The high rate performance of ball-milled Li7MnN4 as negative electrode material in lithium-ion batteries has been investigated at C and 5C rates. An optimization of ball-milling experimental conditions allows to synthesize this metallic nitride with attractive and improved specific capacity and cycle life compared to the pristine compound. The outstanding finding is its excellent cycle life over 50 cycles with a capacity of 240mAhg−1 at 1C rate in the potential range 1.6V/1V. Even at 5C the promoting effect of ball-milling results in a remarkable high and stable capacity of 120mAhg−1 upon cycling, which compares very well with the behavior achieved for Li4Ti5O12 while the pristine material is practically inactive.