Temperature-Dependent Li Storage Performance in Nanoporous Cu-Ge-Al Alloy.

The performance fading process and safety concerns of lithium ion batteries at low temperature (LT) prohibit their application in cold climates. The alloy-type electrodes demonstrate great potentials in stable and dendrite-free anodes at LT. Herein, we report a temperature-dependent Li storage performance in Al-based nanoporous alloy anode. The nanoporous-structured Cu-Ge-Al ternary alloys (NP-CuGeAl) have been designed and prepared by selectively etching Al out. The high-Al-content NP-CuGeAl (acid etching for 6 h, named CGA-6) is composed of multi-intermetallic compounds (denoted as M xN y, M, N = Cu, Al, Ge) with bimodal porous architectures. Investigated as anode at room temperature, the CGA-6 delivers a capacity as high as 479.7 mAh g-1 at 0.5 A g-1 of over 1020 cycles, and the low-Al-content ones show improved LT electrochemical performance. At -20 °C, the CGA-48 (acid etching for 48 h) shows much better performance as compared with the CGA-6. In Situ transmission electron microscopy and ex situ characterizations confirm that the M xN y/Li zM xN y couples are highly reversible and the porous structure is durable upon battery cycling.