Thermophysical Characterization of a Layered P2 Type Structure Na₀.₅₃MnO₂Cathode Material for Sodium Ion Batteries

Over the last decade, the demand for safer batteries with excellent performance and lowercosts has been intensively increasing. The abundantly available precursors and environmentalfriendliness are generating more and more interest in sodium ion batteries (SIBs), especially becauseof the lower material costs compared to Li-ion batteries. Therefore, significant efforts are beingdedicated to investigating new cathode materials for SIBs. Since the thermal characterization ofcathode materials is one of the key factors for designing safe batteries, the thermophysical propertiesof a commercial layered P2 type structure Na0.53MnO2cathode material in powder form weremeasured in the temperature range between−20 and 1200◦C by differential scanning calorimetry(DSC), laser flash analysis (LFA), and thermogravimetry (TG). The thermogravimetry (TG) wascombined with mass spectrometry (MS) to study the thermal decomposition of the cathode materialwith respect to the evolved gas analysis (EGA) and was performed from room temperature up to1200◦C. The specific heat (Cp) and the thermal diffusivity (α) were measured up to 400◦C becausebeyond this temperature, the cathode material starts to decompose. The thermal conductivity (λ)as a function of temperature was calculated from the thermal diffusivity, the specific heat capacity,and the density. Such thermophysical data are highly relevant and important for thermal simulationstudies, thermal management, and the mitigation of thermal runaway

Comprehensive Electrochemical, Calorimetric Heat Generation and Safety Analysis of Na0.53_{0.53}MnO2_{2} Cathode Material in Coin Cells

The sodium ion cells were assembled by using Na$_{0.5}$3MnO$_{2}$ as cathode material, pure sodium metal as anode in case of half coin cells and coconut shell-derived hard carbon in case of full coin cells. Cyclic voltammetry, galvanostatic charge-discharge, and self-discharge analysis were conducted. A good rate capability, capacity retention, coulombic efficiency (99.5%), reproducibility and reversible Na-ion intercalation revealed a satisfactory performance of this cathode material. The safety related parameters including the heat generation during charging-discharging and thermal abuse tests have been executed by the means of sophisticated calorimetry instruments. It was observed that during the charging process less heat was generated than during discharging process. The exothermic reactions during thermal runaway were identified by using an accelerating rate calorimeter and pressure measurements during this thermal abuse test were performed as well. The thermal runaway of full coin cells occurred beyond 190 °C with a temperature rate (dT/dt) of 2.5 °C min$^{−1}$. Such detailed analysis of heat generation and thermal abuse helps finding new and quantitative correlations between different critical thermal and safety related issues in future post Li batteries that are a prerequisite for the design of safer batteries, the safe upscaling and for the adaptation of the thermal management system

Safer Sodium Battery: Thermal and electrochemical studies of Na-ion based batteries

In the recent decade, the community emphasizes the crucial need for the improvement of battery safety and safety remains a critical barrier for this technology. Despite safer battery materials, battery thermal management could be a key to safer post Lithium technology. In that respect, sodium ion based batteries were studied using different electrolyte routes. Thermo-physical and electrochemical analyses depicted the performance of the battery material and the coin cell characteristics. The safety related parameters including the heat generation during charging-discharging and thermal abuse test have been executed by the means of sophisticated calorimetry instruments. Quantitative measurement of the thermal data was performed, and out-gasing during thermal decomposition of the electrolytes has been analysed in order to design a safer battery. This work helps finding new and quantitative correlations between different critical thermal and safety related issues in future post Li batteries. The determined thermal data, gas compositions and safety parameters on coin cell level are needed for the design of a safer battery, the safe upscaling and for the adaptation of the thermal management system

Safer Sodium Battery: Thermal and electrochemical studies of Na-ion based cells

In the recent decade, the community emphasizes the crucial need for the improvement of battery safety and safety remains a critical barrier for this technology. Despite safer battery materials, battery thermal management could be a key to safer post Lithium technology. In that respect, sodium ion based batteries were studied using different electrolyte routes. Thermo-physical and electrochemical analyses depicted the performance of the battery material and the coin cell characteristics. The safety related parameters including the heat generation during charging-discharging and thermal abuse test have been executed by the means of sophisticated calorimetry instruments. Quantitative measurement of the thermal data was performed, and out-gasing during thermal decomposition of the electrolytes has been analysed in order to design a safer battery. This work helps finding new and quantitative correlations between different critical thermal and safety related issues in future post Li batteries. The determined thermal data, gas compositions and safety parameters on coin cell level are needed for the design of a safer battery, the safe upscaling and for the adaptation of the thermal management system

Equilibrium, Thermodynamics, and Kinetic Sorption Studies for the Removal of Coomassie Brilliant Blue on Wheat Bran as a Low-Cost Adsorbent

The sorption studies of coomassie brilliant blue (CBB) from aqueous solution have been carried out on wheat bran (WB). Coomassie brilliant blue on wheat bran was used to study the adsorption behavior under various parameters such as pH, dosage amount, and contact time. It was observed that under optimized conditions up to 95.70% dye could be removed from solution onto WB. Langmuir and Freundlich adsorption isotherms were used to elaborate the results. Freundlich model was found to be fitted well and favored multilayer adsorption. The Freundlich constants n and KF were determined as 0.53 and 2.5 × 10−4. Thermodynamic parameters such as ΔG, ΔH, and ΔS studied were taking into account, showed spontaneous and favorable reaction for coomassie brilliant blue on wheat bran. The maximum adsorption capacity qm was found to be 6.410 mg/g. The investigations show that non treated WB is a low-cost adsorbent for the removal of dyes from textile industry effluents

How battery calorimetry can enhance the lifetime and safety of Lithium-ion and post-Li cells

With increasing energy density safety and thermal management of Li-ion batteries is becoming more and more important, because the thermal runaway can cause an ignition or even explosion with simultaneous release of toxic gases. In the last nine years we have established battery calorimetry as a versatile characterization technique, which allows advancements for the thermal management and the safety of batteries. With six adiabatic Accelerating Rate Calorimeters of different sizes and two sensitive Tian-Calvet calorimeters combined with cyclers we operate Europe’s largest battery calorimeter center, which enables the evaluation of thermodynamic, thermal and safety data on material, cell and pack level under quasiadiabatic and isoperibolic environments for both normal and abuse conditions (thermal, electrical, mechanical). Calorimetry allows the collection of quantitative data required for optimum battery performance and safety. This information is applied to define the requirements for thermal management. It will be explained how the two different types of calorimeters can be used for studies on heat generation and dissipation of Li-ion cells. For that purpose, they are coupled to battery cyclers in order to perform the measurements during charging and discharging of the cells under defined thermal conditions, which are quasiadiabatic or isoperibolic. It will be shown that by measuring the specific heat capacity and the heat transfer coefficient the measured temperature data during cycling can be converted into generated and dissipated heat data, which are needed for the adjustment of the thermal management systems. It will be presented how battery calorimeters provide thermodynamic and thermal stability data on materials level, e.g. of anodes, cathodes or electrolytes or there combinations and allow to perform safety tests on cell and pack level by applying thermal, mechanical or electrical abuse conditions. The studies on materials level are especially important for Post-Li cells, which make use of more abundant materials, such as sodium or magnesium instead of Li, nickel and cobalt, because these data help to develop safe cells from the beginning all along the value chain. For the advanced Li-ion technology, a holistic safety assessment is in the focus, because the thermal runaway can have multiple interacting causes and effects. A test in the calorimeter reveals the entire process of the thermal runaway with the different stages of exothermic reactions. As a result of the different tests quantitative and system relevant data for temperature, heat and pressure development of materials and cells are provided. In addition it will be explained how calorimeters allow studying the thermal runaway propagation in order to develop and qualify suitable countermeasures, such as heat protection barriers, which is currently becoming a very hot topic

Enabling the Electrochemical Performance of Maricite-NaMnPO4 and Maricite-NaFePO4 Cathode Materials in Sodium-Ion Batteries

NaMnPO4 and NaFePO4, polyanion cathode materials, exist in two different phases maricite/natrophilite and maricite/olivine, respectively. Both natrophilite NaMnPO4 and olivine NaFePO4 are electrochemically active and possess a one-dimensional tunnel for sodium-ion migration; however, these two phases are thermodynamically unstable. Therefore, they can be synthesized through an electrochemical route. On the contrary, maricite (m)-NaMnPO4 and maricite (m)-NaFePO4 are thermodynamically stable forms but have a huge activation energy of their diffusion pathways for sodium extraction and insertion in the crystal structure, which hinders electrochemical reactions. Therefore, the electrochemical behaviour of commercial m-NaMnPO4 and m-NaFePO4 has been studied to find a way for enabling them electrochemically. Ball milling and thermal/mechanical carbon coating are employed to reduce the particle size to enhance the electrochemical performance and shorten the diffusion pathway. Moreover, ball milling leads to defects and partial phase transformation. The electrochemical performance of milled-coated NaMnPO4 and NaFePO4 has been thoroughly investigated and compared. The phase transition of NaFePO4 is revealed by a differential scanning calorimeter. As a result, the achievable capacities of both cathode materials are significantly enhanced up to ∼50 mAh.g−1 via the particle size reduction as well as by carbon coating. However, the side reactions and agglomeration problems in such materials need to be minimized and must be considered to enable them for applications

Combined Thermal Runaway Investigation of Coin Cells with an Accelerating Rate Calorimeter and a Tian-Calvet Calorimeter

Commercial coin cells with LiNi0.6Mn0.2Co0.2O2 positive electrode material were investigated using an accelerating rate calorimeter and a Tian-Calvet calorimeter. After cycling and charging to the selected states of charge (SOCs), the cells were studied under thermal abuse conditions using the heat-wait-seek (HWS) method with the heating step of 5 K and a threshold for self-heating detection of 0.02 K/min. The onset temperature and the rate of the temperature rise, i.e., the self-heating rate for thermal runaway events, were determined. The morphology of the positive electrode, negative electrode and the separator of fresh and tested cells were compared and investigated with scanning electron microscopy (SEM). Furthermore, the microstructure and the chemical compositions of the individual components were investigated by X-ray diffraction (XRD) and inductively coupled plasma with optical emission spectrometry (ICP-OES), respectively. In the Tian-Calvet calorimeter, the coin cells with the selected SOCs and the individual components (positive electrode, negative electrode and separator) were heated up with a constant heating rate of 0.1 °C/min (ramp heating mode). Simultaneously, the heat flow signals were recorded to analyze the heat generation. The combination of the three different methods—the HWS method using the ES-ARC, ramp heating mode on both cells and the individual components using the Tian-Calvet calorimeter—together with a post-mortem analysis, give us a complete picture of the processes leading to thermal runaway