Jiang Huize,Han Yu,Wang Hui,Zhu Yuhao,Guo Qingpeng,Jiang Haolong,Zheng Chunman,Xie Kai
The poor interface between the active materials, solid electrolytes, and conductive additives in composite cathode materials is the key factor restricting the performance of the all-solid-state lithium-sulfur battery. Here, the composite cathode material was prepared through the method of one-step ball milling. The sulfide electrolyte Li 3 PS 4 (LPS) was formed on the surface of the active material Li 2 S while the conductive additives were incorporated, and the conductive ions and electronic network were constructed simultaneously. After adding an appropriate amount of carbon nanotubes (cnt), the composite cathode exhibited high specific capacity of 1145.2 mAh g −1 after 30 times of cycling at a current density of 0.2 mA cm −2 , and the battery with ultrahigh areal Li 2 S loading also displays high capacity of 962.6 mA g −1 . The composite cathode with high Li 2 S content (56.3%) was prepared, with excellent performance exhibited: the capacity is 741 mAh g −1 after 30 times of cycling at a current density of 0.2 mA cm −2 .
Without additional sulfide electrolyte, the composite cathode materials were prepared by one-step ball milling with lithium sulfide, phosphorus pentasulfide, acetylene black, and carbon nanotubes as raw materials.
Mixed electronic and oxide ionic conduction was enabled in digermanate-type La2−xCaxGe2O7−x/2 containing Ge3O10 chains and isolated GeO4 units by substitution of La3+ with Ca2+. The structure and solid solution limit of Ca doped La2Ge2O7 were studied by systematic experiments, including rotation electron diffraction (RED), X-ray diffraction (XRD) and neutron powder diffraction (NPD) experiments, etc. The preferred occupation of Ca2+ and oxygen vacancies was investigated by Rietveld analysis of the NPD data. The obtained conducting material La1.925Ca0.075Ge2O6.963 exhibits superior thermal stability and an order of magnitude improvement in conductivity compared to the parent La2Ge2O7 (∼9 × 10−5 S cm−1 at 1000 °C). BVEL calculations reveal that the oxygen vacancies were stabilized and transported within the framework of La2Ge2O7 by sharing oxygen and oxygen exchange between the adjacent Ge3O10 chains and GeO4 units, exhibiting a three-dimensional oxide ion transport nature.
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