The layered Ni-rich oxide LiNi0.8Co0.1Mn0.1O2 cathode has been significantly attractive due to its large reversible capacity (∼200mAhg−1). However, the inherent poor cycling stability of the Ni-based cathode materials is always a serious issue for restricting its commercialization. In this paper, we introduced Li2MnO3 as an electrochemical inactive component in Ni-rich oxide LiNi0.8Co0.1Mn0.1O2 to stabilize its structure. The modified LiNi0.8Co0.1Mn0.1O2 composites with low-content Li2MnO3 were prepared by a solid-state reaction process. The results from XRD structure refinement and SAED confirm that Li2MnO3 phase exists homogeneously in the composites. The modified LiNi0.8Co0.1Mn0.1O2 composites with inactive Li2MnO3 show much better cycling stability and stable average discharge voltage compared with the pristine one when charged to 4.5V. Especially, the modified LiNi0.8Co0.1Mn0.1O2 composite with 10% Li2MnO3 (LNCMO-1090) delivers a reversible capacity of 207mAhg−1 and keeps 155mAhg−1 after 100 cycles at 20mAg−1 (0.1C), corresponding to a capacity retention of 75%, while LiNi0.8Co0.1Mn0.1O2 could only maintain a capacity of 128mAhg−1 with a capacity retention of 59% after 100 cycles. The improved cycling performance of the Li2MnO3-containing electrode could be attributed to the stabilized effect of Li2MnO3 on the electrode surface structure, as evidenced by the lower charge-transfer resistance.