One-stone, two birds: Three-dimensional structure and rich-inorganic solid electrolyte interface derived from Bi nanoparticles modified Ti3C2/CNT/ rGO aerogel for anode-free potassium metal batteries

Potassium (K) metal batteries are very promising next generation electrochemical energy storage system due to the usage of K metal with low cost and high energy density. However, the practical application of K metal batteries and even anode-free K metal batteries are still confronting huge challenges owing to the formation of "dead K" resulting from the uncontrollable growth of K dendrite and the infinite volume variation, as well as the continuous consumption of electrolyte component during charge/discharge processes. Herein, a novel "onestone, two birds" strategy was proposed for the first time by designing a three-dimensional (3D) potassiophilic current collector composed of"Bi nanoparticles modified Ti3C2/CNT/rGO cross-linked 3D porous aerogel hosts (marked as Bi/CTG)"and spontaneously in-situ forming a rich-inorganic SEI layer simultaneously. The modification of Bi nanoparticles could improve potassiophilicity of hosts and guide uniform K metal deposition. The 3D porous structure of Bi/CTG hosts could accommodate the deposited K metal to restrain serious volume variation during K plating/stripping process. Simultaneously, the spontaneous generation of KF and K3Bi between the deposited K metal and Bi/CTG could contribute SEI layer and improve the stability of SEI layer. The integrated merits are conductive to realize stable and reversible cycling of anode-free K metal battery. As a result, Bi/ CTG@Cu//PB anode-free K metal battery delivers extraordinary energy density of 152.8 Wh kg-1 at a power density of 6110 W kg ? 1. This study paves the way to realize high energy density anode-free K metal battery through a simple "one-stone, two birds" strategy.