Hierarchically Porous Li4Ti5O12 Anode Materials for Li‐ and Na‐Ion Batteries: Effects of Nanoarchitectural Design and Temperature Dependence of the Rate Capability

Integrated design of both porous structure and crystalline morphology is expected to open up the way to a new class of materials. This report demonstrates new nanostructured Li₄Ti₅O₁₂ materials with hierarchically porous structures and flower‐like morphologies. Electrochemical studies of the electrodes of Li‐ion and Na‐ion batteries clearly reveal the advantage of nanoarchitectural design of active materials. In addition, the temperature dependence of Na⁺‐insertion/extraction capacity in relation to Li₄Ti₅O₁₂ electrodes is for the first time evaluated and it is found that elevation of the cell operating temperature effectively improves the rate capability of the Na‐ion batteries. Based on the new findings, it is suggested that specially designed Li₄Ti₅O₁₂ materials allow for high‐performance Na‐ion batteries that are available as large‐scale storage devices for applications such as automotive and stationary energy storage.     

Conductive and Catalytic Triple‐Phase Interfaces Enabling Uniform Nucleation in High‐Rate Lithium–Sulfur Batteries

Rechargeable lithium–sulfur batteries have attracted tremendous scientific attention owing to their superior energy density. However, the sulfur electrochemistry involves multielectron redox reactions and complicated phase transformations, while the final morphology of solid‐phase Li₂S precipitates largely dominate the battery's performance. Herein, a triple‐phase interface among electrolyte/CoSe₂/G is proposed to afford strong chemisorption, high electrical conductivity, and superb electrocatalysis of polysulfide redox reactions in a working lithium–sulfur battery. The triple‐phase interface effectively enhances the kinetic behaviors of soluble lithium polysulfides and regulates the uniform nucleation and controllable growth of solid Li₂S precipitates at large current density. Therefore, the cell with the CoSe₂/G functional separator delivers an ultrahigh rate cycle at 6.0 C with an initial capacity of 916 mAh g^?1 and a capacity retention of 459 mAh g^?1 after 500 cycles, and a stable operation of high sulfur loading electrode (2.69–4.35 mg cm^?2). This work opens up a new insight into the energy chemistry at interfaces to rationally regulate the electrochemical redox reactions, and also inspires the exploration of related energy storage and conversion systems based on multielectron redox reactions.     

A Versatile Pyramidal Hauerite Anode in Congeniality Diglyme‐Based Electrolytes for Boosting Performance of Li‐ and Na‐Ion Batteries

For the first time, environmentally friendly sulfur‐rich pyramidal MnS₂ synthesized via a single‐step hydrothermal process is used as a high‐performance anode material in Li‐ion and Na‐ion batteries. The superior electrochemical performance of the MnS₂ electrode along with its high compatibility with ether‐based electrolytes are analyzed in both half‐ and full‐cell configurations. The reversible capacities of ≈84 mAh g^?1 and ≈74 mAh g^?1 at a current density of 50 mA g^?1 are retained in the Li‐ion and Na‐ion full‐cells, respectively, over 200 cycles with excellent capacity retentions. Moreover, important findings regarding activation processes in the presence of a new phase transition and protective electrolyte interphase layer are revealed using ab initio density function theory calculation and in situ potentio‐electrochemical impedance spectroscopy. The detailed complex redox mechanism of MnS₂ in Li/Na half‐cells is also elucidated by ex situ X‐ray photoelectron spectroscopy.