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.

Accelerating Ion Dynamics Under Cryogenic Conditions by the Amorphization of Crystalline Cathodes.

The normal operation of lithium-ion batteries (LIBs) at ultralow temperature (<-40 °C) is significant for cold-climate applications; however, their operation is plagued by the low capacity of the conventional intercalation cathodes due to their sluggish kinetics and the slow solid diffusion of Li+ in their frameworks. Here, it is demonstrated that amorphization is an effective strategy to promote the low-temperature dynamics of cathodes by relieving the blocking effect of a dense lattice structure on ion transport under cryogenic conditions. As a result, due to the decreased charge transport impedance and enhanced Li+ diffusion rate, the obtained covalent amorphous polymer (CAP) with an abundance of pyrazine and carbonyl active sites displays a remarkably outstanding specific capacity of 141 mAh g-1 at -80 °C, which is superior to its structural analog, a covalent crystalline polymer (43.8 mAh g-1 ). Furthermore, 84.7% of the initial capacity of the CAP can be retained after 500 cycles of charge and discharge at -60 °C. Molecular dynamic simulations show that the channel-rich amorphous structure is highly conducive for lithium ions to diffuse quickly in the interstitial space of organic solids. This work provides an effective strategy regarding the amorphization of crystalline cathodes to develop low-temperature (Low-T) batteries.

Healable Lithium Alloy Anode with Ultrahigh Capacity.

Effective recycling of spent Li metal anodes is an urgent need for energy/resource conservation and environmental protection, making Li metal batteries more affordable and sustainable. For the first time, we explore a unique sustainable healable lithium alloy anode inspired by the intrinsic healing ability of liquid metal. This lithium alloy anode can transform back to the liquid state through Li-completed extraction, and then the structure degradation generated during operation could be healed. Therefore, an ultralong cycle life of more than 1300 times can be successfully realized under harsh conditions of 5 mA h cm-2 capacitance by a process of two healing behaviors. This design improves the sustainable utilization of Li metal to a great extent, bringing about unexpected effects in the field of lithium-based anodes even at an unprecedentedly high discharge current density (up to 25 mA cm-2) and capacity (up to 50 mA h cm-2).