Carbon-coated mesoporous LiTi 2 (PO 4 ) 3 nanocrystals with superior performance for lithium-ion batteries

Two-dimensional LiTi2(PO4)3 flakes for enhanced lithium ions battery anode

In this work, the LiTi2(PO4)3 (LTP) flakes have been prepared by employing a template method for lithium-ion batteries with high capacity. The 2D layered structure of LTP offers large aspect ratio and rich active sites, which not only create the large contact area between the electrolyte and electrode, but also promote the diffusion kinetics of Li+. As a result, the Li+ diffusion coefficient of lamellar LTP anode is 3.12 × 10-8 cm2 s-1, while it is only 5.01 × 10-10 cm2 s-1 for granular LTP anode. Further, the lamellar LTP anode delivers a high initial discharge capacity of 986.8 mAh·g-1 at 0.1 A g-1, and remains at 231.1 mAh·g-1 after 100 cycles, which is higher than that of the granular LTP anode (340.5 mAh·g-1 at 1st cycle, 169.3 mAh·g-1 at 100th cycles). Thus, the lamellar LTP should be recommended as a potential anode for high-performance LIBs due to the fast charge-discharge performance and superior cycling stability.

Self-Protecting Aqueous Lithium-Ion Batteries

Capacity degradation and destructive hazards are two major challenges for the operation of lithium-ion batteries at high temperatures. Although adding flame retardants or fire extinguishing agents can provide one-off self-protection in case of emergency overheating, it is desirable to directly regulate battery operation according to the temperature. Herein, smart self-protecting aqueous lithium-ion batteries are developed using thermos-responsive separators prepared through in situ polymerization on the hydrophilic separator. The thermos-responsive separator blocks the lithium ion transport channels at high temperature and reopens when the battery cools down; more importantly, this transition is reversible. The influence of lithium salts on the thermos-responsive behaviors of the hydrogels is investigated. Then suitable lithium salt (LiNO₃ ) and concentration (1 m) are selected in the electrolyte to achieve self-protection without sacrificing battery performance. The shut-off temperature can be tuned from 30 to 80 °C by adjusting the hydrophilic and hydrophobic moiety ratio in the hydrogel for targeted applications. This self-protecting LiMn₂ O₄ /carbon coated LiTi₂ (PO₄ )₃ (LMO/C-LTP) battery shows promise for smart energy storage devices with high safety and extended lifespan in case of high operating temperatures.

Rapid Electron/Ion Transport in CNT/LiTi2(PO4)3@C-N Electrodes for Aqueous Lithium-ion Batteries with High Stability, Flexibility and Safety

Self-supporting and flexible carbon nanotube/Carbon-coated Nitrogen-doped LiTi2(PO4)3 (CNT/LTP@C-N) hybrid films are manufactured via vacuum filtration. LTP@C-N is entangled into CNT networks to build a 3D conductive network. Such hybrid electrodes...

Enhanced Electrochemical Performance of Fast Ionic Conductor LiTi2(PO4)3-Coated LiNi1/3Co1/3Mn1/3O2 Cathode Material

Layered LiNi_1/3Co_1/3Mn_1/3O₂ (NCM333) is successfully coated by fast ionic conductor LiTi₂(PO₄)₃ (LTP) via a wet chemical method. The effects of LTP on the physicochemical properties and electrochemical performance are studied. The results reveal that a highly layered structure of NCM333 can be well maintained with less cation mixing after LTP coating. LTP of about 5 nm thickness is coated on the surface of NCM333. Such an LTP coating layer can effectively suppress the side reactions between NCM333 and electrolyte but will not hinder the lithium ion transmission. As a result, LTP-coated NCM333 owns an improved capability and cyclic performance, for example, NCM333/LTP delivers an initial capacity as high as 121.0 mA h g^-1 with a capacity retention ratio of 82.3% after 200 cycles at 10 C, whereas NCM333 only has an initial capacity of 120.4 mA h g^-1 with a very low capacity retention ratio of 66.4%. This method of using a fast ionic conductor like LTP as a coating material may provide a simple and effective strategy to modify those electrode materials with poor cyclic performance.

Touching the theoretical capacity: synthesizing cubic LiTi2(PO4)3/C nanocomposites for high-performance lithium-ion battery

A cubic LiTi2(PO4)3/C composite is successfully prepared via a simple solvothermal method and further glucose-pyrolysis treatment. The as-fabricated LTP/C material delivers an ultra-high reversible capacity of 144 mA h g-1 at 0.2C rate, which is the highest ever reported, and shows considerable performance improvement compared with before. Combining this with the stable cycling performance and high rate capability, such material has a promising future in practical application.

Bimolecular-induced hierarchical nanoporous LiTi2(PO4)3/C with superior high-rate and cycling performance

Carbon-coated hierarchical LiTi₂(PO₄)₃ was synthesized by a facile bimolecular (glucose and DMEA) assisted hydrothermal reaction and a solid-state reaction, and exhibits excellent high-rate and cycling performance.