钠金属电池因其能量密度高、资源丰富等优势被认为是一种极具前景的电化学储能技术，然而在高面容量下实现电池持续运行是阻碍该系统应用的关键科学问题。
近日，郑州大学陈卫华教授和盖军民研究员等人在Science China Materials发表研究论文，通过工业电镀策略在商业化的铝箔集流体表面精心设计了二维锡/钠锡合金涂层。
本文要点
1) 与目前广泛报道的Sn与Na原位形成Na15Sn4合金不同，设计的Na9Sn4合金界面与钠具有更低的晶格失配率（20.84%），进而形成半共格界面，从而减缓钠金属沉积过程中的晶格应力，并诱导钠在高面容量下致密沉积。2) Sn与阴离子的吸附作用使得更多的PF6−优先参与界面溶剂化结构，从而促进形成薄（10 nm）的富含NaF等无机物的固态电解质界面，增强钠离子的传输，进一步有助于钠金属的均匀沉积，提高钠金属沉积/剥离循环的可逆性和稳定性。3) 衬底在5 mA h cm−2的高面容量下，表现出高达99.7%的平均库仑效率。在60 mA g−1下，全电池展现出600周的循环稳定性，每圈循环衰减率低至0.0018%。Figure 1. Structural characterizations of the Sn-Al substrate. Schematic for (a) the device for Sn-Al substrate preparation and (b) the process of forming an inorganic-rich SEI and a semi-coherent interface. (c) SEM image of Sn-Al with an optical photo (inset). (d) Side-view SEM image of Sn-Al with the corresponding elemental mapping (electroplating for 5 min at 20 mA cm−2). (e) TEM image and FFT image of Sn-Al. (f) XRD patterns of Sn-Al and bare Al foils. Contact angles of (g) the NaPF6 DGM electrolyte (1 mol L−1) and (h) Na on the Sn-Al and bare Al foils.![]()
Figure 2. Electrochemical performance of the Sn-Al substrate. (a) CV performance of Na||Sn-Al and Na||Al asymmetrical batteries. CE of asymmetric batteries using bare Al foils and Sn-Al substrate at (b) 3 mA cm−2 with 3 mA h cm−2 and (c) 5 mA cm−2 with 5 mA h cm−2. (d) Long-term cycling performance of Na/Sn-Al||Na/Sn-Al asymmetric batteries at different current densities. (e) Comparison of the current density, cumulative capacity and ACE of the collectors.![]()
Figure 3. Characterizations and analyses of the sodium metal deposition morphology. (a, b) SEM images and sectional distribution of Na electrodeposited on Sn-Al and bare Al foils. (c) In situ optical microscopy images of Na plating on Sn-Al and bare Al foils. In situ XRD results of the asymmetric batteries with (d) Sn-Al and (e) bare Al foils during the first two cycles at 1 mA cm−2. (f) Comparison of the cumulative reversible capacity, cumulative irreversible capacity, sodium metal capacity consumed by the SEI and “dead” Na on the Sn-Al and bare Al foils after 20 cycles at 1 mA cm−2. (g) SEI on Sn-Al and bare Al foils after 5 cycles at 1 mA cm−2 and (h, i) the corresponding XPS depth profiling characterizations of the F 1s spectra. (j) Adsorption energy and lattice mismatch of Na among different metal atoms. (k) Schematic of three kinds of interfaces formed between Na atoms and diverse metal atom substrates by lattice matching.![]()
Figure 4. Electrochemical performance of full batteries with Sn-Al substrate. (a) Long-term cycling performance of Sn-Al/Na||NFMPP (N/P = 2) at 60 mA g−1. (b) Corresponding specific capacity-voltage curves of Sn-Al/Na||NFMPP (N/P = 2) at different cycles. (c) Comparison of cyclic reversibility in recent reports (the larger the sphere, the smaller the N/P). (d) Long-term cycling performance of Sn-Al||NVP anode-free battery. (e) Corresponding energy efficiency performance of anode-free sodium-metal batteries. (f) Safety test of anode-free sodium-metal pouch battery to light up LED bulbs under normal, folded and cut states.Pei Ma, Yaoyang Zhang, Wenbin Li, Jun Luo, Longfei Wen, Guochuan Tang, Jingjing Gai, Qingbao Wang, Lingfei Zhao, Junmin Ge, Weihua Chen. Tailoring alloy-reaction-induced semi-coherent interface to guide sodium nucleation and growth for long-term anode-less sodium-metal batteries. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3084-4
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