交联型水性粘结剂的制备及其在磷酸铁锂正极的 应用研究

丙烯酸（AA）通过自由基接枝聚合对聚乙烯醇（PVA）进行改性,得到接枝聚合物PVA-g-PAA,并与季戊四醇（PER）交联剂共同作为磷酸铁锂（LFP）正极的交联型水性粘结剂,探讨了交联温度及不同PER使用量对LFP正极电化学性能的影响。交联温度与极片制备工艺温度相吻合,极片在烘干的过程中同时完成交联反应。当PER的加入量为PVA-g-PAA的5mol%时,LFP电极表现出最优的粘结力和电化学稳定性,在0.2 C和1 C倍率下进行充放电循环测试,PVA-g-PAA-c-5%PER在0.2 C倍率下循环100圈后的容量保持率为99.4%,PVA-g-PAA和PVDF的分别为94.4%和88.6%;PVA-g-PAA-c-5%PER在1 C高倍率下循环400圈后的容量保持率为82.6%,而PVA-g-PAA的保持率为78.8%。

Preparation of Crosslinked Aqueous Binder for LiFePO4 Cathode in Lithium-Ion Batteries

Polyvinyl alcohol grafted poly(acrylic acid) (PVA-g-PAA) was synthesized by graft polymerization of acrylic acid (AA) onto PVA through a free radical reaction. PVA-g-PAA and the cross-linking agent pentaerythritol (PER) together were used as an aqueous crosslinkble binder for LiFePO₄ (LFP) cathode, the effect of crosslinking temperature and PER dosage on the electrochemical properties of LFP cathode were investigated. The crosslinking temperature was in good agreement with the temperature of the LFP cathode preparation process, and the crosslinking reaction was performed simultaneously during the drying process. When the PER dosage was 5mol% of PVA-g-PAA, the LFP electrode exhibited the optimum adhesion and electrochemical stability. The LFP electrode with PVA-g-PAA-c-5%PER binder was tested for charge and discharge cycles at 0.2 C and 1 C rates respectively, showing a capacity retention of 99.4% after 100 cycles at 0.2 C in comparison with 94.4% and 88.6% for PVA-g-PAA and PVDF, and maintaining 82.6% of initial capacity after 400 cycles at 1 C high rate as compare with 77.8% for PVA-g-PAA.