In Situ Synthesis of Hierarchical Core Double-Shell Ti-Doped LiMnPO4@NaTi2(PO4)3@C/3D Graphene Cathode with High-Rate Capability and Long Cycle Life for Lithium-Ion Batteries

Olivine-type LiMnPO4 (LMP) cathodes have gained enormous attraction for Li-ion batteries (LIBs), thanks to their large theoretical capacity, high discharge platform, and thermal stability. However, it is still hugely challenging to achieve encouraging Li-storage behaviors owing to their low electronic conductivity and limited lithium diffusion. Herein, the core double-shell Ti-doped LMP@NaTi2(PO4)(3)@C/3D graphene (TLMP@NTP@C/3D-G) architecture is designed and constructed via an in situ synthetic methodology. A continuous electronic conducting network is formed with the unfolded 3D-G and conducting carbon nanoshell. The Nasicon-type NTP nanoshell with exceptional ionic conductivity efficiently inhibits gradual enrichment in by-products, and renders low surfacial/interfacial electron/ion-diffusion resistance. Besides, a rapid Li+ diffusion in the bulk structure is guaranteed with the reduction of MnLi+ antisite defects originating from the synchronous Ti-doping. Benefiting from synergetic contributions from these design rationales, the integrated TLMP@NTP@C/3D-G cathode yields high initial discharge capacity of approximate to 164.8 mAh g(-1) at 0.05 C, high-rate reversible capacity of approximate to 116.2 mAh g(-1) at 10 C, and long-term capacity retention of approximate to 93.3% after 600 cycles at 2 C. More significantly, the electrode design developed here will exert significant impact upon constructing other advanced cathodes for high-energy/power LIBs.