Low cost and environmentally benign crack-blocking structures for long life and high power Si electrodes in lithium ion batteries†
The high capacity Si (4200 mA h g−1, Li4.4Si) commonly undergoes cracking and delamination due to drastic volume change (∼300%) during lithiation/delithiation processes in lithium ion batteries (LIBs). In this work, abundant and sustainable natural polymer gum arabic (GA) and low cost polyacrylic acid (PAA) are used to fabricate Si anodes with resilient, crack-blocking properties. The esterification reaction between GA and PAA establishes a flexible network resulting in reinforced mechanical strength and enhanced coherent strength. Meanwhile, the water vapour resulting from the esterification reaction generates micron-sized pores which relieves the stress and blocks the formation and propagation of cracks. As a result of the crack-blocking effect, the resultant Si anodes present a superior volumetric capacity of 2890 A h L−1. In addition, charge–discharge cycling for more than 1000 cycles is achieved with the Li insertion capacity limited to 1000 mA h g−1 at a 1 C rate.