新能源汽车固态电池中的锂枝晶抑制研究

Study on lithium dendrite suppression in solid state batteries for new energy vehicles

相比于商业化的锂离子电池,固态电池具有更高的能量密度和更好的安全性。然而,固体电解质依旧面临锂枝晶生长的问题。以目前已大规模工业化的聚氧化乙烯(PEO)基电解质作为研究对象,通过将PEO与高杨氏模量的石榴石型电解质复合,抑制了锂枝晶在PEO基复合电解质中的生长,不仅使电解质膜的离子电导率从9.8×10^(-6) S/cm增加到了3.8×10^(-4) S/cm,还使锂/锂对称电池的临界电流密度从0.4 mA/cm^(2)提高到1.6 mA/cm^(2)。与此同时,组装的基于金属锂负极与传统石墨负极的软包电池可分别获得334.5 W·h/kg与218.2 W·h/kg的能量密度。其中,钴酸锂/复合电解质/石墨软包全电池循环1000次后的容量保持率可达92.3%,能够满足新能源汽车的需求。

Solid‑state batteries possess higher energy density and better safety than commercial lithium‑ion batteries.However,solid electrolytes are still suffered from lithium dendrite growth.The current large-scale industrialized polyvinyl oxide(PEO)-based electrolyte was used as the research object.By combining PEO with garnet type electrolyte with high Young′s modulus,the effective inhibition of Li dendrite growth in PEO based composite electrolyte was realized.The ionic conductivity of the electrolyte membrane was increased from 9.8×10^(-6) S/cm to 3.8×10^(-4) S/cm,and the critical current density of the Li/Li symmetric battery was increased from 0.4 mA/cm^(2) to 1.6 mA/cm^(2).Meanwhile,the assembled pouch cell based on Li metal anode and conventional graphite anode could obtain the energy density of 334.5 W·h/kg and 218.2 W·h/kg,respectively.Additionally,the capacity retention rate of Li cobalate/composite electrolyte/graphite pouch cell was 92.3%after 1000 cycles,which met the demand of new energy vehicle.