Carbon Nanotube Interwoven Polyhedrons with Inside-out Lithiophilic Gradients toward Stable Lithium Metal Battery

Abstract

Lithium metal is one of the most potential anode materials for secondary batteries with high energy density. Nevertheless, the uncontrolled dendrite growth, fragile solid electrolyte interphase and theoretical infinite volume expansion during repeated plating/stripping process cause low Coulombic efficiency, short cycle life, and safety hazard. Carbon nanotube interwoven polyhedrons evolved from ZIF-8@ZIF-67 core–shell framework with inside-out lithiophilic gradients are prepared for lithium metal accommodation. The well-designed architecture with decreasing gradient of the main lithiophilic content ZnO from the inside out enables dendrite-free lithium deposition and stripping, and the outer interwoven carbon nanotubes induced by Co nanoparticles provide an optimal path to guide the diffusion of Li ion reduction from inside to outside as well as excellent electron conduction network for the whole anode. As the lithium metal host, the average Coulombic efficiency of lithium metal batteries can reach up to 98.2% (200 cycles) at 1 mA cm−2, and an extended lifespan (1500 h) is achieved at 3 mA cm−2. As was expected, outstanding capacity retention (82.7% after 300 cycles) with a competitive high-mass-loading (18.3 mg cm−2) LiFePO4 cathode at 1 C is realized. This structure design concept expands a promising application pathway of abundant carbon-based materials in lithium metal batteries.