摘要
锂金属是下一代高能量密度电池的关键负极,然而其实用化面临着一系列问题,主要包括循环过程中体积变化大、枝晶生长等。使用三维集流体是解决这些问题的有效方法,然而现有大多数三维集流体存在重量大、体积大、表面亲锂性差、成本高等问题。针对上述问题,本文以低成本的细菌纤维素为前驱体,通过直接碳化制备出具有连通网络的轻质三维碳集流体,其表面均匀分布的含氧官能团可以促进锂离子的均匀成核和沉积,有效抑制了枝晶生长。值得注意的是,该集流体的面密度仅为0.32 mg·cm^(−2),在3 mAh·cm^(−2)比容量的锂金属负极中质量占比仅为28.8%。电化学测试结果表明,该集流体在3 mA·cm^(−2)的高电流密度或4 mAh·cm^(−2)的高循环容量的工作条件下,稳定循环超过150次,并且在对称电池或与LiNi0.8Co0.15Al0.05匹配的全电池中也表现出良好的电化学性能。
Lithium(Li)metal anodes are critical components for next-generation high-energy density batteries,owing to their high theoretical specific capacity(3800 mAh·g^(−1))and low voltage(−3.040 V versus the standard hydrogen electrode).However,their applications are hindered by dendrite growth,which potentially induces inner short circuit and leads to safety issues.Employing three-dimensional(3D)current collectors is an effective strategy to suppress dendrite growth by decreasing the local current density.However,many of the reported 3D current collectors have a lithiophobic surface,which leads to non-uniform Li+ion deposition.Thus,a complicated modification process is required to increase the lithiophilic property of the current collectors.In addition,they have a large weight or volume,which greatly lowers the energy density of the entire anode.In this work,we report a lightweight 3D carbon current collector with a lithiophilic surface by employing the direct carbonization of low-cost bacterial cellulose(BC)biomass.The current collector is composed of electrically conductive,robust,and interconnected carbon nanofiber networks,which provide sufficient void space to accommodate a large amount of Li and buffer the volume changes during Li plating and stripping.More importantly,homogeneously distributed oxygen-containing functional groups on the nanofiber surface are retained by controlling the carbonization temperature.These functional groups serve as uniform nucleation sites and help realize uniform and dendrite-free Li deposition.Notably,the areal mass density of the 3D carbon current collector was only 0.32 mg·cm^(−2) and its mass ratio in the whole anode was 28.8%,with a capacity of 3 mAh·cm^(−2).This 3D carbon current collector facilitates the stable working of the half cells for 150 cycles under a high current density of 3 mA·cm^(−2) or a high capacity of 4 mAh·cm^(−2).Symmetric cells exhibit a steady cycling life as long as 600 h under a current density of 1 mA·cm^(−2) and a capacity of 1 mAh·cm^(−2).Moreover,appreciable cycling performance was realized in the full cells when the anodes were paired with LiNi0.8Co0.15Al0.05 cathodes.Furthermore,the low-cost raw materials and the simple preparation method promise significant potential for the future applications of the proposed 3D current collectors.
作者
张云博
林乔伟
韩俊伟
韩志远
李曈
康飞宇
杨全红
吕伟
Yunbo Zhang;Qiaowei Lin;Junwei Han;Zhiyuan Han;Tong Li;Feiyu Kang;Quan-Hong Yang;Wei Lü(Tsinghua-Berkeley Shenzhen Institute(TBSI),Tsinghua University,Shenzhen 518055,Guangdong Province,China;Shenzhen Geim Graphene Center,Tsinghua Shenzhen International Graduate School,Tsinghua University,Shenzhen 518055,Guangdong Province,China;State Key Laboratory of Chemical Engineering,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China.)
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2021年第2期142-150,共9页
Acta Physico-Chimica Sinica
基金
国家重点研发计划(2018YFE0124500)
国家自然科学基金(51972190)
广东省杰出青年自然科学基金(2017B030306006)
深圳市科技计划基础研究(学科布局)项目(JCYJ20180508152037520)资助。
关键词
锂金属负极
细菌纤维素
三维集流体
锂枝晶
含氧官能团
Lithium metal anode
Bacterial cellulose
Three-dimensional current collector
Lithium dendrite
Oxygen-containing functional group