Norihiro Togasaki

Prediction of degradation in lithium−ion batteries is critical to ensure battery safety. In this study, we report for the first time that electrochemical impedance spectroscopy (EIS) predicts serious capacity fade in lithium−ion batteries, which results from charge−discharge cycling under overcharge conditions. A nickel cobalt aluminum oxide (NCA) lithium-ion cell shows a two-stage capacity fade in the overcharge condition with an upper cutoff voltage (UCV) of 4.4 V. The capacity gradually decre

Among the recent advancements in lithium–oxygen (Li–O2) chemistries, redox mediators (RMs) have been revealed to play a significant role in decreasing overpotential on charging and in improving cycling performance. However, an intrinsic problem is redox shuttle of RMs, which leads to degraded RM utilization and induces the accumulation of discharge products on the cathode surface; this remains a significant issue in the current battery cell configuration (Li anode/separator/cathode). To address

Lithium nitrate (LiNO3) is a potential option for the lithium salt in lithium−oxygen (Li−O2) batteries because it reduces the charging overpotential on carbon-based cathodes and protects the lithium metal anode from side reactions. However, the cycling stability of an electrolyte containing LiNO3 in the presence of cathode catalysts has not yet been studied. In this paper, we report an improvement in the cycling performance of δ-MnO2 cathodes in Li−O2 batteries using LiNO3 in comparison with tha

In all-solid-state batteries (ASSB), increasing the thickness of electrodes is essential for increasing the energy density. However, this limits the C-rate performance, particularly for electrodes with a large volume fraction of active materials (AMs), transport of ions in the electrode is hindered, leading to poor utilization of AMs in ASSBs. To accelerate the development of ASSBs, it is highly desirable to develop analytical methods for understanding the utilization of AMs in thick electrodes.

Addressing the reuse of lithium ion batteries (LIBs) extracted from used battery packs is an option for addressing environmental concerns. To guarantee their safety, the development of non-destructive analysis to identify LIBs exposed to over-discharge is mandatory. In this study, over-discharge-induced degradation in graphite/nickel cobalt aluminum oxide (NCA) lithium ion cells was investigated using differential voltage analysis (DVA) and electrochemical impedance spectroscopy (EIS). Two-stage

For a battery module where single cells are connected in series, the single cells should each have a similar state of charge (SOC) to prevent them from being exposed to an overcharge or over-discharge during charge–discharge cycling. To detect the existence of unbalanced SOC cells in a battery module, we propose a simple measurement method using a single-frequency response of electrochemical impedance spectroscopy (EIS). For a commercially available graphite/nickel-cobalt-aluminum-oxide lithium-

A solvate ionic liquid (SIL) of highly concentrated 4.0 M lithium nitrate (LiNO3) in a dimethylsulfoxide solution is introduced for lithium-oxygen batteries. As a redox mediator (RM), highly concentrated LiNO3 in the SIL works more effectively than the lower concentrated one to decompose lithium peroxide (Li2O2) on the cathode with an extremely low charging voltage of 3.6 V. In addition, X-ray photoelectron spectroscopy analysis confirms that side products during discharging and charging are mar

Cycle life of series-connected lithium-ion battery (LIB) modules in the presence or absence of an overcharged cell is reported, and degradation behavior is characterized by electrochemical impedance spectroscopy (EIS) and differential voltage analysis (DVA). Three-stage capacity decay is solely observed in modules in the presence of an overcharged cell, which is exposed to a state of charge (SoC) of ≥105% during cycling. The module without overcharged cells or with an overcharged cell at an SoC

In lithium–sulfur (Li–S) batteries, the impregnation of sulfur into electrically conductive materials of porous carbon plays a significant role in preventing the dissolution of lithium polysulfide (LiPS) into an electrolyte solution and improving cycling performance. However, this strategy does not render high-energy density to Li–S cells because of the limited amount of sulfur in porous carbon. Once the sulfur overflows out of porous carbon because of the significant volume change occurring dur

<p>In lithium–sulfur (Li–S) batteries, encapsulation of sulfur in activated carbon (AC) materials is a promising strategy for preventing the dissolution of lithium polysulfide into electrolytes and enhancing cycle life, because instead of solid–liquid–solid reactions, quasi-solid-state (QSS) reactions occur in the AC micropores. While a high weight fraction of sulfur in S/AC composites is essential for achieving a high energy density of Li–S cells, the deterioration mechanisms under such c

Dimethylsulfoxide (DMSO) is an attractive solvent for use in lithium-oxygen (Li–O 2 ) batteries because of its superior stability of carbon cathodes, Li ion conductivity, O 2 diffusion coefficient, discharge voltage, and specific capacity. Some literatures of Li-O 2 batteries have reported more than one hundred cycles using DMSO-based electrolytes. This good cycling performance is based on the stable charge-discharge behavior on the cathode reaction. In general, the coulombic amount used during