Stochastic many-particle model for LFP electrodes

In the framework of non-equilibrium thermodynamics, we derive a new model for many-particle electrodes. The model is applied to LiFePO4 (LFP) electrodes consisting of many LFP particles of nanometer size. The phase transition from a lithium-poor to a lithium-rich phase within LFP electrodes is controlled by both different particle sizes and surface fluctuations leading to a system of stochastic differential equations. An explicit relation between battery voltage and current controlled by the thermodynamic state variables is derived. This voltage–current relation reveals that in thin LFP electrodes lithium intercalation from the particle surfaces into the LFP particles is the principal rate-limiting process. There are only two constant kinetic parameters in the model describing the intercalation rate and the fluctuation strength, respectively. The model correctly predicts several features of LFP electrodes, viz. the phase transition, the observed voltage plateaus, hysteresis and the rate-limiting capacity. Moreover we study the impact of both the particle size distribution and the active surface area on the voltage–charge characteristics of the electrode. Finally we carefully discuss the phase transition for varying charging/discharging rates

Phase transition in a rechargeable lithium battery

We discuss the lithium storage process within a single-particle cathode of a lithium-ion battery. The single storage particle consists of a crystal lattice whose interstitial lattice sites may be empty or reversibly filled with lithium atoms. The resulting evolution equations describe diffusion with mechanical coupling and incorporate volume changes, phase transitions and surface tension. In order to simulate the dynamics, we assume spherical symmetry and fast bulk diffusion of the lithium atoms, which lead to a core shell model. We verify the common assumption of phase nucleation at the external boundary of the particle. This model is capable to predict voltage-capacity behaviour. For slow charging rates, we compare the results with experimental voltage-capacity plots exhibiting hysteretic behaviour. We observe that hysteresis cannot be described within the setting of a single-particle cathode. The origin of this fact is discussed in detail. The result is of enormous importance because single-particle models, in particular core shell models, up to now are very popular in the chemical literature

Availability of rhenium-188 from the alumina-based tungsten-188/Rhenium-188 generator for preparation of rhenium-188-labeled radiopharmaceuticals for cancer treatment

Rhenium-188 (β- = 2.2 MeV; γ- = 155 keV; T(1/2) 16.9 hours) is an attractive therapeutic radioisotope which is produced from decay of the reactor-produced tungsten-188 parent (T1/2 69 days) and thus conveniently obtained on demand by elution from the alumina-based tungsten-188/rhenium-188 generator system. The rhenium-188 is obtained as sodium perrhenate by elution of the generator with 0.9% saline. The post elution use of disposable tandem, ion-exchange columns is a simple method for the concentration of rhenium-188 saline solutions with specific volumes > 500 mCi/ml. This method can also extend the useful shelf-life of the generator, which can be as long as one year. The long useful shelf-life of the generator is expected to provide rhenium-188 at very reasonable costs for routine preparation of a variety of radiopharmaceuticals for the treatment of a variety of cancers

Reactor-produced radioisotopes from ORNL for bone pain palliation

The treatment of painful skeletal metastases is a common clinical problem, and the use of therapeutic radionuclides which localize at metastatic sites has been found to be an effective method for treatment of pain, especially for multiple sites for which the use of external beam irradiation is impractical. There are currently several metastatic-targeted agents radiolabeled with various therapeutic radionuclides which are in various stages of clinical investigation. Since neutron rich radionuclides are produced in research reactors and often decay by emission of beta(-) particles, most radionuclides used for bone pain palliation are reactor-produced. Key examples of radionuclides produced by single neutron capture of enriched targets include rhenium-186 and samarium-153. In addition, generator systems are also of interest which provide therapeutic daughter radionuclides from the decay of reactor-produced parent radionuclides. One important example is rhenium-188, available from generators via decay of reactor-produced tungsten-188. Tin-117m is an example of a reactor-produced radionuclide which decays with the emission of low-energy conversion electrons rather than by beta(-) decay. Each of these agents and/or radionuclides has specific advantages and disadvantages, however, the ideal agent for bone pain palliation has not yet been identified. The goal of this paper is to briefly review the production and use of several reactor-produced radionuclides for bone pain palliation, and to discuss the role of the ORNL High Flux Isotope Reactor(HFIR) for the production of many of these radionuclides

Response and long-term control of bone metastases after peptide receptor radionuclide therapy with (177)Lu-octreotate

Peptide receptor radionuclide therapy (PRRT) is an efficient treatment for gastroenteropancreatic neuroendocrine tumors (GEP NETs), with outstanding overall response rates and survival. However, little is known about the particular efficacy regarding bone metastasis (BM)