Summary of Chemistry doctoral thesis: Synthesis of LiFexM1-xPO4/graphene nanocomposite as cathode material to improve electrochemical properties for lithium-ion batteries

Nanocomposite material LiFe1-xMxPO4/Gr was successfully synthesized achieving it with single phase. It’s response required electrochemical parameters of positive electrode materials for Li-ion batteries such as: improved diffusion coefficient and conductivity, higher capacity comparative with LFP in same conditional synthesis.
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Summary of Chemistry doctoral thesis: Synthesis of LiFexM1-xPO4/graphene nanocomposite as cathode material to improve electrochemical properties for lithium-ion batteries MINISTRY OF EDUCATION VIETNAM ACADEMY OF AND TRAINING SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY ---------------------------------- LA THI HANG SYNTHESIS OF LiFe1-xMxPO4/GRAPHENE NANOCOMPOSITE AS CATHODE MATERIAL TO IMPROVE ELECTROCHEMICAL PROPERTIES FOR LITHIUM-ION BATTERIES SUMMARY OF THESIS Major: Theoretical and Physical Chemistry Code: 9440119 HCMC-2019 The Thesis has been performed at: Institute of Applied Materials Science (IAMS) – Graduate University Science and Technology – Vietnam Academy of Science and Technology (VAST) ……..….………… Advisor 1: Assoc. Prof. Nguyen Nhi Tru Advisor 2: Assoc. Prof. Le My Loan Phung Reviewer 1: … Reviewer 2: … Reviewer 3: …. The thesis was presented at National level Council of Doctoral Thesis Assessment held at Graduate University of Science and Technology – Vietnam Academy of Science and Technology at….on…… The Thesis can be stored at: - The Library of Graduate University of Science and Technology - -National Library of Vietnam INTRODUCTION 1. The important role of thesis These days the seriousness surrounding and pertaining to the-renewable energy crisis can cause exploited demands to the surrounding ecosystems leading to depletion, pollution and climate change including the alarming negative effects such as eroded environments. For these reasons, renewable energy should be increasingly promoted and developed further development and research such as: solar, wind and tide… thereby reducing our reliance on fossil fuels and the depletion of crucial ecosystems. However, these resources have huge disadvantages that are intermittent and dependent on conditional factors related to the climate, so using them poses many challenges for its application. Therefore, solving these problems requires the creation of efficient energy storage devices for the development of renewable energy transferred from chemical energy to electrical energy. This is an important role and strategy toward the improvement of renewable energy for global solutions. Since the advent of these technologies the rechargeable of Li-ion batteries were born, it brings many achievements for application science to contribute enhancement of new technology and various type of batteries for modern electrical and electronic technology. Rechargeable batteries are devices which enable energy storage and release directly as electricity; by means of highly reversible electrochemical reactions. Today, this storage dominates market in Portable mobile electronics with more potentials than other devices consideration: Large battery power, high energy density, light weight, safe and stability, as well as design flexibility. With good characteristic, Li-ion batteries could replace traditional storage. In recent years, Li-ion batteries have been considered the main structure to investigate electrochemical properties, especially, material electrode. Actually, Commercial rechargeable LiCoO2 for Li-ion batteries with specific capacity: 248 mAh.g-1 has been the choice material in the predominate market with the electronic devices in this field since the commercialization by Sony Energitech in 1992. However, this compound using cathode material has met some limitations with respect to charge-discharge issue, additionally safe, unfriendly environments at expensive costs (rate of 0.001% Co, 1.5% Fe in the Earth). LiFePO4 structural olivine is excellent choice with prolonged it’s life time, deeply cycle stability, environmental friendliness, and advantageous low cost but olivine structure has only one channel of direction [010], the intrinsic electronic conductivity of LFP olivine structure. Actually, LiFePO4 (LFP) has one huge drawback shown due to its rigid orthorhombic and Li+ diffusion rate is considerably low to reach it’s full theoretical capacity during battery operation. Plainly, it’s oxidation properties from Fe2+ to Fe3+ make it a less suitable choice, these problems lead to poor performance with Li-ion batteries to meet some challenges due with commercialization. To solve this problem, researchers in the world focus on improvement of ionic conductivity (10-9-10-10 S.cm-1) and diffusion coefficient (10-12-10-14 cm2.S-1) ion Li+ in order to enhance higher capacity in a high rate charge-discharge by this method of expansion; instinct-LFP: doping metal as a new material LiFexM1-xPO4 (LFMP) or coating carbon (LFP/C) and reduced size. Recently, the publication of these materials using cathode to enhancement of electrochemical properties for Li ion batteries have related to doping metals or coating graphene as individuality instead of linking together in recent decades. Furthermore, the number of international publications on metal-doped LiFePO4 materials and coated and graphene has been limited with LiFexM1-xPO4/graphene composite nano materials less or none of researches studied deeply the differences with several kinds of electrochemical performance by evaluation of the kinetic element of Li+ ion diffusion process into olivine structure. According 1 to international publications in the world as well as inheriting previous research based knowledge, this thesis was chosen as its basis. “Synthesis of LiFexM1-xPO4/graphene nanocomposite as cathode material to improve electrochemical properties for lithium-ion batteries. In this study, therein, survey the influence various rate of metal-doped materials on diffusion kinetic pr ...