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).