Effect of Conductive Material Morphology on Spherical Lithium Iron Phosphate

Engendering High Energy Density LiFePO4 Electrodes with Morphological and Compositional Tuning

Improving the energy density of Li-ion batteries is critical to meet the requirements of electric vehicles and energy storage systems. In this work, LiFePO₄ active material was combined with single-walled carbon nanotubes as the conductive additive to develop high-energy-density cathodes for rechargeable Li-ion batteries. The effect of the morphology of the active material particles on the cathodes' electrochemical characteristics was investigated. Although providing higher packing density of electrodes, spherical LiFePO₄ microparticles had poorer contact with an aluminum current collector and showed lower rate capability than plate-shaped LiFePO₄ nanoparticles. A carbon-coated current collector helped enhance the interfacial contact with spherical LiFePO₄ particles and was instrumental in combining high electrode packing density (1.8 g cm^-3) with excellent rate capability (100 mAh g^-1 at 10C). The weight percentages of carbon nanotubes and polyvinylidene fluoride binder in the electrodes were optimized for electrical conductivity, rate capability, adhesion strength, and cyclic stability. The electrodes that were formulated with 0.25 wt.% of carbon nanotubes and 1.75 wt.% of the binder demonstrated the best overall performance. The optimized electrode composition was used to formulate thick free-standing electrodes with high energy and power densities, achieving the areal capacity of 5.9 mAh cm^-2 at 1C rate.

Improvement of Lithium Storage Performance of Silica Anode by Using Ketjen Black as Functional Conductive Agent

In this paper, SiO₂ aerogels were prepared by a sol–gel method. Using Ketjen Black (KB), Super P (SP) and Acetylene Black (AB) as a conductive agent, respectively, the effects of the structure and morphology of the three conductive agents on the electrochemical performance of SiO₂ gel anode were systematically investigated and compared. The results show that KB provides far better cycling and rate performance than SP and AB for SiO₂ anode electrodes, with a reversible specific capacity of 351.4 mA h g⁻¹ at 0.2 A g⁻¹ after 200 cycles and a stable 311.7 mA h g⁻¹ at 1.0 A g⁻¹ after 500 cycles. The enhanced mechanism of the lithium storage performance of SiO₂-KB anode was also proposed.

Inorganic Fillers in Composite Gel Polymer Electrolytes for High-Performance Lithium and Non-Lithium Polymer Batteries

Among the various types of polymer electrolytes, gel polymer electrolytes have been considered as promising electrolytes for high-performance lithium and non-lithium batteries. The introduction of inorganic fillers into the polymer-salt system of gel polymer electrolytes has emerged as an effective strategy to achieve high ionic conductivity and excellent interfacial contact with the electrode. In this review, the detailed roles of inorganic fillers in composite gel polymer electrolytes are presented based on their physical and electrochemical properties in lithium and non-lithium polymer batteries. First, we summarize the historical developments of gel polymer electrolytes. Then, a list of detailed fillers applied in gel polymer electrolytes is presented. Possible mechanisms of conductivity enhancement by the addition of inorganic fillers are discussed for each inorganic filler. Subsequently, inorganic filler/polymer composite electrolytes studied for use in various battery systems, including Li-, Na-, Mg-, and Zn-ion batteries, are discussed. Finally, the future perspectives and requirements of the current composite gel polymer electrolyte technologies are highlighted.