以金属铜箔(Cu)/铝箔(Al)和复合铜箔(MC)/复合铝箔(MA)为研究对象,研究了复合集流体对磷酸铁锂电池性能的影响。箔材电阻、热收缩及极片剥离强度等理化性能对比表明,塑料基复合箔材存在轻微热收缩,同时箔材电阻会增加;复合箔材沉积的金属层多孔结构可提升极片剥离,但较薄的金属层造成极片电阻提升,其中MA极片电阻提升最明显。将复合箔材极片与金属箔材极片匹配得到4组软包锂电池,并对其电性能和安全性能进行测试。结果表明:由于MA正极片较MC负极片电阻提升更多,会造成电池极化增加,故在恒流充入比和充放电压差、欧姆阻抗(R_s)、固体电解质界面膜阻抗(R_SEI),常温循环容量保持率等方面MC电池均优于MA电池;MA较MC塑料基底层更厚且导电性更差,故能够在滥用过程中快速切断电池内部短路避免热失控;复合箔材能够在短路过程最高温度、过充充电截止时间、针刺最高温度等方面有效提升电池安全性能,且MA对安全性能提升较MC更有效。

Metal copper foil (Cu)/aluminum foil (Al) and composite copper foil (MC)/composite aluminum foil (MA) were selected as research objects to investigate the influence of composite current collectors on the performance of lithium iron phosphate batteries.Comparative analysis of physical and chemical properties-including foil resistance,thermal shrinkage,and electrode peel strength-indicated that plastic-based composite foils showed a slight thermal shrinkage and the foil resistance increased simultaneously.The porous structure of the metal layer deposited on the composite foils could enhance the electrode peel strength,but the thinner metal layer caused an increase in electrode resistance.Among them,the MA electrode had the most obvious effect.Four sets of pouch batteries were obtained by matching composite foil electrode with metal foil electrode,and their electrical and safety performance were compared.It was shown that due to the greater increase in resistance of the MA cathode electrode compared to the MC anode electrode,the battery polarization would increase.Consequently,MC-based batteries outperformed MA-based batteries in terms of constant current charging ratio,charging-discharging voltage difference,resistance impedance (R_s),and SEI membrane impedance (R_SEI),and room-temperature cycle capacity retention rate.However,because the MA plastic substrate layer was thicker and had lower conductivity than that of MC,it could quickly cut off the internal short circuit of the battery during abuse to avoid thermal runaway.The composite foils could effectively improve the battery safety performance in terms of the highest temperature during short circuit,the cutoff time for overcharge charging,and the maximum temperature of the needle puncture,and the MA was more effective in improving the safety performance than the MC.