Recent Advancements in Interface between Cathode and Garnet Solid Electrolyte for All Solid State Li-ion Batteries

doi:10.15541/jim20180512

Abstract

Abstract:

All-solid-state lithium battery (ASSLB) with inorganic solid state electrolytes is one of promising candidates for electric vehicles and large-scale smart grids for storage of alternative energy resources due to their benefits in safety, energy density, operable temperature range, and longer cycle life. As the key component in ASSLB, inorganic lithium-ion-based solid-state electrolytes (SSEs), especially the garnet-type solid electrolytes that own ionic conductivities in the order of 10 ^-3 S·cm ^-1 at room temperature and are relative safe vs. Li metal, have obvious advantages in ASSLB. However, interfacial instability and their poor solid-solid contact between garnet and cathode result in high interfacial resistance, low efficiency, and poor cycle performance. Based on these understandings and analyses of interface characteristics and issues, this work presents a brief review on modification of interface, covering composite cathode, composite electrolyte, interface engineering, and interface layer．Some approaches of improving interface wettability and future research directions of ASSLB are given as well, which endeavor to realize the practical applications of ASSLB.

Key words: inorganic solid state electrolyte, composite electrolyte, interfacial wettability, interfacial impendence, interface modification, review

CLC Number:

TM911

LI Dong, LEI Chao, LAI Hua, LIU Xiao-Lin, YAO Wen-Li, LIANG Tong-Xiang, ZHONG Sheng-Wen. Recent Advancements in Interface between Cathode and Garnet Solid Electrolyte for All Solid State Li-ion Batteries[J]. Journal of Inorganic Materials, 2019, 34(7): 694-702.

Figures/Tables 8

Fig. 1 Conductivity of different types of solid electrolytes at room temperature[17]

Fig. 2 Driving force for interphase formation between electrolyte, and cathode, with varying voltage from 0 to 5 V vs lithium metal [Legend: blue, LCO; red, LMO; green, LFP; thick line, LLZO; thin line, LLTO]. The calculated intrinsic stability windows are marked along the bottom for reference[50]

Fig. 3 (a) Typical scanning electron microscope (SEM) image of the interface between composite cathodes and LLZTO electrolyte; (b) SEM image for the surface of LLZTO ceramic; SEM images of the composite cathodes which were measured in (c) the second-electron and (d) the back-scatter-electron mode[53]

Fig. 4 Schematic illustration of the synthesis procedure[57] (a) Microscale LLZO particles; (b) Nanoscale LLZO particles; (c) Nanoscale LLZO slurry; (d) Cathode layer of LFP; (e) LLZO film; (f) All-solid-state battery of Li/LLZO/LFP

Fig. 5 (a) Schematic illustrations of non-modified and Nb-modified LLZ/LiCoO2 interfaces. The mutual diffusion between LLZO and LiCoO2 produces non-Li+-conductive phases such as a crystalline La2CoO4 phase. Nb-modified LLZ/LiCoO2 interface suppresses the mutual diffusion and produce Li+-conductive amorphous phase; (b) Cross-sectional-HAADF-STEM image of a Nb-modified interface between LLZO and LiCoO2[65]. EDX elemental mappings in (b) for Co (red), Nb (purple), and La (green) are overlaid in the dashed-line-enclosed region. The top Pt is a protective layer for FIB processes

Fig. 6 SEM image of the interface between LFP composite cathode containing 15wt% polymer and the LLZTO composite electrolyte[72]

Fig. 7 Solid-state LFP or LFMP/Li cells using PEO/LLZTO@IL membranes[78]

Table 1 Performances of ASSLBs based on garnet-type Li7La3Zr2O12 solid electrolytes

Electrolyte	Ion-conductivity/ (mS·cm^-1)	Cathode materials	Interface Engineering	Test condition	Discharge capacity /(mAh·g^-1)	Ref.
Li_6.20Ga_0.30La_2.95Rb_0.05Zr₂O₁₂	1.62	LiFePO₄	Coating	60 ℃, 5 μA·cm^-2 2.8-4.0 V	152(1^st), 110(20^th)	[24]
Li_6.4La₃Zr_1.4Ta_0.6O₁₂	1.60	LiFePO₄	Coating	60 ℃, 0.05C 2.76-4.00 V	150(1^st), 140(100^th)	[53]
Li₇La₃Zr₂O₁₂	2.40	LiFePO₄	Coating	25 ℃ 0.1C	160.4 (1^st), 136.8 (100^th)	[57]
Li_6.75La₃Zr_1.75Nb_0.25O₁₂	1.67	LiCoO₂	PLD	25 ℃, 3.5 μA·cm^-2 2.5-4.2 V	129 (1^st), 127(100^th)	[61]
Li_6.8(La_2.95Ca_0.05)(Zr_1.75Nb_0.25)O₁₂	0.36	LiCoO₂	Co-sintering	1 μA·g^-1, 3.0-4.2 V	78(1^st)	[47]
Li₇La₃Zr₂O₁₂(1.7wt% Al, 0.1wt% Si)	0.68	LiCoO₂	PLD	1 mA·cm^-2, 3.2-4.2 V	80 (1^st)	[65]
Li_6.75La₃Zr_1.75Nb_0.25O₁₂	1.23	LiCoO₂	Screen-printing	25 ℃, 10 μA·cm^-23.00-4.05 V	85(1^st)	[64]
Li_6.75La₃Zr_1.75Ta_0.25O₁₂	～1.00	LiCoO₂	Coating+ co-sintering	5 μA·cm^-2	101.3(1^st)	[54]
Li_6.75La₃Zr_1.75Ta_0.25O₁₂	0.74	LiNi_0.5Co_0.2Mn_0.3O₂	Tape casting	80 ℃, 5 μA·cm^-23.0-4.6 V	123.3 (1^st), 76.6 (5^th)	[56]
Li_6.25Al_0.25La₃Zr₂O₁₂	0.50	Li₄Ti₅O₁₂	Coating	95 ℃, 2-8 μA·g^-1 1.0-2.5 V	15(1^st)	[81]

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