Search Results (4)

This article presents a novel aging-coupled predictive thermo-electrical dynamic modeling tool tailored for primary lithium manganese dioxide ($Li\text{-}Mn{O}_2$) batteries in active implantable medical devices (AIMDs). The aging mechanisms of rechargeable lithium batteries are well documented using computationally intensive physics-based models, unsuitable for real-time onboard monitoring in AIMDs due to their high demands. There is a critical need for efficient, less demanding modeling tools for accurate battery health monitoring and end-of-life prediction as well as battery safety assessment in these devices. The presented model in this article simulates the battery terminal voltage, remaining capacity, temperature, and aging during active discharge, making it suitable for real-time health monitoring and end-of-life prediction. We incorporate a first-order dynamic for internal resistance growth, influenced by time, temperature, discharge depth, and load current. By adopting Arrhenius-type kinetics and polynomial relationships, this model effectively simulates the combined impact of these variables on battery aging under diverse operational conditions. The simulation handles both the continuous micro-ampere-level demands necessary for device housekeeping and periodic high-rate pulses needed for therapeutic functions, at a constant ambient temperature of 37 °C, mimicking human body conditions. Our findings reveal a gradual, nonlinear increase in internal resistance as the battery ages, rising by an order of magnitude over a period of 5 years. Sensitivity analysis shows that as the battery ages and load current increases, the terminal voltage becomes increasingly sensitive to internal resistance. Specifically, at defibrillation events, the ${\displaystyle \frac{\partial V}{\partial R}}$ trajectory dramatically increases from ${10}^{-12}$ to ${10}^{-8}$, indicating a fourth-order-of-magnitude enhancement in sensitivity. A model verification against experimental data shows an R² value of 0.9506, indicating a high level of accuracy in predicting the $Li\text{-}Mn{O}_2$ cell terminal voltage. This modeling tool offers a comprehensive framework for effectively monitoring and optimizing battery life in AIMDs, therefore enhancing patient safety. Full article

Thermo-rechargeable batteries, or tertiary batteries, are prospective energy-harvesting devices that are charged by changes in the battery temperature. Previous studies on tertiary batteries have utilized an electrolyte solution, yet the volume of this electrolyte solution could be a disadvantage in terms of the heat capacity given to the tertiary batteries. To overcome this drawback, the performance of an electrolyte-free tertiary battery consisting of physically joined Na_1.60Co[Fe(CN)₆]_0.902.9H₂O (NCF90) and Na_0.72Ni[Fe(CN)₆]_0.685.1H₂O (NNF68) thin films was investigated for the first time. During thermal cycling between 5 °C and 15 °C, the thermal voltage (V_TB) was observed to be 8.4 mV. This result is comparable to the V_TB of conventional tertiary batteries that use electrolyte solutions made of NCF90 and NNF68 thin films. Full article

Extensive research on electrode materials has been sparked by the rising demand for high-energy-density rechargeable lithium-ion batteries (LIBs). Graphite is a crucial component of LIB anodes, as more than 90% of the commercialized cathodes are coupled with the graphite anode. For the advanced graphite anode, the fast charge–discharge electrochemical performance and the thermal stability need to be further improved in order to meet the growing demand. Herein, a graphite anode material’s thermo-electrochemical stability was improved by the surface coating of lithium phosphate (Li₃PO₄; LPO). The graphite anode with a well-dispersed LPO-coating layer (graphite@LPO) demonstrated significant improvement in the cycle and rate performances. The graphite@LPO sample showed a capacity retention of 67.8% after 300 cycles at 60 °C, whereas the pristine graphite anode failed after 225 cycles, confirming the ameliorated thermo-electrochemical stability and cyclability by LPO coating. The improved thermo-electrochemical stability of the graphite@LPO anode was validated by the full-cell tests as well. The performance enhancement by LPO-coating is due to the suppression of the growth of the surface film and charge-transfer resistances during the repeated cycling, as evidenced by the electrochemical impedance spectroscopy analysis. Full article

A thermo-rechargeable battery or tertiary battery converts thermal energy into electric energy via an electrochemical Seebeck coefficient. The manufacturing of the tertiary batteries requires a pre-oxidation step to align and optimize the cathode and anode potentials. The pre-oxidation step, which is not part of the secondary battery manufacturing process, makes the manufacturing of tertiary batteries complex and costly. To omit the pre-oxidation step, we used partially oxidized Prussian blue analogs, i.e., Na${}_x$Co[Fe(CN)${}_6$]${}_y$zH${}_2$O (Co-PBA) and Na${}_x$Ni[Fe(CN)${}_6$]${}_y$zH${}_2$O (Ni-PBA), as cathode and anode materials. The modified tertiary battery without the pre-oxidation step shows good thermal cyclability between 10 ${}^{\circ }$C and 50 ${}^{\circ }$C without detectable deterioration of the thermal voltage ($V_{\mathrm{cell}}$) and discharge capacity ($Q_{\mathrm{cell}}$). Full article