| dc.description.abstract | Traditional lithium batteries typically require liquid electrolytes as a conducting medium using porous membranes to separate the positive and negative electrodes. However, this conventional method not only involves significant time and solvent recovery efforts during the production of the membrane but also raises safety concerns due to the high flammability of liquid electrolytes. Therefore, in this study, we adopted a solvent-free and electrolyte-minimized approach using photopolymerization to rapidly produce a solid-state electrolyte.
From a polymer perspective, conductivity in the solid-state electrolyte requires long-chain polymer segments for ion transport while remaining unaffected by crystalline regions. To achieve this, we utilized a co-polymerization of PEGDA and MA, combined with PEO, to form a networked crosslinked polymer matrix that provides ion conductivity and electron insulation. To further enhance the conductivity, we introduced additives such as SCN and LiTFSI, which undergo a crystalline-to-conductive transition mechanism. Experimental results demonstrated high capacity values of 148.5 mAh/g and 111.7 mAh/g at 0.5C and 1C rates, respectively, with the addition of 30% SCN. Moreover, the electrolyte maintained a capacity retention of over 90% even after numerous charge-discharge cycles. However, due to SCN′s lower molecular strength, excessive amounts led to a decline in the mechanical properties of the electrolyte membrane. To address this issue, we incorporated LAGP to form a composite electrolyte, comprising polymer, inorganic ceramic material, and additives, thereby creating three pathways for conductivity.
Nevertheless, LAGP itself undergoes reduction when it comes into contact with lithium metal. To mitigate this effect, we first applied a uniform LAGP slurry and subsequently poured the polymer liquid for photopolymerization, resulting in a composite thin film with LAGP aggregating on one side (cathode side). In further experiments, the addition of 5% LAGP and 30% SCN exhibited excellent electrochemical performance, with high capacities of 154.9 mAh/g (at 0.5C) and 110.1 mAh/g (at 1C). Additionally, the strength of the material approached values comparable to those before the addition of SCN. This study successfully developed a composite electrolyte that fulfills five key criteria: rapid production, environmental friendliness, mechanical strength, safety, and electrochemical performance for solid state lithium battery. | en_US |