Self‐supporting Sn foil is a promising high‐volumetric‐capacity anode for lithium ion batteries (LIBs), but it suffers from low initial Coulombic efficiency (ICE). Here, mechanical prelithiation is adopted to improve ICE, and it is found that Sn foils with coarser grains are prone to cause electrode damage. To mitigate damage and prepare thinner lithiated electrodes, 3Ag0.5Cu96.5Sn foil is used that has more refined grains (5–10 µm) instead of Sn (50–100 µm), where the abundant grain boundaries (GBs) offer more sliding systems to release stress and reduce deep fractures. Thus, the thickness of Li_x3Ag0.5Cu96.5Sn can be reduced to 50 µm, compared to 100 µm Li_xSn. When the foils contact open air, the Sn‐Li‐O(H) products are more stable than Li‐O(H), thus Li_x3Ag0.5Cu96.5Sn shows outstanding air stability. The as‐prepared 50 µm foil anode achieves stable 200 cycles in LiFePO₄//Li_x3Ag0.5Cu96.5Sn full cell (≈2.65 mAh cm⁻²) and the capacity retention is 95%. Even at 5C, the capacity of Li_x3Ag0.5Cu96.5Sn is still up to ≈1.8 mAh cm⁻². The cycle life of NCM523//Li_x3Ag0.5Cu96.5Sn full cell exceeds that of NCM523//Li. Furthermore, 70 µm Li_x3Ag0.5Cu96.5Sn is used as double‐sided anode for a 3 cm × 2.8 cm pouch cell and its actual volumetric capacity density is 674 mAh cm⁻³ after 50 cycles.

中文翻译：

---

机械预镀锡合金箔电极：全电池性能高达200个循环

自支撑锡箔是用于锂离子电池（LIB）的有前途的高容量阳极，但它的初始库仑效率（ICE）较低。在此，通过机械预镀以改善ICE，发现晶粒粗大的Sn箔容易造成电极损坏。为了减轻损坏并制备更薄的锂化电极，使用了3Ag0.5Cu96.5Sn箔，该箔具有更细的晶粒（5–10 µm）而不是锡（50–100 µm），在此，丰富的晶界（GBs）提供了更多的滑动系统释放应力并减少深部裂缝。因此，与100μm的Li _x Sn相比，Li _x 3Ag0.5Cu96.5Sn的厚度可以减小到50μm 。当箔片接触露天时，Sn-Li-O（H）产品比Li-O（H）更稳定，因此Li _x3Ag0.5Cu96.5Sn表现出出色的空气稳定性。制备的50 µm箔阳极可在LiFePO ₄ // Li _x 3Ag0.5Cu96.5Sn满电池（≈2.65mAh cm ^-2）中实现稳定的200个循环，容量保持率为95％。即使在5C，Li _x 3Ag0.5Cu96.5Sn的容量仍高达≈1.8mAh cm ^-2。NCM523 // Li _x 3Ag0.5Cu96.5Sn满电池的循环寿命超过NCM523 // Li。此外，将70 µm Li _x 3Ag0.5Cu96.5Sn用作3 cm x 2.8 cm袋式电池的双面阳极，经过50次循环后，其实际容量密度为674 mAh cm ^-3。