For use in lithium-ion batteries, researchers from the East China University of Science and Technology have enhanced the electrochemical performance of nickel-rich cathodes. Due to their high energy density and low cost, nickel-rich multilayer cathodes have a lot of potential for usage in next-generation high-energy lithium-ion batteries. The quick capacity fading that occurs with prolonged use of these cathodes is a drawback. A simple, one-step dual-modification technique has been developed by researchers from the East China University of Science and Technology to address this issue and improve the cathode’s structural capability.
To meet the need for the green energy transition, lithium-ion batteries with high energy density are urgently required. The restricted specific capacity of lithium ions’ cathode material currently limits their application. Nickel-rich layered cathodes always have rapid capacity fading as a result of the structural and interfacial instability that results from prolonged operation.
Scientists have employed several techniques, such as surface coating and element doping with the cathode materials, to find solutions to these issues. However, the structural and interfacial instabilities cannot be resolved simultaneously by a single modification method. While the coating materials often have poor lithium-ion conductivity, raising the interfacial impedance and lowering the specific capacity, this technique fails to stop the cathode/electrolyte process.
The researchers realized that a high-efficiency dual modification was required to produce improved nickel-rich oxides with a high specific capacity and long cycling life. In order to address the commercial demands of nickel-rich cathodes, the researchers’ approach offers a straightforward, one-step dual-modification strategy that reduces the interfacial parasitic side reactions and improves structural stability. The co-modified cathode that the researchers created has good long-term cycling stability and better electrochemical performance.
The team created the titanium-doped and lithium yttrium dioxide-coated (LiYO2) nickel-rich multilayer cathode using a straightforward one-step sintering technique. In order to create a solid mass of material, this method applies pressure and heat. The new method improves the cathode’s structural integrity while reducing the damage caused by interfacial parasites.
The scientists next used X-ray diffraction to analyze the cathode’s crystalline structure. Scanning electron microscopy was used to study the cathode morphologies. In order to characterize the hyperfine structure and element distribution, the scientists employed transmission electron microscopy. The surface element compositions and valence states were investigated using X-ray photoelectron spectra. The outcomes showed that their cathode material had significantly better capacity retention than the unmodified cathode materials, with values of 96.3% after 100 cycles and 86.8% after 500 cycles.
The LiYO2 coating layer functions as a physical barrier that considerably inhibits the dissolution of transition metal ions and interfacial parasitic side reactions, improving the stability of the cathode-electrolyte interface. The strong titanium-oxygen interactions efficiently stabilize the lattice oxygen and reduce the disorder caused by the lithium and nickel. The performance of the new cathode for use in lithium-ion batteries has improved due to its remarkable electrochemical stability and faster lithium-ion diffusion rate.
The group wants to develop its large-scale production strategy in the future.
Published in the journal Particuology, the paper is titled “Integrating trace Ti-doping and LiYO2-coating to stabilise Ni-rich cathodes for lithium-ion batteries.”