张宁等:硼掺杂镍酸锂的改性研究 1017. 是减小的幅度和峰偏移程度存在差别.图5(c)对 参考文献 比了LNiO2/Li和B掺杂LiNiO2lLi在第106圈的 [1] Xu GL,Liu X,Daali A,et al.Challenges and strategies to advance 微分容量曲线变化.从图可知,B掺杂LiNiO2和 high-energy nickel-rich layered lithium transition metal oxide LNiO2相比有较大的微分容量曲线峰面积,表明 cathodes for harsh operation.Adv Funct Mater,2020,30(46): B掺杂抑制了LiNiO2因非均匀应力导致的晶间裂 2004748 纹的产生.另外,B掺杂LiNiO2微分容量曲线在电 [2]Li J W.Li Y.Yi W T.et al.Improved electrochemical 压为3.5V和4.2V的氧化还原峰更大,表明B掺 performance of cathode material LiNio.sCoo.Mno.1O2 by doping 杂可以有效抑制LiNO2循环过程中阻抗的增加, magnesium via co-precipitation method.J Mater Sci:Mater Electron,2019,30(8):7490 从而提高材料的循环性能. [3]Li J W.Li Y.Guo Y N,et al.A facile method to enhance 为证明以上推论,对样品循环前后进行了 electrochemical performance of high-nickel cathode material EIS测试,分别以阻抗谱的实部(Z)和虚部(Zm) Li(NiosCoo.Mno.)O via Ti doping.J Mater Sci:Mater Electron, 为横纵坐标作Nyquist图,测试结果如图5(d)所 2018,29(13):10702 示.对以上EIS结果进行了阻抗谱的拟合,所选用 [4]Deng T,Fan X L,Cao L S,et al.Designing in-situ-formed 的等效电路如图5(d)中所示2-2),具体拟合结果 interphases enables highly reversible cobalt-free LiNiOz cathode 如表2所示.其中,R为电解液的阻抗,R为接触 for Li-ion and Li-metal batteries.Joule,2019.3(10):2550 阻抗,R,为电化学反应阻抗24-2由图5(d)和表2 [5]Xu C.Marker K.Lee J,et al.Bulk fatigue induced by surface reconstruction in layered Ni-rich cathodes for Li-ion batteries.Nar 可知,循环前B掺杂LiNiO,电极有略大的阻抗,可 Mater,2021,20(1):84 能和该样品有更多的LN混排有关,同时和微 [6] An F Q,Zhao H L,Cheng Z,et al.Development status and 分容量曲线以及CV的测试结果一致.而106次循 research progress of power battery for pure electric vehicles.Chin 环之后,B掺杂LiNiO2的R。和R分别为116.0和 JEmg,2019,41(1)上:22 235.22cm2,明显小于LiNi02的125.1和378.52-cm2 (安富强,赵洪量,程志,等.纯电动车用锂离子电池发展现状与 B掺杂提高了LNiO2电化学循环过程中的电化学 研究进展.工程科学学报,2019,41(1):22) 转移过程,有效抑制了循环过程中阻抗的增长,提 [7]Wang L C,Li L,Wang H Y,et al.Fast capacitive energy storage 高了循环容量保持率 and long cycle life in a deintercalation-intercalation cathode material.Smal,2020,16(13):1906025 表2用ZView拟合得到的循环前后的阻抗值 [8]Li J,Harlow J,Stakheiko N,et al.Dependence of cell failure on Table 2 Electrochemical impedance spectroscopy fitting results cut-off voltage ranges and observation of kinetic hindrance in using ZView (2-cm) LiNio.sCo0.1sAloosO2.JElectrochem Soc,2018,165(11):A2682 Condition Sample R R [9]Zhang N.Li J.Li H Y,et al.Structural,electrochemical,and LiNiO, 3.7 10.9 20.1 thermal properties of nickel-rich LiNi,Mn,Co.O materials.Chem Before cycles B doped LiNiOz Mater,2018,30(24:8852 4.1 14.4 24.2 [10]Li H Y,Cormier M,Zhang N,et al.Is cobalt needed in Ni-rich LiNiO2 11.6 125.1 378.5 After cycles positive electrode materials for lithium ion batteries?J B doped LiNiOz 10.4 116.0 235.2 Electrochem Soc,2019,166(4):A429 [11]Li H Y,Zhang N,Li J,et al.Updating the structure and 3结论 electrochemistry of Li NiOz for 0x1.J Electrochem Soc,2018, 165(13):A2985 (1)本文通过共沉淀-高温固相法成功制备了 [12]Liu A,Zhang N,Li H Y,et al.Investigating the effects of B掺杂LiNiO2样品 magnesium doping in various Ni-rich positive electrode materials (2)B掺杂有效增大了LiO6八面体间距,有利 for Lithium ion batteries.J Electrochem Soc,2019,166(16): 于L的运输 A4025 (3)B掺杂(B摩尔分数为1%)无法有效抑制 [13]Ohzuku T,Ueda A,Kouguchi M.Synthesis and characterization of Li1-Nio99B0.o1O2充放电过程中“03一M一03一01” LiAlNivO2(R3-m)for lithium-ion (shuttlecock)batteries.J Electrochem Soc,1995,142(12):4033 相转变的问题,但是相比于LiNO2,B的引入稳定 [14]Li W D,Liu X M,Celio H,et al.Mn versus Al in layered oxide 了晶体结构,缓解了材料因为非均匀应力造成的 cathodes in lithium-ion batteries:A comprehensive evaluation on 晶间裂纹和活性材料损失,从而抑制了循环过程 long-term cyclability.Ady Energy Mater,2018,8(15):1703154 中的阻抗增长,提高了材料的循环稳定性 [15]Steiner J,Cheng H,Walsh J,et al.Targeted surface doping with是减小的幅度和峰偏移程度存在差别. 图 5(c)对 比了 LiNiO2 //Li 和 B 掺杂 LiNiO2 //Li 在第 106 圈的 微分容量曲线变化. 从图可知,B 掺杂 LiNiO2 和 LiNiO2 相比有较大的微分容量曲线峰面积,表明 B 掺杂抑制了 LiNiO2 因非均匀应力导致的晶间裂 纹的产生. 另外,B 掺杂 LiNiO2 微分容量曲线在电 压为 3.5 V 和 4.2 V 的氧化还原峰更大,表明 B 掺 杂可以有效抑制 LiNiO2 循环过程中阻抗的增加, 从而提高材料的循环性能. 为证明以上推论 ,对样品循环前后进行 了 EIS 测试,分别以阻抗谱的实部(Zre)和虚部(Zim) 为横纵坐标作 Nyquist 图,测试结果如图 5( d)所 示. 对以上 EIS 结果进行了阻抗谱的拟合,所选用 的等效电路如图 5(d)中所示[22−23] ,具体拟合结果 如表 2 所示. 其中,Rs 为电解液的阻抗,Rc 为接触 阻抗,Rct 为电化学反应阻抗[24−25] . 由图 5(d)和表 2 可知,循环前 B 掺杂 LiNiO2 电极有略大的阻抗,可 能和该样品有更多的 Li+ /Ni2+混排有关,同时和微 分容量曲线以及 CV 的测试结果一致. 而 106 次循 环之后,B 掺杂 LiNiO2 的 Rc 和 Rct 分别为 116.0 和 235.2 Ω·cm2 ,明显小于LiNiO2 的125.1 和378.5 Ω·cm2 . B 掺杂提高了 LiNiO2 电化学循环过程中的电化学 转移过程,有效抑制了循环过程中阻抗的增长,提 高了循环容量保持率. 表 2 用 ZView 拟合得到的循环前后的阻抗值 Table 2 Electrochemical impedance spectroscopy fitting results using ZView (Ω·cm2 ) Condition Sample Rs Rc Rct Before cycles LiNiO2 3.7 10.9 20.1 B doped LiNiO2 4.1 14.4 24.2 After cycles LiNiO2 11.6 125.1 378.5 B doped LiNiO2 10.4 116.0 235.2 3 结论 (1)本文通过共沉淀−高温固相法成功制备了 B 掺杂 LiNiO2 样品. (2)B 掺杂有效增大了 LiO6 八面体间距,有利 于 Li+的运输. (3)B 掺杂(B 摩尔分数为 1%)无法有效抑制 Li1−xNi0.99B0.01O2 充放电过程中“O3—M—O3—O1” 相转变的问题,但是相比于 LiNiO2,B 的引入稳定 了晶体结构,缓解了材料因为非均匀应力造成的 晶间裂纹和活性材料损失,从而抑制了循环过程 中的阻抗增长,提高了材料的循环稳定性. 参 考 文 献 Xu G L, Liu X, Daali A, et al. Challenges and strategies to advance high-energy nickel-rich layered lithium transition metal oxide cathodes for harsh operation. Adv Funct Mater, 2020, 30(46): 2004748 [1] Li J W, Li Y, Yi W T, et al. Improved electrochemical performance of cathode material LiNi0.8Co0.1Mn0.1O2 by doping magnesium via co-precipitation method. J Mater Sci: Mater Electron, 2019, 30(8): 7490 [2] Li J W, Li Y, Guo Y N, et al. A facile method to enhance electrochemical performance of high-nickel cathode material Li(Ni0.8Co0.1Mn0.1)O2 via Ti doping. J Mater Sci: Mater Electron, 2018, 29(13): 10702 [3] Deng T, Fan X L, Cao L S, et al. Designing in-situ-formed interphases enables highly reversible cobalt-free LiNiO2 cathode for Li-ion and Li-metal batteries. Joule, 2019, 3(10): 2550 [4] Xu C, Märker K, Lee J, et al. Bulk fatigue induced by surface reconstruction in layered Ni-rich cathodes for Li-ion batteries. Nat Mater, 2021, 20(1): 84 [5] An F Q, Zhao H L, Cheng Z, et al. Development status and research progress of power battery for pure electric vehicles. Chin J Eng, 2019, 41(1): 22 (安富强, 赵洪量, 程志, 等. 纯电动车用锂离子电池发展现状与 研究进展. 工程科学学报, 2019, 41(1):22) [6] Wang L C, Li L, Wang H Y, et al. Fast capacitive energy storage and long cycle life in a deintercalation-intercalation cathode material. Small, 2020, 16(13): 1906025 [7] Li J, Harlow J, Stakheiko N, et al. Dependence of cell failure on cut-off voltage ranges and observation of kinetic hindrance in LiNi0.8Co0.15Al0.05O2 . J Electrochem Soc, 2018, 165(11): A2682 [8] Zhang N, Li J, Li H Y, et al. Structural, electrochemical, and thermal properties of nickel-rich LiNixMnyCozO2 materials. Chem Mater, 2018, 30(24): 8852 [9] Li H Y, Cormier M, Zhang N, et al. Is cobalt needed in Ni-rich positive electrode materials for lithium ion batteries? J Electrochem Soc, 2019, 166(4): A429 [10] Li H Y, Zhang N, Li J, et al. Updating the structure and electrochemistry of LixNiO2 for 0≤x≤1. J Electrochem Soc, 2018, 165(13): A2985 [11] Liu A, Zhang N, Li H Y, et al. Investigating the effects of magnesium doping in various Ni-rich positive electrode materials for Lithium ion batteries. J Electrochem Soc, 2019, 166(16): A4025 [12] Ohzuku T, Ueda A, Kouguchi M. Synthesis and characterization of LiAl1/4Ni3/4O2 (R3 -m) for lithium-ion (shuttlecock) batteries. J Electrochem Soc, 1995, 142(12): 4033 [13] Li W D, Liu X M, Celio H, et al. Mn versus Al in layered oxide cathodes in lithium-ion batteries: A comprehensive evaluation on long-term cyclability. Adv Energy Mater, 2018, 8(15): 1703154 [14] [15] Steiner J, Cheng H, Walsh J, et al. Targeted surface doping with 张 宁等: 硼掺杂镍酸锂的改性研究 · 1017 ·