Nanostructured Silicon–Carbon 3D ElectrodeArchitectures for High-Performance Lithium-Ion Batteries

摘要

Silicon is an attractive anode material for lithium-ion batteries. However, silicon anodes have the issue of volume change, which causes pulverization and subsequently rapid capacity fade. Herein, we report organic binder and conducting diluent-free silicon–carbon 3D electrodes as anodes for lithium-ion batteries, where we replace the conventional copper (Cu) foil current collector with highly conductive carbon fibers (CFs) of 5–10 μm in diameter. We demonstrate here the petroleum pitch (P-pitch) which adequately coat between the CFs and Si-nanoparticles (NPs) between 700 and 1000 °C under argon atmosphere and forms uniform continuous layer of 6–14 nm thick coating along the exterior surfaces of Si-NPs and 3D CFs. The electrodes fabricate at 1000 °C deliver capacities in excess of 2000 mA h g^–1 at C/10 and about 1000 mA h g^–1 at 5 C rate for 250 cycles in half-cell configuration. Synergistic effect of carbon coating and 3D CF electrode architecture at 1000 °C improve the efficiency of the Si–C composite during long cycling. Full cells using Si–carbon composite electrodeand Li1.2Ni0.15Mn0.55Co0.1O2-based cathode show high open-circuit voltageof >4 V and energy density of >500 W h kg^–1. Replacementof organic binder and copper current collector by high-temperaturebinder P-pitch and CFs further enhances energy density per unit areaof the electrode. It is believed that the study will open a new realmof possibility for the development of Li-ion cell having almost doublethe energy density of currently available Li-ion batteries that issuitable for electric vehicles.