Spaced-Confined Janus Engineering Enables Controlled Ion Transport Channels and Accelerated Kinetics for Secondary Ion Batteries

Abstract

The large grain boundary resistance between different components of the anode electrode easily leads to the low ion transport efficiency and poor electrochemical performance of lithium-/sodium-ion batteries (LIBs/SIBs). To address the issue, a Janus heterointerface with a Mott−Schottky structure is proposed to optimize the interface atomic structure, weaken interatomic resistance, and improve ion transport kinetics. Herein, Janus Co/Co 2 P@carbon-nanotubes@core−shell (Janus Co/ Co 2 P@CNT-CS) refined urchin-like architecture derived from metal−organic frameworks is reported via a coating−phosphating process, where the Janus Co/Co 2 P heterointerface nanoparticles are confined in carbon nanotubes and a core−shell polyhedron. Such a Janus Co/Co 2 P heterointerface shows the strong built-in electric field, facilitating the controllable ion transport channels and the high ion transport efficiency. The Janus Co/Co 2 P@CNT-CS refined urchin-like architecture composed of a core−shell structure and the grafting carbon nanotubes enhances the structure stability and electronic conductivity. Benefiting from the spaced-confined Janus heterointerface engineering and synergistic effects between the core−shell structure and the grafting carbon nanotubes, the Janus Co/Co 2 P@CNT-CS refined urchin-like architecture demonstrates the fast ion transport rate and excellent pseudocapacitance performance for LIBs/SIBs. In this case, the Janus Co/ Co 2 P@CNT-CS refined urchin-like architecture shows high specific capacities of 709 mA h g −1 (200 cycles) and 203 mA h g −1 (300 cycles) at a current density of 500 mA g −1 for LIBs/SIBs, respectively.

Flexible Self-Supporting MOF-Based Bean Pod Cube Hollow Nanofibers for Ultralong Cycling and High Rate Na Storage

“…The sodium storage performance of the SNC2-600 anode, compared with other previously designed flexible Sn-based anodes, is summarized in Table S1. The excellent high-rate and ultralong cycling performance of SNC2-600 can be attributed to several factors: (i) the hollow structure alleviates volume expansion during Na + insertion/desertion at high current density; (ii) the MOF-based bean pod cube structure in which SnS x particles are encapsulated within the carbon matrix enables the electrode to maintain structural stability; and (iii) the 3D conductive carbon nanofibers network shortens the electron/Na + transfer path and accelerates the reaction kinetics.…”