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The intercalation of lithium ions into graphite electrode is the key underlying mechanism of modern lithium-ion batteries. However, co-intercalation of lithium-ions and solvent into graphite is considered undesirable because it can trigger the exfoliation of graphene layers and destroy the graphite crystal, resulting in poor cycle life. Here, it is demonstrated that the [lithium–solvent]+ intercalation does not necessarily cause exfoliation of the graphite electrode and can be remarkably reversible with appropriate solvent selection. First-principles calculations suggest that the chemical compatibility of the graphite host and [lithium–solvent]+ complex ion strongly affects the reversibility of the co-intercalation, and comparative experiments confirm this phenomenon. Moreover, it is revealed that [lithium–ether]+ co-intercalation of natural graphite electrode enables much higher power capability than normal lithium intercalation, without the risk of lithium metal plating, with retention of ≈87% of the theoretical capacity at current density of 1 A g−1. This unusual high rate capability of the co-intercalation is attributed to the (i) absence of the desolvation step, (ii) negligible formation of the solid–electrolyte interphase on graphite surface, and (iii) fast charge-transfer kinetics. This work constitutes the first step toward the utilization of fast and reversible [lithium–solvent]+ complex ion intercalation chemistry in graphite for rechargeable battery technology.

Due to unparalleled theoretical capacity and operation voltage, metallic Li is considered as the most attractive candidate for lithium‐ion battery anodes. However, Li metal electrodes suffer from uncontrolled dendrite growth and consequent interfacial instability, which result in an unacceptable level of performance in cycling stability and safety. Herein, it is reported that a marginal amount (1.5 at%) of magnesium (Mg) doping alters the surface properties of Li metal foil drastically in such a way that upon Li plating, a highly dense Li whisker layer is induced, instead of sharp dendrites, with enhanced interfacial stability and cycling performance. The effect of Mg doping is explained in terms of increased surface energy, which facilitates plating of Li onto the main surface over the existing whiskers. The present study offers a useful guideline for Li metal batteries, as it largely resolves the longstanding shortcoming of Li metal electrodes without significantly sacrificing their main advantages. [ABSTRACT FROM AUTHOR]

• SnSe nanocrystals integrated with carbon nanotube were successfully obtained a facile colloidal synthetic method. • Downsized SnSe nanocomposites exhibit excellent electrochemical property in lithium ion battery. • The reaction mechanism of SnSe NC/CNT is elucidated by operando XRD and ex-situ XAS. [Display omitted] Tin selenide has been considered as one of the most promising anode materials for lithium-ion battery owing to its high theoretical capacity. In this work, a facile colloidal synthetic method was successfully used to obtain nanocomposites comprising ~7 nm SnSe nanocrystals and carbon nanotubes (SnSe NC/CNT). When applied as anode materials in lithium-ion battery, the SnSe NC/CNT nanocomposites exhibited excellent electrochemical performance with a reversible capacity of 706.5 mAh g−1 after 300 cycles at a constant current density of 200 mA g−1. The SnSe NC/CNT nanocomposites also delivered the high reversible capacity of 532.0 mAh g−1 at a high current density of 1.0 A g−1. The SnSe nanocomposites are advantageous to the ion and electron transport. Interconnected by CNT after annealing at 200 °C, SnSe NC/CNT nanocomposites can accommodate the volume expansion even after 300 cycles. The complex conversion and alloying reaction are studied by X-ray diffraction and X-ray absorption near edge structure. [ABSTRACT FROM AUTHOR]

Conversion reaction-based transition metal oxides have shown high reversible capacity compared to conventional intercalation reaction-based materials. However, their practical applications have been impeded by a poor cycle life resulted from their low electrical conductivity and huge volume changes. During the past decade, remarkable advances have been achieved in the preparation of nanostructured transition metal oxides for conversion reaction anodes. Among the various shaped nanomaterials, core-shell structure with a carbon shell showed excellent electrochemical performance. Herein, we prepared peapod-like MnO@C nanowires as one special type of core-shell structure, and we elucidated the structure-properties relationship in peapod-like MnO@C nanowires for Li-ion batteries. The morphology of the manganese oxide particles inside the carbon layer could be simply controlled by adjusting the parameters in the carbonization process. The optimized composites exhibited excellent cycling performance without decreasing the capacity, and outstanding rate properties. The optimized structure can maximize the advantages such as structural durability against the stress involving huge volume changes, as well as minimize the side reaction at the surface. • We elucidated the structure-properties relationship in peapod-like MnO@C nanowires for Li-ion batteries. • The morphology of the particles inside the carbon layer could be controlled by adjusting the parameters for carbonization. • The optimized composites exhibited excellent cycling performance and rate properties. • The optimized structure can maximize the advantages such as structural durability against the stress involving huge volume changes. [ABSTRACT FROM AUTHOR]