The pursuit of highly efficient electrocatalysts is of utmost significance in the relentless drive to enhance the electrochemical performance of lithium-sulfur batteries. These electrocatalysts enable a predominant contribution (~75%) to the overall discharge capacity during cycling by facilitating the rapid conversion of long-chain lithium polysulfides into insoluble short-chain products (Li₂S₂ and Li₂S). Herein, high entropy sulfides derived from high entropy metal glycerate templates are synthesized and utilized as electrocatalysts. Among the evaluated materials, high entropy sulfides containing Ni, Co, Fe, Mg, and Ti (GS-3) showcases modulated spherical morphology, uniform elemental distribution, and efficient catalytic properties, outperforming high entropy sulfides containing Ni, Co, Fe, Mg, and Zn (GS-1) and high entropy sulfides containing Ni, Co, Cu, Mg, and Zn (GS-2). Consequently, a typical lithium-sulfur battery incorporating the GS-3/S/KB cathode (S loading ~2.3 mg cm⁻²) demonstrates a high initial discharge capacity of ~1061 mAh g⁻¹ at 0.5 C and stable cycling (1500 cycles) at the lowest capacity decay rate of 0.032% per cycle. The results are superior to the electrochemical performance of GS-1/S/KB (~945 mAh g⁻¹, 0.034%), GS-2/S/KB (~909 mAh g⁻¹, 0.086%), and S/KB (~748 mAh g⁻¹, 0.19%) cells. This work highlights the incorporation of titanium and other metal elements into the sulfide structure, forming high entropy sulfides (i.e., GS-3) that facilitates efficient catalytic conversion and enhances the cycling performance of lithium-sulfur batteries.

Electron/ion-conductive flexible copolymer PEDOT-PDMS (poly(3,4-ethylenedioxythiophene)-poly(dimethylsiloxane)) was successfully developed, which not only effectively optimizes high-voltage NaLiFePO₄F cathode through dripping on electrode surface but also improves high-capacity Si anode through in-situ polymerization on the surface of Si particles. Theoretical calculation and experiments indicate that π-π conjugated structure in PEDOT-PDMS molecular chains easily interacts with PF₆^– anions, providing electron transfer pathways and preventing HF production. Moreover, Li ions transfer through Si-O in the amorphous phase of the copolymer, and its Young’s modulus at rupture is 1.17±0.10 MPa. The in-situ TEM results directly confirm that the polymer layer provides conducting pathways and buffers the stress induced by lithiation. With the NaLiFePO₄F coated cathode, the cells show good cycle stability (~100% of capacity retention after 500 cycles) and high chemical diffusion coefficient of lithium-ions (1.89×10^–9 cm²·s^–1 and 1.20×10^–9 cm²·s^–1). In the case of coated Si anode, a capacity of 1512 mAh·g^–1 is retained after 1000 cycles at 0.5 C with a capacity retention of 69.8% in terms of the highest specific capacity around the 160^th cycle. This work opens a new avenue for the simultaneous optimization of cathode and anode with a functional polymer.

Since lithium sulfur (Li-S) energy storage devices are anticipated to power portable gadgets and electric vehicles owing to their high energy density (2600 Wh·kg^–1); nevertheless, their usefulness is constrained by sluggish sulfur reaction kinetics and soluble lithium polysulfide (LPS) shuttling effects. High electrically conductive bifunctional electrocatalysts are urgently needed for Li-S batteries, and high-entropy oxide (HEO) is one of the most promising electrocatalysts. In this work, we synthesize titanium-containing high entropy oxide (Ti-HEO) (TiFeNiCoMg)O with enhanced electrical conductivity through calcining metal-organic frameworks (MOF) templates at modest temperatures. The resulting single-phase Ti-HEO with high conductivity could facilitate chemical immobilization and rapid bidirectional conversion of LPS. As a result, the Ti-HEO/S/KB cathode (with 70 wt.% of sulfur) achieves an initial discharge capacity as high as ~1375 mAh·g^–1 at 0.1 C, and a low-capacity fade rate of 0.056% per cycle over 1000 cycles at 0.5 C. With increased sulfur loading (~5.0 mg·cm^–2), the typical Li-S cell delivered a high initial discharge capacity of ~607 mAh·g^–1 at 0.2 C and showcased good cycling stability. This work provides better insight into the synthesis of catalytic Ti-containing HEOs with enhanced electrical conductivity, which are effective in simultaneously enhancing the LPS-conversion kinetics and reducing the LPS shuttling effect.