Electron/ion Conductor Double-coated LiNi0.8Co0.1Mn0.1O2 Li-ion Battery Cathode Material and Its Electrochemical Performance

The Ni-rich layered cathode material LiNi0.8Co0.1Mn0.1O2 presents a high specific capacity and relatively low cost, however, the inherent structure instability during the electrochemical cycling process hinders its application widely. Universally, the strategy of surface coating can be used to improve the structural stability of the material and then improve its electrochemical performance. This work combines the high-speed solid-phase coating method and the high-temperature sintering method to coat the electronic conductor antimony tin oxide and lithium-ion conductor lithium metaphosphate on the surface of the LiNi0.8Co0.1Mn0.1O2 material, respectively. The electron/ion conductor double coating layer forms a charge conversion and transport channel on the surface of the LiNi0.8Co0.1Mn0.1O2. The electronic conductivity of the double-coated LiNi0.8Co0.1Mn0.1O2 material increased from 2.17x10(-3) S.cm(-1) to 1.02x10(-2) S.cm(-1), and the diffusion coefficient of lithium-ion also increased from 7.05x10(-9) cm(2).s(-1) to 2.88x10(-8) cm(2).s(-1). At the same time, due to strong P-O bonds and stable metal oxides, the double-coating layer on the surface of the LiNi0.8Co0.1Mn0.1O2 material can effectively restrain the irreversible phase transitions, and it also can inhibit the interfacial reactions under high electrode potential. The electrochemical performance test demonstrated that the cyclability and rate performance of LiNi0.8Co0.1Mn0.1O2 material improved due to surface modification. The cathode assembled with double-coated LiNi0.8Co0.1Mn0.1O2 material can maintain a reversible capacity of 161.1 mAh.g(-1) after 150 cycles at 1 C (after being activated at 0.1 C for two cycles, 1 C=180 mA.g(-1)) during 2.7 similar to 4.3 V ( vs. Li/Li+), with a capacity retention of 87.1%. This coated LiNi0.8Co0.1Mn0.1O2 material also displays a specific capacity as high as 133 mAh.g(-1) at 10 C. In comparison, the pristine LiNi0.8Co0.1Mn0.1O2 delivers a capacity of only 113 mAh.g(-1) after 100 cycles and a reversible capacity retention rate of less than 60% (a decay rate of 0.4% per cycle).