Amorphous GeSnSe nanoparticles as a Li-Ion battery anode with High-Capacity and long cycle performance.

A new ternary amorphous GeSnSe (GSS) nanopowder was effectively synthesized by using ball milling under inert atmosphere. Its topographical, microstructural and elemental characterizations revealed the formation of nanoparticles with undefined shape, short-range order and the tailored stoichiometry. Remarkably, this novel amorphous material demonstrates its competences as a promising Li-ion host anode, exhibiting a high cycle performance with a specific charge capacity of 963 mAh g-1 at an applied C-rate of 0.2C with a coulombic efficiency > 99.4 % after 300 cycles. Its high specific capacity, large rate capability, acceptable capacity retention and long cycle life could be attributed to a dual Li-ion storage mechanism that consists mostly of multiple reversible electrochemical processes as conversion and alloying reactions and capacitive processes. Moreover, its stable volume expansion (34 %), moderate electrode polarization (248.9 mV), reasonable charge transfer resistance (83 Ω) and apparent Li-ion diffusion coefficients between 10-9 - 10-14 cm2 s-1 could be promoted by a synergistic effect between Ge (capacity), Sn (conductivity) and Se (stability), which plays an important role on the stability and high cycle performance of the promising GSS-based anode.

Facile one-pot synthesis of lithium metal nanoparticles for superior lithium-ion anode applications.

A capable one-step method, femtosecond laser ablation of solids in liquids, was successfully applied to prepare lithium metal nanoparticles to mitigate the initial capacity loss and improve the electrochemical performance of a graphite-based electrode as a Li-host anode. Remarkably, according to the physicochemical characterization, this advanced optical method allowed to obtain uniform spheroidal and crystalline Li nanoparticles with an average particle size <20 nm. These novel ultrafine Li nanoparticles significantly decrease the initial capacity loss of a graphite-based anode, leading to reach high coulombic efficiency (>99 %), good specific charge capacity (322 mAh/g), and superior capacity retention (96 %) at an applied current density of 100 mA g-1 after 200 cycles.

Influence of the fluoroethylene carbonate on the electrochemical behavior of Bi3Ge4O12 as Lithium-ion anode.

Systematic ex-situ X-ray diffraction (XRD) characterization and electrochemical study revealed the key roles that the cut-off voltage and fluoroethylene carbonate (FEC) additive play on improving electrochemical performance of the Bi3Ge4O12-based (BGO) electrode. The ex-situ XRD analysis revealed that BGO particles suffer multiphase transitions during the (dis)charge reactions, being observed some phases as Bi2O2.33, BiLi3, Li2O, Ge4Li15, Ge2Li7, Ge3Li7, Ge5Li22, Ge4Li9, Bi2O3 and GeO2. The electrochemical evaluation exhibited that the addition of 5 v/v% of FEC in 1.0 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate and diethyl carbonate (EC: DEC) at an applied cut-off voltage (1.5 V vs Li/Li+) improves the specific capacity (29%, delivering 479 mAh g-1), capacity retention (12%) and rate capability (369 mAh g-1 at 1000 mA g-1) of the BGO-based electrode. Also, FEC promotes the formation of a stable solid-electrolyte interface (SEI) layer on the anode at a cut-off voltage of 1.5 V vs Li/Li+. It displays the lowest values of SEI and charge transfer (CT) resistances, and electrode polarization, improving the reversibility of the alloying reactions related to Ge-Li and Bi-Li and maintaining their redox activity after 100 cycles, according to dQ dV-1 data.