电化学-热耦合模型是锂离子电池设计开发过程的关键技术。采用基于WLTC(Worldwide Light-duty Test Cycle)工况的锂离子电池电化学-热耦合模型,分析了111型镍钴锰酸锂电池(Li(Ni_(x)Co_(y)Mn_(z))O_(2))同侧极耳分布的方形电池的温度场...电化学-热耦合模型是锂离子电池设计开发过程的关键技术。采用基于WLTC(Worldwide Light-duty Test Cycle)工况的锂离子电池电化学-热耦合模型,分析了111型镍钴锰酸锂电池(Li(Ni_(x)Co_(y)Mn_(z))O_(2))同侧极耳分布的方形电池的温度场以及电特性,并优化极耳尺寸及极耳间距。研究发现,WLTC工况下放电倍率对温度场和电特性有显著影响,随着放电倍率的增大,WLTC工况的两个循环结束时刻电池的最大温升和温差均以凹型曲线的趋势升高,放电倍率为2C时温升达12.705℃、温差为1.359℃;电压曲线的变化趋势也随放电倍率的增大而大幅下降。进一步研究发现,电池的最大温升和温差与正、负极耳的宽度及极耳间距显著相关,当正极耳宽度为0.03 m,负极耳宽度为0.05 m时,电池的最大温升与温差最小;当正、负极耳间距为0.05 m时,电池的最大温升与温差最小。展开更多
高镍三元材料LiNi _(0.8) Co_( 0.1 )Mn _(0.1) O _(2)(NCM811)因在高电压下具有高理论比容量而被广泛应用,与高镍材料如LiNi _(0.5) Co _(0.2) Mn _(0.3) O _(2)(NCM523)、LiNi _(0.6) Co _(0.2) Mn _(0.2) O _(2)(NCM622)等相比存在...高镍三元材料LiNi _(0.8) Co_( 0.1 )Mn _(0.1) O _(2)(NCM811)因在高电压下具有高理论比容量而被广泛应用,与高镍材料如LiNi _(0.5) Co _(0.2) Mn _(0.3) O _(2)(NCM523)、LiNi _(0.6) Co _(0.2) Mn _(0.2) O _(2)(NCM622)等相比存在循环性能差的缺陷。为解决这一问题,提出向碳酸酯电解液中加入电解液成膜添加剂三(三甲基硅烷)硼酸酯(TMSB),以提升NCM811/石墨软包电池的循环性能。结果表明,加入2 wt%TMSB可提高NCM811/石墨软包电池的容量保持率。通过理论计算及形貌表征发现,TMSB能够通过提前氧化还原成膜保护电池电极,从而改善电池循环性能。展开更多
LiNi0.8Co0.1Mn0.1O2(NCM811)|SiOx-graphite(SiO-Gr.)battery chemistry is of intensive attention because its achievable practical energy density is approaching impressively 300 Wh Kg^(-1).However,it still suffers rapid c...LiNi0.8Co0.1Mn0.1O2(NCM811)|SiOx-graphite(SiO-Gr.)battery chemistry is of intensive attention because its achievable practical energy density is approaching impressively 300 Wh Kg^(-1).However,it still suffers rapid capacity fades during repeated cycles,both chemical,electrochemical and mechanical irreversibility contribute.A comprehensive understanding behind the fading behavior of the cell chemistry is required before fully realize the benefits of this chemistry.Herein,the in-situ thickness variation is introduced as a diagnostic technique and is performed on 5-55 Ah NCM811|SiO-Gr cells.With the help of Li reference electrode and in-situ X-ray diffraction device,the correspondence between thickness variation and the electrode potential is carefully investigated.Firstly,the NCM811|SiO-Gr cell is characterized with the maximum cell thickness at around 80%state-of-charge(SOC)in the discharge process,rather than at 100%SOC.Secondly,the electrochemical behaviors during rate charge/discharge are diagnosed,and a Li platting signal is resolved from thickness variation profile at 2C.This work confirms that the thickness monitoring is a nondestructive and informative complement to conventional diagnostic techniques for failure analysis of pouch cells.展开更多
以Li2CO3和Ni0.5Co0.2Mn0.3(OH)2为原料,采用高温固相烧结法,合成高压实型NCM523正极材料。用X射线衍射(XRD)、扫描电子显微镜(SEM)、压实密度及充放电测试等方法,对材料的结构、形貌和电化学性能进行了表征,研究了掺杂Sr元素对三元正...以Li2CO3和Ni0.5Co0.2Mn0.3(OH)2为原料,采用高温固相烧结法,合成高压实型NCM523正极材料。用X射线衍射(XRD)、扫描电子显微镜(SEM)、压实密度及充放电测试等方法,对材料的结构、形貌和电化学性能进行了表征,研究了掺杂Sr元素对三元正极材料性能的影响。实验结果表明,掺Sr后,三元正极材料的一次颗粒和晶胞体积增大;掺杂样品的压实密度达到3.70 g/cm3,比未掺杂样品提高7.2%左右。掺Sr量为0.10%的样品,1C下比容量达到154 m Ah/g,体积比能量密度比未掺杂样品高8%,100周循环后,所合成的高压实型NCM523材料的容量保持率达到94.2%。展开更多
文摘高镍三元材料LiNi _(0.8) Co_( 0.1 )Mn _(0.1) O _(2)(NCM811)因在高电压下具有高理论比容量而被广泛应用,与高镍材料如LiNi _(0.5) Co _(0.2) Mn _(0.3) O _(2)(NCM523)、LiNi _(0.6) Co _(0.2) Mn _(0.2) O _(2)(NCM622)等相比存在循环性能差的缺陷。为解决这一问题,提出向碳酸酯电解液中加入电解液成膜添加剂三(三甲基硅烷)硼酸酯(TMSB),以提升NCM811/石墨软包电池的循环性能。结果表明,加入2 wt%TMSB可提高NCM811/石墨软包电池的容量保持率。通过理论计算及形貌表征发现,TMSB能够通过提前氧化还原成膜保护电池电极,从而改善电池循环性能。
基金funded by the Ministry of Science and Technology of China(No.2019YFE0100200,2019YFA0705703)the National Natural Science Foundation of China(No.22075064,No.21875057,U1564205 and 51706117)+1 种基金the Key-Area Research and Development Program of Guangdong Province(No.2020B090919005)the Tsinghua University Initiative Scientific Research Program(No.2019Z02UTY06).
文摘LiNi0.8Co0.1Mn0.1O2(NCM811)|SiOx-graphite(SiO-Gr.)battery chemistry is of intensive attention because its achievable practical energy density is approaching impressively 300 Wh Kg^(-1).However,it still suffers rapid capacity fades during repeated cycles,both chemical,electrochemical and mechanical irreversibility contribute.A comprehensive understanding behind the fading behavior of the cell chemistry is required before fully realize the benefits of this chemistry.Herein,the in-situ thickness variation is introduced as a diagnostic technique and is performed on 5-55 Ah NCM811|SiO-Gr cells.With the help of Li reference electrode and in-situ X-ray diffraction device,the correspondence between thickness variation and the electrode potential is carefully investigated.Firstly,the NCM811|SiO-Gr cell is characterized with the maximum cell thickness at around 80%state-of-charge(SOC)in the discharge process,rather than at 100%SOC.Secondly,the electrochemical behaviors during rate charge/discharge are diagnosed,and a Li platting signal is resolved from thickness variation profile at 2C.This work confirms that the thickness monitoring is a nondestructive and informative complement to conventional diagnostic techniques for failure analysis of pouch cells.
文摘以Li2CO3和Ni0.5Co0.2Mn0.3(OH)2为原料,采用高温固相烧结法,合成高压实型NCM523正极材料。用X射线衍射(XRD)、扫描电子显微镜(SEM)、压实密度及充放电测试等方法,对材料的结构、形貌和电化学性能进行了表征,研究了掺杂Sr元素对三元正极材料性能的影响。实验结果表明,掺Sr后,三元正极材料的一次颗粒和晶胞体积增大;掺杂样品的压实密度达到3.70 g/cm3,比未掺杂样品提高7.2%左右。掺Sr量为0.10%的样品,1C下比容量达到154 m Ah/g,体积比能量密度比未掺杂样品高8%,100周循环后,所合成的高压实型NCM523材料的容量保持率达到94.2%。
