In-situ synthesis of freestanding porous SnO_x-decorated Ni₃Sn₂ composites with enhanced Li storage properties

In this paper, novel freestanding 3D hierarchical porous SnO_x-decorated Ni₃Sn₂ (3D-HP SnO_x@Ni₃Sn₂) composites are synthesized facilely by two-step chemical dealloying of designed as-cast Sn-45 at.% Ni alloy in different corrosive solutions. The results show that the 3D-HP SnO_x@Ni₃Sn₂ composites have a typical bimodal pore size distribution composed of a micron-sized ligament-channel structure with highly nanoporous channel walls built by ultrafine SnO_x (x = 1, 2) nanoparticles (3–6 nm). The unique 3D-HP composites as a binder-free integrated anode for lithium ion batteries (LIBs) display a significantly improved Li storage performance with first reversible capacity of 2.68 mAh cm⁻² and good cycling stability with 85.1% capacity retention and over 98.4% coulombic efficiency after 100 cycles (just 0.004 mAh cm² per cycle for capacity fading). This can be mainly ascribed to the synergistic effect between chemically inert 3D microporous Ni₃Sn₂ substrate with robust mechanical stress buffer and good transfer mass channels and in-situ growth of nanoporous SnO_x with large specific surface areas and high electrochemical active sites. We believe that the present work can offer a promising anode candidate toward advanced LIBs.