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Oxide Nanomaterials for Lithium-Ion Batteries

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Oxide Nanomaterials for Lithium-Ion Batteries

Tech Area / Field

  • MAT-CER/Ceramics/Materials
  • MAT-SYN/Materials Synthesis and Processing/Materials
  • PHY-SSP/Solid State Physics/Physics

Статус
3 Approved without Funding

Дата регистрации
27.07.2005

Ведущий институт
Institute of Microelectronics Technology and High Purity Materials, Russia, Moscow reg., Chernogolovka

Поддержка институтов

  • Institute of Problems of Chemical Physics, Russia, Moscow reg., Chernogolovka

Соавторы

  • Ener1, Inc., USA, FL, Ft. Lauderdale\nMER Corporation, USA, AZ, Tucson

Краткое описание проекта

Starting from 1992, when rechargeable lithium-ion batteries were introduced into the market, they have become power sources most used for advanced portable electronic devices: cell phones, notebooks, video cameras and etc. Lithium-ion batteries are specified by high power density, good cyclability and high output voltage. Now the fields of application of lithium-ion batteries extend to both the design of large-scale power devices (power sources for electric vehicles and energy storage systems) and the design of microbatteries used in microsystem technics. Therefore, the urgent important task is further enhancement of power capacity and other operating characteristics of available lithium-ion batteries. Moreover, a possible wide application of these batteries in high-power equipment makes it necessary to solve the problem of their high cost and the environment protection.

Electric parameters of lithium-ion batteries are to a great extent defined by the properties of cathode materials. The most appropriate cathode materials are lithiated oxides of Co, Ni, and Mn. Oxide materials used now are of polycrystalline form with micrometer-sized (1-10 μm) particles. An essential progress in the enhancement of specific capacity of batteries and the improvement of their kinetic parameters could be expected from using cathode materials formed of crystallites of nanometer size. An improvement of electric parameters of batteries involving nanomaterials can result from the following reasons. Oxide nanoparticles can provide for a higher degree of their intercalation by lithium during a shorter period of time as a result of shorter distances of lithium ions diffusion. It is expected that cathode materials formed of oxide nanoparticles will be more resistant to cyclic mechanical tension appearing as a result of changes in the crystal lattice accompanying intercalation/deintercalation of lithium ions. However, this possibility of the improvement of electrochemical properties of lithium-ion batteries has not been realized so far since synthetic procedures used now (both high- and low-temperature ones) do not allow one to obtain nanomaterials with precise stoichiometry of the resulting compounds.

The goal of the project is the development of new methods of the synthesis of nanoparticles of lithiated Co, Ni, and Mn oxides and their solid solutions to form cathode materials for lithium-ion batteries with high electrochemical characteristics.

The general working schedule for project realization includes:


1. Development of new low-temperature methods for the synthesis of oxide nanoparticles:
  • investigation of the possibility of low-temperature synthesis using ultrasound dispersion of starting mixtures of reagents;
  • search for new gel-forming media to be used in sol-gel syntheses;
  • testing new fluxing materials for low-temperature syntheses of desired compounds.
2. Establishment of correlations between phase content, elemental composition, crystal structure and electrochemical properties of fabricated nanoparticles and conditions of their synthesis, which include investigations of:
  • cationic composition of nanoparticles versus reaction temperature, time of heat treatment, and reagent ratio of starting mixtures;
  • average oxidation state of transition metals;
  • conditions for the formation of a high-temperature phase at low-temperature syntheses;
  • stability of phases obtained by various methods at extreme extraction of lithium and the determination of a limiting degree of extraction, provided a retention of the initial structure.
3. Development of methods, which provide improved electrochemical characteristics (cycling life and stability) of cathode materials:
  • investigation of doping by transition and non-transition metals, which substitute cobalt, nickel and manganese in cathode materials on stability of resulting compounds;
  • monitoring stability of electrochemical characteristics of cathode materials formed of particles covered by layers of oxides or other compounds of different metals (Mg, Sn, Al, and etc.) to prevent degradation of particle surface;
  • investigation of the effect of reagent purity (content of controllable and random admixtures) on stability of operating parameters of the final product.

The project team includes specialists in chemical technology, materials science, crystallography and solid-state electrochemistry. Their wide experience will be used in project realization. They performed a series of physicochemical and physical investigations of processes when synthesizing cathode materials based on lithiated metal oxides and studied electrochemical characteristics thereof. They also developed technology for the preparation of a great number of substances of high purity grade, performed fundamental studies of phase formation in metal-oxide systems and solved crystal structures of metal oxides. The participants of the project are now well enough experienced in the study of structures and physical properties of nanomaterials. They developed a number of methodologies for these studies.


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