This application focuses on the study of two important lithium ion battery materials. We intend to use our newly developed cell design which allows for the cycling of battery materials with conventional rates and the in situ collection of neutron diffraction patterns. In this proposal we seek to first study the orthosilicate polyanion Li2MSiO4 (M= Fe, Mn and Co), this material has shown promise as a new candidate for battery materials, however, questions still remain as to the structural changes occurring during cycling particularly during the removal of the a second lithium to achieve the full capacity of this material. We would then like to study the new battery cathode LiFeSO4F which forms two polymorths with distinct electrochemical behavior. Study of this new battery material will add to the fundamental knowledge of the field.