为满足能源需求,高容量电池体系如锂硫电池、

2019-08-23
本网记者
原创
101
摘要:为满足能源需求,高容量电池体系如锂硫电池、锂-空气电池、锂金属电池等成为研究热点。在这些体系中,锂金属负极存在许多问题:  (1)锂枝晶的生长容易引发短路,造成安全隐患

为满意能源需求,高容量电池系统如锂硫电池、锂-空气电池、锂金属电池等成为研讨热门。
在这些系统中,锂金属负极存在许多问题:  (1)锂枝晶的成长简单引发短路,形成安全隐患;  (2)固体电解质界面膜(Solid electrolyteinter phase, SEI)的不安稳性,导致电解液的耗费并下降电池库伦功率和循环寿数,这些问题严峻阻止了这些高容量电池系统的开展和实践使用。
  固态电解质具有较高的离子电导率和必定的机械强度,在很大程度上可进步锂电池安全性,即便在全固态锂电池(All-solid-state Li batteries,ASSLBs)中发作短路,不可燃的固态电解质也可防止着火和爆破的发作。
  别的,固态电解质可确保电池的高能量/功率密度和长循环寿数,在进步电池安稳性方面有很大开展潜力。
但电解质-电极间往往有较大界面电阻,阻止了离子传输。
  最近,Luo等经过在石榴石型固态电解质外表堆积硅层,完成电解质外表从疏锂到亲锂的改变,减小固-固界面电阻,对进步锂金属电池的安全安稳性有重要意义。
  Figure 1. Transitionfrom Super-lithiophobicity to Super-lithiophilicity of Garnet leads to a muchsmaller interfacial resistance.  试验以Nb、Ca共掺杂Li7La3Zr2O12为研讨系统,制备Li6.85La2.9Ca0.1Zr1.75Nb0.25O12(LLZ)固态电解质。
其间Nb可安稳立方相,增强锂离子传导;Ca可下降烧结温度。
经过PECVD在外表堆积很薄的硅层,可使界面电阻减小7倍,并保持安稳的循环功能。
该团队还经过理论核算对该现象进行证明。
  综上,该作业提出经过堆积亲锂金属可有用下降固态电解质-电极界面电阻,对进步锂金属电池的安全性具有指导意义。
  Figure 2.Evaluation of LLZ wettability with Li metal. (a) Schematic showing the designed LLZ pellet with only one half (orange) selectively coated with amorphous Si.(b) SEM image showing the contrast between the bare LLZ area and the Si-coatedarea. (c) A homemade setup for the wettability evaluation, where molten Li was loaded in a stainless steel boat on a hot plate (~200 °C). Digitalimages of the half-coated LLZ pellet before and after dipping in molten Li for.(d) 0, (e) 1, and (f) 4 s. This shows the dramatic wettability transition of LLZ from superlithiophobicity to superlithiophilicity using an amorphous Si coating.  Figure 3. Electrochemical performance of symmetriccells using Si-coated and bare LLZ. Schematic illustration showing the structure of symmetric cells with (a) LLZ or (b) Si-coated LLZ SSEs.(c)Electrochemical impedance spectroscopy (EIS) measurements of symmetric cells where the interfacial resistance of the Si-coated garnet cell was significantlydecreased. (inset) Digital image of a Li/Si-coated LLZ/Li symmetric cell. (d)Long-term cycling performance of the Li/Si-coated LLZ/Li symmetric cell at current densities of 0.05 and 0.1mA/cm2. (e) Voltage profiles of theLi/Si-coated LLZ/Li symmetriccell at current densities of 0.1 and 0.2 mA/cm2.  相关研讨成果宣布在闻名刊物Journal of the American Chemical Society上(DOI:10.1021/jacs.6b06777. WeiLuo,Yunhui Gong,Yizhou Zhu,Kun Kelvin Fu et al. Transition from Superlithiophobicity to Superlithiophilicity of Garnet Solid-State Electrolyte.J. Am. Chem. Soc. 2016.)

欧根耐高低温有限公司

欧根耐高低温有限公司