Boosting interfacial charge transfer and inspiring new insights into the α-Ni(OH)2 anode via novel double heterostructures in Li-ion batteries

Abstract

Heterostructure materials are expected to promote the development of high-performance Li-ion batteries (LIBs) to alleviate the increasingly serious energy crisis. For MXene-based composites with double heterostructures, however, simple and effective synthesis strategies are scarce. Herein, based on the layered Ti₃C₂T_x MXene (denoted as T-MX), α-Ni(OH)₂/TiO₂@T-MX double heterostructures is architected via a one-step solvothermal method. As anodes for LIBs, the composite electrodes are equipped with fast interfacial charge transfer and deliver considerable cycling performance (602.4 mAh g⁻¹ after 480 cycles at 0.1 A g⁻¹). Specially, inspired by the lithium storage behavior of α-Ni(OH)₂/TiO₂@T-MX anode, for the first time, the hidden electrochemical mechanism of α-Ni(OH)₂ anode-stepwise and reversible conversion reactions to α-NiOOH and further to NiO₂-are clearly revealed by various ex situ techniques and the characterizations for cycled electrodes. Moreover, density functional theory (DFT) calculations, combined with experimental results, confirm the charge redistribution arising from the construction of double heterostructures, which enhances the interfacial charge transport and the multi-step conversion reaction of α-Ni(OH)₂. This work offers unique insights into the design of MXene-based heterostructures and the studies of multiphase transformation mechanisms of composite electrodes.