LiF-Rich Alloy-Doped SEI Enabling Ultra-Stable and High-Rate Li Metal Anode.

Li metal is regarded as the "Holy Grail" in the next generation of anode materials due to its high theoretical capacity and low redox potential. However, sluggish Li ions interfacial transport kinetics and uncontrollable Li dendrites growth limit practical application of the energy storage system in high-power device. Herein, separators are modified by the addition of a coating, which spontaneously grafts onto the Li anode interface for in situ lithiation. The resultant alloy possessing of strong electron-donating property promotes the decomposition of lithium bistrifluoromethane sulfonimide in the electrolyte to form a LiF-rich alloy-doped solid electrolyte interface (SEI) layer. High ionic alloy solid solution diffusivity and electric field dispersion modulation accelerate Li ions transport and uniform stripping/plating, resulting in a high-power dendrite-free Li metal anode interface. Surprisingly, the formulated SEI layer achieves an ultra-long cycle life of over 8000 h (20,000 cycles) for symmetric cells at a current density of 10 mA cm-2. It also ensures that the NCM(811)//PP@Au//Li full cell at ultra-high currents (40 C) completes the charging/discharging process in only 68 s to provide high capacity of 151 mAh g-1. The results confirm that this scalable strategy has great development potential in realizing high power dendrite-free Li metal anode.

Organic-Inorganic Hybridization Engineering of Polyperylenediimide Cathodes for Efficient Potassium Storage.

Polyperylenediimide (PDI) is always subject to its modest conductivities, limited reversible active sites and inferior stability for potassium storage. To address these issues, herein, we firstly propose an organic-inorganic hybrid (PDI@Fe-Sn@N-Ti3 C2 Tx ), where Fe/Sn single atoms are bound to the N-doped MXenes (N-Ti3 C2 Tx ) via the unsaturated Fe/Sn-N3 bonds, and functionalized with PDI via d-π hybridization, forming a high conjugated δ skeleton. The resulted hybrid cathode endowed with enhanced electronic/ionic conductivities, lowered dissociation barriers of multiple redox centers and a stable cathode electrolyte interphase layer displays a 14-electron involved high-rate capacities and long cycle life. Moreover, it shows competitive performance in full cells even under different folding states and low operating temperatures.

Fabricating ferromagnetic MoS2-based composite exposed to simulated sunlight for sodium storage.

A light- and magnetic stimuli-responsive MoS2 composite electrode material is designed and evaluated as an anode material of sodium ion batteries. Through the assistance of simulated sunlight, suppressed dendritic sodium growth, buffered volume deformation, promoted electrochemical reaction kinetics, and improved structural stability are simultaneously achieved. Meanwhile, ferroelectric polarization enhances the separation efficiency of photogenerated carriers. The collisions among electrons are dramatically decreased; in turn, the thermal stability of the battery is improved via the tailored orientation of active materials. A stable protective solid-state electrolyte interface film is formed via the photogenerated electrons and the magnetohydrodynamics effect, depressing the growth of sodium dendrites. The porous three-dimensional heterostructure is conducive for promoting transmission of charges and the diffusion of ions, effectively reducing the local current density of metals, further inhibiting the growth of sodium dendrites during deposition and peeling processes. Density functional theoretical calculations also verify that the fabricated MoS2 composite possesses intensified electron density, and exhibits fast reaction kinetics in repeated cycles and lowered sodium adsorption energy. The optical field and the rational magnetic fabrication technology can fundamentally solve the bottleneck problems restricting the development of batteries, mitigating the energy crisis.