吉大-郎兴友&蒋青 AFM | 均匀mxene接枝共晶Al-Ce合金作为可充电铝离子电池的柔性可逆负极材料

近日，吉林大学-郎兴友/蒋青团队等人在Advanced Functional Materials上发表重要文章，论文题为“Uniformly MXene-Grafted Eutectic Aluminum-Cerium Alloys as Flexible and Reversible Anode Materials for Rechargeable Aluminum-Ion Battery”。铝具有高地球丰度、低成本、高理论容量和安全性能等优点，是一种极具吸引力的多价金属水性电池负极材料，可用于大规模储能。然而，由于铝剥离/镀的不可逆性和枝晶生长，目前最先进的基于铝阳极的水铝离子电池长期存在充电性能差、库仑效率低等问题。本文报道了用均匀超薄MXene (MXene/E-Al97Ce3)原位接枝共晶铝-铈合金作为可充电水系铝离子电池的柔性、可逆和无枝晶负极材料。MXene作为稳定的固体电解质间相抑制副反应，而纳米结构的E-Al97Ce3利用共生的α-Al金属和金属间质Al11Ce3片层，实现了Al的定向剥离和沉积，MXene/E-Al97Ce3复合电极在低氧浓度的三氟甲烷磺酸铝(Al(OTF)3)水溶液中表现为可逆和无枝晶铝剥离/电镀，电压极化为±54 mV，持续时间≥1000 h。这些优越的电化学性能使得由MXene/E-Al97Ce3负极和AlxMnO2正极组成的软包装铝离子电池在1 A g^-1时具有≈360 mAh g^-1的高初始放电容量，在循环500次后保持≈85%的放电容量，库仑效率高达99.5%。

第一作者：Qing Ran

通讯作者：Xing-You Lang, Qing Jiang

通讯单位：吉林大学

论文DOI：10.1002/adfm.202211271

Figure 1. Scheme and microstructural characterizations of hybrid electrodes. a,b) Schemes for scalable cold rolling technology to prepare lamella-nanostructured flexible E-Al97Ce3 foils composed of alternating α-Al metal and intermetallic Al11Ce3 lamellas (a) and fabrication of MXene/E-Al97Ce3 hybrid electrodes by in situ growth of MXene on the constituent Al11Ce3 lamellas of E-Al97Ce3 (b). c) Photograph of flexible MXene/E-Al97Ce3 hybrid electrodes. d) XRD patterns of monometallic Al foil (gray line), lamella-nanostructured E-Al97Ce3 alloy (blue line) and MXene/E-Al97Ce3 hybrid electrodes (pink line). The line patterns show reference cards 04–0787 and 19-0006 for face-centered cubic Al (gray) and body-centered orthorhombic Al11Ce3 (green) according to JCPDS, respectively. e) Raman spectra of monometallic Al foil (grey line), E-Al97Ce3 alloy (blue line) and MXene/E-Al97Ce3 hybrid electrodes (pink line). f–i) Typical SEM backscattered electron image of f) MXene/E-Al97Ce3 hybrid electrodes and the corresponding EDS elemental mapping of g) Ti, h) Al, and i) Ce j,k) High-resolution XPS spectra of Ti 2p in MXene/E-Al97Ce3 (j) and free-standing MXene (k).

Figure 2. Oxygen sensitivity of Al-based electrodes. a,b) Tafel polarization curves of MXene/E-Al97Ce3, E-Al97Ce3 alloy and monometallic Al electrodes in ambient 2 m Al(OTF)3 aqueous electrolyte with CO2 = ≈8.9 mg L−1 and ≈0.13 mg L−1. Scan rate: 5 mV s−1. c,d) Al stripping/plating behaviors of symmetric cells of monometallic Al, E-Al97Ce3 alloy, and MXene/E-Al97Ce3 hybrid electrodes at current density of 0.5 mA cm−2 in Al(OTF)3 aqueous electrolytes with CO2 = ≈8.9 mg L−1 and ≈0.13 mg L−1. e,f) EIS spectra of symmetric cells of monometallic Al, E-Al97Ce3 alloy, and MXene/E-Al97Ce3 hybrid electrodes, in 2 m Al(OTF)3 aqueous electrolytes with CO2 = ≈8.9 mg L−1 and ≈0.13 mg L−1.

Figure 3. Electrochemical properties of Al-based electrodes in symmetric cells. a), Representative voltage profiles of Al stripping and plating in MXene/E-Al97Ce3 symmetric cell with CO2 = ≈0.13 mg L−1, which are performed at current density of 1 mA cm−2 for 10 h. b,c), Typical SEM backscattered electron image of MXene/E-Al97Ce3 hybrid electrode after Al stripping and then plating with the capacity of 10 mAh cm−2 and their corresponding EDS elemental mapping of Al, Ce as well as Ti in MXene. d), Long-term cycling stability of Al stripping/plating for symmetric cells based on MXene/E-Al97Ce3, E-Al97Ce3, and Al electrodes at 0.5 mA cm−2 in 2 M Al(OTF)3 aqueous electrolyte with CO2 = ≈0.13 mg L−1. Insets: Voltage profiles of monometallic Al (left), E-Al97Ce3 (middle) and MXene/E-Al97Ce3 (right) in initial five and last five Al stripping/plating cycles. e-g, EIS spectra of symmetric cells for MXene/E-Al97Ce3 e), E-Al97Ce3 f) and monometallic Al g) before and after Al stripping/plating for 192, 192, and 48 h, respectively. h), Rate performance of symmetric cells of MXene/E-Al97Ce3, E-Al97Ce3, and monometallic Al electrodes in 2 m Al(OTF)3 aqueous electrolyte with CO2 = ≈0.13 mg L−1 at various rates from 1 C to 5 C (which correspond to the current densities ranging from 0.5 to 2.5 mA cm−2). Inset: Enlarged voltage-time profiles comparing the stripping/plating behaviors of MXene/E-Al97Ce3 and E-Al97Ce3 electrodes at different rates.

Figure 4. Electrochemical performance of full Al-ion cells. a), Representative CV curves for full Al-ion cells, which are constructed with MXene/E-Al97Ce3 hybrid electrode or monometallic Al foil as anode and AlxMnO2/C as cathode, 2 m Al(OTF)3 aqueous electrolyte with CO2 = ≈0.13 mg L−1 as electrolyte. Scan rate: 0.1 mV s−1. b), Typical galvanostatic charging/discharging voltage profiles for full MXene/E-Al97Ce3||AlxMnO2/C and Al||AlxMnO2/C cells. Current density: 0.1 A g−1. c), Rate capabilities of full MXene/E-Al97Ce3||AlxMnO2/C and Al||AlxMnO2/C cells, which are performed at various current densities ranging from 0.1 to 5 A g−1. d), Comparison of EIS spectra for full MXene/E-Al97Ce3||AlxMnO2/C and Al||AlxMnO2/C cells. Inset: Enlarged EIS spectra of full MXene/E-Al97Ce3||AlxMnO2/C and Al||AlxMnO2/C cells. e), Capacity retentions and coulombic efficiencies of full MXene/E-Al97Ce3||AlxMnO2/C and Al||AlxMnO2/C cells in a long-term charge/discharge cycling measurement at 1 A g−1 (2 C). f), Capacity retention of bended soft-package MXene/E-Al97Ce3||AlxMnO2/C cell. g,h), Optical photographs of soft-package MXene/E-Al97Ce3||AlxMnO2/C cell at bending angles of 0° and 90° when powering an electric mini-fan.

【总结】

综上所述，作者开发了均匀的Mxene接枝E-Al97Ce3合金作为高柔性和可逆的铝基负极，用于高性能水基可充电铝离子电池。MXene作为人工固体电解质间相，通过减少钝化氧化层，抑制了不良的副反应，促进了Al³⁺的迁移，MXene/E-Al97Ce3杂化电极表现出无枝晶和可逆的铝剥离和镀行为，在2 M Al(OTF)3水电解质中，超低氧浓度(≈0.13 mg L^-1)，0.5 mA cm^-2电压极化低至±54 mV。其中，共生的单金属α-Al和金属间质Al11Ce3片材分别作为Al³⁺资源的电活性材料和二维纳米图，利用它们不同的腐蚀电位，定向引导Al剥离然后电沉积。在MXene和片层纳米结构E-Al97Ce3的协同作用下，对称的MXene/E-Al97Ce3电池在>1000 h内表现出稳定的电压分布和Al剥离和镀铝的对称平台，能量效率高达≈99.2%。这些优异的电化学性能是由软封装AR-MIBs与MXene/E-Al97Ce3负极和碳布支撑的AlxMnO2正极组装而成的，显示出优越的速率性能和卓越的循环稳定性。在充放电电流密度为1 A g^-1的条件下，经过500次循环后，AlxMnO2的初始放电容量(≈360 mAh g^-1，基于AlxMnO2的负载质量)仍能保持约85%的放电容量。由于MXene/E-Al97Ce3电极具有良好的柔韧性，使得MXene/E-Al97Ce3||AlxMnO2/C软封装电池在机械约束下能够很好地为小型风扇供电。这些优秀的特性使它成为有潜力的电源。

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