High ion conductivity based on a polyurethane composite solid electrolyte for all-solid-state lithium batteries

Polyurethane-P2S5 composite-based solid-state electrolyte assists low polarization and high stability all-solid-state lithium-ion batteries

Block copolymer electrolytes represented by polyurethane (PU) have become the forefront field of organic solid-state electrolytes for high-performance lithium-metal batteries due to their superb mechanical properties. However, due to the existence of mechanical hard segments, discontinuous ion transition at the electrolyte-electrode contact is inevitable, which leads to a series of problems such as terrible polarization phenomena, poor cycle stability and inadequate capacity retention. Here, we propose a new strategy to improve the chemical stability and interaction of electrolyte-electrode by modulating soft segments, which successfully reduces the polarization phenomenon. Then a new composite polymer solid electrolyte based on block copolymer PU (abbr. SPE) was prepared by ion-conduct segment modification using P2S5 with high lithium-ion affinity, and the ion conductivity of the SPE reached 7.4 × 10-4 S cm-1 (25 °C) and 4.3 × 10-3 S cm-1 (80 °C) respectively. The assembled LFP|SPE|Li displays a high specific capacity and stable charging/discharging platforms. Besides, an excellent retention capacity of 90% is obtained after 2000 cycles at 5C, and the lithium symmetric battery exhibits no significant polarization over 750 h. This work provides a viable strategy to suppress the polarization phenomenon to develop new block copolymer electrolytes with long cycle stability and high capacity retention.

Double-layer Composite Gel Polymer Electrolyte for Organic Sodium-metal Batteries

Organic cathode materials have the advantages of abundant raw materials, high theoretical specific capacity, controllable structure and easy recycling. Pyrene-4,5,9,10-tetraone (PTO), as one of the typical organic cathode materials, achieves efficient storage and release of Na + . However, its good solubility in traditional organic liquid electrolytes is detrimental to the cyclic stability of batteries. To address this issue, the double-layer composite gel polymer electrolyte (DLCGPE) consisting of poly (ionic liquid) gel polymer electrolyte and plastic crystal electrolyte was developed and applied to organic sodium-metal batteries. This as-prepared DLCGPE displays an ionic conductivity of 2.17×10 -4 S cm -1 and an electrochemical window of 4.8 V. The as-fabricated sodium-symmetric batteries maintain interfacial stability after 500 h of cycling. Furthermore, the PTO/Na batteries could also retain a specific capacity of 201 mAh g -1 after 300 cycles, confirming that DLCGPE achieves the purpose of inhibiting PTO dissolution and maintaining batteries stability. This work broadens the application of asymmetric electrolytes in organic secondary battery.