Cathode Material with Nanorod Structure—An Application for Advanced High-Energy and Safe Lithium Batteries

Abstract

We have developed a novel cathode material based on lithium−nickel−manganese−cobalt oxide, where the manganese concentration remains constant throughout the particle, while the nickel concentration decreases linearly and the cobalt concentration increases from the center to the outer surface of the particle. This full concentration gradient material with a fixed manganese composition (FCG−Mn-F) has an average composition of Li[Ni 0.60 Co 0.15 Mn 0.25 ]O 2 and is composed of rod-shaped primary particles whose length reaches 2.5 μm, growing in the radial direction. In cell tests, the FCG−Mn-F material delivered a high capacity of 206 mAh g −1 with excellent capacity retention of 70.3% after 1000 cycles at 55 °C. This cathode material also exhibited outstanding rate capability, good low-temperature performance, and excellent safety, compared to a conventional cathode having the same composition (Li[Ni 0.60 Co 0.15 Mn 0.25 ]O 2 ), where the concentration of the metals is constant across the particles.

Improved Performances of Li[Ni0.65Co0.08Mn0.27]O2Cathode Material with Full Concentration Gradient for Li-Ion Batteries

“…This result implies that ) unless CC License in place (see abstract • C, respectively. As reported in our previous papers, 15 the higher capacity from the FCG cathode is ascribed to the higher Ni 2+ concentration in the outer surface region, leading to the two-electron reaction of (Ni 2+ ⇔Ni 4+ ). As shown in Figure 4b and 4d, the FCG cathode showed much enhanced cycling performance over CC cathode with capacity retention of 97.9 % and 96.5% after 50 cycles at 25…”

“…15 Based on the proposed material design concept, we can design various cathode materials with different gradient compositions.…”

“…We believe that the improved cycling performance of the FCG cathode likely due to the increased stability against the HF attack by decreasing the Ni concentration and increasing the Mn concentration at the surface and the reduced reactivity with the electrolyte by lowering the specific surface area and thus suppressing the increase in interfacial impedance during cycling. 15,18 To study the further reason for the improved cycling properties of the FCG cathode, electrochemical impedance spectroscopy (EIS) were performeded as a function of cycle number (1 st , 30 th , and 100 th ) at the charged state at 4.5 V and 55…”

Radially aligned hierarchical columnar structure as a cathode material for high energy density sodium-ion batteries

“…Spherical particles, made up of [Ni 0.6 Co 0.05 Mn 0.35 ](OH) 2 assembled with a radially aligned columnar structure on which the chemical composition hierarchically varies from the inner end to the outer end, were synthesized via co-precipitation 36,37 . Two solution tanks were used to control the concentrations of the transition metals.…”

“…To overcome the limited capacity of O3-type cathodes, it is important to create unique morphologies that endow highcapacity, long-term cyclability and high energy density. Through our prior works 36,37 , we suggested that the nanorod-structured full concentration gradient materials are beneficial in performing outstanding electrochemical properties and excellent safety in lithium-ion batteries system, because the dense rod assembly could minimize surface area contacting with electrolyte, in which the environment, in turn, renders active materials less exposure in acidic electrolyte due to NaPF 6 salt (HF attack).…”