Hybrid Lithium-Ion/Metal Electrodes Enable Long Cycle Stability and High Energy Density of Flexible Batteries

High-energy, stable, and flexible lithium batteries are highly demanded for next-generation flexible and wearable electronics. Although the cycling stability of flexible lithium-ion batteries (LIBs) is high, their energy density reaches the bottleneck because of the use of graphite anode. On the other hand, flexible lithium-metal batteries provide higher energy density because of the use of lithium (Li) metal anode, but the cycling stability is poor. Herein, a new type of flexible hybrid lithium-ion/metal battery (f-LIMB) is reported, which simultaneously possesses enhanced energy density, stable cycling behavior, and outstanding flexibility. f-LIMB is enabled by using the prelithiated carbon cloth as the anode, which improves the initial Coulombic efficiency by a prior formation of solid electrolyte interface, benefits the subsequent deposition of Li metal due to the preformed lithiophilic Li_xC₆ compounds, and enhances the cycle life and energy density of batteries through a Li compensation mechanism. The f-LIMB full cell possesses an improved gravimetric and volumetric energy density by as much as 64% and 67%, in comparison to the flexible LIB counterpart, and pertains high capacity retention of 84% after 1000 charge/discharge cycles. In addition, the f-LIMB can be readily bent down to a small radius of 2.5 mm.