Realizing High-Energy and Stable Wire-Type Batteries with Flexible Lithium-Metal Composite Yarns

High-capacity and omnidirectionally flexible wire-type lithium (Li)-metal batteries represent a feasible technology for the realization of electronic textiles. However, the use of commercially available Li-metal wires as anodes nowadays confronts many electrochemical and mechanical issues such as dendrite formation, low yield strength, and poor fatigue resistance. Here, a flexible and stable Li-metal composite yarn (LMCY) is designed via a fast capillary filling of molten Li into metallic carbon yarn for fabricating high-energy-density and long-lasting wire-type Li-metal batteries. LMCY shows outstanding electrochemical cyclic stability, mechanical strength, flexibility, and durability. Pairing lithium-iron phosphate (LFP) with the LMCY as anode results in a foldable LFP||Li full cell that delivers a high energy density over 290 Wh L-1 and a long lifetime over 800 cycles with a capacity retention of over 50% after 750 charge/discharge cycles. The seamless integration of this wire-shape LFP||Li cell with commercial textiles is demonstrated as a built-in power supply to wearable electronics, while maintaining the excellent breathability of the textiles. LMCYs are also adaptable to other high-performance wire-type batteries, such as lithium-sulfur battery.

Automated summary

Flexible and stable Li-metal composite yarn (LMCY) is designed for high-energy-density and long-lasting wire-type Li-metal batteries, showing outstanding performance. Pairing with lithium-iron phosphate (LFP) can deliver high energy density and long lifetime in a foldable full cell configuration.