Developing high-safety Li-metal anodes (LMAs) are extremely important for the application of high-energy Li-metal batteries. The recently state-of-the-art technologies, strategies and perspectives for developing LMAs are comprehensively summarized in this review.

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 at 50 mA g ), excellent rate capability (430 mA h g at 10 A g ), and long-term cycling stability (no obvious capacity decay over 5000 cycles at 1 A g ) 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 at 50 mA g ) without the occurrence of such α → β phase transition and excellent full-cell performances as coupling with commercial LiFePO and LiNi Co Mn O cathodes in LIBs as well as Na V (PO ) O F cathode in SIBs.

Among the transition metal oxides as anode for lithium ion batteries (LIBs), MnO material should be the most promising one due to its many merits mainly relatively low voltage hysteresis. However, it still suffers from inferior rate capabilities and poor cycle life arising from kinetic limitations, drastic volume changes and severe agglomeration of active MnO particulates during cycling. In this paper, by integrating the typical strategies of improving the electrochemical properties of transition metal oxides, we had rationally designed and successfully prepared one superior MnO based nanohybrid (MnO@C/RGO), in which carbon-coated MnO nanoparticles (MnO@C NPs) were electrically connected by the threedimensional conductive networks composed of flexible graphene nanosheets. Electrochemical tests demonstrated that, the MnO@C/RGO nanohybrid not only showed the best Li storage performance in comparison with the commercial MnO material, MnO@C NPs and carbon nanotubes enhanced MnO@C NPs, but also exhibited much improved electrochemical properties compared with most of the previously reported MnO-based materials. The superior electrochemical properties of the MnO@C/RGO nanohybrid included high specific capacity (up to 847 mAh g -1 at 80 mA g -1 ), excellent high-rate capabilities (for example, delivering 451 mAh g -1 at a very high current density of 7.6 A g -1 ) and long cycle life (800 cycles without capacity decay). More importantly, we had for the first time achieved the charging/discharging of MnO-based materials without capacity increase even after 500 cycles by adjusting the voltage range, making the MnO@C/RGO nanohybrid more possible to be really practical anode material for LIBs. 42 CuO 43 and MoO 3 , 44 in which MnO may be the most promising one due to its relatively lower voltage hysteresis (<0.8 V) compared to other TMOs, suitable reversible potential (~1.0V vs. Li + /Li), high density (5.43 g cm -3 ), as well as the high theoretical capacity of 756 mA h g -1 , relatively low cost and environmental benignity. [28][29][30] Nevertheless, the intrinsically low conductivity of MnO material

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