梯度多孔结构设计提升高镍层状氧化物正极材料高压循环稳定性  

Gradient-porous-structured Ni-rich Layered Oxide Cathodes Improve the High Voltage Cycling Stability

作　　者：王舒玮 张建勋 成业 章立寒 田华军 李宝华 Wang Shuwei;Zhang Jianxun;Cheng Ye;Zhang Lihan;Tian Huajun;Li Baohua(Key Laboratory of Power Station Energy Transfer Conversion and Systems Ministry of Education,North China Electric Power University,Beijing 102206,China;Tsinghua Shenzhen International Graduate School,Shenzhen 518055,China;Shenzhen Engineering Research Center on Key Technology of Next-Generation Power and Energy-Storage Battery,Shenzhen 518055,China;BGRIMM Technology Group,Beijing 100160,China;College of Materials Science&Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]华北电力大学电站能量传递转化与系统教育部重点实验室,北京102206 [2]清华大学深圳国际研究生院,深圳518055 [3]深圳市下一代动力与储能电池关键技术工程研究中心,深圳518055 [4]矿冶科技集团有限公司,北京100160 [5]北京工业大学材料科学与工程学院,北京100124

出　　处：《化学学报》2024年第11期1134-1141,共8页Acta Chimica Sinica

基　　金：国家自然科学基金(Nos.52302249,12304003,52072208,52261160384,22379085和52302278)资助。

摘　　要：高镍层状氧化物(LiNi_(x)Co_(y)Mn_(1-x-y)O_(2),x≥0.8,NCM)由于其具有较低的生产成本、较高的能量密度和工作电压,是下一代高能量密度锂离子电池的重要正极材料.然而,由于锂化/去锂化时高镍正极材料内部应变累积和颗粒破裂,导致其高压循环稳定性受二次颗粒机械失效的严重影响,限制其大规模的应用.本工作报道了一种简单的共沉淀合成方法,成功地将梯度分布的孔结构引入到多晶NCM二次颗粒中,可以有效地缓解NCM一次颗粒中各向异性带来的体积变化、抑制晶间裂纹和晶内裂纹,同时减缓阻抗增加.此梯度多孔结构的高镍NCM正极材料可以充电到4.5 V的高电压,同时具有180.1 mAh·g^(-1)(1 C,25℃)的超高比容量,在充放电循环300次后仍有87.6%的容量保持率.而且,该正极材料在-20~60℃的宽温度范围内,都能表现出高的可逆容量和显著增强的循环稳定性.这项研究表明,梯度多孔结构设计能够有效均匀化应力分布,有望解决高镍层状氧化物高压循环过程的结构不稳定性,该方法简单可行,易于大规模工业化.Nickel-rich layered oxides(LiNi_(x)Co_(y)Mn_(1-x-y)O_(2),x≥0.8,NCM)are the most promising cathode material for next-generation high-energy batteries owing to their low production cost,high specific capacity and high operating voltage.However,the practical deployment of high-voltage NCM cathodes is still plagued by mechanical failure of NCM secondary particles due to the internal strain accumulation and particle crack during(de)lithiation.Herein,we report a convenient coprecipitation strategy to introduce gradient porous structure into the polycrystalline NCM secondary particles.Through multistage micro-and nanostructural tailoring from hydroxide precursor in coprecipitation process to the lithiated oxide during the lithiation stage,which refers to optimal engineering of the precursor micro-and nano-structure by introducing extra organic polymer(polystyrene-acrylonitrile copolymer)as heterogeneous nucleation seeds and alkyl diphenyl ether disulfonate disodium as dispersants,we optimize the primary particle morphology containing nano-voids and secondary particle containing gradient porous structure of the cathode.Through high-resolution aberration-corrected scanning transmission electron microscopy and scanning electron microscopy,the detailed gradient porous structure of the as-obtained nickel-rich layered oxide cathode is clarified,and the formation of gradient porous structure is attributed to the rapid diffusion of the carbonized organic matter by the calcination treatment under oxygen atmosphere during the lithiation stage.This gradient-porousstructured nickel-rich layered oxide cathode can mitigate the anisotropic volume change of the primary particles,suppress intergranular/intragranular cracks and limit impedance growth effectively.The as-obtained cathode exhibits high specific capacity of 180.1 mAh·g^(-1)(1 C,25℃)and capacity retention of 87.6%after 300 cycles even charged to a high cut-off voltage of 4.5 V.Moreover,this cathode presents enhanced high reversible capacity and cycling stability in a wid

关 键 词：高镍层状氧化物 高电压 机械失效 梯度多孔结构 宽温度范围 

分 类 号：TM9[电气工程—电力电子与电力传动]