Nanoscale Interface Modification of LiCoO₂by Al₂O₃Atomic Layer Deposition for Solid-State Li Batteries

Abstract

Cycle stability of solid-state lithium batteries (SSLBs) using a LiCoO 2 cathode is improved by atomic layer deposition (ALD) on active material powder with Al 2 O 3 . SSLBs with LiCoO 2 /Li 3.15 Ge 0.15 P 0.85 S 4 /77.5Li 2 S-22.5P 2 S 5 /Li structure were constructed and tested by charge-discharge cycling at a current density of 45 μA cm −2 with a voltage window of 3.3 ∼ 4.3 V (vs. Li/Li + ). Capacity degradation during cycling is suppressed dramatically by employing Al 2 O 3 ALD-coated LiCoO 2 in the composite cathode. Whereas only 70% of capacity retention is achieved for uncoated LiCoO 2 after 25 cycles, 90% of capacity retention is observed for LiCoO 2 with ALD Al 2 O 3 layers. Electrochemical impedance spectroscopy (EIS) and transmission electron microscopy (TEM) studies show that the presence of ALD Al 2 O 3 layers on the surface of LiCoO 2 reduces interfacial resistance development between LiCoO 2 and solid state electrolyte (SSE) during cycling.

Thermodynamic stability of sulfide electrolyte/oxide electrode interface in solid-state lithium batteries

“…Similar systems have also been examined in details [13,14]. Their results can be interpreted in terms of the present chemical potential diagrams results.…”

“…Detailed analyses [12][13][14] were made on the elemental distribution for S, P, and Co across a thin high resistive layer by STEM- Since the stability region of CoS 2 in the oxygen potential scale is still limited, a large oxygen potential gap should appear between the LiCoO 2 electrode and CoS 2 -rich electrolyte. ii) The present analyses suggest that the highly resistive layer may consist of amorphous metal oxysalts (lithium, cobalt phosphate or sulfate).…”

“…There have been investigations on the interface stability between sulfide electrolytes and oxide electrodes such as LiCoO 2 . To overcome this issue, experimental investigations were made on elemental distributions across the interface [12][13][14]. Detailed analyses lead to some considerations of the chemical processes which take place across the interfaces.…”

Comparative Study of TiS 2 /Li-In All-Solid-State Lithium Batteries Using Glass-Ceramic Li 3 PS 4 and Li 10 GeP 2 S 12 Solid Electrolytes

“…For example, Li x MO 2 (M = Co, Ni, Mn, etc., 0 ≤ x ≤ 1) cathode materials used in conventional LIBs show poor performance originating from the low oxidation onset potential of sulfide SEs (∼3 V vs. Li/Li + ) [15][16][17] and incompatibility with the sulfide SE [14]. Stable metal oxide coatings, such as Li 4 Ti 5 O 12 [14], LiNbO 3 [4,20], Li-Si-O [15], Al 2 O 3 [21], and BaTiO 3 [22], are necessary to reduce large charge transfer resistances at the interface between the sulfide SE and oxide cathode. The underlying mechanism can be explained in terms of blocking of interatomic diffusion [23] or suppression of the formation of a space charge layer in the sulfide SE [14,22].…”

Effect of Fluoroethylene Carbonate in the Electrolyte for LiNi0.5Mn1.5O4 Cathode in Lithium-ion Batteries

“…and conversion type (CoO, FeO, NiO, etc. ), as potential candidates for the negative electrode in LIBs [3][4][5][6][7]. These anode materials suffer from pulverization because of the large volume change during lithiation and delithiation.…”