Large-scale synthesis of SiOC composites for stable Li-ion battery anode and dendrite-free Li metal deposition

Abstract

SiOC is an ideal anode material for Li-ion batteries due to its high specific capacity and low volume fluctuation. However, the large-scale preparation of SiOC still faces challenges such as complex processes and expensive raw materials. Additionally, the excellent compatibility of SiOC with Li-ion implies its inherentpotential for guiding Li metal deposition, but SiOC has rarely been used to investigate the Li metal deposition and/or suppress lithium dendrite growth. In this work, nearly kilogram-scale preparation of SiOC composites was realized using a consecutive chemical vapor deposition method with an inexpensive silane coupling agent as the precursor at the laboratory level. As a result, the as-prepared SiOC as anode exhibits favorable rate performance, negligible volume fluctuations and ultra-long cycle stability (∼2000cycles). Furthermore, SiOC as substrates for guiding lithium metal deposition shows low nucleation overpotential (2.0 mV) and ultra-long cycle stability in half cell (650cycles at 1.0 mA cm−2), symmetrical cell (5000 h at 1.0 mA cm−2) and full cell (800cycles at 1.0C). Density functional theory (DFT) calculation and finite element simulations reveal that the presence of SiOC on the copper foil can not only enable a significant enhancement of Li adsorption but also promote uniform distribution of electric field and Li+ concentration gradient. Finally, SiOC can be used to fabricate an anode-free Li metal battery, further enhancing the energy density of batteries.