Uniform Fe<i>_x</i>Ni<i>_y</i> Nanospheres: Cost-Effective Electrocatalysts for Nonaqueous Rechargeable Li–O₂ Batteries

Uniform Fe<i>_x</i>Ni<i>_y</i> nanospheres were synthesized via a simple solvothermal method and used as electrocatalysts for Li–O₂ batteries. Fe₇Ni₃ nanospheres exhibited relatively high catalytic activities in the electrochemical tests. They delivered a reversible capacity of more than 7000 mAh/g_KB and gave a discharge–charge voltage gap reduction of 250 mV compared with Ketjen Black

Nanoscale Coating of LiMO₂ (M = Ni, Co, Mn) Nanobelts with Li⁺‑Conductive Li₂TiO₃: Toward Better Rate Capabilities for Li-Ion Batteries

By using a novel coating approach based on the reaction between MC₂O₄·<i>x</i>H₂O and Ti­(OC₄H₉)₄, a series of nanoscale Li₂TiO₃-coated LiMO₂ nanobelts with varied Ni, Co, and Mn contents was prepared for the first time. The complete, thin Li₂TiO₃ coating layer strongly adheres to the host material and has a 3D diffusion path for Li⁺ ions. It is doped with Ni²⁺ and Co³⁺ ions in addition to Ti⁴⁺ in LiMO₂, both of which were found to favor Li⁺-ion transfer at the interface. As a result, the coated nanobelts show improved rate, cycling, and thermal capabilities when used as the cathode for Li-ion battery

Durable Carbon-Coated Li₂S Core–Shell Spheres for High Performance Lithium/Sulfur Cells

Lithium sulfide (Li₂S) is an attractive cathode material with a high theoretical specific capacity (1166 mAh g^–1). However, the poor cycle life and rate capability have remained significant challenges, preventing its practical application. Here, Li₂S spheres with size control have been synthesized for the first time, and a CVD method for converting them into stable carbon-coated Li₂S core–shell (Li₂S@C) particles has been successfully employed. These Li₂S@C particles with protective and conductive carbon shells show promising specific capacities and cycling performance with a high initial discharge capacity of 972 mAh g^–1 Li₂S (1394 mAh g^–1 S) at the 0.2C rate. Even with no added carbon, a very high Li₂S content (88 wt % Li₂S) electrode composed of 98 wt % 1 μm Li₂S@C spheres and 2 wt % binder shows rather stable cycling performance, and little morphology change after 400 cycles at the 0.5C rate