Hierarchical Carbon Decorated Li₃V₂(PO₄)₃ as a Bicontinuous Cathode with High‐Rate Capability and Broad Temperature Adaptability

Abstract

and fair theoretical specifi c capacity (197 mAh g −1 for complete extraction of three lithium ions when charged to 4.8 V, 133 mAh g −1 when cycled between the potential window of 3.0-4.3 V). [12][13][14] In particular, because of its sodium super ionic conductor (NASICON) structure, monoclinic Li 3 V 2 (PO 4 ) 3 provides a 3D pathway for Li + insertion/ extraction, which results in a very high ion diffusion coeffi cient (from 10 −9 to 10 −10 cm 2 s −1 ). [15][16][17][18][19] However, Li 3 V 2 (PO 4 ) 3 suffers a poor electronic conductivity (2.4 × 10 −7 S cm −1 at room temperature) due to the nature of its separated VO 6 octahedral arrangement, which significantly limits its rate performance and the further commercialization. [20][21][22][23][24] Carbon coating is an economic and feasible technique that is widely used to improve the electronic conductivity. [ 14,17,[25][26][27][28] However, the common carbon coating could only provide an electron pathway on the nanoscale for individual particles. In comparison, the architecture combining the nanoscale carbon coating and the microscale carbon network could provide hierarchical pores for the electrolyte to pass through, which may supply a highly conductive network for both electrons and lithium ions, promoting the fast charge/discharge processes. [ 6,[29][30][31][32] In addition, the fast kinetics enabled by this architecture would be benefi cial for the battery performance at low temperature, which is a key issue in the application.Here, we propose a feasible and environmentally friendly one-pot method utilizing glucose as both the carbon source and the reducing agent (functioned by the aldehyde group). Via the optimization of the interface reaction, hierarchical carbon (nanoscale amorphous carbon coating and microscale carbon network) decorated Li 3 V 2 (PO 4 ) 3 is obtained (Schematic, Figure 1 ). This unique architecture can provide the following three important features simultaneously: 1) continuous electron conduction enabled by hierarchical carbon, 2) rapid ion transport enabled by electrolyte-fi lled macro/ mesopore network, and 3) a buffered protective carbon shell. The obtained cathode material achieved an enhanced rate capability (121 mAh g −1 at rate up to 30 C), superior cycling stability Developing rechargeable lithium ion batteries with fast charge/discharge rate, high capacity and power, long lifespan, and broad temperature adaptability is still a signifi cant challenge. In order to realize the fast and effi cient transport of ions and electrons during the charging/discharging process, a 3D hierarchical carbon-decorated Li 3 V 2 (PO 4 ) 3 is designed and synthesized with a nanoscale amorphous carbon coating and a microscale carbon network. The Brunauer-Emmett-Teller (BET) surface area is 65.4 m 2 g −1 and the porosity allows for easy access of the electrolyte to the active material. A specifi c capacity of 121 mAh g −1 (91% of the theoretical capacity) can be obtained at a rate up to 30 C. When cycled at a rate of 20 C, the capacity retention is 77...

Indirect growth of mesoporous Bi@C core–shell nanowires for enhanced lithium-ion storage

“…All the Nyquist plots were obtained at an amplitude of 10 mV versus the same potential of 0.8 V with a frequency Fig. 39 (b) Charge/discharge curves of the Bi@C core-shell NWs at a current density of 100 mA g −1 .…”

Carbon-coated rhombohedral Li3V2(PO4)3 as both cathode and anode materials for lithium-ion batteries: electrochemical performance and lithium storage mechanism

“…The theoretical capacity is 131 mAh/g, corresponding to the extraction of two Li + ions. However, m-LVP exhibits multiple plateaus in the discharge curves at 4.1, 3.7, and 3.6 V. [30][31][32] In comparison, r-LVP shows more appealing discharge curves with the very flat plateau at 3.75 V vs. Li + /Li, although it cannot be directly synthesized. Nazar et al first reported the synthesis of r-LVP through a topotactic ion-exchange from r-Na 3 V 2 (PO 4 ) 3 in the concentrated LiNO 3 solution.…”

Electrochemical characterization for lithium vanadium phosphate with different calcination temperatures prepared by the sol–gel method

“…Its high working potential (~4.0 V) can better satisfy the requirements of lithium ion batteries in electric vehicles (EVs) and hybrid electric vehicles (HEVs). Therefore, the Li 3 V 2 (PO 4 ) 3 cathode material has been developed to replace in lithium ion batteries [9,[17][18][19][20][21][22].…”