Carbon-coated hybrid crystals with fast electrochemical reaction kinetics for ultra-stable and high-load sodium-ion batteries

Owing to its high theoretical capacity and low cost, Sn has attracted significant attention in sodium-ion batteries. However, the slow kinetics of electrochemical reactions and the rapid decay of capacity resulting from drastic changes in the volume of Sn, as well as persistent side reactions between Sn and the organic electrolyte during the (de)sodium process, have limited its commercialization. To improve the electrochemical performance of Sn-based materials, the bottom-up method is normally used to prepare carbon-coated nanoparticles. However, its complex preparation processes and harsh conditions make it unsuitable for practical applications. Herein, a carbon-coated hybrid crystal composite (Sn/SnO x @C) was prepared using an up-bottom method with commercial Sn/SnO nanoparticles. Various effects accelerate the electrochemical kinetics and inhibit the coarsening of Sn crystals. The Sn/SnO x @C composite electrode exhibited capacity retention of 80.7% even after approximately 1000 cycles (360.4 mAh·g −1 ) at a current density of 1 A·g −1 . The high-load Na 3 V 2 (PO 4 ) 3 ||Sn/SnO x @C full cell presents a capacity retention rate of 91.7% after 150 cycles at the current density of 0.5 A·g −1 . This work may significantly accelerate the commercialization of the Sn/SnO x @C composite in sodium-ion batteries with high energy density. Graphical abstract