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Sweden have faced decreasing groundwater storage with critical low groundwater levels for several years. Gotland is one example with issues of providing freshwater due to the low groundwater levels. These circumstances can be related to impacts caused by early agriculture development, an increased demand of freshwater and climate change. There is a need in this region to increase the groundwater storage to ensure enough freshwater. The aim of the study is to increase freshwater storage. Digital geographical information system (GIS) was chosen as a tool in this study in order to cover large geographical areas.  The study was divided into two parts, with focus to determine hydrological and hydrogeological conditions and to identify suitable areas where groundwater storage could be increased. The first part studied: specific capacity, groundwater storage, groundwater balance and topographic wetness index. The second part locked at four methods to increase freshwater storage: Lakes, controlled drainage, wetland and subsurface dam. The result tells us that lakes have the potential to provide freshwater for the municipal distribution network. The controlled drainage method has the ability reduce the outflow of surface water and to increase the groundwater infiltration. Earlier drained wetland areas was identified which could serve as freshwater storage. Suitable areas for subsurface dams were identified. They could work as a large groundwater storage as a decentralized system with the ability to provide groundwater for wells that are spread out. However the identified areas for each methods needs further investigations in more detail to determine the accuracy of the results.

Current commercial intercalation cathodes are approaching their theoretical capacity edges, which limits further improvement of the energy density in Li-ion batteries. To overcome this limitation, Li-rich antiperovskite cathodes were developed, utilizing both cationic and anionic redox activities. This class of materials has the general formula (Li2TM)ChO, where TM and Ch represent a transition metal (Fe, Mn, Co) and chalcogen ion (S, Se), respectively. This work focuses on understanding the reaction mechanism, exploring novel approaches for optimizing the electrochemical performance, and developing a scalable synthesis method for the antiperovskite cathodes. Firstly, the effect of substituting S by Se in the solid-state synthesized (Li2Fe)SO on the structural and electrochemical performance is thoroughly investigated. The anionic substitution was found to improve the structural and thermal stabilities of (Li2Fe)SO material. The cyclic voltammetry data confirmed both the cationic (Fe) and anionic (S/Se) redox activities, with possibility of controlling the anionic redox potential through the anionic substitution. It was observed that the electrochemical performance exhibits a non-linear dependence on the degree of anionic substitution. Among the prepared (Li2Fe)S1-xSexO (x = 0.1-0.9) compositions, (Li2Fe)S0.7Se0.3O exhibited the best electrochemical performance with a specific capacity 245 mAhg-1 and good cycling stability at low current rate. Ex-situ and in-situ measurements suggested an enhanced structural stability of (Li2Fe)S0.7Se0.3O during electrochemical cycling compared to (Li2Fe)SO, which could be one of the reasons for its superior performance at low current rates. The second part of this work focuses on understanding the reaction mechanism of (Li2Fe)SeO prepared by solid-state reaction (SSR) method and exploring the impact of cationic substitution of Fe by Mn on its structural and electrochemical properties. Electrochemical investigations showed that the cationic redox activity leads to a reversible cycling behaviour, indicating its role in the stable performance. Whereas, the anionic redox activity leads to partial decomposition of the (Li2Fe)SeO cathode to an electrochemically active phase. In general, although the electrochemical activity of the phase resulting from the partial decomposition of any antiperovskite composition can compensate the initial capacity loss, it opens a channel for capacity fading over long term of cycling. The (Li2Fe)SeO cathode could deliver an initial specific discharge capacity of 165 mAhg-1, which declined to only 140 mAhg-1 after 100 cycles, indicating a good cycling performance. Even at high current rate (1C), the (Li2Fe)SeO could provide a reasonable specific capacity of 100 mAhg-1. Replacing Fe with Mn reduced the overall redox activity of the cationic and anionic redox processes, when using active material: carbon: binder weight ratio of 70:15:15 wt. %. This may result from impeded kinetics and the Jahn-Teller effect associated with Mn2+/3+ redox. However, low substitution levels can be beneficial in optimizing the performance while minimizing the negative effects associated with Mn2+/3+ redox pair. Modifying the electrode ratio to 85:10:5 wt. % improved the specific capacity for (Li2Fe0.9Mn0.1)SeO, surpassing that of the unsubstituted (Li2Fe)SeO cathode. These findings highlight the role of controlled substitution and electrode ratio in optimizing the electrochemical performance of antiperovskite cathodes. The third part of this work focuses on developing scalable, controllable, and sustainable synthesis of antiperovskite cathodes using mechanochemical (MC) method based on ball milling (BM), which is crucial for practical application. Both (Li2Fe)SeO and (Li2Fe)SO antiperovskite cathodes have been successfully prepared by direct MC without the need for external heating, which is advantageous for energy saving. Post-heat treatment after the milling was found to be an effective strategy for controlling the morphological and electrochemical properties of both materials. Both ball-milled materials revealed similar reaction mechanism to the (Li2Fe)SeO prepared by SSR method, involving both cationic and anionic redox activities. The ball-milled (Li2Fe)SeO displayed an average specific discharge capacity of 255 mAhg-1 at 0.1C and 138 mAhg-1 at 1C in the potential range 1-3 V. Transmission electron microscopy and magnetic investigations revealed a partial conversion of the mechanochemically synthesized (Li2Fe)SeO into an electrochemically active Fe1-xSex phase during the anionic redox process. On the other hand, mechanochemically synthesized (Li2Fe)SO exhibited an average specific discharge capacity of 340 and 133 mAhg-1 at 0.1C and 1C, respectively, in the potential range 1-3 V. Excluding the anionic redox activity of both materials by restricting the potential scanning range was found to be advantageous for enhancing the cycling stability over long range of cycling. This highlights the critical role of controlling the potential range on the electrochemical performance and cyclability of these materials.

A prototype 3-dimensional (3D) anode, based on multiwall carbon nanotubes (MWCNTs), for Li-ion batteries (LIBs), with potential use in Electric Vehicles (EVs) was investigated. The unique 3D design of the anode allowed much higher areal mass density of MWCNTs as active materials, resulting in more amount of Li+ ion intake, compared to that of a conventional 2D counterpart. Furthermore, 3D amorphous Si/MWCNTs hybrid structure offered enhancement in electrochemical response (specific capacity 549 mAhg-1). Also, an anode stack was fabricated to further increase the areal or volumetric mass density of MWCNTs. An areal mass density of the anode stack 34.9 mg/cm2 was attained, which is 1,342% higher than the value for a single layer 2.6 mg/cm2. Furthermore, the binder-assisted and hot-pressed anode stack yielded the average reversible, stable gravimetric and volumetric specific capacities of 213 mAhg-1 and 265 mAh/cm3, respectively (at 0.5C). Moreover, a large-scale patterned novel flexible 3D MWCNTs-graphene-polyethylene terephthalate (PET) anode structure was prepared. It generated a reversible specific capacity of 153 mAhg-1 at 0.17C and cycling stability of 130 mAhg-1 up to 50 cycles at 1.7C.