No abstract

Smart electronics and wearable devices require batteries with increased energy density, enhanced safety, and improved mechanical flexibility. However, current state‐of‐the‐art Li‐based rechargeable batteries (LBRBs) use highly reactive and flowable liquid electrolytes, severely limiting their ability to meet the above requirements. Therefore, solid polymer electrolytes (SPEs) are introduced to tackle the issues of liquid electrolytes. Nevertheless, due to their low Li+ conductivity and Li+ transference number (LITN) (around 10−5 S cm−1 and 0.5, respectively), SPE‐based room temperature LBRBs are still in their early stages of development. This paper reviews the principles of Li+ conduction inside SPEs and the corresponding strategies to improve the Li+ conductivity and LITN of SPEs. Some representative applications of SPEs in high‐energy density, safe, and flexible LBRBs are then introduced and prospected.

Lithium (Li)‐metal batteries (LMBs) with high‐voltage cathodes and limited Li‐metal anodes are crucial to realizing high‐energy storage. However, functional electrolytes that are compatible with both high‐voltage cathodes and Li anodes are required for their developments. In this study, the use of a moderate‐concentration LiPF6 and LiNO3 dual‐salt electrolyte composed of ester and ether co‐solvents (fluoroethylene carbonate/dimethoxyethane, FEC/DME), which forms a unique Li+ solvation with aggregated dual anions, that is, PF6− and NO3−, is proposed to stabilize high‐voltage LMBs. Mechanistic studies reveal that such a solvation sheath improves the Li plating/stripping kinetics and induces the generation of a solid electrolyte interphase (SEI) layer with gradient heterostructure and high Young's modulus on the anode, and a thin and robust cathode electrolyte interface (CEI) film. Therefore, this novel electrolyte enables colossal Li deposits with a high Coulombic efficiency (≈98.9%) for 450 cycles at 0.5 mA cm−2. The as‐assembled LiǁLiNi0.85Co0.10Al0.05O2 full batteries deliver an excellent lifespan and capacity retention at 4.3 V with a rigid negative‐to‐positive capacity ratio. This electrolyte system with a dual‐anion‐aggregated solvation structure provides insights into the interfacial chemistries through solvation regulation for high‐voltage LMBs.

No abstract

The development of ultrahigh-voltage lithium metal batteries is one of the most promising ways to increase the energy density. However, commercial ethylene carbonate (EC)-based electrolytes have poor compatibility with both...

Wearable electronics require lightweight and flexible batteries, of which lithiumsulfur (Li-S) batteries are of great interest due to their high gravimetric energy density. Nevertheless, flexible Li-S batteries have unsatisfactory electrochemical performance owing to electrode fracture during repeated bending, the volume change of sulfur species and the severe shuttle effect. Binders play essential roles in these batteries but have always lacked attention. Herein, a self-healing polyvinylpyrrolidone-polyethyleneimine (PVP-PEI) binder cross-linked by hydrogen bonds, which also regulates polysulfide redox kinetics, is reported. The dynamic hydrogen-bonding networks repair the cracks and ensure the integrity of the electrode while numerous polar groups such as CO and -NH 2 suppress the shuttle effect by immobilizing polysulfides. Therefore, Li-S batteries with the PVP-PEI binder exhibit excellent cycling stability (a capacity decay rate of 0.0718% per cycle at 1 C after 450 cycles), an outstanding areal capacity of 7.67 mAh cm −2 even under a high sulfur loading (7.1 mg cm −2 ) and relatively lean electrolyte conditions (E/S ratio = 8 µL mg −1 ). Flexible Li-S pouch cells using the PVP-PEI binder show a stable performance for 140 cycles and a favorable capacity retention of over 95% after 2800 bending cycles, confirming its application potential in high-performance flexible Li-S batteries.

No abstract

No abstract