Abstract
Li metal batteries are being intensively investigated as a means to achieve higher energy density when compared with standard Li-ion batteries. However, the formation of dendritic and mossy Li metal microstructures at the negative electrode during stripping/plating cycles causes electrolyte decomposition and the formation of electronically disconnected Li metal particles. Here we investigate the use of a Cu current collector coated with a high dielectric BaTiO3 porous scaffold to suppress the electrical field gradients that cause morphological inhomogeneities during Li metal stripping/plating. Applying operando solid-state nuclear magnetic resonance measurements, we demonstrate that the high dielectric BaTiO3 porous scaffold promotes dense Li deposition, improves the average plating/stripping efficiency and extends the cycling life of the cell compared to both bare Cu and to a low dielectric scaffold material (i.e., Al2O3). We report electrochemical tests in full anode-free coin cells using a LiNi0.8Co0.1Mn0.1O2-based positive electrode and a LiPF6-based electrolyte to demonstrate the cycling efficiency of the BaTiO3-coated Cu electrode.
Highlights
Li metal batteries are being intensively investigated as a means to achieve higher energy density when compared with standard Li-ion batteries
The formation of high surface area dendritic and mossy Li metal morphologies, in combination with the fierce reactivity of Li metal with conventional non-aqueous organic electrolytes, leads to an irreversible loss of active Li. This is associated with the formation of a solid electrolyte interphase (SEI) and the formation of electronically disconnected Li metal particles
Modelling of the early stages of nucleation and growth under heterogeneous electrodeposition indicates that surface inhomogeneities, particle size and wettability of the negative electrode play a critical role in facilitating dendrite formation[19]
Summary
Li metal batteries are being intensively investigated as a means to achieve higher energy density when compared with standard Li-ion batteries. BTO Li drops to zero, after the characteristic Sand’s time, plating becomes inhomogeneous and amplified growth of dendrites is induced[18] These features necessitate the adoption of strategies that enhance ion mobility, increase the transference number and introduce a large negative electrode surface area. Modelling of the early stages of nucleation and growth under heterogeneous electrodeposition indicates that surface inhomogeneities, particle size and wettability of the negative electrode play a critical role in facilitating dendrite formation[19]. This implies that dendrite growth can be steered by controlling these parameters as experimentally demonstrated[20]. To overcome or circumvent these issues, various strategies aimed at controlling the
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