Solid electrolytes are ion-conducting solids that replace the liquid salt solution in an electrochemical cell and act at the same time as the separator between the electrodes. Garnet-type oxide ceramics doped with aluminium, niobium or germanium reach conductivities of 10-4 to 10-3 S per centimetre at room temperature once they are sintered to high density [1], and substitution on the zirconium site has been reported to raise the value further [2]. Sulfide glasses and glass-ceramics conduct lithium faster, in some compositions above 10-3 S per centimetre, and being softer they can be densified by cold pressing, but they release hydrogen sulfide on contact with moisture [3]. Polymer and ceramic-polymer composite electrolytes trade conductivity for compliance and ease of processing [4]. In a cell the total resistance is rarely set by the bulk alone: grain boundaries, space-charge layers and the electrode-electrolyte interface add to it, and the contact area changes as the electrode expands and contracts during cycling, so interlayers and external pressure are used to keep the interface intact [5]. Lithium penetration along grain boundaries and pores limits the usable current density, and how to suppress it without raising the interfacial resistance is still debated [3].
- solid electrolyte
- ionic conductivity
- garnet
- sulfide electrolyte
- all-solid-state battery
- electrode-electrolyte interface
Advanced Battery Materials and Technologies·Electrical and Electronic Engineering·Engineering·Physical Sciences
References
- Ji, Y.; Zhou, C.; Lin, F.; Li, B.; Yang, F.; Zhu, H.; Duan, J.; Chen, Z.; Submicron-Sized Nb-Doped Lithium Garnet for High Ionic Conductivity Solid Electrolyte and Performance of Quasi-Solid-State Lithium Battery. Materials 2020, 13, 560, 10.3390/ma13030560.
- Hu, S.; Li, Y.F.; Yang, R.; Yang, Z.; Wang, L.; Structure and ionic conductivity of Li7La3Zr2-xGexO12 garnet-like solid electrolyte for all solid state lithium ion batteries. Ceramics International 2018, 44, 6614-6618, 10.1016/j.ceramint.2018.01.065.
- Sakuda, A.; Hayashi, A.; Tatsumisago, M.; Sulfide Solid Electrolyte with Favorable Mechanical Property for All-Solid-State Lithium Battery. Scientific Reports 2013, 3, 2261, 10.1038/srep02261.
- Kobayashi, Y.; All-solid-state lithium secondary battery with ceramic/polymer composite electrolyte. Solid State Ionics 2002, 152-153, 137-142, 10.1016/s0167-2738(02)00366-1.
- Chen, K.; Yamamoto, K.; Orikasa, Y.; Uchiyama, T.; Ito, Y.; Yubuchi, S.; Hayashi, A.; Tatsumisago, M.; Nitta, K.; Uruga, T.; et al. Effect of introducing interlayers into electrode/electrolyte interface in all-solid-state battery using sulfide electrolyte. Solid State Ionics 2018, 327, 150-156, 10.1016/j.ssi.2018.10.010.