Enhanced Electrochemical Performance of Rare-Earth Metal-Ion-Doped Nanocrystalline Li4Ti5O12 Electrodes in High-Power Li-Ion Batteries

Multi-layering of carbon conductivity enhancers for boosting rapid recharging performance of high mass loading lithium ion battery electrodes

The ability of lithium ion batteries (LIBs) to provide rapid charging characteristics while retaining a substantial energy storage capacity is of paramount significance for their applicability in portable smart electronic devices. In this research, an effective approach to enhance re-charging rates of LIB cells was developed through incorporating carbon nanotube (CNT) conductivity boosters strategically into Li4Ti5O12 (LTO) electrodes. A layer-by-layer spray coating was exploited to manufacture multi-layer architectures that comprise sequential, discrete electrode layers of CNT-rich LTO and CNT-free LTO, aiming at promoting charge transfer kinetics of high mass loading electrodes. Initially, the optimal proportion of a CNT-rich layer and its best location within multi-layer electrode structures were investigated in half-cell configurations. The best performing multi-layer was then paired with a spray-coated LiFePO4 (LFP) positive electrode in full-cell LIBs, offering attractive power performance of ∼ 1500 W/kg that outperformed conventional LTO || LFP combinations.

Facile Synthesis of Pre-Lithiated LiTiO2 Nanoparticles for Quick Charge and Long Lifespan Anode in Lithium-Ion Batteries

Titanium dioxide (TiO2) has been widely used as an alternative anodic material for lithium-ion batteries (LIBs) due to its ultrahigh capacity retention and long cycle lifespan. However, the restriction of lithium insertion, intrinsically poor electronic conductivity, and sluggish lithium ionic kinetics of bulk TiO2 hinder their specific capacity and rate performance. Herein, LiTiO2 nanoparticles (NPs) are synthesized via a facile ball milling method by the reaction of anatase TiO2 with LiH. The as-prepared LiTiO2 NPs have strong structural stability and a "zero strain" effect during the repeated intercalation/deintercalation, even at low potential. As anodic materials for LIBs, LiTiO2 NPs exhibit a superior rate performance of ∼100 mA h g-1 at 10C (3350 mA g-1) with a capacity retention of 100% after 1000 cycles, which is 5 times higher than that of the original commercial anatase TiO2 powder. The higher specific capacity of LiTiO2 NPs is attributed to the increased conversion of Ti3+ to Ti2+ on the porous surface of LiTiO2 NPs, which provides a more capacitive contribution. This study not only provides a new fabrication approach toward Ti-based anodes for ultrafast LIBs but also underscores the potential importance of embedding lithium into transition metal oxides as a strategy for boosting their electrochemical performance.

Spray fabrication of additive-free electrodes for advanced Lithium-Ion storage technologies

Polymer binders and carbon conductivity enhancers are inevitably required to make improvements in structural durability and electrochemical performance of lithium-ion battery (LIB) electrodes, although these additive constituents incur weight and volume penalties on the overall battery capacity. Here, additive-free electrode architectures were successfully fabricated over 20 × 20 cm2 electrode areas using a layer-by-layer spray coating approach, with the ultimate goal to boost gravimetric/volumetric electrode capacity and to reduce the total cost of LIB cells. Initially, the binder fraction of spray-coated Li4Ti5O12 (LTO) electrodes was reduced progressively, from 40 to 0 wt%. The electrochemical behavior of electrodes was then re-optimized as a proportion of conductivity enhancers within the binder-free electrode decreased to zero. Further, the otherwise identical spray coating process was applied to manufacture LiFePO4 (LFP) positive electrodes, leading to all-additive-free full-cell LIB configurations with attractive energy density of ∼310 Wh/kg and power performance of ∼1500 W/kg.