Abstract: This disclosure provides systems, methods, and apparatus related to fluorinated lithium- and manganese-rich layered oxides. In one aspect, a method includes mixing metal precursors to form a first mixture. The metal precursors include a lithium precursor and a manganese precursor. A halide mixture is mixed with the first mixture to form a second mixture. The halide mixture includes a fluorine precursor and a chlorine reaction medium. The second mixture is heat treated to generate a fluorinated Li- and Mn-rich oxide.