improving electrical conductivity, while relatively less work were aimed to optimize regularly desired microstructure for accelerating mass (Li + ) transfer and enhancing tap density simultaneously (Table S1, Supporting Information). [20][21][22]28,29 ] Actually, as has been recognized that the Li + transport in electrolyte to approach the active site may also be rate-limiting factor at high rates, [ 13,30 ] and the tap density directly infl uence the volumetric energy density of the fi nal LIBs, which is also very important for EVs and HEVs. [ 10,16 ] On the other side, compared with performance study, the theoretical research of this area was relatively rare. [ 1,16 ] Therefore, it is still highly desirable to design an ideal-structured LFP/CNTs composite with substantially improved electronic and ionic transport kinetics as well as high tap density for EVs and HEVs applications, and the inherent reason for electrochemical performance improvment of such kind of composite was also needed to deeply undstood from the theoretical aspect.Herein, we presented a unique hierarchically porous C@LFP/ CNTs microsphere composite via a facile hydrothermal approach combined with high-temperature calcinations using the relative low-cost Fe 3+ source as the raw material. In such a composite, CNTs as an electronic conductive component were in situ and uniformly embedded into the LFP open porous microspheres to form a conductive CNTs network, meanwhile the interlaced pore networks facilitated rapid Li + supplies, which made each C@LFP/CNTs microsphere to be an effective microreactor for fast electrochemical reactions. Meanwhile, the amorphous carbon bridged the CNTs network, and thus further improved the electronic conductivity of the whole composite. Besides, the microsphere morphology guaranteed a large tap density of the composite for high volumetric energy density supplies. It should be noted that CNTs is also an electrochemical capacitor material by storing energy in electric double layer. As reported previously, in a composite electrode, the capacitor component could promote a fast capacity response, which buffered the infl uence on LIB component under high-rate charge or discharge, and thereby, benefi cial for its rate performance and cycling stability. [ 13 ] For comparison purpose, a composite decorated by single amorphous carbon (C@LFP) was also prepared and investigated. The electrochemical test results demonstrated that the C@LFP/ CNTs composite indeed exhibited impressive rate capability (73 mAh g −1 at 60 C) and cycling stability (98% capacity retention over 1000 cycles at 10 C) combined with a high volumetric energy density (443 Wh L −1 at 10 C). To deeper understand the improved electrochemical performance of C@LFP/CNTs, the compound interfacial property of LFP and CNTs were further studied by a density functional theoretical (DFT) calculation.Lithium-ion batteries (LIBs) have been widely investigated in the past two decades for energy storage in electric vehicles (EVs) and hybrid electric vehicles (HEVs) for the...