(Keynote) Facile Fabrication of High-Performance Lib Anode and Cathode Materials on Al and Ti By Smart Anodization and Hybrid Electrodeposition
Authors: Kure-Chu Song-Zhu , Inoue Takato , Sakuma Yota , Chen Xuewen , Hihara Takehiko , Yashiro Hitoshi 
Published: December 2020

Aluminum and titanium materials are well known as typical light metals which are widely applied to versatile products for their high corrosion resistance, conductive and decorative properties, etc. Recently, aluminum and titanium materials are paid extensive attention to battery industry, using as current collectors or electrode materials. Lithium-ion batteries (LIBs) are known as important power sources in many electric/electronic products such as cellular phones, digital cameras, portable computers, as well as electric vehicles (EVs) and hybrid electric vehicles (HEVs). To meet the ever-expanding needs for lithium-ion battery industry, it is an urgent task to develop new technologies for producing LIB materials with optimal performance-safety balance, and to substituting conventional sintering-casting process by cost-effective process in manufacture of LIBs. In this study, we report three new processes to fabricate cathode and anode materials for LIBs as below.

Fabrication of Li-V-Mn-Ni-O composite films on Al by a hybrid electrodeposition for LIB Cathodes

Fig.1a shows a cross-sectional scheme of Li-V-Mn-Ni-O composite films on Al foils. Different from the conventional sintering methods for producing LiCoO2-based LIB cathodes, we proposed a novel hybrid electrodeposition to fabricate Li-V-Mn-Ni-O composite films directly on Al, which is expected to increase the working potential with Li ions above 4 V vs. Li+/Li and to decrease the cost of active materials. The composite films were obtained by a cathodic electrodeposition in ethanol-water bath containing V5+、Ni2+, Mn2+, and Li+ ions. Before electrodeposition, an electro-etching pretreatment was adopted to enhance the adhesion between the Al substrate and the electrodeposits. It is found that the resultant composite films after annealing consists of V2O5, Li2MnO4, NiOOH, and metallic Li components. The cyclic voltammetric measurements detected three peaks at 3.2, 4.01, and 4.33 V vs. Li+/Li, which can be ascribed to the Li extraction reactions from the substance mentioned above, indicating the composite films worked as active materials as LIB cathodes.

Formation of nanoporous TiO2-TiO-TiN composite films on Ti by a smart anodization for LIB anodes

Nanoporous anodic TiO2 films are considered as promising LIB anode materials to solve the safe issue caused by lithium electrodeposition during charge/discharge process as use C-base anodes conventionally. However, the poor conductivity and low theoretic capacity of TiO2 materials are big concerns for practical uses for high density LIBs. Here, we formed successfully nanoporous TiO2-TiO-TiN composite films on Ti foils by a smart anodization in aqueous NO3
–-based solutions and found that the inclusion of conductive TiN component in TiO2 matrix film improved the electronic conductivity effectively (Fig.1.b). The TiO2-TiO-TiN composite films after being heated at 150–500 ºC can be used as binder-conductive reagent free LIB anodes and exhibited higher capacity than ordinary TiO2 films.

Fabrication of TiO2-TiN/M-MOx (M = Sn, Mo) composite films on Ti by Hybrid electrolytic process

In order to increase the capacity of anodic TiO2-TiN films, we conducted various electrodeposition of Sn-based and Mo-based materials with high theoretic capacities into the anodic TiO2-TiN matrix films, as shown in Fig.1c. The inclusion of highly conductive TiN component in TiO2 matrix film during anodization endows the necessary electronic conductivity for the successive cathodic hybrid electrodeposition of various active materials with high theoretic capacities. The one approach is to fill Sn and SnO2 nanoparticles into TiO2-TiN matrix films by using an acidic plating bath containing different Sn ions. This not only increased the areal specific capacity in 4–9 times compared to the anodic TiO2-TiN films, but also improved the conductivity of the composite films. Another approach is to fill Mo-based materials from a molybdate solution. It is found by XPS analysis that the resultant Mo-based deposits composed of molybdate oxides (MoO2-MoO3) and molybdate nitrides (Mo2N-MoN). The electrodeposition of Mo-based materials into TiO2-TiN films improved the conductivity of the composite films significantly due to the high conductive components of molybdate nitrides. As a result, TiO2-TiN/MoOx-MoyN composite films exhibited around 5 times higher discharge capacity than the TiO2-TiN films and excellent cycling performance with a retention of 97%, indicating a promising anode material with high power density and high safety for LIBs.

Figure 1