Polyanionic compounds have been heavily investigated as possible electrode materials in lithium- and sodium-ion batteries. Chief among these is lithium iron phosphate (LiFePO4) which adopts the olivine structure and has a potential of 3.5 V vs. Li/Li+. Many aspects of ion transport, solid-solution behaviour and their relation to particle size in olivine systems are not entirely understood. Morphology, unit cell parameters, purity and electrochemical performance of prepared LiFePO4 powders were greatly affected by the synthetic conditions. Partially delithiated olivines were heated and studied by Mössbauer spectroscopy and solid-solution behaviour by electron delocalization was observed. The onset of this phenomenon was around 470-500 K in bulk material but in nanocrystalline powders, the onset of a solid solution was observed around 420 K. The isostructural manganese member of this family (LiMnPO4) was also prepared hydrothermally. Owing to the thermal instability of MnPO4, partially delithiated LiMnPO4 did not display any solid-solution behaviour. Phosphates based on the tavorite (LiFePO4OH) structure include LiVPO4F and LiFePO4(OH)1-xFx which may be prepared hydrothermally or by solid state routes. LiVPO4F is a high capacity (2 electrons/transition metal) electrode material and the structures of the fully reduced Li2VPO4F and fully oxidized VPO4F were ascertained. Owing to structural nuances, the potential of the iron tavorites are much lower than that of the olivines. The structure of Li2FePO4F was determined by a combined X-ray and neutron diffraction analysis. The electrochemical properties of very few phosphates based on sodium are known. A novel fluorophosphate, Na2FePO4F, was prepared by both solid state and hydrothermal methods. This material exhibited two two-phase plateau regions on cycling in a half cell versus sodium but displayed solid-solution behaviour when cycled versus lithium, where the average potential was 3.3 V. On successive cycling versus Li a decrease in the sodium content of the active material was observed, which implied an ion-exchange reaction occurred between the material and the lithium electrolyte. Studies of polyanionic materials as positive electrode materials in alkali metal-ion batteries show that some of these materials, namely those which contain iron, hold the most promise in replacing battery technologies currently available.

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This paper aims on the study of developing the firmware program for the monitor chips designed inside the battery set of a Notebook power management system, with the function of monitoring safety during battery charge/discharge via the chips; meanwhile, to estimate the residual capacity of the battery. Owing to the chemistry properties of the battery, whose residual capacity will be affected by the current flow during charge/discharge, high/low of the ambient temperature, fatigue of the battery, as a result, variations of the residual capacity will be presented in non-linear. Therefore, in estimation of the battery residual capacity, using the curve learned from the practical experiment on the battery charge/discharge to be the basis for us to find out the appropriate parameters under the relevant influence factors for revision. It will be more accurate in estimation of the battery residual capacity. At the same time, the battery signal can be transmitted to the managing end of the Notebook power management system via the system management interface, which may enable the system to operate more efficiently.

Natural graphite from cheap and abundant natural sources is an attractive anode material for lithium ion batteries. We report on modifications of such a common natural graphite, whose electrochemical performance is very poor, with solutions of (NH4)2S2O8, concentrated nitric acid, and green chemical solutions such of e.g. hydrogen peroxide and ceric sulfate. These treatments resulted in markedly im-proved electrochemical performance (reversible capacity, coulombic efficiency in the first cycle and cycling behavior). This is attributed to the effective removal of active defects, formation of a new dense surface film consisting of oxides, improvement of the graphite stability, and introduction of more nanochannels/micropores. These changes inhibit the decomposition of electrolyte solution, pre-vent the movement of graphene planes along a-axis direction, and provide more passage and storage sites for lithium. The methods are mild, and the uniformity of the product can be well controlled. Pilot experiments show promising results for their application in industry.

The use of Lithium-ion batteries in the automotive industry has increased tremendously in the last few years. The anticipated increase in demand of lithium to power electric and hybrid cars has prompted researchers to examine the long term sustainability lithium as a transportation resource. To provide a better understanding of future availability, this thesis presents a systems framework for the key processes and materials and energy flows involved in the electric vehicle lithium-ion battery life cycle, on a global scale. This framework tracks the flow of lithium and energy inputs and outputs from extraction, to production, to on road use, and all the way to end of life recycling and disposal. This process flow model is the first step in developing a life cycle analysis model for lithium that will eventually help policymakers assess the future role of lithium battery recycling, and at what point in time establishing a recycling infrastructure becomes imminent.

For the broad commercial success of electric vehicles (EVs), it is essential to deeply understand how batteries behave in this challenging application. This thesis has therefore been focused on studying automotive lithium-ion batteries in respect of their performance under EV operation. Particularly, the  need  for  simple  methods  estimating  the  state-of-health  (SOH)  of batteries during EV operation has been addressed in order to ensure safe, reliable, and cost-effective EV operation. Within  the  scope  of  this  thesis,  a  method  has  been  developed  that  can estimate the SOH indicators capacity and internal resistance. The method is solely based on signals that are available on-board during ordinary EV operation  such  as  the  measured  current,  voltage,  temperature,  and  the battery  management  system’s  state-of-charge  estimate.  The  approach  is based on data-driven battery models (support vector machines (SVM) or system  identification)  and  virtual  tests  in  correspondence  to  standard performance  tests  as  established  in  laboratory  testing  for  capacity  and resistance determination. The proposed method has been demonstrated for battery data collected in field tests and has also been verified in laboratory. After a first proof-of-concept of the method idea with battery pack data from a plug-in hybrid electric vehicle (PHEV) field test, the method was improved with the help of a laboratory study where battery electric vehicle (BEV) operation of a battery  cell  was  emulated  under  controlled  conditions  providing  a thorough validation possibility. Precise partial capacity and instantaneous resistance  estimations  could  be  derived  and  an  accurate  diffusion resistance estimation was achieved by including a current history variable in the SVM-based model. The dynamic system identification battery model gave precise total resistance estimates as well. The SOH estimation method was also applied to a data set from emulated hybrid electric vehicle (HEV) operation of a battery cell on board a heavy-duty vehicle, where on-board standard  test  validation  revealed  accurate  dynamic  voltage  estimation performance of the applied model even during high-current situations. In order to exhibit the method’s intended implementation, up-to-date SOH indicators have been estimated from driving data during a one-year time period. / <p>QC 20150914</p>

Utilization of amorphous metallic alloy has received much attention for use in numerous microelectronic and electrochemical devices since they provide unique electrical, thermal conductivity, and magnetic properties. To develop these functional properties, it is essential to understand the amorphous structure and the property relationships. First principles calculations provide insight into the structure, thermodynamic stability, electronic and magnetic properties of amorphous alloys. For Ru- and Co-based alloys, the thermodynamic stability was examined by calculating the mixing energy along with those of crystalline counterparts. The amorphous RuP, CoP, RuB, and CoB alloys, become energetically more favorable than their crystalline counterparts at moderate P(B) content. The atomistic structures have well-defined local structures depending on the atomic size ratio and electronic interactions between constituent elements. Their local ordering is attributed to strong p-d hybridization, which contributes to stabilizing the Ru(Co)-P(B) alloys. Surface segregation of P(B) and interfacial adhesion with copper were also studied. Li-X (X: Si, Ge, and Sn) were examined when 1 or 2 Li atoms are inserted into the interstitial sites. Li insertion in the tetrahedral site, which is the most preferable site in the diamond matrix, causes outward displacement and charge localization around the X neighbors, thereby weakening of the covalent bonds leading to destabilization of the host matrix. We present the energetics, structure, electronic and mechanical properties of crystalline and amorphous Li-X (X: Si, Ge, Sn, and Si+Sn) alloys. Our calculations show that the incorporation of Li leads to disintegration of the tetrahedrally-bonded X network into small clusters of various shapes. Electronic structure analysis highlights that the charge transfer leads to weakening or breaking of X bonds with the growing splitting between s and p states, and consequently the Li-X alloys softens with increasing Li content. / text

Today’s information-centered world leads the ever-increasing consumer demand for more powerful, multifunctional portable devices. Additionally, recent developments on long-lasting energy sources and compliant, flexible systems, have introduced new required features to the portable devices industry. For example, wireless sensor networks are in urgent need of self-sustainable, easy-to-deploy, mobile platforms, wirelessly interconnected and accessible through a cloud computing system. The objective of my doctoral work is to develop integration strategies to effectively fabricate mechanically flexible, energy-independent systems, which could empower sensor networks for a great variety of new exciting applications. The first module, flexible electronics, can be achieved through several techniques and materials. Our main focus is to bring mechanical flexibility to the state-of-the-art high performing silicon-based electronics, with billions of ultra-low power, nano-sized transistors. Therefore, we have developed a low-cost batch fabrication process to transform standard, rigid, mono-crystalline silicon (100) wafer with devices, into a thin (5-20 m), mechanically flexible, optically semi-transparent silicon fabric. Recycling of the remaining wafer is possible, enabling generation of multiple fabrics to ensure lowcost and optimal utilization of the whole substrate. We have shown mono, amorphous and poly-crystalline silicon and silicon dioxide fabrics, featuring industry’s most advanced high-/metal-gate based capacitors and transistors. The second module consists on the development of efficient energy scavenging systems. First, we have identified an innovative and relatively young technology, which can address at the same time two of the main concerns of human kind: water and energy. Microbial fuel cells (MFC) are capable of producing energy out the metabolism of bacteria while treating wastewater. We have developed two micro-liter MFC designs, one with carbon nanotubes (CNT)-based anode and the second with a more sustainable design and easy to implement. Power production ranges from 392 to 100 mW/m3 depending on design. Additionally we have explored a flexible thermoelectric generator (0.139 μW/cm2) and a lithium-ion battery (~800 μAh/m2) for back-up energy generation and storage. Future work includes the implementation of a self-powered System-on-Package which gathers together energy generation, storage and consumption. Additionally we are working to demonstrate Complementary Metal-Oxide-Semiconductor (CMOS) circuitry on our flexible platform, as well as memory systems.

Applications of biotechnology in drug delivery and medical instrumentation and energy storage have been gaining popularity. Especially, utilization of biotechnology for energy storage is attracting attention due to its environmentally friendly nature and cost efficiency. In this project, a filamentous bacteriophage, M13, to fabricate metal oxide battery electrodes. M13 phage is 6.5 nm wide and 800 nm long, and can act as a template to produce nano-sized metal oxide particles. A method to prepare manganese oxide electrodes was developed, where the phage is integrated with the oxide into a nanocomposite. The composite material was used to make a high capacity electrode for lithium ion batteries. The M13 templated manganese oxide, Mn3O4, could deliver a high initial capacity of 766 mAh/g, and recorded a stabilized discharge capacity of ~800 mAh/g even after 60 cycles.

The exploration of functional materials to store renewable, clean, and efficient energies for electric vehicles (EVs) has become one of the most popular topics in both material chemistry and electrochemistry. Rechargeable lithium batteries and fuel cells are considered as the most promising candidates, but they are both facing some challenges before the practical applications. For example, the low discharge capacity and energy density of the current lithium ion battery cannot provide EVs expected drive range to compete with internal combustion engined vehicles. As for fuel cells, the rapid and safe storage of H2 gas is one of the main obstacles hindering its application. In this thesis, novel mesoporous/nano functional materials that served as cathodes for lithium sulfur battery and lithium ion battery were studied. Ternary lithium transition metal nitrides were also synthesized and examined as potential on-board hydrogen storage materials for EVs. Highly ordered mesoporous carbon (BMC-1) was prepared via the evaporation-induced self-assembly strategy, using soluble phenolic resin and Tetraethoxysilane (TEOS) as precursors and triblock copolymer (ethylene oxide)106(propylene oxide)70(ethylene oxide)106 (F127) as the template. This carbon features a unique bimodal structure (2.0 nm and 5.6 nm), coupled with high specific area (2300 m2/g) and large pore volume (2.0 cm3/g). The BMC-1/S nanocomposites derived from this carbon with different sulfur content exhibit high reversible discharge capacities. For example, the initial capacity of the cathode with 50 wt% of sulfur was 995 mAh/g and remains at 550 mAh/g after 100 cycles at a high current density of 1670 mA/g (1C). The good performance of the BMC-1C/S cathodes is attributed to the bimodal structure of the carbon, and the large number of small mesopores that interconnect the isolated cylindrical pores (large pores). This unique structure facilitates the transfer of polysulfide anions and lithium ions through the large pores. Therefore, high capacity was obtained even at very high current rates. Small mesopores created during the preparation served as containers and confined polysulfide species at the cathode. The cycling stability was further improved by incorporating a small amount of porous silica additive in the cathodes. The main disadvantage of the BMC-1 framework is that it is difficult to incorporate more than 60 wt% sulfur in the BMC-1/S cathodes due to the micron-sized particles of the carbon. Two approaches were employed to solve this problem. First, the pore volume of the BMC-1 was enlarged by using pore expanders. Second, the particle size of BMC-1 was reduced by using a hard template of silica. Both of these two methods had significant influence on improving the performance of the carbon/sulfur cathodes, especially the latter. The obtained spherical BMC-1 nanoparticles (S-BMC) with uniform particle size of 300 nm exhibited one of the highest inner pore volumes for mesoporous carbon nanoparticles of 2.32 cm3/g and also one of the highest surface areas of 2445 m2/g with a bimodal pore size distribution of large and small mesopores of 6 nm and 3.1 nm. As much as 70 wt% sulfur was incorporated into the S-BMC/S nanocomposites. The corresponding electrodes showed a high initial discharge capacity up to 1200 mAh/g and 730 mAh/g after 100 cycles at a high current rate 1C (1675 mA/g). The stability of the cells could be further improved by either removal of the sulfur on the external surface of spherical particles or functionalization of the C/S composites via a simple TEOS induced SiOx coating process. In addition, the F-BMC/S cathodes prepared with mesoporous carbon nanofibers displayed similar performance as the S-BMC/S. These results indicate the importance of particle size control of mesoporous carbons on electrochemical properties of the Li-S cells. By employing the order mesoporous C/SiO2 framework, Li2CoSiO4/C nanocomposites were synthesized via a facile hydrothermal method. The morphology and particle size of the composites could be tailored by simply adjusting the concentrations of the base LiOH. By increasing the ratio of LiOH:SiO2:CoCl2 in the precursors, the particle size decreased at first and then went up. When the molar ratio is equal to 8:1:1, uniform spheres with a mean diameter of 300-400 nm were obtained, among which hollow and core shell structures were observed. The primary reaction mechanism was discussed, where the higher concentration of OH- favored the formation of Li2SiO3 but hindered the subsequent conversion to Li2CoSiO4. According to the elemental maps and TGA of the Li2CoSiO4/C, approximately 2 wt% of nanoscale carbon was distributed on/in the Li2CoSiO4, due to the collapse of the highly ordered porous structure of MCS. These carbons played a significant role in improving the electrochemical performance of the electrode. Without any ball-mill or carbon wiring treatments, the Li2CoSiO4/C-8 exhibited an initial discharge capacity of 162 mAh/g, much higher than that of the sample synthesized with fume silica under similar conditions and a subsequent hand-mixing of Ketjen black. Finally, lithium transition metal nitrides Li7VN4 and Li7MnN4 were prepared by high temperature solid-state reactions. These two compounds were attempted as candidates for hydrogen storage both by density functional theory (DFT) calculations and experiments. The results show that Li7VN4 did not absorb hydrogen under our experimental conditions, and Li7MnN4 was observed to absorb 7 hydrogen atoms through the formation of LiH, Mn4N, and ammonia gas. While these results for Li7VN4 and Li7MnN4 differ in detail, they are in overall qualitative agreement with our theoretical work, which strongly suggests that both compounds are unlikely to form quaternary hydrides.