Lithium-rich layered electrode materials are of interest as a promising candidate of cathodes for lithium-ion batteries because of their excellent electrochemical properties. The electrochemical performance of these materials is mainly regulated by preparation conditions during synthesis and calcination process. Here, microspherical Li1.2Mn0.54Co0.13Ni0.13O2 (LMNCO) particles are synthesized through steady pH value control with carbon dioxides bubbling method in co-precipitation process using a simple reactor. SEM images present that CP-LMNCO sample prepared through the assistance of carbon dioxides has spherical particle morphology, while sample (TP-LMNCO) without carbon dioxides assistance shows large nanoparticles agglomeration. The CP-LMNCO electrode demonstrates superior electrochemical performance, which exhibits capacity retention of 97.76% after 100 cycles compared with only 81.94% for TP-LMNCO electrode at 1C (250mAg−1). Even at a higher current density (5C), the CP-LMNCO electrode shows reversible capacity up to 105.4mA h g−1. The remarkably improved electrochemical performance of CP-LMNCO electrode is ascribed to spherical morphology with small surface area which decreases side reactions with electrolyte during cycling and smaller primary sizes which reduce lithium ion (Li+) diffusion distance. Furthermore, the synthesis of spherical materials using metal sulfate with high concentration (up to 5M) as starting agents are attempted under carbon dioxides assisted conditions, and as-prepared materials also show improved performance.