The Preparation And Electrochemistry Stablization Of Three-dimensional Tin/PPy As Anode For Lithium Ion Batteries

Lithium-ion batteries are widely used nowadays as important power sources for portable electronic devices and electric vehicle applications due to their high energy density, high voltage, and long lifespan. Promising candidates as anode materials include silicon, tin, germanium and various metal oxides which possess high theoretical capacities. However, these materials all suffer drastic volume change during repeated lithiation/delithiation which would deteriorate the electrochemical performance greatly. In order to meet the urgent need for the development of new generation of high-performance lithium-ion batteries, it's very important to optimize the electrode system.Here, the three-dimensional structures are constructed from two aspects: conductive network supported nanosturcture and self-supporting array structure. This paper demonstrated the synthesis of 3D Sn NPs/PPy network and Sn-Cu@PPy nanotube array as anode materials to enhance the Sn-based electrode structural stability. The formation mechanism of the distinct structures are discussed in detail, and fundamental studies using field-emission scanning electron microscope, high-resolution transmission electron microscope, charge/discharge measurements, and electrochemical impedance spectroscopy have helped to elucidate the advantages of these disigned hybrid anode materials. The 3D designs offered marked improvements in energy and power density. 3D Sn NPs/PPy network anode delivered a high capacity of 511 mAh g^-1 after 200 cycles, according to 85% capacity retention, which was much higher than those of Sn and Sn@PPy anodes. The Sn-Cu@PEO NT array electrode exhibited a high reversible capacity of 628 mAh g^-1 over 200 cycles, corresponding to 63% capacity retention, which was much higher than that of pure Sn nanowire anode. Particularly, these designed structures can greatly reduce Li+ migration distance, allow easy penetration of the electrolyte, and increase the electronic conductivity owing to the binder-free system. Furthermore, the combination with conformal PPy coating offers high conductivity, excellent mechanical stability and promising solid-electrolyte interphase?SEI? film stablization.