Abstract：
Solid-state lithium batteries using solid polymer electrolytes can improve the safety and energy density of batteries. Smoother lithium-ion channels are necessary for solid polymer electrolytes with high ionic conductivity. The porosity and channel structure of the polymer film affect the transfer of lithium ions. However, their controllable synthesis remains a big challenge. Here, we developed a simple synthesis approach toward wrinkled microporous polymer electrolytes by combining the amphoteric (water solubility and organic solubility) polymer in three polymer blends. The homogeneous blend solution spontaneously wrinkled to vertical fold channels as the solvent evaporated. Two minor polymers, poly(vinyl pyrrolidone) (PVP) and polyetherimide (PEI), formed close stacks, and Janus PVP was dispersed in the poly(vinylidene fluoride) (PVDF) matrix. The interfacial tensions between the three polymers were different, so stress was produced when they solidified. The solvent was evaporated to the top layer of the polymers when the temperature increased. The bottom layer wrinkled owing to the stress during solidification. The evaporation of the solvent generated micropores to form the lithium-ion channel. They helped Li+ transference and created a wrinkled microporous PVDF-based polymer electrolyte, which achieved an ionic conductivity of 5.1 × 10-4 S cm-1 and a lithium-ion transference number of 0.51 at room temperature. Meanwhile, the good flame retardancy and tensile strength of the polymer electrolyte film can improve the safety of the battery. At 0.5C and room temperature, the batteries with a LiFePO4 cathode and the wrinkled microporous LiTFSI/PEI/PVP/PVDF electrolyte reached a high discharge specific capacity of 122.1 mAh g-1 at the 100th cycle with a Coulombic efficiency of above 99%. The results of tensile and self-extinguishing tests show that the polymer electrolyte film has good safety application prospects.
摘要：
使用固体聚合物电解质的固态锂电池可以提高电池的安全性和能量密度。对于具有高离子电导率的固体聚合物电解质，需要更平滑的锂离子通道。聚合物膜的孔隙率和通道构造影响锂离子的转移。然而,它们的可控合成仍然是一个巨大的挑战。这里,我们开发了一种简单的合成方法，通过将两性（水溶性和有机溶解度）聚合物结合在三种聚合物共混物中，对起皱的微孔聚合物电解质。当溶剂蒸发时,均匀的共混物溶液自发起皱至垂直折叠通道。两种次要聚合物，聚乙烯吡咯烷酮（PVP）和聚醚酰亚胺（PEI），形成紧密的堆栈，和JanusPVP分散在聚(偏二氟乙烯)(PVDF)基质中。三种聚合物之间的界面张力不同，所以当它们凝固时就产生了压力。当温度升高时,将溶剂蒸发至聚合物的顶层。底层由于固化过程中的应力而起皱。溶剂的蒸发产生微孔以形成锂离子通道。他们帮助Li+转移，并创造了一种起皱的微孔PVDF基聚合物电解质，在室温下，离子电导率为5.1×10-4Scm-1，锂离子迁移数为0.51。同时,聚合物电解质膜良好的阻燃性和拉伸强度可以提高电池的安全性。在0.5C和室温下，具有LiFePO4阴极和起皱的微孔LiTFSI/PEI/PVP/PVDF电解质的电池在第100次循环时达到122.1mAhg-1的高放电比容量，库仑效率超过99％。拉伸和自熄性试验结果表明，聚合物电解质膜具有良好的安全应用前景。
