Energy storage and conversion systems, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting, have played vital roles in the reduction of fossil fuel usage, addressing environmental issues and the development of electric vehicles. The fabrication and surface/interface engineering of electrode materials with refined structures are indispensable for achieving optimal performances for the different energy-related devices. Atomic layer deposition (ALD) and molecular layer deposition (MLD) techniques, the gas-phase thin film deposition processes with self-limiting and saturated surface reactions, have emerged as powerful techniques for surface and interface engineering in energy-related devices due to their exceptional capability of precise thickness control, excellent uniformity and conformity, tunable composition and relatively low deposition temperature. In the past few decades, ALD and MLD have been intensively studied for energy storage and conversion applications with remarkable progress. In this review, we give a comprehensive summary of the development and achievements of ALD and MLD and their applications for energy storage and conversion, including batteries, supercapacitors, fuel cells, solar cells, and photoelectrochemical water splitting. Moreover, the fundamental understanding of the mechanisms involved in different devices will be deeply reviewed. Furthermore, the large-scale potential of ALD and MLD techniques is discussed and predicted. Finally, we will provide insightful perspectives on future directions for new material design by ALD and MLD and untapped opportunities in energy storage and conversion.

Atomic/molecular layer deposition for energy storage and conversion.

The orthosilicate, Li2MSiO4 (M = Mn, Fe, Co, Ni, …), is a competitive cathode material for next generation high-capacity (∼330 mA h g−1 with a possible 2 Li+ extraction per formula unit) rechargeable lithium-ion batteries. It is an alternative to other polyanionic compounds because the raw materials of Fe/Mn-containing oxidates and silica are abundant, cost effective, very safe, environmentally friendly, and its Si–O bond is at least as stable as other polyoxyanion groups with an excellent cycling performance. This review highlights the research progress related to the Li2MSiO4 cathode materials in terms of the phase transition of the structure, synthetic methods and techniques for improving the electrochemical performance.

Advances in high-capacity Li2MSiO4 (M = Mn, Fe, Co, Ni, …) cathode materials for lithium-ion batteries

Atomic layer deposition (ALD) provides a promising route for depositing uniform thin-film electrodes for Li-ion batteries. In this work, bis(methylcyclopentadienyl) nickel(II) (Ni(MeCp)2) and bis(cyclopentadienyl) nickel(II) (NiCp2) were used as precursors for NiO ALD. Oxygen plasma was used as a counter-reactant. The films were studied by spectroscopic ellipsometry, scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray reflectometry, and X-ray photoelectron spectroscopy. The results show that the optimal temperature for the deposition for NiCp2 was 200–300 °C, but the optimal Ni(MeCp)2 growth per ALD cycle was 0.011–0.012 nm for both precursors at 250–300 °C. The films deposited using NiCp2 and oxygen plasma at 300 °C using optimal ALD condition consisted mainly of stoichiometric polycrystalline NiO with high density (6.6 g/cm3) and low roughness (0.34 nm). However, the films contain carbon impurities. The NiO films (thickness 28–30 nm) deposited on stainless steel showed a specific capacity above 1300 mAh/g, which is significantly more than the theoretical capacity of bulk NiO (718 mAh/g) because it includes the capacity of the NiO film and the pseudo-capacity of the gel-like solid electrolyte interface film. The presence of pseudo-capacity and its increase during cycling is discussed based on a detailed analysis of cyclic voltammograms and charge–discharge curves (U(C)).

Atomic Layer Deposition of NiO to Produce Active Material for Thin-Film Lithium-Ion Batteries

Recent Insights into Rate Performance Limitations of Li-ion Batteries

Li-rich and Ni-rich transition metal oxides: Coating and core-shell structures

The authors deposited thin films of tin oxide on substrates of silicon and stainless steel by using atomic layer deposition (ALD) with tetraethyltin precursors. In this process, the authors used various coreactants such as water, oxygen, remote oxygen plasma, hydrogen peroxide, and ozone. The growth rates of films were studied as functions of the deposition temperature, the pulse times of the precursor and coreactant, and the number of ALD cycles, and the optimal growth conditions were determined. The film growth rates were found to be 0.025, 0.045, and 0.07 nm per cycle within the optimal growth conditions and ALD temperature windows for H2O2, O3, and O2 plasma, respectively. Using H2O or O2 did not prompt film growth. The films deposited using O3 and H2O2 had good continuity and low roughness, while the morphology of a coating prepared using oxygen plasma depended greatly on the deposition temperature. The films produced at temperatures below 300 °C were amorphous, irrespective of the coreactant used. X...

Atomic layer deposition of tin oxide using tetraethyltin to produce high-capacity Li-ion batteries

In this study, thin films of tin dioxide have been synthesized on substrates of silicon and stainless steel by atomic layer deposition (ALD) with tetraethyl tin and by inductively coupled remote oxygen plasma as precursors. Studies of the surface morphology by scanning electron microscopy show a strong dependence on synthesis temperature. According to the x-ray photoelectron spectroscopy measurements, the samples contain tin in the oxidation state +4. The thickness of the thin films for electrochemical performance was approximately 80 nm. Electrochemical cycling in the voltage range of 0.01–0.8 V have shown that tin oxide has a stable discharge capacity of approximately 650 mAh/g during 400 charge/discharge cycles with an efficiency of approximately 99.5%. The decrease in capacity after 400 charge/discharge cycles was around 5–7%. Synthesized SnO2 thin films have fast kinetics of lithium ions intercalation and excellent discharge efficiency at high C-rates, up to 40C, with a small decrease in capacity of less than 20%. Specific capacity and cyclic stability of thin films of SnO2 synthesized by ALD exceed the values mentioned in the literature for pure tin dioxide thin films.

Characterization and Electrochemical Performance at High Discharge Rates of Tin Dioxide Thin Films Synthesized by Atomic Layer Deposition

The cyclic stability of thin films (~40 nm) of an anode material based on tin dioxide at charging voltages of 2.5, 1.5, and 0.8 V was studied. The electrodes were prepared on a Picosun R-150 installation using tetraethyltin and remote inductively coupled oxygen plasma.

Cyclic stability of the anode material based on tin(IV) oxide for thin-film current sources

This article presents a study of cathode material LiNi0.8Co0.1Mn0.1O2 using continuous in situ x-ray diffractometry during cycling of a rechargeable cell in the range of 2.7 V to 4.8 V. Changes in the crystal structure LiNi0.8Co0.1Mn0.1O2 during charge–discharge were studied. Capacitance drop due to degradation, and dependence parameters of the material unit cell on the voltage are shown. The causes of irreversible structural degradation of the cathode material during intercalation and deintercalation of lithium ions were investigated. Results of our work can help to find a possible solution to decrease the degradation factors by understanding the degradation mechanism.

Structural Transformation of LiNi 0.8 Co 0.1 Mn 0.1 O 2 Cathode Material During Cycling with Overcharge Investigated by in situ X-ray Diffraction

Thin films of tin(IV) oxide were deposited in a Picosun R-150 installation from tetraethyltin using remote inductively coupled plasma at temperatures lower than 200°C with the aim of developing a material for thin-film current sources. The thickness and morphology of the films were studied by spectral ellipsometry and scanning electron microscopy. Both the thickness and roughness of the films considerably decrease with an increase in the synthesis temperature in the interval 100–180°C. The films are X-ray amorphous. As shown by X-ray photoelectron spectroscopy, tin in the films is in oxidation state +4.

P. A. Novikov

Papers

Atomic layer deposition of tin oxide using tetraethyltin to produce high-capacity Li-ion batteries

Characterization and Electrochemical Performance at High Discharge Rates of Tin Dioxide Thin Films Synthesized by Atomic Layer Deposition

Cyclic stability of the anode material based on tin(IV) oxide for thin-film current sources

Structural Transformation of LiNi 0.8 Co 0.1 Mn 0.1 O 2 Cathode Material During Cycling with Overcharge Investigated by in situ X-ray Diffraction

Low-temperature deposition of tin(IV) oxide films for thin-film power sources