Double-network aerogel-derived spongy 3D porous MnO/C composite for lithium-ion batteries with increasing capacity

Abstract

The uneven dispersion of MnO easily leads to local volume change, resulting in the crushing and pulverizing of electrode. Herein, a spongy three-dimensional (3D) porous MnO/C composite was fabricated by pyrolysis of the double-network (DN) aerogel composed of agar (AG) and Mn-crosslinked sodium alginate (SA). The spongy MnO/C composite has homogeneous distribution and uniform size ultrafine MnO nanoparticles embedded into 3D porous carbon network and shows high BET surface area of 363 m2 g−1, which can not only improve the electrical conductivity, but effectively confine the expulsion of MnO and restrain the crushing and pulverizing of electrode. As anode for LIBs, the spongy MnO/C composite exhibits superior rate capability (574 mAh g−1, 2 A g−1) and excellent cycling stability. The capacity gradually increases during the cycling process, reaching 1270 mAh g−1 after 500 cycles at 2 A g−1. The rising capacity can be attributed to the following reasons: 1) more Mn2+ was oxidated to higher valence, 2) The enhanced amorphism of MnO improves Li+ diffusion kinetics, 3) the reversible form and decomposition of SEI.