Tailor-Made Gives the Best Fits: Superior Na/K-Ion Storage Performance in Exclusively Confined Red Phosphorus System.

As the most promising anodic candidate for alkali ion batteries, red phosphorus (P) still faces big challenges, such as the poor rate and cycling performance, which are caused by the insulative nature and the large volume change throughout the alloy/dealloy process. To ameliorate above issues, the traditional way is confining P into the carbon host. However, investigations on maximizing P utilization are inadequate; in other words, how to achieve entire confinement with a high loading amount is still a problem. Additionally, the application of P in potassium-ion batteries (PIBs) is in its infant stage, and the corresponding potassiation product is controversial. Herein, a nitrogen-doped stripped-graphene CNT (N-SGCNT) as carbon framework is prepared to exclusively confine ultrafine P to construct P@N-SGCNT composites. Benefitting from the in situ cross-linked structure, N-SGCNT loaded with 41.2 wt % P (P2@N-SGCNT) shows outstanding Na+/K+ storage performance. For instance, P2@N-SGCNT exhibits high reversible capacities of 2480 mAh g-1 for sodium-ion batteries (SIBs) and 762 mAh g-1 for PIBs, excellent rate capabilities of 1770 mAh g-1 for SIBs and 354 mAh g-1 for PIBs at 2.0 A g-1, and long cycling stability (a capacity of 1936 mAh g-1 after 2000 cycles for SIBs and 319 mAh g-1 after 1000 cycles for PIBs). Furthermore, due to this exclusively confined P structure, the K+ storage mechanism with the end product of K4P3 has been identified by experimental and theoretical results.

Revealing the Role of Liquid Metals at the Anode-Electrolyte Interface for All Solid-State Lithium-Ion Batteries.

All-solid-state lithium-ion batteries (ASSLIBs) are receiving tremendous attention for safety concerns over liquid system. However, current ASSLIBs still suffer from poor cycling and rate performance because of unfavorable interfacial contact between solid electrolyte and electrodes, especially in the alloy-based anode. To wet the solid electrode/electrolyte interface, accommodate volume change, and further boost kinetics, liquid metal Ga is introduced into the representative Sb anode, and its corresponding role is comprehensively revealed by experimental results and theoretical calculations for the first time. In addition to interface contact and strain accommodation, with the aid of in situ generation of liquid metal Ga, the lithiation/de-lithiation activity of Sb is stimulated, showing outstanding rate and cycling performance in half cells. Furthermore, benefited from the in situ chemical reaction, TiS2 powder can be directly used to construct a novel "Li-free" TiS2|LiBH4|GaSb full cell, which exhibits an outstanding capacity retention of 226 mA h g-1 after 1000 cycles at a current density of 0.5 A g-1. This work provides guidance for implementing future rational design of alloy anodes within ASSLIBs.

Exploring the sodium ion storage mechanism of gallium sulfide (Ga2S3): a combined experimental and theoretical approach.

Developing sodium ion battery (SIB) anode materials of a low-cost and high-capacity nature for future large-scale applications still involves challenges. Herein, we have reported gallium sulfide (Ga2S3) as a novel SIB anode material for the first time. Ga2S3 nanorods have been synthesized via the facile hydrothermal preparation of a GaOOH precursor with subsequent H2S annealing. Mixed with graphene upon electrode preparation, this Ga2S3 electrode maintains a reversible specific capacity of 476 mA h g-1 after 100 cycles at a current density of 0.4 A g-1, with a coulombic efficiency of over 99%. Ex situ XRD analysis and theoretical calculations are employed to comprehensively elucidate the detailed sodium ion storage mechanism of Ga2S3, which is composed of initial Na+ intercalation, a subsequent multi-step conversion reaction between S and Na+, and an eventual alloying reaction between Ga and Na+ with the end product of Na7Ga13. Further kinetics analysis has demonstrated that the conversion reaction is the rate-limiting step due to a multi-step reaction with the intermediate phase of GaS. Moreover, the appearance of liquid metal Ga, as confirmed via TEM observations and theoretical calculations, can serve as a self-healing agent that repairs cracks in the electrode. Our findings shed light on the further design of Ga-based materials, and they also can be extended to solid-state-battery systems.