# Development of Ti/Ni Nanolayered Structures to
## 1 Introduction  
Supercapacitor, known as ultra-capacitor or electrochemical capacitor, considers one of the main keys for developing energy storage devices because of its good safety, long cycling life and high-power performance [1; 2; 3; 4; 5; 6; 7; 8; 9]. According to the mechanisms of charge storage, the materials of electrode have been generally classified into three types, including battery-type electrodes with diffusion-controlled Faradaic processes, pseudo-capacitor electrodes with surface electron-transfer processes, and electrochemical double-layer capacitor (EDLC) electrodes with reversible ion adsorption processes. Because of an increasing the demand of electric vehicles, many authors focused on developing the energy storage devices through constructing hybrid supercapacitors to enhance energy densities without the decline of power densities. It was achieved by combining the EDLC electrodes as negative electrodes with the battery-type electrodes as positive electrodes [10; 11]. In this trend, the electrochemical performance of supercapacitors was improved through the battery-type electrodes in the terms of energy density, specific capacitance, and working potential window leading to the balance between chemical (high-power output) and physical (high energy output) characteristics [12; 13; 14; 15; 16]. Therefore, various battery-type electrode materials were developed using Fe\({}_{3}\)O\({}_{4}\), V\({}_{2}\)O\({}_{5}\), Co\({}_{3}\)O\({}_{4}\), NiCo\({}_{2}\)S\({}_{4}\), and NiCo\({}_{2}\)O\({}_{4}\) for supercapacitors [17; 18; 19].  
Layered double hydroxides (LDHs) belong to a large family of inorganic nanolayered structures consisting of several nanolayers. These nanolayers, which contain di- and tri-valent cations, act as a cationic host because presence of di- with tri-valent metals produces positive charges. By intercalating anions among these nanolayers, nanolayered structures of LDHs are produced through host-guest interaction [20; 21; 22]. Recently, the applications of LDHs in the field of supercapacitors as battery-type materials have been attracted attention because of their high regulation of dominant compositions without the structure transformation. For instance, Ni-Co-Al-LDHs achieved high specific capacitance by [PERSON] et al. [23], where 2369 F/g was observed at a current density of 1 A/g. In addition, [PERSON] et al. reported that the maximum specific capacitance of Co-Mn LDHs was observed at the current density of 0.7 A/g and was 1063 F/g with 96% cycling stability for 5000 cycles [24]. Moreover, new opportunities for accelerating ion diffusion processes during Faradaic reactions was attractive through the exchangeable characteristic of interlayer anions among the nanolayers of LDHs host to control the inter-planar spacing and interlayer building block [24].  
Although, wide variety of materials has tested for supercapacitors [23; 24; 25; 26; 27], Ni-Ti LDHs have seldom been investigated in this field. Ni-Ti-cyanate LDHs have not reported, not even by the latest literature available [26; 27]. In this trend, the current study focuses on preparation of series of Ni-Ti LDHs. Formation of Ni-Ti LDHs at different reaction times is investigated by different techniques. Furthermore, the effect of the molar ratio of Ni/Ti on formation of LDH structure is examined through intercalation of cyanate anions. The electrochemical behavior of the prepared materials is deeply studied in the field of supercapacitors.