(Invited) A Facile Three-Dimensional Lightweight Current Collector Strategy for High Energy Density Lithium Metal Batteries

Despite the great achievement in the development of rechargeable lithium (Li) metal batteries (LMBs) with high energy densities, their practical application is still facing difficulties due to the intrinsic issues of Li metal anode (LMA) including high reactivity and dendritic Li formation which cause low Coulombic efficiency, constant loss of Li and electrolyte, and unstable solid electrolyte interphase (SEI) layer, etc. Additionally, from the structural point of view, LMA which consists of Li foil on the two-dimensional copper (Cu) current collector brings the formidable loss of the areal capacity that leads to less specific energy density since Cu is non-faradaic and one of the heavy metals. Further, the “hostless” feature of LMA induces more issues like volume expansion and limited utilization of Li. To address such issues, a metal-coated polymeric three-dimensional (3D) scaffold is designed here. In this study, Cu is selected as an electronic conductivity provider, and electrospun polyimide (PI) is chosen as a 3D scaffold because of its high thermal stability and good mechanical properties. Cu-coated PI (Cu@PI) was produced via a facile electroless process. Driven by the structural/material uniqueness, the developed 3D Cu@PI current collector enables a uniform/continuous Li-ion conduction pathway thus leading to dense Li deposition and enhancing the electrochemical performance of LMBs containing the electrochemically deposited Li on Cu@PI and the specific energy density due to the great reduction in substrate weight. We anticipate the suggested new strategy of 3D structured LMAs would lead to a facile route toward the high energy density LMBs beyond the conventional technologies.