In Situ Encapsulating α-MnS into N,S-Codoped Nanotube-Like Carbon as Advanced Anode Material: α → β Phase Transition Promoted Cycling Stability and Superior Li/Na-Storage Performance in Half/Full Cells

Abstract

Incorporation of N,S-codoped nanotube-like carbon (N,S-NTC) can endow electrode materials with superior electrochemical properties owing to the unique nanoarchitecture and improved kinetics. Herein, α-MnS nanoparticles (NPs) are in situ encapsulated into N,S-NTC, preparing an advanced anode material (α-MnS@N,S-NTC) for lithium-ion/sodium-ion batteries (LIBs/SIBs). It is for the first time revealed that electrochemical α → β phase transition of MnS NPs during the 1st cycle effectively promotes Li-storage properties, which is deduced by the studies of ex situ X-ray diffraction/high-resolution transmission electron microscopy and electrode kinetics. As a result, the optimized α-MnS@N,S-NTC electrode delivers a high Li-storage capacity (1415 mA h g^-1 at 50 mA g^-1 ), excellent rate capability (430 mA h g^-1 at 10 A g^-1 ), and long-term cycling stability (no obvious capacity decay over 5000 cycles at 1 A g^-1 ) with retained morphology. In addition, the N,S-NTC-based encapsulation plays the key roles on enhancing the electrochemical properties due to its high conductivity and unique 1D nanoarchitecture with excellent protective effects to active MnS NPs. Furthermore, α-MnS@N,S-NTC also delivers high Na-storage capacity (536 mA h g^-1 at 50 mA g^-1 ) without the occurrence of such α → β phase transition and excellent full-cell performances as coupling with commercial LiFePO₄ and LiNi_0.6 Co_0.2 Mn_0.2 O₂ cathodes in LIBs as well as Na₃ V₂ (PO₄ )₂ O₂ F cathode in SIBs.

Keywords: Li/Na storage; N,S-codoped carbon; phase transition; α-MnS; β-MnS.