Low‐Resistive LiCoO₂/Li_1.3Al_0.3Ti₂(PO₄)₃ Interface Formation by Low‐Temperature Annealing Using Aerosol Deposition

Abstract

Interfacial resistance at electrode‐high Li+ conductive solid electrolytes must be reduced well to develop high‐power all‐solid‐state batteries using oxide‐based solid electrolytes (Ox‐SSBs). Herein, crystalline electrode films of LiCoO2 (LCO) are formed on a high Li+ conductive crystalline‐glass solid electrolyte sheet, Li1.3Al0.3Ti2(PO4)3 (LATP) (σ25 °C = 1 × 10−4 S cm−1), at room temperature by aerosol deposition (AD), and the effects of the annealing temperature on the interfacial resistivities (Rint) at the LCO/LATP are investigated. The Rint visibly increases by annealing over 500 °C with the growth of Co3O4 as a reactant. In contrast, Rint is reduced to ≈100 Ω cm2 by low‐temperature annealing at 250–350 °C due to superior contact through the structural rearrangement of an artificial metastable interface formed by the AD. These results are applied to bulk‐type Ox‐SSB, Li/Li7La3Zr2O12(LLZ)/LCO–LATP, and our best Ox‐SSB delivers a discharge capacity of 100 mA cm−2 at 100 °C.

Co-sintering process of LiCoO2 cathodes and NASICON-type LATP solid electrolytes studied by X-ray diffraction and X-ray absorption near edge structure

“…However, the sintering of the reactive substances often results in undesired side reactions. [19][20][21][22][23][24] For example, a highly ion-conducting solid electrolyte, LATP and a high-capacity cathode material, LCO which is practically used in conventional liquid LIBs, fatefully react with each other to produce completely different species instead of forming a well-defined interface. 1,23 Although a few experimental results on the co-sintering products of LCO and LATP studied by XRD have been reported, [25][26][27] the main purpose of these previous reports was not the clarification of the reaction mechanism but fabrication of ASSLIBs.…”

“…[19][20][21][22][23][24] For example, a highly ion-conducting solid electrolyte, LATP and a high-capacity cathode material, LCO which is practically used in conventional liquid LIBs, fatefully react with each other to produce completely different species instead of forming a well-defined interface. 1,23 Although a few experimental results on the co-sintering products of LCO and LATP studied by XRD have been reported, [25][26][27] the main purpose of these previous reports was not the clarification of the reaction mechanism but fabrication of ASSLIBs. Hence, co-sintering was performed only for short periods of time (1-2 h) to form well-defined interfaces with a relatively high ion-conductivity while avoiding or minimizing the undesired reaction between LCO and LATP.…”

“…However, the sintering of the reactive substances often results in undesired side reactions. 19–24 For example, a highly ion-conducting solid electrolyte, LATP and a high-capacity cathode material, LCO which is practically used in conventional liquid LIBs, fatefully react with each other to produce completely different species instead of forming a well-defined interface. 1,23…”

All‐Solid‐State Thin Film μ‐Batteries for Microelectronics

“…There are many available deposition technologies for thin film growth, including sol-gel method, [301][302][303][304] inkjet printing, [305,306] rf-sputtering, [174,206,210,229,230,258,307,308] plasma spray PVD (PS-PVD), [309] PLD, [310,311,312] chemical vapor deposition (CVD), [313] aerosol deposition, [314] ion-beam assisted deposition, [315] and ebeam evaporation. [316] The review article by Lobe et al [308] well documented various deposition technologies.…”

Structural Analysis of the LiCoPO4 Electrode/NASICON-Type Li1.3Al0.3Ti1.7(PO4)3 Solid Electrolyte Interface

“…The conventional manufacturing process to obtain the oxide-based solid electrolyte/electrode material interfaces is sintering at high temperatures , because those materials have a high melting point and poor plasticity. However, co-sintering of oxide-based solid electrolytes and electrode materials often results in undesirable side reactions. − For example, sintering the mixture of highly Li-ion-conducting NASICON-type solid electrolytes (LiM 2 (PO 4 ) 3 ) and layered rock salt-type (LiMO 2 ) or spinel-type lithium metal oxides (LiM 2 O 4 ) often induces severe side reactions. − In our previous study, we found that a NASICON-type solid electrolyte, Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP), and a layered rock salt-type cathode material, LiCoO 2 , commonly used in conventional liquid LIBs, reacted with each other to produce various species rather than forming a well-defined interface, even at 300 °C …”