High-stability tin/carbon battery electrodes produced using reduction expansion synthesis

Abstract

This study shows high stability Sn (10wt %)/carbon Li-ion battery anodes can be made via the Reduction Expansion Synthesis (RES) process. Hybrid Sn/C anodes had an initial capacity of 425 mAh g-1 which stabilized to ~340 mAh g-1 after less than 10 cycles. Unlike earlier Sn/C anodes, capacity remained virtually constant for more than 180 additional cycles. Neat carbon independently tested for Li capacity had a steady specific capacity of 280 mAh g-1. The difference detected between the pure carbon and Sn/C cases are consistent with Sn having the theoretical capacity of ~1000mAh g-1. The high stability of the RES derived anodes, relative to earlier Sn based electrodes, is postulated to exist because RES synthesis enables the formation of direct, strong bond between Sn and carbon substrate atoms, hence reducing the rate of Sn electrode disintegration and capacity fade due to expansion upon lithiation. X-ray diffraction and transmission electron microscopy are consistent with this postulate as both show an initial Sn particles size of only a few nanometers and minimal growth after cycling. Reduced interface resistance is also indicative of unique Sn-carbon bond.