Li7La2.75Ca0.25Zr1.75Nb0.25O12@LiClO4 composite film derived solid electrolyte interphase for anode-free lithium metal battery

Abstract

Lithium metal is considered as an ideal anode material for lithium-ion batteries, because of its highest theoretical specific capacity, energy density, low reduction potential, and lightweight. However, its practical application is being hindered by factors such as the presence of uncontrolled interfacial reactions with liquid electrolytes, unstable solid electrolyte interphase (SEI), dendrite formation due to inhomogeneous lithium-deposition and poor cycle life. Herein, Lithium ion conducting composite film comprising of cubic garnet (Li7La2.75Ca0.25Zr1.75Nb0.25O12) (LLCZN), polyvinylidene fluoride (PVDF) and lithium perchlorate (LiClO4) salt is prepared by electrospinning. The composite film induces inorganic-rich solid electrolyte interphase which is mechanically stable to suppress the formation of lithium dendrites. The Li‖Cu@LLCZN/PVDF(84:16)LiClO4 cell exhibits negligible polarization compared to a bare copper one (Li‖Cu) performed in 1 M LiPF6 ethylene carbonate (EC) diethyl carbonate (DEC) (1:1 v/v ratio) electrolyte at a current density of 0.2 mA cm−2. Moreover, the anode free full cell configuration (Cu@LLCZN/PVDF‖NMC) demonstrates improved capacity retention of 58.66% and average coulombic efficiency of 97.6% after 30th cycles. The as-synthesized composite film induces inorganic rich (LiF and LiCl) SEI and gives required mechanical strength to suppress the lithium dendrite formation. These features endow the Cu anode with stable interface chemistry which is essential to the realization of anode-free lithium metal batteries.