Solid‐State Batteries Based on Organic Cathode Materials

Abstract

Organic cathode materials (OCMs) possess high resource sustainability, large structural diversity, high theoretical energy density, and potentially low cost, however, suffer from the dissolution problem in liquid non‐aqueous electrolyte. Solid‐state batteries (SSBs) are regarded as the final solution of Li and Na metal batteries because of the intrinsic safety, but hindered by many challenges including the poor contact with rigid inorganic cathode materials. Therefore, applying OCMs in SSBs is probably a win‐win strategy to compensate for their respective deficiency. In this review, some fundamental knowledge of OCMs and SSBs are briefly introduced at first, with emphasis on different types of solid‐state electrolytes (SSEs). Then the reported works on OCM‐based SSBs are summarized by classifying them into non‐ceramic, semi‐ceramic, and all‐ceramic ones. Finally, we conclude our understandings on the main scientific issues and possible solutions. To sum up, the combination of OCMs and SSBs brings about many new challenges but also opportunities towards their practical application.

Organic Cathodes, a Path toward Future Sustainable Batteries: Mirage or Realistic Future?

“…A fast capacity drop most often occurs due to the high solubility of the active material, which can be, in certain cases, accompanied by shuttling of redox active species, resulting in a very low Coulombic efficiency . Solubility issues can be addressed by electrolyte tuning targeting the lower solubility of active materials in an electrolyte or by increasing the concentration of the salts or variation of solvents. − Other methods for limiting the dissolution of active material are being grafted onto an insoluble support, , infiltration inside mesoporous materials, − use of ionoselective membranes, use of ionic liquids, , semipermeable electrolytes (ceramic, polymer, and gel), ,− and polymerization (Figure ). ,,, However, certain approaches only slow or delay dissolution, and special care has to be taken to evaluate dissolution during prolonged cycling at low rates.…”

Reviving Cost‐Effective Organic Cathodes in Halide‐Based All‐Solid‐State Lithium Batteries

“…This configuration not only enhances safety but also allows for the potential use of lithium metal as an anode, offers a wide operating temperature range, and reduces packaging requirements [13–15] . More importantly, the inherent properties of inorganic SEs could intrinsically address the dissolution and shuttle issues associated with organic cathode materials, paving the way for utilizing readily available and cost‐effective commercial organic small molecules as cathode materials [16,17] …”

“…Unlike organic liquid electrolytes, inorganic SEs are believed to fundamentally inhibit the loss of organic cathode materials [16,17] . Given that some sulfide‐based all‐solid‐state lithium‐organic batteries have been reported, we first tried the PQ cathode with a representative sulfide SE Li 6 PS 5 Cl (LPSC).…”

“…[13][14][15] More importantly, the inherent properties of inorganic SEs could intrinsically address the dissolution and shuttle issues associated with organic cathode materials, paving the way for utilizing readily available and cost-effective commercial organic small molecules as cathode materials. [16,17] To date, a diverse range of inorganic SEs with distinct characteristics have been developed, such as oxides, sulfides, and halides. [14,18,19] Among them, sulfide-based SEs (e.g., Li 10 GeP 2 S 12 and Li 6 PS 5 Cl) have garnered significant attention because of their high ionic conductivity and good processibility.…”

“…Unlike organic liquid electrolytes, inorganic SEs are believed to fundamentally inhibit the loss of organic cathode materials. [16,17] Given that some sulfide-based all-solid-state lithium-organic batteries have been reported, we first tried the PQ cathode with a representative sulfide SE Li 6 PS 5 Cl (LPSC). The LPSC, synthesized by ball milling and post annealing, showed a cubic structure with F4 À 3 m space group and a high ionic conductivity of 1.5×10 À 3 S cm À 1 , which were consistent with previous reports (Figure S4).…”