Co_(0.1)Fe_(0.9)S_(2)@Li_(7)P_(3)S_(11)正极材料的制备及其在全固态锂电池中的性能

Co_(0.1)Fe_(0.9)S_(2)@Li_(7)P_(3)S_(11)composite cathode material for all-solid-state lithium batteries

全固态锂电池采用金属硫化物FeS_(2)作为正极材料能实现较高的可逆比容量,但是循环过程中较大的应力/应变和不良的固固接触引起的界面失效,严重影响了其在全固态锂电池中的电化学性能。本工作采用溶剂热法制备了Co掺杂FeS_(2)的纳米颗粒,随后在Co_(0.1)Fe_(0.9)S_(2)纳米颗粒表面原位沉积离子电导率较高的Li_(7)P_(3)S_(11)固体电解质,获得Co_(0.1)Fe_(0.9)S_(2)@Li_(7)P_(3)S_(11)纳米复合材料,并将其应用于全固态锂电池中,过渡金属Co的掺杂能提高FeS_(2)的电化学反应动力学性能,而Li_(7)P_(3)S_(11)固体电解质原位包覆能进一步改善固固接触,提高界面锂离子传输特性,继而提高全固态锂电池电化学性能。进一步通过透射电子显微镜(TEM)表征,证实了Li_(7)P_(3)S_(11)固体电解质包覆在Co_(0.1)Fe_(0.9)S_(2)纳米颗粒表面。电化学测试表明,Li_(7)P_(3)S_(11)固体电解质颗粒的包覆能有效提高以FeS_(2)为活性物质的全固态锂电池的充放电比容量和循环稳定性。Co_(0.1)Fe_(0.9)S_(2)@Li_(7)P_(3)S_(11)复合材料在200 mA/g的电流密度下,首次放电比容量达到882.1 mA·h/g,循环100圈后放电比容量仍保持在670.9mA·h/g。本研究有助于推动金属硫化物正极材料在全固态锂电池中的应用,从而为实现更高能量密度的全固态锂电池提供实验依据。

All-solid-state lithium batteries with metal sulfide pyrite(FeS_(2))as cathode can achieve a high reversible specific capacity.However,the large stress/strain and poor solidsolid contact during cycling seriously impedes the electrochemical performances of all-solidstate lithium batteries.In this work,Co-doped FeS_(2)nanoparticles are synthesized by the solvothermal method,and the Li_(7)P_(3)S_(11)solid electrolytes are in-situ coated on the surface of Co_(0.1)Fe_(0.9)S_(2)nanoparticles to form Co_(0.1)Fe_(0.9)S_(2)@Li_(7)P_(3)S_(11)nanocomposite materials.The doping of the transition metal Co can improve the electrochemical reaction kinetics of FeS_(2),and the in-situ coating of Li_(7)P_(3)S_(11)solid electrolyte can further improve the solid-solid contact and lithium-ion transportation at the interface,which results in excellent electrochemical performances of the all-solid-state lithium batteries.Transmission electron microscopy observation confirms that Li_(7)P_(3)S_(11)solid electrolyte is coated on the surface of Co_(0.1)Fe_(0.9)S_(2)nanoparticles.Electrochemical performance tests show that the coating of Li_(7)P_(3)S_(11)solid electrolyte can effectively improve the specific capacity and cycling stability of FeS_(2)-based all-solid-state lithium batteries.The Co_(0.1)Fe_(0.9)S_(2)@Li_(7)P_(3)S_(11)composite cathode delivers a high discharge capacity of 882.1 mA·h/g at 200 mA g^(−1) and maintains a value of 670.9 mA·h/g after 100 cycles.This work can promote the application of metal sulfide cathode materials for all-solidstate lithium batteries and provide experimental evidence for the development of all-solid-state lithium batteries with a higher energy density.