Mixed-conducting interlayer boosting the electrochemical performance of Ni-rich layered oxide cathode materials for lithium ion batteries

• Published in: Journal of power sources 2019-05, Vol.421 (C), p.91-99
• Main Authors: Fan, Qinglu, Yang, Shaodian, Liu, Jun, Liu, Haodong, Lin, Kaiji, Liu, Rui, Hong, Chaoyu, Liu, Liying, Chen, Yan, An, Ke, Liu, Ping, Shi, Zhicong, Yang, Yong
• Format: Article
• Language: English
• Subjects: ENERGY STORAGE; Graphene; Li3PO4; LiNi0.8Co0·1Mn0·1O2; Mixed-conducting interlayer; Synergistic effect
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.03.014

In this work, a unique artificial interface combing characteristics of both high ionic and electronic conductivities has been successfully constructed at the surface of Ni-rich LiNi0·8Co0·1Mn0·1O2 (NCM811). The ionic conductor layer is fabricated through reacting H3PO4 with the lithium residuals on the surface of NCM811 to form Li3PO4. The interface with high electronic conductivity is constructed by attaching graphene fragments to the NCM811 spherical particles. Due to the synergistic effect of the Li3PO4 coating layer and the graphene network, the modified sample (GN-LPO-NCM811) exhibits high capacity retention of 94.3% after 150 cycles at 0.5C between 3.0 and 4.3 V, while the pristine material shows a much lower retention of only 88.1%. In addition, the GN-LPO-NCM811 also presents improved cycling stability at elevated temperature of 55 °C. Even at an extremely high rate of 10C, the GN-LPO-NCM811 still remains 70% of its original capacity, while the pristine NCM811 only delivers 50% of the capacity. The stable cycling performance of GN-LPO-NCM811 is demonstrated in a full cell with graphite anode at ambient temperatures. Importantly, the thermal stability of the modified samples is also greatly enhanced. This study provides an effective method to improve the electrochemical performance of LiNi0·8Co0·1Mn0·1O2. •The residual Li species on the surface of NCM811 were transformed into Li3PO4.•Build a mixed-conducting interlayer with fast ionic and electronic conductivities.•The modified samples show excellent cycling stability and high rate performance.•The performance of NCM811 was enhanced at both room and high temperature.•The mixed-conducting interlayer improves the thermal stability of NCM811.