• Journal of Electrical Engineering and Technology
• /
• v.13 no.5
• /
• pp.1927-1934
• /
• 2018

In this paper, we studied the state of charge (SOC) estimation algorithm of a high-capacity lithium secondary battery for electric vehicles (EVs) considering temperature characteristics. Nonlinear characteristics of high-capacity lithium secondary batteries are represented by differential equations in the mathematical form and expressed by the state space equation through battery modeling to extract the characteristic parameters of the lithium secondary battery. Charging and discharging equipment were used to perform characteristic tests for the extraction of parameters of lithium secondary batteries at various temperatures. An extended Kalman filter (EKF) algorithm, a state observer, was used to estimate the state of the battery. The battery capacity and internal resistance of the high-capacity lithium secondary battery were investigated through battery modeling. The proposed modeling was applied to the battery pack for EVs to estimate the state of the battery. We confirmed the feasibility of the proposed study by comparing the estimated SOC values and the SOC values from the experiment. The proposed method using the EKF is expected to be highly applicable in estimating the state of the high-capacity rechargeable lithium battery pack for electric vehicles.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.26 no.6
• /
• pp.421-428
• /
• 2021

Lithium-ion secondary batteries exhibit advantageous characteristics such as high voltage, high energy density, and long life, allowing them to be widely used in both military and daily life. However, the lithium-ion secondary battery does have its limitation; for example, the output power and capacity are readily decreased due to the increased internal impedance during discharging at a lower temperature (-32℃, military requirement). Also, during charging at a lower temperature, lithium dendrite growth is accelerated at the anode, thereby decreasing the battery capacity and life as well. This paper describes a study that involves increasing the internal temperature of lithium-ion secondary battery by energy circulation operation in a low-temperature environment. The energy circulation operation allows the lithium-ion secondary battery to alternately charge and discharge, while the internal resistance of lithium-ion battery acts as a heating element to raise its own temperature. Therefore, the energy circulation operation method and device were newly designed based on the electrochemical impedance spectroscopy of the lithium-ion secondary battery to mediate the battery performance at a lower temperature. Through the energy circulation operation of lithium ion secondary battery, as a result of the heat generated from internal resistance in an extremely low-temperature environment, the temperature of the lithium-ion secondary battery increased by more than 20℃ within 10 minutes and showed a 75% discharging capacity compared with that at room temperature.

• Transactions of the Korean hydrogen and new energy society
• /
• v.30 no.1
• /
• pp.43-48
• /
• 2019

This study investigates the electrochemical characteristics of the hybrid cell that combined the advantageous characteristics of Li secondary battery and supercapacitor, high energy density and high power density, respectively. Electrochemical behaviors of the hybrid cell was characterized by charge/discharge, cycle and impedance tests. The hybrid cell using Li secondary battery and supercapacitor had better discharge capacity and cycle performance than that of using Li secondary battery only. Proper design of such a hybrid cell system is expected to result in substantial benefits to the well being of the Li secondary battery. The hybrid cell involving Li secondary battery for high energy density and supercapacitor for high power density may be the possible solution for future energy storage system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.67 no.12
• /
• pp.1619-1625
• /
• 2018

Portable electronic devices secondary batteries can cause fire and explosion due to micro-current change in addition to the situation of short-circuit inrush current, safety can not be secured with a general operation limited current fuse. Therefore, in secondary battery, it is necessary for the protector to satisfy both the limit current type operation in the open-short-circuit inrush current and the current detection operation characteristic in the micro current change situation and for this operation, a fuse for the current detection type secondary battery protection circuit can be applied. The purpose of this study is to design a protection device that operates stably in the hazardous situation of small capacity secondary battery for portable electronic devices through the design of low melting fuse elements alloy of sensing type fuse and secures stability in abnormal current state. As a result of the experiment, I-T and V-T operation characteristics are satisfied in a the design of the alloy of the current sensing type self-contained low melting point fuse and the resistance of the heating resistor. It is confirmed that it can prevent accidents of short circuit over-current and micro current change of secondary battery.

• Journal of the Korean Electrochemical Society
• /
• v.10 no.1
• /
• pp.31-35
• /
• 2007

In this review article, we are going to explain the recent development of lithium secondary batteries for a cellular phone. There are three kinds of rechargeable batteries for cellular phones such as nickel-cadmium, nickel-metal hydride, and lithium ion or lithium ion polymer. The lithium secondary battery is one of the most excellent battery in the point of view of energy density. It means very small and light one among same capacity batteries is the lithium secondary battery. The market volume of lithium secondary batteries increases steeply about 15% annually. The trend of R&D is focused on novel cathode materials including $LiFePO_4$, novel anode materials such as lithium titanate, silicon, and tin, elecrolytes, and safety insurance.

• IE interfaces
• /
• v.18 no.4
• /
• pp.402-411
• /
• 2005

Secondary batteries with high performance are essential in widespread use of modern portable devices such as cellular phones and laptop computers. High energy density, long cycle life, and safety are some of important requirements for secondary battery. To achieve such characteristics, a mixing proportion of electrolyte solution ingredients in the battery should be carefully chosen. In this paper, using statistical design of mixture experiments (DOME), we attempt to find an optimum condition of designing the secondary battery. DOME has a distinct feature in that the experimental region is represented by simplex, rather than hypercube, because the sum of blend proportions should be unity. Several designs based upon this point have been proposed for mixture experiments. Among them, an extreme vertices design is employed in this paper because there are a couple of blend constraints to be considered. In order to investigate how the mixing proportion interacts with other manufacturing factors, a fractional factorial design is also included across the extreme vertices design. As a result, we find that the blend proportion of solution ingredients has a significant effect on battery performances. By simultaneously optimizing two battery capacities, this paper proposes an optimum blend proportion according to process factor settings.

• Transactions of the Korean hydrogen and new energy society
• /
• v.26 no.1
• /
• pp.54-63
• /
• 2015

The secondary battery using sodium is investigating as one of power storage system and power in electric vehicles. The secondary battery using sodium as a sodium battery and sodium ion battery had merits such as a abundant resources, high energy density and safety. Sodium battery (sodium molten salt battery) is operated at lower temperature ($100^{\circ}C$) compared to NAS and ZEBRA battery ($300{\sim}350^{\circ}C$). Sodium ion battery is investigating as one of the post lithium ion battery. In this paper, it is explained for the principle and recent research trends in sodium molten salt and sodium ion battery.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.17 no.3
• /
• pp.378-386
• /
• 2014

In this paper, safety evaluation method simulating battlefield environment was studied to verify military operability of commercial lithium secondary battery. Based on the MIL-STD-2105D and STANAG standards, safety tests of lithium secondary battery module were conducted, such as bullet impact, fragment impact, fast cook-off and slow cook-off. All results satisfied the safety evaluation criteria, founded on military standard. It suggests that the lithium secondary module has high potential to be applied in a military power source. The safety evaluation methods developed in this paper can be valuable to propose the new military standards for commercial lithium secondary batteries.

• Proceedings of the KIEE Conference
• /
• 1990.07a
• /
• pp.207-210
• /
• 1990

The purpose of this study is to research and develop polymer secondary battery. This paper describes the first discharge characteristics of PAn/Li-Al secondary battery. PAn was prepared in $HBF_4$ aqueous solution by galvanostatic electropolymerization and then used as cathode active material. PAn/Li-Al secondary battery was prepared in 2025 coin type. Characteristics of this battery are summarized as follows. ${\bullet}$ Open curcuit voltage and discharge end voltage was 3.5V and 2.9V, respectively. ${\bullet}$ The ratio of electricities in discharge to theoretical electricities in all undoping of PAn cathode was 56% at constant current discharge of 1mA. ${\bullet}$ The capacity density, energy density and maximum power density per weight of PAn electroactive material were 56.1Ah/kg, 168.4Wh/kg and 16.9kW/kg, respectively.

• Asian Journal of Innovation and Policy
• /
• v.12 no.3
• /
• pp.345-362
• /
• 2023

As the widespread adoption and proliferation of electric vehicles continue, the secondary battery market is experiencing rapid growth. However, lithium-ion batteries, which constitute a majority of secondary batteries, present high risks of fire and explosion. Solid-state batteries are thus garnering attention as the next-generation batteries since they eliminate fire hazards and significantly reduce the risk of explosions. Against this background, the study aimed to analyze research trends and provide insights by examining 2,927 domestic papers related to solid-state batteries over the past decade (2013-2022). Specifically, we used topic modeling to extract major keywords associated with solid-state batteries research and to explore the network characteristics across major topics. The changes in research on solid-state batteries were analyzed in-depth by calculating topic dominance by year. The findings provide an overview of the emerging trends in domestic solid-state battery research, and might serve as a valuable reference in shaping long-term research directions.