yuan, Shen Chunyue, Zhang Ziqi, Chen Wei

2022, 2(5): 509-517. doi: 10.1016/j.esci.2022.04.003

Abstract(193) HTML (82) PDF(44)

Abstract:
Aqueous rechargeable zinc metal batteries display high theoretical capacity along with economical effectiveness, environmental benignity and high safety. However, dendritic growth and chemical corrosion at the Zn anodes limit their widespread applications. Here, we construct a Zn/Bi electrode via in-situ growth of a Bi-based energizer upon Zn metal surface using a replacement reaction. Experimental and theoretical calculations reveal that the Bi-based energizer composed of metallic Bi and ZnBi alloy contributes to Zn plating/stripping due to strong adsorption energy and fast ion transport rates. The resultant Zn/Bi electrode not only circumvents Zn dendrite growth but also improves Zn anode anti-corrosion performance. Specifically, the corrosion current of the Zn/Bi electrode is reduced by 90% compared to bare Zn. Impressively, an ultra-low overpotential of 12 mV and stable cycling for 4000 h are achieved in a Zn/Bi symmetric cell. A Zn–Cu/Bi asymmetric cell displays a cycle life of 1000 cycles, with an average Coulombic efficiency as high as 99.6%. In addition, an assembled Zn/Bi-activated carbon hybrid capacitor exhibits a stable life of more than 50, 000 cycles, an energy density of 64 Wh kg⁻¹, and a power density of 7 kW kg⁻¹. The capacity retention rate of a Zn/Bi–MnO₂ full cell is improved by over 150% compared to a Zn–MnO₂ cell without the Bi-based energizer. Our findings open a new arena for the industrialization of Zn metal batteries for large-scale energy storage applications.

Tuning the local electronic structure of oxygen vacancies over copper-doped zinc oxide for efficient CO₂ electroreduction

Wang Ke, Liu Dongyu, Liu Limin, Liu Jia, Hu XiaoFei, Li Ping, Li Mingtao, Vasenko Andrey S., Xiao Chunhui, Ding Shujiang

2022, 2(5): 518-528. doi: 10.1016/j.esci.2022.08.002

Abstract(83) HTML (29) PDF(13)

Abstract:
Oxygen vacancies in metal oxides can serve as electron trap centers to capture CO₂ and lower energy barriers for the electrochemical CO₂ reduction reaction (CO₂RR). Under aqueous electrolytes, however, such charge-enriched active sites can be occupied by adsorbed hydrogen (H*) and lose their effectiveness for the CO₂RR. Here, we develop an efficient catalyst consisting of Cu-doped, defect-rich ZnO (Cu–ZnO) for the CO₂RR, which exhibits enhanced CO Faradaic efficiency and current density compared to pristine ZnO. The introduced Cu dopants simultaneously stabilize neighboring oxygen vacancies and modulate their local electronic structure, achieving inhibition of hydrogen evolution and acceleration of the CO₂RR. In a flow cell test, a current density of more than 45 mA cm⁻² and a CO Faradaic efficiency of > 80% is obtained for a Cu–ZnO electrocatalyst in the wide potential range of −0.76 V to −1.06 V vs. Reversible Hydrogen Electrode (RHE). This work opens up great opportunities for dopant-modulated metal oxide catalysts for the CO₂RR.

Precipitate-stabilized surface enabling high-performance Na_0.67Ni_0.33-xMn_0.67Zn_xO₂ for sodium-ion battery

Wang Kuan, Zhang Zhengfeng, Cheng Sulan, Han Xiao, Fu Junjie, Sui Manling, Yan Pengfei

2022, 2(5): 529-536. doi: 10.1016/j.esci.2022.08.003

Abstract(78) HTML (28) PDF(12)

Abstract:
Electrode interfacial degradations are the key challenges for high-performance rechargeable batteries, usually mitigated through surface modification/coating strategies. Herein, we report a novel mechanism to enhance the surface stability of P2 layered cathodes by introducing a high density of dopant-enriched precipitates. Based on microscopic analysis, we show that forming a high density of precipitates at the grain surface can effectively suppress surface cracking and corrosion, which not only improves the surface/interface stability but also effectively suppresses the intergranular cracking issue. Increasing the doping level can lead to a greater density of precipitates at the surface region, which results in higher surface stability and increased cycling stability of the P2 layered cathode for a sodium-ion battery. We further reveal that prolonged cycling can induce the formation of a precipitate-free surface region due to the loss of Zn dopant and Na. Our in-depth microanalysis reveals cycling-induced dynamic structural evolution of the P2 layered cathodes, highlighting that dopant segregation-induced precipitation is a new approach to achieving high interfacial stability.

Stable Ni-rich layered oxide cathode for sulfide-based all-solid-state lithium battery

Wang Yue, Wang Zhixuan, Wu Dengxu, Niu Quanhai, Lu Pushun, Ma Tenghuan, Su Yibo, Chen Liquan, Li Hong, Wu Fan

2022, 2(5): 537-545. doi: 10.1016/j.esci.2022.06.001

Abstract(660) HTML (301) PDF(137)

Abstract:
Sulfide-based all-solid-state lithium-ion batteries (ASSLIBs) are one of the most promising energy storage technologies due to their high safety and ionic conductivity. To achieve greater energy density, a Ni-rich layered oxide LiNi_xCo_yM_1-x-yO₂ (NCM, M = Mn/Al, x ≥ 0.6) is desirable due to its relatively high voltage and large capacity. However, interfacial side reactions between the NCM and sulfide solid electrolytes lead to undesirable interfacial passivation layers and low ionic conductivity, thereby degrading the electrochemical performance of NCM sulfide all-solid-state batteries. Herein, a time-/cost-effective sulfidation strategy is exploited to sulfidize a Ni-rich NCM88 cathode in a mixed gas atmosphere of N₂ and CS₂. A new type of cathode (NCM88-S) with an ultrathin (~2 nm) surface layer is obtained, which significantly reduces the interfacial side reactions/resistance and improves the interfacial stability. The resulting NCM88-S/Li₆PS₅Cl/Li₄Ti₅O₁₂ ASSLIB exhibits superior performance, including a high discharge specific capacity (200.7 mAh g⁻¹) close to that of liquid batteries, excellent cycling performance (a capacity retention of 87% after 500 cycles), and satisfactory rate performance (158.3 mAh g⁻¹ at 1C).

Engineering iron-group bimetallic nanotubes as efficient bifunctional oxygen electrocatalysts for flexible Zn–air batteries

Niu Yanli, Gong Shuaiqi, Liu Xuan, Xu Chen, Xu Mingze, Sun Shi-Gang, Chen Zuofeng

2022, 2(5): 546-556. doi: 10.1016/j.esci.2022.05.001

Abstract(144) HTML (53) PDF(20)

Abstract:
Air cathode performance is essential for rechargeable zinc–air batteries (ZABs). In this study, we develop a self-templated synthesis technique for fabricating bimetallic alloys (FeNi₃), bimetallic nitrides (FeNi₃N) and heterostructured FeNi₃/FeNi₃N hollow nanotubes. Owing to its structural and compositional advantages, FeNi₃/FeNi₃N exhibits remarkable bifunctional oxygen electrocatalytic performance with an extremely small potential gap of 0.68 V between the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). Theoretical calculations reveal reduced Gibbs free energy for the rate-limiting O–O bond formation during OER due to the self-adaptive surface reconfiguration, which induces a synergistic effect between Fe(Ni)OOH developed in situ on the surface and the inner FeNi₃/FeNi₃N. ZAB fabricated using the FeNi₃/FeNi₃N catalyst shows high power density, small charge/discharge voltage gap and excellent cycling stability. In addition to its excellent battery performance, the corresponding quasi-solid-state ZAB shows robust flexibility and integrability. The synthesis method is extended to prepare a CoFe/CoFeN oxygen electrocatalyst, demonstrating its applicability to other iron-group elements.

Pseudo-concentrated electrolytes for lithium metal batteries

Wang Huaping, Liu Jiandong, He Jian, Qi Shihan, Wu Mingguang, Li Fang, Huang Junda, Huang Yun, Ma Jianmin

2022, 2(5): 557-565. doi: 10.1016/j.esci.2022.06.005

Abstract(126) HTML (53) PDF(20)

Abstract:
Lithium metal batteries suffer from short lifespans and low Coulombic efficiency (CE) due to the high reactivity of Li and the poor stability of the solid electrolyte interphase (SEI). Herein, we propose the concept of a pseudo-concentrated electrolyte (PCE) induced by an electron-deficient additive (4-pyridylboronic acid; 4-PBA) to form a robust, LiF-rich SEI, thus addressing the above issues. Molecular dynamics simulations confirm that 4-PBA can increase the coordination number of anions in the Li⁺ solvation sheath to achieve pseudo-concentrated LiPF₆ in the electrolyte. Moreover, the 4-PBA can scavenge harmful PF₅ decomposed from LiPF₆ to stabilize the LiF-rich SEI. The resulting robust LiF-rich SEI promotes Li growth along the SEI/Li interface and represses the growth of Li dendrites. Thus, excellent performance is achieved, with a high CE of 97.1% for a Li||Cu cell at 1.0 mA cm⁻², and over 950 cycles at 0.5 mA cm⁻² for Li||Li symmetric cells with 1.0 wt% 4-PBA electrolyte. Meanwhile, the resulting stable boron-containing cathode electrolyte interphase enables Li||LiNi₀_·₆Co₀_·₂Mn₀_·₂O₂ (NCM622) cells to achieve excellent stability, with a capacity retention of 86.9% after 200 cycles.

Recent Articles 2022, Volume 2, Issue 5

Recent Articles
2022, Volume 2, Issue 5