Applications Of POMs-based Polymer Electrolytes In Electrochemical Energy Storage

Severe hazards caused by liquid leakage,flammability and poor chemical stability of the currently used batteries with liquid electrolytes limit their applications in large scale.Substituting solid electrolytes for liquid electrolytes offers an efficacious route conducted to address the inherent drawbacks of liquid electrolytes.In this paper,a kind of POMs-based organic-inorganic composite electrolyte is developed and applied to different electrochemical energy storage systems.The main results of this research obtained are as follows:(1)A new class of POMs-based polymer electrolyte(PPE)is designed and prepared,which incorporates Li7[V15O36(CO3)](LVC)into polyethylene oxide(PEO).LVC with the capability of dissociating Li+ partially can increase pathways for Li+transmission in PPE,resulting in a higher ion conductivity.The ionic conductivity for PPE can reach 9.13 × 10-5 S cm-1 at 40?,and the electrochemical stability window is broadened to 5.35 V.(2)Employed to LiFePO4|Li batteries,LiFePO4|C batteries and Li|Li batteries,the electrochemical behaviours of PPE are investigated.The discharge specific capacity of LiFePO4|Li batteries after 180 cycles exceeds 148 mAh g-1 obtained at 0.5 C.PPE acting as electrolytes,LiFePO4|C batteries are assembled and provided with superior safety as the onset temperature of self-heating process reaches up to 181.4?,and the thermal runaway process does not occur within the range of 360?.In addition,the Li|Li symmetrical battery exhibits good cycle stability,and there is no significant voltage polarization increase after 1300 h.With the prolongation of storage time,the interface impedance of LilLi symmetric battery shows a downward tendency,indicating that the prepared PPE can form a stable interface against lithium metal and has a good ability to inhibit the growth of lithium dendrite.(3)The prepared PPE is applied to all-solid-state POMs-based symmetrical battery system and explored the electrochemical behaviors.The all-solid-state LVC|PPE|LVC symmetrical batteries possess a low interface impedance at 40? and exibit a reversible specific capacity of?110 mAh g-1 for the first cycle,and still maintain a stable specific capacity of 103 mAh g-1 after 300 cycles.