High rate performance of lithium manganese nitride and oxynitride as negative electrodes in lithium batteries

The performance of Li7.9MnN3.2O1.6 and Li7MnN4 as electrode materials in lithium batteries was analyzed. At 1C rate, capacities of 180 and 230 mAh/g, respectively, were obtained after 50 cycles. If the first charge is done at 0.1C, outstanding capacities of 120–135 mAh/g are observed after 100 cycles at 5C. More lithium can be removed during the charge at 0.1C, leading to a large amount of lithium vacancies that enhance mobility and rate capability. It is proposed that incomplete filling of the vacancies occurs upon cycling, so that the mobility remains high. This performance compares well to that of Li4Ti5O12.