*3.1.7 Synthesis of Minoxidil; (MNX); [(2,4-diamino-6-piperidinopyrimidine 3-oxide) (171)]*

Minoxidil (MNX) is a direct vasodilator introduced in the early 1970s for the treatment of hypertension [101]. Its first literature appearance was in 1968 and preliminary trials were first described in man in 1969 [102].

Coincidentally, physicians observed hair regrowth and generalized hypertrichosis in balding patients, which led to the development of a topical minoxidil formulation for treating androgenetic alopecia (AGA) first in male and then in female individuals [26, 103, 104].

An easy protocol for the synthesis of minoxidil drug in a two-step procedure is done, using magnetic nanoparticles of ferrites, which have been widely used as green and efficient heterogeneous catalysts in the synthesis of organic compounds, where these nano catalysts provide prominent advantages such as simple synthetic procedure, high catalytic activity, chemical reactivity and perfect reusability.

Magnetic nanoparticles (MNPs) of CoFe2O4 were prepared through a solid-state grinding procedure, in an agate mortar, where a mixture of CoCl2, Fe (NO3)39H2O, NaOH, and NaCl in a molar ratio of 1:2:8:2 was mixed, ground for 45 min at room temperature, then the excess amount of salt was removed from the reaction mixture, the obtained residue was dried in an oven at 80°C for 60 min, calcinated at 300, 500, 700, and 900°C within 80 min (20 min at each temperature) (**Figure 33**) [105].

*Synthetic Approaches for Pharmacologically Active Decorated Six-Membered Diazines DOI: http://dx.doi.org/10.5772/intechopen.109103*

**Figure 33.**

*Synthesis of Minoxidil (171). Reagents and conditions: a) Nano CoFe2O4 (5 Mol%), H2O2 (0.5 ml), ETOH, reflux, 60 min, 95%; b) Piperidine, reflux, 120 min, 80%.*

First step was carried out by N-oxidation of 6-chloro-2,4-diaminopyrimidine (168) using (30%, 0.5 mL) H2O2 in the presence of CoFe2O4 magnetic nanocatalyst (5 mol %) in 5 ml ethanol under reflux conditions for 60 min to get 2,6-diamino-4-chloropyrimidine N-oxide (169) in yield (95%).

A nucleophilic substitution reaction using boiling piperidine (106°C) under neat conditions with 2,6-diamino-4-chloro-pyrimidine N -oxide (169), for 120 min was then carried as step two, affording 2,4-diamino-6-piperidinopyrimidine 3-oxide (minoxidil, (171)) product in high yield (80%) and purity without requiring any further purification.


*Article* **Thermal Decomposition Characteristics of PEO/LiBF4/LAGP Composite Electrolytes**

**Jacob Denney and Hong Huang \***

Department of Mechanical and Materials Engineering, Wright State University, Dayton, OH 45435, USA<EMAIL_ADDRESS>
**\*** Correspondence<EMAIL_ADDRESS>
**Abstract:** Lithium-based batteries with improved safety performance are highly desired. At present, most safety hazard is the consequence of the ignition and flammability of organic liquid electrolytes. Dry ceramic-polymer composite electrolytes are attractive for their merits of non-flammability, reduced gas release, and thermal stability, in addition to their mechanical strength and flexibility. We recently fabricated free-standing solid composite electrolytes made up of polyethylene oxide (PEO), LiBF4 salt, and Li1+xAlxGe2−x(PO4)3 (LAGP). This study is focused on analyzing the impacts of LAGP on the thermal decomposition characteristics in the series of PEO/LiBF4/LAGP composite membranes. It is found that the appropriate amount of LAGP can (1) significantly reduce the organic solvent trapped in the polymer network and (2) increase the peak temperature corresponding to the thermal degradation of the PEO/LiBF4 complex. In the presence of LAGP, although the peak temperature related to the degradation of free PEO is reduced, the portion of free PEO, as well as its decomposition rate, is effectively reduced, resulting in slower gas release.

**Keywords:** lithium; LAGP; electrolyte; composite; thermal decomposition

### **1. Introduction**

Lithium-ion batteries (LIBs), because of their high energy density and good discharge/charge cycle life, have evolved and dominated in markets from powering electronic devices and electric vehicles to energy storage in renewable grid systems. In these broad applications, occasional firing or explosive accidents resulting from LIBs have raised serious concerns. At present, battery researchers and manufacturers are dedicating to develop lithium-based batteries with improved safety performance, in addition to enhancing their power specs [1–7]. External protections, with the help of electronic accessories, like thermal fuse, pressure vents, and PTC element, have been integrated in LIB batteries to mitigate thermal runaway. However, internal protection based on the choice of safe materials is believed to be the "ultimate" solution to the safety issue. Recently, many key battery components have been developed towards minimizing thermal runaway, including surfacemodified electrodes, non-flammable electrolytes, multifunctional separators, overcharging or flame-retardant additives, and thermally switchable current collectors.

Solid electrolytes, referring to ion-conducting ceramics or dry polymers, as well as polymer–ceramic composites, have many merits and are known for non-volatility, nonflammability, and high thermal decomposition temperatures, etc., to address the safety issues [8,9]. Composite polymer electrolytes (CPEs), which combine characteristics of polymer and ceramic electrolytes, with potential to overcome the drawbacks of each kind, are becoming more attractive [10–13]. For instance, the unique mechanical properties of CPEs provide enough strength to resist lithium dendrite penetration and meantime flexibility to ensure good interface contact. All-solid-state LIBs made up of CPEs are becoming more attractive and are recognized as a key technology for next-generation energy-storage systems.

**Citation:** Denney, J.; Huang, H. Thermal Decomposition Characteristics of PEO/LiBF4/LAGP Composite Electrolytes. *J. Compos. Sci.* **2022**, *6*, 117. https://doi.org/ 10.3390/jcs6040117

Academic Editor: Stelios K. Georgantzinos

Received: 20 March 2022 Accepted: 11 April 2022 Published: 14 April 2022

**Publisher's Note:** MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

Research on the thermal stability and safety of LIBs made up of dry CPEs is still in the infancy stage [14]. Extensive studies on CPEs had emphasized on increasing ionic conductivity, improving mechanical flexibility, and enhancing interfacial stability [15–23]. In the published reports, most thermal characteristics of CPEs presented are limited to temperatures below 100 ◦C, within which the glass transition temperature (Tg) and crystallization temperature (Tc) are known to be critical to ionic conductivities. In some papers, thermalgravimetric decomposition profiles up to 500 ◦C were presented, while in-depth analyses on the decomposition behaviors of CPEs are lack of discussion. Among sparse reports on thermal stabilities of PEO (polyethylene oxide)-based electrolytes, inconsistences or controversial conclusions are noted. Xia and Angulakshimi [24,25] observed that the addition of LiTFSI to PEO increased thermal decomposition temperature (Tdec) of PEO from 200 ◦C to 300 ◦C. However, Joost [26] found that Tdec of PEO was lowered in PEO/LiTFSI and that the decomposition has multiple stages. Similarly to CPE systems, Cheng [27] found that adding 30% LLZO increased the Tdec of PEO, while Piana [28] observed an opposite trend in the PEO/LAGP-based electrolytes.

Among various CPE formulations, active ceramic fillers with high ionic conductivities are favorable, especially when a high content of ceramic fillers is required. Li1+xAlxGe2−x(PO4)3 (LAGP) is known for its high room-temperature ionic conductivity (10−3–10−4 S/cm) and good stability with moisture. Furthermore, it is risk-free of thermal runaway and subsequent fires and allows high-temperature operation [29–32]. Researchers have studied the electrochemical characteristics of PEO/LiTFSI/LAGP systems and demonstrated their satisfactory cycling and rate performances in lithium-ion, as well as lithium batteries [33–36]. In our previous publications, we have reported the method of fabricating free-standing lithiated PEO with LAGP solid composite electrolytes and investigated the impacts of lithium salt and LAGP loading on electrical and mechanical properties [37,38]. To our knowledge, there is sparse in-depth research on thermal stability and safety matters in the PEO/Li-salt/LAGP electrolyte systems, especially with the composition of high LAGP loadings. This study is focused on understanding the impact of LAGP ceramic loadings on thermal decomposition characteristics of PEO and LiBF4 in the PEO/LiBF4/LAGP composite systems. LiBF4 salt was selected in consideration of its favorable conducting merits in liquid electrolytes and its thermal properties fundamentally distinguished from LiTFSI. We performed in-depth quantitative analyses based on the thermogravimetric results, which will be presented in this paper.

### **2. Materials and Experimental**

A series of free-standing membranes from pure PEO, PEO/LiBF4, to lithiated PEO with different amounts of Li1.4Al0.4Ge1.6(PO4)3 (LAGP) were fabricated and analyzed in this study. PEO at a molecular weight of 400,000, anhydrous LiBF4, and anhydrous acetonitrile (AN) are all purchased from Sigma-Aldrich without further treatment. LAGP powders were synthesized via a two-step solid reaction method. The mixture of precursors was firstly heated at 600 ◦C for 6 h in air at a rate of 1 ◦C/min. The resultant powders were then subjected to milling in a high-energy shaker mill (SPEX Sample Prep 8000M Mill, Metuchen, NJ, USA) for 3 h before firing at 900 ◦C at a rate of 2 ◦C/min for 24 h in air. The as-synthesized LAGP powders were further milled for 24 h until the average particle size was in the sub-micron range.

Acetonitrile is the solvent used to dissolve PEO and LiBF4. LAGP, LiBF4, and PEO with predetermined compositions were mixed in AN at 50 ◦C in a dry room with a controlled moisture level. Afterwards, the viscous solution was transferred into a glove box (with moisture less than 5 ppm). Casting and drying were executed in the glove box at a pressure of 1 kPa followed by a constant argon flow at room temperature for up to five days. All of the membranes were sealed and stored in the glove-box prior to usage. Detailed synthesis process, structures, morphologies, and ionic conductivities of the electrolyte membranes were reported elsewhere [37].

In all of the electrolyte membranes, the molar ratio of EO to Li is fixed at 8.0 which was reported to have highest ionic conductivity [39]. This value corresponds to the mass ratio of 3.75 between PEO and LiBF4, i.e., mPEO mLiBF4 = 3.75. The composition of LAGP relative to (PEO + LAGP), i.e., ( mLAGP mPEO+mLAGP ), increases from 20 wt% to 60 wt%.

The nomenclature of the samples, the nominal weight percentage of each component and corresponding mass ratios are listed in Table 1.

**Table 1.** The nomenclature of the composite electrolyte membranes and the nominal composition of each component in the samples.

All of the samples were analyzed using the TA Instrument TGA Q5000. A few preliminary tests were performed to determine the appropriate temperature range. Excluding the LAGP portion, all other components completely decomposed below 450 ◦C. Hence the systematic TGA tests were set from room temperature to 450 ◦C. The heating rate was varied from 5 to 20 ◦C/min. At different heating rate, the characteristics of the TGA profile did not alter except the temperatures of weight loss uniformly shifted with the heating rate, which is common in thermal analyses. Hence, a high heating rate of 20 ◦C/min was selected in this study to align with the rapid thermal runaway process. The samples weighted between 15 mg and 20 mg were loaded into open platinum pans. The purge gas was nitrogen. The sample flow rate was 25 mL/min and the balance purge gas ran at a flow rate of 10 mL/min. TA Trios software was used to calculate the first derivative thermogravimetric data (DTG). The weight loss was determined from TGA profiles. The onset temperature, (Tonset), the peak temperature (Tp), and the max weight loss rate within each thermal event were determined from the DTG profiles.

### **3. Results and Discussion**

The TGA and DTG profiles of the PEO/LiBF4/LAGP series are shown in Figure 1a,b. For better comparison and visualization, the TGA plots superimpose all together while the DTG profiles are plotted with a constant offset on the y-axis. Three distinguishable thermal events are observed from the electrolyte membranes. An initial small amount of weight loss occurs in the temperature range of 60–160 ◦C. Major weight loss onsets in the vicinity of 230 ◦C for all the electrolyte membranes independent of LAGP content. The thermal decomposition completes at 430 ◦C or lower. Within 230 ◦C and 430 ◦C, the electrolyte membranes exhibit two distinct thermal events with a different peak temperature and max decomposition rate. When the temperature exceeds 430 ◦C, the weight remains constant, showing a long plateau. The amount of weight loss, onset and peak temperatures, and the weight loss rate appear to vary with membrane compositions, which will be analyzed and discussed in the following section.

Figure 2 plots the first event weight loss (below 160 ◦C) as a function of LAGP amount. With increasing LAGP amount in the CPE membranes, the weight loss within this temperature range shows a reducing trend. Commercial pure LiBF4 salt with no special treatment is known to contain traces of HF acid, which is inevitable upon exposure to moisture in production and storage. According to Lu [40], about 2.1 wt% weight loss peaked at 73 ◦C was observed in TGA from pure anhydrous LiBF4, resulting from the free HF acid

removal. Based on the composition of LiBF4 in our electrolyte membranes, the maximum HF acid amount is estimated to be less 0.4 wt%. However, seen in Figure 2, the PEO/LiBF4 membrane has a total weight loss of 12.8 wt% below 160 ◦C. In the LAGP60 membrane, the weight loss decreases to 4.5 wt% but still more than ten times the estimated HF amount. Since all our membranes were fabricated in a dry room and stored in a glove box with moisture less than 5 ppm, this weight loss cannot be related to the removal of free HF or any uptake moisture.

**Figure 1.** (**a**) TGA and (**b**) DTG profiles (offset by 0.4 interval for better visualization), obtained from the series of PEO/LiBF4/LAGP composite electrolyte membranes. For comparison, pure PEO plots are included.

**Figure 2.** The experimental weight loss below 160 ◦C and the calculated amount of AN solvent trapped in the electrolyte membranes as a function of LAGP content.

In fabricating polymer electrolyte membranes, acetonitrile solvent was used to dissolve the PEO and LiBF4 salt. Due to the strong interaction between LiBF4 and acetonitrile, a certain amount of AN solvent could be trapped within the electrolyte membranes after the drying process. This phenomenon was reported previously [41,42]. The boiling point of acetonitrile is 82 ◦C. When it is associated with a lithium salt, the evaporation temperature will increase but can be completely evaporated under 160 ◦C [43]. Accordingly, we submitted that the weight loss between 60 ◦C and 160 ◦C observed in the electrolyte membranes corresponds to the amount of AN trapped. Based on the membrane composition and the weight loss, the amount of AN trapped is calculated and also plotted as a function of LAGP loading (see Figure 2). In the neat PEO membrane, there is only 0.35 wt% AN solvent trapped. By contrast, 11.4 wt% AN is trapped in the PEO/LiBF4 electrolyte membrane. Interestingly, the addition of ceramic LAGP appears to weaken the LiBF4-AN interaction, leading to the gradually reduced amount of AN in the membranes. The impact of LAGP is also reflected by the slightly decreased evaporation rate and inflection point as a function of LAGP content (see Figure 1b).

The major weight loss seen between 230 ◦C to 430 ◦C is the consequence of the thermal decomposition of LiBF4 and PEO, as LAGP is known to be inactive to either LiBF4 or PEO and remains thermally stable below 450 ◦C. Pure LiBF4 powder or PEO membrane completes thermal decomposition in one event peaked at 277 ◦C and 417 ◦C, respectively, consistent with previous reports [40,44,45]. Seen in Figure 1, all the electrolyte membranes exhibit two distinct thermal events, with different weight-loss slopes (see Figure 1a) and two rate peaks (see Figure 1b), in this temperature range. Hereby, we refer to the two thermal events as stage-1 and stage-2 decompositions of the electrolyte membrane. The transition temperature (T1→2) from stage-1 to stage-2 is selected at the saddle point between the two weight-loss rate peaks. Stage-1 regime (230 ◦C to T1→2) is related with decomposition of LiBF4, while stage-2 regime (T1→2 to 430 ◦C) is the characteristic of free PEO decomposition.

Figure 3a plots the weight loss at each stage, i.e., M1 for stage-1 and M2 for stage-2, as a function of the LAGP content. It is interesting to see that M1 is more than the nominal amount of Li-salt, suggesting that a portion of PEO are complexed with LiBF4 and degraded at the lower temperature. Considering the M1 value is the sum of all the LiBF4 (MLiBF4) and complexed PEO portion (MPEO,c) in the electrolyte, i.e., M1 = MLiBF4 + MPEO,c, the mass ratio of M1−MLiBF4 MLiBF4 will reflect the mass ratio between PEO and LiBF4 in the complex. Therefore, M1−MLiBF4 MLiBF4 = MPEO,c MLiBF4 . On the other hand, the M2 value corresponds to

**Figure 3.** (**a**) Mass losses in stage-1 (M1) and stage-2 (M2) between 230 ◦C and 430 ◦C; (**b**) mass ratios, i.e., M1/M2, calculated MPEO,c/MLiBF4 in the complex, MPEO,c/MPEO,f, as well as nominal MPEO,n/MLiBF4,n in the electrolytes membranes, in correlation with LAGP content.

Figure 3b show that the series of mass ratios, i.e., M1 M2 , MPEO,c MLiBF4 , MPEO,c MPEO,f , as a function of LAGP content in the membrane. For comparison, the nominal ratio between PEO and LiBF4, MPEO,n MLiBF4,n = 3.75, is also included in Figure 3b. Interestingly, all the mass ratios change insignificantly with LAGP content. From the values of MPEO,c MLiBF4 , it is determined that the EO/Li+ molar ratio is in the range of 4.0–5.0 for all the electrolyte membranes. This observation corroborates well with the fact that PEO and lithium salt can readily form complexes with EO/Li ratio in the range of 4–6 [46,47]. The present results suggest that stable complexes of (PEO)nLiBF4 exist in all the PEO/LiBF4/LAGP membranes and they are dominant in the thermal degradation within stage-1. Seen also in Figure 3b, MPEO,c MPEO,f changes insignificantly with LAGP content, indicating the portion between the complex PEO and free PEO is constant in all of the electrolyte membranes.

Figure 4 plots the peak decomposition temperatures related with the two thermal events. In the PEO/LiBF4 membrane, the peak decomposition temperature of stage-1 (Tp,1) is at 318 ◦C, higher than pure LiBF4 (277 ◦C), but much lower than free PEO (417 ◦C). The stage-2 decomposition at an almost constant rate is centered around 415 ◦C, characteristic of free PEO. Apparently, the "complexed" PEO appears less stable than "free" PEO, possibly catalyzed by LiBF4. In the electrolyte membranes consisting of LAGP, Tp,1 increases to 345 ◦C in LAGP20, followed by a slightly decrease to 331 ◦C in LAGP50. Tp,1 recovers to 317 ◦C in LAGP60. This trend can be attributed to the impacts of excess LAGP on weakening interactions between PEO and LiBF4. The presence of LAGP has a more significant impact on the free PEO decomposition at stage-2. The peak temperature of "free PEO" (Tp,2) is reduced to 370 ◦C in LAGP20 membrane and gradually recesses till to 339 ◦C in LAGP60 membrane. LAGP appears to accelerate the free PEO decomposition at reduced temperatures.

**Figure 4.** Two peak temperatures, Tp,1 and Tp,2, within the major decomposition occurred in all the membranes.

The 450 ◦C residue in all the electrolyte membranes should be made up of the nominal LAGP, LiF decomposed from LiBF4, and PEO ashes. The actual amount of PEO ashes, calculated by subtracting the masses of LAGP and LiF from the residue, is plotted as a function of LAGP (see Figure 5). Neat PEO results in ash residue of 2.06 wt% at 450 ◦C. For comparison, the projected values, assuming the ash is proportional to the PEO amount, is also plotted in Figure 5. Results show that the actual PEO ash from the PEO/LiBF4 electrolyte is only 1.02 wt%, about 60% of the projected value. The actual amount of PEO ashes continuously decreases upon increasing LAGP content and reaches almost

zero in the LAGP60 membrane. This observation supports the findings discussed in the previous session that the presence of lithium-salt and LAGP ceramics catalytically accelerate PEO decomposition.

**Figure 5.** Projected and actual amount of PEO ashes in the 450 ◦C residue from all of the electrolyte membranes in relation with the nominal LAGP composition.

The impacts of LAGP on the thermal stability of the electrolyte membranes can be considered in the following aspects. Firstly, adding ceramics effectively reduces the active amount of polymer and lithium salt, and hence, the amount of gas release resulting from their decomposition [48]. This is readily observed from the TGA profiles. Seen in Figure 1a, the total released gas at 450 ◦C is 90 wt% for PEO/LiBF4, 70 wt% for LAGP30, and only 30 wt% for LAGP60. Taking occurrence at 50% mass loss, the temperature increases from 320 ◦C for PEO/LiBF4, to 345 ◦C for LAGP20 and 360 ◦C for LAGP50. Secondly, the major decomposition rate decreases and peak temperature increases in the presence of appropriate LAGP. Seen in Figure 1b, the maximum decomposition rate at the peak temperature is much lower in PEO/LiBF4 compared with virgin PEO membrane. As LAGP composition increases, the maximum decomposition rate is continuously decreasing. For the stage-1 decomposition event, the peak rate is 1.0 wt% per ◦C occurring at 320 ◦C for PEO/LiBF4, while the peak rate is reduced to 0.4 wt% per ◦C occurring at 336 ◦C for LAGP50. Thirdly, although the presence of LAGP reduces the peak decomposition temperature of the "free PEO" portion (about 40 wt% of total PEO composition), the presence of LAGP reduces the gas-release rate simultaneously. For instance, the stage-2 peak decomposition rate is 2.6 wt% per ◦C for the neat PEO membrane but this rate reduces to 1.3 wt% per ◦C for the LAGP50 electrolyte membrane. In general, a reduced decomposition rate can delay flame ignition and spread over the material [35]. We performed a flammability test on the PEO/LiBF4/LAGP membranes. Neat PEO and PEO/LiBF4 electrolyte membranes were easily ignited and quickly burned into ashes upon contact with flame. A significant reduction in flammability with self- extinguishing behavior was observed in the LAGP20 and LAGP30 membranes. When LAGP content is 50 wt% or greater, the composite electrolyte membranes could not be ignited even after repeated exposure and direct contact with the flame. This observation is consistent with Guo's results from the

PvDF-HFP/LiTFSI/LAGP system [35]. The thermally stable LAGP ceramic can act as a barrier capable of reducing/preventing ignition and flammability.

### **4. Conclusions**

This study was intended to perform in-depth quantitative analyses on the series of freestanding PEO/LiBF4/LAGP composite electrolyte membranes based on thermogravimetric results. Major thermal decomposition begins at 230 ◦C and completes at 430 ◦C, observed in all of these electrolyte membranes. It is found that the present membrane fabrication and drying process results in 11 wt% of AN solvent trapped in the PEO/LiBF4 electrolyte membrane. The AN in the electrolyte membrane will not only lead to potential safety concerns but also affect electrochemical performance. The presence of LAGP can effectively reduce the amount of AN trapped in the membrane when drying at room temperature. The decomposition of PEO/LiBF4 shows a maximum rate of 1.0 wt% per ◦C at 320 ◦C, much lower than neat PEO. The reduction can be attributed to the complex formation between PEO and Li-salt. Adding and increasing the amount of LAGP ceramic particles into the PEO/LiBF4 electrolyte system, there are several benefits towards improving the thermal stability of the electrolyte membrane. Increasing the LAGP composition in the electrolyte membrane effectively reduces the net amount of flammable PEO and LiBF4, as well as the solvent trapped in the electrolyte membrane. As a result, the net amount of gas release from the electrolyte membrane can be significantly reduced upon thermal decomposition. With an appropriate amount of LAGP (e.g., 20–30 wt%), the peak temperature reflecting decomposition of the PEO/LiBF4 complex can be increased by several tens of degrees Celsius. Although the decomposition of free PEO portion in the electrolytes occurs at a lower temperature in the presence of LAGP, its peak decomposition rate is reduced, which is beneficial to delay flame ignition and spread and, therefore, to mediate the dramatic thermal runaway.

**Author Contributions:** Conceptualization, H.H.; methodology, J.D. and H.H.; formal analysis, H.H.; investigation, J.D. and H.H.; data curation, J.D. and H.H.; writing—original draft preparation, H.H.; writing—review and editing, H.H.; supervision, H.H. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**


**2. State of the Art and Related Work**

There is a broad and extensive bibliography related to the work on Home Energy Management Systems (HEMSs) architecture and strategies, semantic representation of SH and HEMS concepts, DR strategies from within the SH and interfacing with the SG. In this section, we will briefly cover some of the most relevant works from our proposal perspective, sorted in reverse chronological order and categorised into two families: existing architectures and ontological work related to the interoperability of the solution.

#### *2.1. Architecture and Security*

Machorro-Cano et al. present HEMS-IoT [14]; a machine learning-based HEMS for energy saving, ensuring comfort and security while reducing energy consumption. The proposed architecture consists of seven layers, from presentation to device, in which information security is considered between presentation, IoT services and management layers, contemplating both authentication and authorisation. It does not mention DR or DER management as part of the proposed HEMS, nor explores the possibility of its integration with existing HAS, although its management layer does apply a semantic approach to home management, utilising a self-developed ontology to represent the main domotic concepts. Overall it presents a monolithic structure that goes from device to presentation, where interoperability has not been approached.

Elshaafi et al. [15] explore an approach to decentralised automated DR and home energy management. The proposed architecture is implemented using a multi-agent system with three different levels: home, aggregator and distribution system operator (being the latter two SG-related). At the home level, they define only two agents: the device agent and the HEMS agent. Their combined objective is to reduce the energy bill while respecting user preferences and comfort. While device agents encapsulate the communications with the home devices, the HEMS agent is responsible for the grunt of the work: planning, optimising and communicating with SG agents. This architecture does not consider the existence of a previous HAS. The final solution is presented in the form of a home gateway device that will directly interact with smart devices, although it does consider DER management through the different device agents. It addresses interoperability by proposing the usage of standard communication interfaces (OSGi: Open Services Gateway initiative [16]) and REST interfaces) and the use of Web Ontology Language (OWL) for information modelling. Finally, the proposed architecture takes into consideration the privacy and security of home users by using XACML (eXtendible Access Control Markup Language [17]) as an attribute-based access control platform, controlling the visibility of home devices to the HEMS agent.

The MAS2TERING project [18] defines a multi-agent system consisting of the following agents: *Distribution system operator agent*, *Aggregator agent*, *Central home energy management agent*, *Microgeneration agent*, *Appliance agent* and *Battery agent* whose interactions aim at delivering demand-side management through the supply chain, from generation to consumer appliances. This architecture does not cover security aspects, nor the integration with existing HASs or home energy management.

Zhang et al. propose iHEMS [19], a publish-subscribe communications infrastructure, using Information-Centric Networking (specifically Content Centric Networking) as the communication backbone. It does not rely on securing the communication channels but on encrypting the data itself, using a secure-group communications scheme above the pub-sub layer. The architecture itself contemplates the different devices interconnected through the Information Centric Networking-based pub-sub substrate, as well as a *Directory Service*, which devices use to publicise their data and a *Group Controller* in charge of key management for encryption/decryption.

Digital Environment Home Energy Management System (DEHEMS) project [20] proposes a service-based architecture, consisting of a remote server where the knowledge base is deployed, which in turn is fed from a *Data Collector* located in the home, to which sensors, devices, appliances and display devices are connected using wireless interfaces.

Rosello-Busquet et al. [21] propose a home gateway for a HEMS system, to control the devices in a home network at the service level. Built over the OSGi framework, it uses DogOnt ontology as the base for its knowledge base data repository. The architecture is composed of six bundles: *Knowledge Base*, *Interface*, *Network n*, *Networks Manager*, *Manager* and *Network Emulator*.

ThinkHome by Reinisch et al. [22] describes a multi-agent system architecture with two main premises: ensuring energy efficiency at home and comfort optimisation. The control strategies realised by the multi-agent system are split into problem aspects which are directly mapped to the different agents of the framework: *Control*, *Users*, *Global Goals*, *Context Inference*, *Auxiliary Data*, *Knowledge Base Interface* and *Building Automation System Interface*.

After the bibliographical review performed in architecture and security, we can conclude that none of the reviewed works considers all the previously described concerns of a modern prosumer-oriented SH in their architecture. None addresses data model and communications interoperability simultaneously to enable successful interaction with other service providers, such as external device platforms, Smart Hubs and the SG. Finally, security was covered by some works, but mostly in the communications domain, not placing the focus on data privacy, which represents a major concern in the complex SH ecosystem.

#### *2.2. Ontological Background*

To model the information in SHEMSs, a wide range of topics had to be covered, which resulted in an extensive survey of the different existing related ontologies. The topics or areas covered include grid DR management, home DR management, DER management, energy metering and performance assessment, energy saving advice, (home) infrastructure, user preferences, weather and environmental and sensor data: to name but a few. It is needless to say that no single ontology covers all of the required areas and that they all differ in the level of detail with which the different concepts are captured.

To summarise the ontological state of the art, Table 1 categorises the most relevant surveyed works according to our specific use case. Later, in Section 3.4, the mapping of those ontologies to specific elements in our proposal will be presented.

**Table 1.** Ontology summary.

\* Grayed rows are imported in DABGEO.

Smart Energy Domain Ontology (SARGON) [25] extends SAREF (Smart Applications REFerence [35]) but, unlike SAREF4EE, focuses on the control and monitoring of distribution electrical grids, integrating it with building energy automation.

OSEIM and NewOSEIM [23,24] leverage semantic reasoning over an ontology presenting knowledge about the internal and external environment of a home, to achieve intelligent energy management.

DABGEO [26] is an ontology semantically equivalent to OEMA [36], a previous ontology by the same authors. It improves on the former by offering a modular ontology that can be imported into subsets, facilitating its adoption in custom use-case scenarios. As its predecessor, it links and extends concepts from other previous ontologies. The base of the ontology network is ThinkHome, to which SAREF4EE, EnergyUse and ProSGV3 have been added.

EnergyUse framework [27] for home energy-saving advice applications, enriches PowerONT [37] (the power consumption ontology) with other ontologies and maps it to JSON-LD.

MAS2TERING ontology [18,38], developed under the homonymous project, implements USEF (Universal Smart Energy Framework [39]) through multi-agent systems. The purpose of the ontology is the representation of the data of different SG domains and to provide interoperability between SG agents and stakeholders. It is based in Energy@Home [40] and CIM (International Electrotechnical Commission's Common Information Model [41]).

The DNAS framework presents an ontology [30] to represent energy-related occupant behaviour to understand total energy consumption in buildings.

The MIRABEL [32,42] ontology for modelling flexibility in SG energy management, allows actors to express their energy flexibility for a specific device. It also represents energy profiles for devices, as well as production and storage devices.

BOnSAI [33,43] presents an ontology for incorporating Ambient Intelligence in Smart Buildings that can be used for energy management and monitoring. Includes concepts about functionality, QoS, hardware, users and context.

#### **3. Proposal**

The general or conceptual architecture of our proposal (Figure 3) is composed of multiple Energy Management Components (EMCs) responsible for a specific domain within home energy management, which interact with each other to pursue their goals, cooperating toward a common objective of increasing energy efficiency and reducing energy costs of the home.

**Figure 3.** Knowledge Base-centred architecture of the Smart Home Energy Management System.


**About the Editors**

### **Kikuko Shoyama**

Dr. Kikuko Shoyama is an Associate Professor at the Department of Regional and Comprehensive Agriculture, College of Agriculture, Ibaraki University, Japan. Her research interests are in the quantitative analysis of socio-ecological systems related to land use change, ecosystem services, and disaster resilience, in particular, the role of scenario modeling in decision-making under uncertain and changing environmentd. She contributed to the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) as a Lead Author for the Methodological Assessment on Scenarios and Models of Biodiversity and Ecosystem Services.

### **Rajarshi Dasgupta**

Dr. Rajarshi Dasgupta is a Senior Policy Researcher in the Integrated Sustainability Center, Institute for Global Environmental Strategies. His research interests are risk-sensitive land use planning, ecosystem-based disaster risk reduction (Eco-DRR), socio-environmental scenario planning, spatial quantification of ecosystem services, community-based conservation, and disaster risk management. He served as a Lead Author (LA) for the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services (IPBES) Asia-Pacific Regional Assessment Report and Assessment of Sustainable Use of Wild Species, and a Chapter Scientist and contributing author for the Intergovernmental Panel on Climate Change's (IPCC) sixth assessment report (WG II).

### **Ronald C. Estoque**

Dr. Ronald C. Estoque is a Senior Researcher at the Center for Biodiversity and Climate Change, Forestry and Forest Products Research Institute, Japan. He is, by profession, a forester and geo-environmental scientist. His research interests are at the interface between nature and society (sustainability; land change; ecosystem services; forest cover change; urbanization; and climate change mitigation, vulnerability, risk, and adaptation), with the application of various tools and techniques including remote sensing and GIS. He was a Contributing Author (CA) to the Intergovernmental Panel on Climate Change's (IPCC) sixth assessment report (WG II, Chapter 10). Currently, he serves as a Review Editor (RE) for the Intergovernmental Science-Policy Platform for Biodiversity and Ecosystem Services' (IPBES) nexus assessment (Chapter 2).


Contents

**III**

**Chapter 19 285**

**Chapter 20 299**

**Chapter 21 315**

Ethical Deliberation in the Allocation of Respirators and Beds

Geospatial Clustering of Mobile Phone Use and Tuberculosis Health

Improving Healthcare Access through Digital Health: The Use of

*by Sunny Ibeneme, Nkiruka Ukor, Joseph Okeibunor and Felicitas Zawaira*

*Juliana Dias Reis Pessalacia, Priscila Kelly da Silva Neto, Marcela Tavares de Souza and Tatiana Carvalho Reis Martins*

during the Covid-19 Pandemic in Brazil *by Maristela Rodrigues Marinho, Sandra Pinto,*

Outcomes among African Health Systems

Information and Communication Technologies

*by Najeeb Al-Shorbaji*

Preface

The concept of healthcare access is continuously evolving. It is globally recognized that healthcare-seeking behavior tends to involve seeking access to multiple

healthcare providers. This book covers a range of topics related to healthcare access, including occupational health and safety, occupational hygiene, universal health coverage, economic aspects of healthcare services, issues related to low-resource primary healthcare settings, factors influencing access to reliable healthcare, emergency healthcare access, issues of ethical deliberation in the allocation of resources, patient satisfaction, laboratory services, medical tourism, and healthcare access and usefulness of advanced technologies in healthcare delivery. As an extended responsibility, healthcare providers can create mechanisms to facilitate subjective decision-making in accessing the right kind of healthcare services as well as various options to support financial needs to bear healthcare-related expenses while seeking health and fulfilling the healthcare needs of the population. Adequate healthcare access not only requires the availability of comprehensive healthcare facilities but also affordability and knowledge of the availability of these services. This volume brings together experiences and opinions from global leaders to develop affordable,

sustainable, and uniformly available options to access healthcare services.

**Dr. Amit Agrawal**

**Dr. Srinivas Kosgi**

Dharwad, India

Department of Psychiatry,

Bhopal, India

Department of Neurosurgery,

All India Institute of Medical Sciences,

Dharwad Institute of Mental Health and Neurosciences,


3.1.1. Fuzzy Set

A fuzzy set is used to address the issues that exist in an uncertain environment. It was proposed by Zadeh when attempting to solve multiple criteria decision-making problems. If the set *Z* & is a triangular fuzzy number (TFN), each value of the membership function is in the range [0, 1]:

$$\mu\_{\widehat{Z}}(\mathbf{x}) = \begin{cases} \frac{(\mathbf{x} - \mathbf{j})}{(k - j)} & j \le \mathbf{x} \le k \\\ \frac{(l - \mathbf{x})}{(l - k)} & k \le \mathbf{x} \le l \\\ 0 & \end{cases} \tag{1}$$

Each value of membership, which includes the left (the lowest value to evaluate) and right (the highest value to evaluate) representatives, of a TFN is shown below:

$$\overline{\mathbf{N}} = (\mathbf{N}^{1(\mathbf{y})}, \mathbf{N}^{r(\mathbf{y})}) = (\mathbf{j} - (\mathbf{k} - j)\text{ y, } l + (\mathbf{k} - d)\text{ y}), \text{ y} \in [0, 1].$$

A triangular fuzzy number can be described as in Figure 4.

**Figure 4.** A triangular fuzzy number (TFN).


**Author details**

Hesham Mohamed Abdal-Salam Yehia\* and Said Mahmoud Said Department of Biotechnology, HST Company, Cairo, Egypt

\*Address all correspondence to<EMAIL_ADDRESS>
© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Improving the Quality of Drinking Water by Raising the pH Levels Using a Natural Na2SiO3… DOI: http://dx.doi.org/10.5772/intechopen.112856*

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