Manufacture of Lithium Lanthanum Titanate Active Material as a Lithium-Ion Capacitor Anode Using Solid-State Reaction Methods

Lithium lanthanum titanate, Li 0.2 La 0.6 TiO 3 (LLTO) was synthesized for the manufacture of lithium-ion capacitors using the solid-state reaction method. in this study, the active ingredients were synthesized using variations of lithium and lanthanum as raw materials. The raw materials used are Li 2 CO 3 , La 2 O 3 , and TiO 2 . The three raw materials were mixed according to the stoichiometric calculations then added 13 ml of Ethanol solution so that the raw materials were mixed evenly during the milling process for 5 hours. Sintering was carried out for 8 hours at 800 o C and then at 1150 o C for 12 hours. The sintered powder was ground using a mortar and pastel and then sieved on a 400 mesh sieve. The anode sheet was made by mixing the active ingredients: PVDF: Super-P with a composition of 85:10:5 by adding 3 ml of DMAC solvents. The characterization test was carried out using XRD while the electrochemical test used CV and EIS. The XRD result shows the formation of the main phase and the impurity phase with the main phase percent of 96.4%.

How to cite: S. Humaidi, A. Rifai, E. Pratiwi, "Manufacture of lithium lanthanum titanate active material as a lithium-ion capacitor anode using solid-state reaction methods," Journal of Technomaterial Physics, vol. 5, no.

Introduction
Lithium-ion capacitors were first produced in 2001 and are considered to be one of the most effective devices for energy storage.LIC can provide high power density (>10 kW/Kg) and long lifetimes (typically > 5000 cycles) [1] - [4].However, to meet the need for greater electrical energy, an efficient lithium-ion supercapacitor (LIC) was developed further.Lithium-Ion Capacitors are rechargeable energy storage systems, which belong to the class of hybrid capacitors or asymmetric capacitors and can b classified between lithium-ion batteries and electric double-layer capacitors (EDLC) where the positive electrode uses activated carbon as in conventional EDLC [5] - [8].Lithium Ion Supercapacitor (LIC) is an ideal choice which has a higher energy density than electric double-layer capacitors and has a better rate capacity than lithium-ion batteries [9].Supercapacitors have several advantages, namely higher power density, Faster charging, and longer cycle life and shelf life.This shows that the supercapacitor has a much greater energy density than conventional capacitors and a much greater power density than the battery.
The most important criterion for selecting anode material is the potential of the electrode.Li 4 Ti 5 O 12 material is known as a high-grade anode material, while its drawbacks, such as low capacity and too high working potential can severely limit the output energy density of a full cell.So, there is still a big challenge to find suitable host material for Li + with multiple functions of high capacity and safe potency.therefore, the material Li 3X La 2X TiO 3 a group of beneficial anode materials was developed as seen this anode shows a high specific capacity of 225 mA.h.g -1 and supports 3000 cycles involving a reversible phase transition.Without reducing the particle size from micro to nanoscale, its speed performance has surpassed that of nanostructured Li 4 Ti 5 O 12 .further characterization and calculations revealed that pseudocapacitance determines the lithium and ion storage processes that are favorable for electronic transport such as electric cars and are responsible for the advancement of the technology [10].

Method
In this study, the synthesis of lithium lanthanum titanate with a solid-state reaction method.the research includes raw material preparations, synthesis process, drying process, calcination process, and characterization.anode material Li 0.2 La 0.6 TiO 3 (LLTO) was synthesized for the manufacture of lithium-ion capacitors using the solid-state reaction method.in this study, the active ingredients were synthesized using variations of lithium and lanthanum as raw materials.the raw materials used are Li 2 CO 3 , La 2 O 3 , and TiO 2 .The three raw materials were mixed according to the stoichiometric calculations then added 13 ml of Ethanol solution so that the raw materials were mixed evenly in the milling process for 5 hours.After milling using a planetary ball miller, the sample will be dried at 70 o C to remove the remaining ethanol in the sample.Sintering was carried out for 8 hours at 800 o C and then at 1150 o C for 12 hours.The sintered powder was ground using a mortar and pastel and then sieve on a 400 mesh sieve.The anode sheet was made by mixing the active ingredients: PVDF: Super-P with a composition of 85:10:5 by adding 3 ml of DMAC solvents.The characterization test was carried out using XRD while the electrochemical test used Electrochemical impedance Spectroscopy (EIS) and Cyclic Voltammetry (CV).At different velocities of 0.1 mV/s -1 -10 mV/s -1 shows broad anode and cathode peaks with a quasirectangular shape that extends across all scanning speeds indicating the contribution of pseudocapacitive during the intercalation and deintercalation process of the relationship between currents at A certain potential with a scan rate can determine the b-value determined by the ion storage mechanism and can be calculated by plotting slope (slope) log(I) log(V).To be more specific, an ab value of 0.5 means the process is completely diffusion controlled, while an ab value of 1.0 indicates a faradaic contribution from charge transfer with surface or subsurface atoms (pseudocapacitance effect) or a non-faradaic contribution from the electrical double layer effect.Quantitatively, the capacitive contribution can be determined by separating the current (I) at a certain potential (V) into capacitive (linear relationships with sweeps rates marked as k1(V)V and diffusion control (proportional to V 1/2 ) marked as k2(V)V 1/2 as in the equation ( 1) and (2):

CV Analysis
(2) Where k1 and k2 are constants for a certain potential (V) and can be calculated by plotting where k1 is the slope (slope line) and k2 is the Y-axis intersection so that we can see the area comparison diffusion and capacitive.When the sweep speed increases, the role of the capacitive contribution increases, so the addition of the amount of lanthanum affects the value of the capacitive contribution where the more the amount of lanthanum, the higher the value of the capacitive contribution.

EIS Analysis
Electrochemical Impedance Spectroscopy (EIS) testing was carried out to determine the value of the electrical conductivity of the electrochemical cell.The shape of the EIS curve obtained is a semicircle and a straight line.Semicircle in EIS is related to the value of electron resistance (R e ) and charge transfer resistance (R ct ).While the straight line indicates the presence of diffusion or the process of intercalation and deintercalation of lithium then fitting using NOVA software so that the data obtained is more specific.Where the conductivity level is inversely proportional to the resulting resistance, it can be concluded that, if the conductivity value of a material is large, the resistance value is small, and vice versa.the conductivity of each sample can b determined by equations ( 3), (4), and (5) σ ions = ; (3) where R tot = Ingredients + R ion , then the conductivity value of Li 0.2 La 0.6 TiO 3 is σ total = 0.76 x 10 -5 S/cm.

Conclusion
In summary, XRD results state that the sample has been successfully forming the main phase of 96.4%, the results of CV show that the addition of the amount of lanthanum affects the value of the capacitive contribution where the more the amount of lanthanum, the higher the capacitive contribution the value will be by 73%, from the EIS test results show that the conductivity value of the material of 0.76 x 10 -5 S/cm.

Figure 2 .
Figure 2. Cyclic Voltammetry Analysis of Li 0.2 La 0.6 TiO 3 ; a) CV curves at different Scanrate; b) Peak Current vs Scan rate logs; c) Capacitive and Diffusion Area at a Scanrate of 10 mV.S -1 ; d) Pseudocapacitive Percentage at Different Scanrate