Hierarchical hollow dual Core–Shell carbon nanowall-encapsulated p–n SnO/SnO2 heterostructured anode for high-performance lithium-ion-based energy storage

A hierarchical hollow SnO/SnO2 heterostructure anode surrounded by a dual carbon layer (DCL@SnO/SnO2), inner (host) and outer carbon layers, was successfully designed via a simple hydrothermal method with a single Sn precursor to achieving high-performance Li-ion batteries (LIBs) and Li-ion capacitors (LICs). The carbon nanotube (CNT)-based inner carbon host and an ultrathin outer amorphous carbon layer introduced at the SnO/SnO2 heterostructure had good elasticity and high electrical properties to prevent volume change and ensure fast Li-ion transport during cycling, respectively. Meanwhile, the SnO/SnO2 heterostructure comprising p-type SnO and n-type SnO2 facilitated further fast interfacial Li-ion transfer within the p–n SnO/SnO2 heterojunction anode via the acceleration effect induced by the built-in electric field (BEF). The resulting half cells LIBs consisting DCL@SnO/SnO2 anode shows a high reversible specific capacity of 902.1 mAh g−1 after 500 cycles at a current density of 1400 mA g−1. The specific capacity of 347.04 mAh g−1 was still maintained even at a high current density of 10 000 mA g−1. Moreover, the maximum energy and power density of 125 W kg−1 and 200 Wh kg−1, respectively, were achieved from the half cells LIC comprising DCL@SnO/SnO2 anode (LIC-DCL@SnO/SnO2).