Constructing high performance Li-rich Mn-based cathode via surface phase structure controlling and ion doping

Abstract

Li-rich Mn-based cathode materials are one kind of the promising potential candidates to electric vehicles powered by high-energy density lithium-ion batteries due to its much higher theoretical energy density. Unfortunately, the rapid capacity fading and voltage decay are the most critical factors affecting its practical application. Herein, Li1·17Na0·02Mn0·54Ni0·13Co0·13O2 (PN-LMNCO) is prepared via surface phase structure controlling and ion doping through an architecture strategy of surface lithium deficiency. It is found that the existence of lithium deficiencies can induce surface phase transformation, and thus resulting in an in-situ spinel surface conversion film, which can restrain the structure degradation during subsequent charge/discharge process. In addition, because of the larger ion radius than Li+, Na+ doping can effectively increase the spacing between Li layers, and thus improve the rate capacity. Accordingly, the as-prepared sample displays as a significantly higher initial coulombic efficiency (91.2%). After 200 cycles at 1 C, the PN-LMNCO can retain 94.7% discharge specific capacity. Furthermore, PN-LMNCO can still show a good discharge capacity of 214 mA h g−1 even at a high current rate of 5 C. Therefore, this work can preferably meet the need of the development of electric vehicle for high-energy density Lithium-ion battery.