Bottom-up lithium growth guided by Ag concentration gradient in 3D PVDF framework towards stable lithium metal anode

Three-dimensional (3D) frameworks have received much attention as an effective modification strategy for next-generation high-energy–density lithium metal batteries. However, the top-growth mode of lithium (Li) on the 3D framework remains a tough challenge. To achieve a uniform bottom-up Li growth, a scheme involving Ag concentration gradient in 3D PVDF framework (C-Ag/PVDF) is proposed. Ag nanoparticles with a concentration gradient induce an interface activity gradient in the 3D framework, and this gradient feature is still maintained during the cycle. As a result, the C-Ag/PVDF framework delivers a long lifespan over 1800 h at a current density of 1 mA cm−2 with a capacity of 1 mAh cm−2, and shows an ultra-long life (>1300 h) even at a high current density of 4 mA cm−2 with a capacity of 4 mAh cm−2. The advantage of concentration gradient provides further insights into the optimal design of the 3D framework for stable Li metal anode.