Synthesis and electrochemical evaluation of carbon coated Cu6Sn5 alloy-graphite composite lithium battery anodes

Abstract

With a view to minimize the unavoidable large volume changes of tin based Cu 6 Sn 5 alloy anodes, a composite Cu 6 Sn 5 /graphite anode has been prepared via. a mechanical alloying process and subsequently coated with disordered carbon through pyrolysis of PVC. Phase pure products with better crystallinity and preferred surface morphology were obtained, as evident from PXRD and SEM respectively. Upon electrochemical charge-discharge, the intermetallic Cu 6 Sn 5 alloy-graphite composite anode was found to exhibit an enhanced initial discharge capacity of 564 mAh g -1 followed by significant capacity fade (>20%) especially after five cycles. On the other hand, carbon coated Cu 6 Sn 5 alloy-graphite composite demonstrated promising electrochemical properties such as steady reversible capacity (~200 mAh g -1 ), excellent cycle performance (<5% capacity fade) and high coulombic efficiency (~98%) via. significant reduction of volume changes. The carbon coating offers buffering and conductive actions on the anode active material and thereby enhances the electrochemical behavior of carbon coated Cu 6 Sn 5 alloy/graphite composite anode material.

Materials and Electrochemistry: Present and Future Battery

“…More recently hollow nanospheres of various materials including metals, oxides and semiconductorshave been considered as potential anodes [45][46][47][48]. Preparation methods for nanospheres with hollow interiors typically involve the removal of sacrificial templates, including silica [49] and polymer latex spheres [50], or reducing metal nanoparticles.…”

“…Preparation methods for nanospheres with hollow interiors typically involve the removal of sacrificial templates, including silica [49] and polymer latex spheres [50], or reducing metal nanoparticles. [45] The hollow Li active nanospheres serve as barriers to particle pulverisation and provide a large surface area to buffer the volume change in Li insertion/de-insertion, consequently improving the capacity retention. Hollow nanospheres of Sb with substantially superior capacity retentionthan its counterpart nanoparticles at higher rates have been reported.…”

Energy Storage: Battery Materials and Architectures at the Nanoscale

“…Further strategies have been investigated to minimise such secondary electrolyte reactions by uniformly coating the alloy composite surface with a less reactive protecting layer. [38] More recently hollow nanospheres of various materials including metals, oxides and semiconductors have been considered as potential anodes. [39][40][41] Preparation methods for nanospheres with hollow interiors typically involve the removal of sacrificial templates, including silica [42] and polymer latex spheres [43], or reducing metal nanoparticles.…”

Nanotemplated platinum fuel cell catalysts and copper–tin lithium battery anode materials for microenergy devices

“…Recently, a composite Cu 6 Sn 5 -graphite anode has been synthesised through a ball milling process, and a subsequent carbon coating is given by pyrolysis of polyvinyl chloride (PVC) [41]. This new type of carbon coated Cu 6 Sn 5 -graphite composite anode material showed excellent cycle performance with a capacity fade of less than 5% and reversible capacity as high as 200 mA h g -1 .…”