Hybrid graphite anodes with vertical nanochannels for high-capacity and long-cycle lithium-ion batteries

Abstract

Graphite is commonly utilized as an anode material for lithium-ion batteries (LIBs) due to its stable cycling performance. To improve the energy density of LIBs, hybrid graphite anodes operating on Li intercalation and plating mechanisms have gained significant attention. However, repetitive plating/stripping reactions on the graphite surface lead to the continuous accumulation of irreversible “dead” Li species, thereby causing severe capacity fade and safety risk. Herein, we report an etched graphite (EG) hybrid anode with vertically oriented nanochannels on the basal plane to enhance the reversibility of Li plating and stripping. A metal oxide-catalyzed oxidation process at reduced temperatures (<500 °C) is developed to selectively etch the basal plane of graphite and to form vertical nanochannels. The resulting nanochannels play a crucial role in enhancing the electrode reversibility by providing abundant active sites for homogeneous Li intercalation and metal nucleation and by facilitating the formation of robust LiF-rich solid–electrolyte interphases. Furthermore, the EG hybrid anode effectively regulates the Li+ distribution within the porous electrode even under fast charging conditions (3C = 12 mA cm−2) and thus suppresses the formation of dead Li species. A full cell with the EG hybrid anode and LiNi0.8Co0.1Mn0.1O2 cathode exhibits higher capacity retention (62.3%) over 800 cycles at a state of charge (SOC) = 150% as compared with a bare graphite full cell. This study underscores the effectiveness of graphite surface engineering in enabling reversible Li plating/stripping reactions for advanced LIBs with hybrid anodes.