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%。
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.
[1] DUNN B, KAMATH H, TARASCON J M.Electrical energy storage for the grid: A battery of choices[J]. Science, 2011, 334(6058): 928-935. DOI: 10.1126/science.1212741.
[2] SHI Y, ZHOU X Y, ZHANG J, et al.Nanostructured conductive polymer gels as a general framework material to improve electrochemical performance of cathode materials in li-ion batteries[J]. Nano letters, 2017, 17(3): 1906-1914. DOI: 10.1021/acs.nanolett.6b05227.
[3] KIM J W, KIM D H, OH D Y, et al.Surface chemistry of LiNi0.5Mn1.5O4 particles coated by Al2O3 using atomic layer deposition for lithium-ion batteries[J]. Journal of power sources, 2015, 274: 1254-1262. DOI: 10.1016/ j.jpowsour.2014.10.207.
[4] GOODENOUGH J B, KIM Y.Challenges for rechargeable li batteries[J]. Chemistry of materials, 2010, 22(3): 587-603. DOI: 10.1021/cm901452z.
[5] JEONG Y K, KWON T W, LEE I, et al.Hyperbranched β-cyclodextrin polymer as an effective multidimensional binder for silicon anodes in lithium rechargeable batteries[J]. Nano letters, 2014, 14(2): 864-870. DOI: 10.1021/nl404237j.
[6] RYOU M H, KIM J, LEE I, et al.Mussel-inspired adhesive binders for high-performance silicon nanoparticle anodes in lithium-ion batteries[J]. Advanced materials, 2013, 25(11): 1571-1576. DOI: 10.1002/adma.201203981.
[7] HAN Z J, YABUUCHI N, SHIMOMURA K, et al.High-capacity Si-graphite composite electrodes with a self-formed porous structure by a partially neutralized polyacrylate for Li-ion batteries[J]. Energy & environmental science, 2012, 5(10): 9014-9020. DOI: 10.1039/C2EE22292B.
[8] LI C C, LIN Y S.Interactions between organic additives and active powders in water-based lithium iron phosphate electrode slurries[J]. Journal of power sources, 2012, 220: 413-421. DOI: 10.1016/j.jpowsour.2012.07.125.
[9] WANG Q S, PING P, ZHAO X J, et al.Thermal runaway caused fire and explosion of lithium ion battery[J]. Journal of power sources, 2012, 208: 210-224. DOI: 10.1016/j.jpowsour.2012.02.038.
[10] BUQA H, HOLZAPFEL M, KRUMEICH F, et al.Study of styrene butadiene rubber and sodium methyl cellulose as binder for negative electrodes in lithium-ion batteries[J]. Journal of power sources, 2006, 161(1): 617-622. DOI: 10.1016/j.jpowsour.2006.03.073.
[11] YUE L, ZHANG L Z, ZHONG H X.Carboxymethyl chitosan: A new water soluble binder for Si anode of Li-ion batteries[J]. Journal of power sources, 2014, 247: 327-331. DOI: 10.1016/j.jpowsour.2013.08.073.
[12] ZHONG H X, ZHOU P, YUE L, et al.Micro/nano-structured SnS2 negative electrodes using chitosan derivatives as water-soluble binders for Li-ion batteries[J]. Journal of applied electrochemistry, 2014, 44(1): 45-51. DOI: 10.1007/s10800-013-0590-x.
[13] SUN M H, ZHONG H X, JIAO S R, et al.Investigation on carboxymethyl chitosan as new water soluble binder for LiFePO4 cathode in Li-ion batteries[J]. Electrochimica acta, 2014, 127: 239-244. DOI: 10.1016/j.electacta.2014.02.027.
[14] ZHONG H X, HE A Q, LU J D, et al.Carboxymethyl chitosan/conducting polymer as water-soluble composite binder for LiFePO4 cathode in lithium ion batteries[J]. Journal of power sources, 2016, 336: 107-114. DOI: 10.1016/j.jpowsour.2016.10.041.
[15] HE J R, WANG J L, ZHONG H X, et al.Cyanoethylated carboxymethyl chitosan as water soluble binder with enhanced adhesion capability and electrochemical performances for LiFePO4 cathode[J]. Electrochimica acta, 2015, 182: 900-907. DOI: 10.1016/j.electacta.2015.10.006.
[16] HE J R, ZHONG H X, WANG J L, et al.Investigation on xanthan gum as novel water soluble binder for LiFePO4 cathode in lithium-ion batteries[J]. Journal of alloys and compounds, 2017, 714: 409-418. DOI: 10.1016/j.jallcom.2017.04.238.
[17] HUANG J X, WANG J L, ZHONG H X, et al.N-cyanoethyl polyethylenimine as a water-soluble binder for LiFePO4 cathode in lithium-ion batteries[J]. Journal of materials science, 2018, 53(13): 9690-9700. DOI: 10.1007/s10853-018-2247-y.
[18] HE J R, ZHANG L Z.Polyvinyl alcohol grafted poly (acrylic acid) as water-soluble binder with enhanced adhesion capability and electrochemical performances for Si anode[J]. Journal of alloys and compounds, 2018, 763: 228-240. DOI: 10.1016/j.jallcom.2018.05.286.
[19] QUINTERO S M M, PONCE F R V, CREMONA M, et al. Swelling and morphological properties of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) hydrogels in solution with high salt concentration[J]. Polymer, 2010, 51(4): 953-958. DOI: 10.1016/j.polymer.2009.12.016.
[20] LU Y, WANG D F, LI T, et al.Poly(vinyl alcohol)/poly(acrylic acid) hydrogel coatings for improving electrode-neural tissue interface[J]. Biomaterials, 2009, 30(25): 4143-4151. DOI: 10.1016/j.biomaterials.2009.04.030.
[21] SONG J X, ZHOU M J, YI R, et al.Interpenetrated gel polymer binder for high-performance silicon anodes in lithium-ion batteries[J]. Advanced functional materials, 2014, 24(37): 5904-5910. DOI: 10.1002/adfm.201401269.
