Stamping Flexible Li Alloy Anodes

Abstract

Li metal holds great promise to be the ultimate anode choice owing to its high specific capacity and low redox potential. However, processing Li metal into thin‐film anode with high electrochemical performance and good safety to match commercial cathodes remains challenging. Herein, a new method is reported to prepare ultrathin, flexible, and high‐performance Li–Sn alloy anodes with various shapes on a number of substrates by directly stamping a molten metal solution. The printed anode is as thin as 15 µm, corresponding to an areal capacity of ≈3 mAh cm–2 that matches most commercial cathode materials. The incorporation of Sn provides the nucleation center for Li, thereby mitigating Li dendrites as well as decreasing the overpotential during Li stripping/plating (e.g., <10 mV at 0.25 mA cm–2). As a proof‐of‐concept, a flexible Li‐ion battery using the ultrathin Li–Sn alloy anode and a commercial NMC cathode demonstrates good electrochemical performance and reliable cell operation even after repetitive deformation. The approach can be extended to other metal/alloy anodes such as Na, K, and Mg. This study opens a new door toward the future development of high‐performance ultrathin alloy‐based anodes for next‐generation batteries.

Lithium reduction reaction for interfacial regulation of lithium metal anode

“…Owing to the good electrical conductivity and mechanical properties, Li-based alloys generally ensure rapid Li + diffusion and inhibit lithium dendrite growth by reducing the Li nucleation barrier. 61,62 Huggins et al previously emphasised the importance of an interface with high ionic diffusion for the suppression of dendrites. 63 For instance, Au, Ag, Zn, and Mg can be lithiated to form solid solution species that exhibit zero overpotential during lithium deposition, while C, Sn, and Si species have low solubility in lithium to form composite alloy phases that exhibit lower nucleation overpotentials.…”

Mechanism understanding for stripping electrochemistry of Li metal anode

“…Therefore, it is regarded Li-rich composite alloys have attracted great attention as a novel electrode because they can present a matrix to promote the uniform plating/stripping behaviors of Li. [167][168][169][170] The diffusion of Li atoms in alloys involves another diffusion mechanism. Li atoms are much smaller than the matrix atoms and distributed in the lattice gaps of the matrix.…”

Challenge-driven printing strategies toward high-performance solid-state lithium batteries

“…Due to its simple operation, cost-effectiveness, high reliability, and high efficiency, transfer printing can fabricate tiny, ultrathin, and exible batteries in high-throughput manner. 44 However, the adhesion requirement at the interfaces is hard to satisfy and the stamps should be designed according to the desirable printed patterns.…”

“…Besides, this method can be readily extended to other alloy anodes as well as to versatile substrates with any shapes, which promotes the practical usage of dendrite-free Li anode in thin-lm batteries. 44 Printing an Li protective layer with good mechanical strength and stable chemical properties is also a promising method for suppressing Li dendrite growth and large volume expansion. Various printing techniques can ensure controllable thickness, a low-cost process, scalable methodology, and reliable performance.…”