Achieving Dendrite-Free Zinc Metal Anodes via Molecule Anchoring and lon-Transport Pumping.

The potential for scale-up application has been acknowledged by researchers for rechargeable aqueous zinc-ion batteries (ZIBs). Nonetheless, the progress of the development is significantly impeded due to the instability of the interface between the zinc anode and electrolyte. Herein, efficient and environmentally benign valine (Val) were introduced as aqueous electrolyte additive to stabilize the electrode/electrolyte interface (EEI) via functional groups in additive molecules, thus achieving reversible dendrite-free zinc anode. The amino groups present in Val molecules have a strong ability to adsorb on the surface of zinc metal, enabling the construction of anchored molecular layer on the surface of zinc anodes. The strongly polar carboxyl groups in Val molecules can act as ion-transport pumps to capture zinc ions in the electric double layer (EDL) through coordination chemistry. Therefore, this reconstructed EEI could modulate the zinc ion flux and simultaneously suppress side reactions and dendritic growth of Zn. Consequently, a long stable cycling up to 1400 h at a high current density of 20 mA cm-2 is achieved. Additionally, Zn//V2O5 full cell with Val additive exhibit enhanced cyclability, retaining 77 % capacity after 3000 cycles, displaying significant potential in promoting the commercialization of ZIBs.

Molecular Coupling Strategy Achieving In Situ Synthesis of Agglomeration-Free Solid Composite Electrolytes.

Solid composite electrolytes (SCEs) synergize inorganic and polymer merits for viable commercial application. However, inferior filler-polymer interfacial stability ultimately leads to the agglomeration of inorganic particles and greatly impedes Li+ migration. Herein, triethoxyvinylsilane (VTEO) is employed to form a strong chemical interaction between poly(vinylene carbonate) (PVC) and montmorillonite (MMT) via in situ solidification, which eliminates the agglomeration and improves interfacial compatibility. Consequently, the obtained solid composite electrolytes (PVC-s-MMT) achieve increased Li+ conductivity (0.4 mS cm-1 at 25 °C), enhanced transference number (0.74), and increased oxidation potential (5.2 V). The Li/PVC-s-MMT/LiFePO4 cells exhibit outstanding cycling performance (>99.5% after 600 cycles) at 1C at room temperature. Moreover, density functional theory (DFT) calculations are applied to uncover the fast interfacial conducting channels of PVC-s-MMT. Our work provides a feasible in situ synthesis method to prepare agglomeration-free SCEs, which is highly compatible with existing battery production processes of liquid electrolytes.

Mg Doped Li-LiB Alloy with In Situ Formed Lithiophilic LiB Skeleton for Lithium Metal Batteries.

High energy density lithium metal batteries (LMBs) are promising next-generation energy storage devices. However, the uncontrollable dendrite growth and huge volume change limit their practical applications. Here, a new Mg doped Li-LiB alloy with in situ formed lithiophilic 3D LiB skeleton (hereinafter called Li-B-Mg composite) is presented to suppress Li dendrite and mitigate volume change. The LiB skeleton exhibits superior lithiophilic and conductive characteristics, which contributes to the reduction of the local current density and homogenization of incoming Li+ flux. With the introduction of Mg, the composite achieves an ultralong lithium deposition/dissolution lifespan (500 h, at 0.5 mA cm-2) without short circuit in the symmetrical battery. In addition, the electrochemical performance is superior in full batteries assembled with LiCoO2 cathode and the manufactured composite. The currently proposed 3D Li-B-Mg composite anode may significantly propel the advancement of LMB technology from laboratory research to industrial commercialization.

Selenium-Doped Cathodes for Lithium-Organosulfur Batteries with Greatly Improved Volumetric Capacity and Coulombic Efficiency.

For the first time a new strategy is reported to improve the volumetric capacity and Coulombic efficiency by selenium doping for lithium-organosulfur batteries. Selenium-doped cathodes with four sulfur atoms and one selenium atom (as the doped heteroatom) in the confined structure are designed and synthesized; this structure exhibits greatly improved volumetric/areal capacities, and a Coulombic efficiency of almost 100% for highly stable lithium-organosulfur batteries. The doping of Se significantly enhances the electronic conductivity of battery electrodes by a factor of 6.2 compared to pure sulfur electrodes, and completely restricts the production of long-chain lithium polysulfides. This allows achievement of a high gravimetric capacity of 700 mAh g-1 close to its theoretical mass capacity, an exceptional volumetric capacity of 2457 mAh cm-3 , and excellent capacity retention of 92% after 400 cycles. Shuttle effect is efficiently weakened since no long-chain polysulfides are detected from in situ UV/vis results throughout the entire cycling process arising from selenium doping, which is theoretically confirmed by density functional theory calculations.