Dual Modification of Olivine LiFe_0.5Mn_0.5PO₄ Cathodes with Accelerated Kinetics for High-Rate Lithium-Ion Batteries

Abstract

Developing olivine-type lithium ferromanganese phosphates with high ionic/electronic conductivity is vital to promote their practical application in long-life and high-rate lithium-ion batteries (LIBs). Herein, we propose a dual modification strategy combining C-coating and Nb-doping and apply it to enhance LiFe0.5Mn0.5PO4 cathode materials. The uniform and compact C-coating layer successfully fabricates the high-speed conductive network among primary particles and meantime prevents the attack of electrolytes. The strong Nb–O coordination can effectively accelerate ion diffusion and electron transport within the nanoparticles while suppressing the Jahn–Teller effect of Mn3+. The dual modifications synergistically improve the LiFe0.5Mn0.5PO4 cathode materials with superior lithium-storage capacities of 152 and 115 mAh g–1 at 0.1 and 5 C, respectively. Furthermore, it exhibits an impressive cycling performance with an ultrahigh capacity retention of 95.4% after 1000 cycles at 1 C. These findings extend the application of surface-to-bulk co-modification in developing novel cathode materials used in high-performance LIBs.

LiMn0.8Fe0.2PO4/C Nanoparticles via Polystyrene Template Carburizing Enhance the Rate Capability and Capacity Reversibility of Cathode Materials

“…People’s attention has been drawn to the quick consumption of oil and gas and the growing severity of environmental problems, which brings great scientific and technological opportunities and challenges for the development of sustainable energy storage and conversion systems. , In the past few decades, lithium-ion batteries (LIBS) have occupied a dominant position in the power market of lightweight electronic gadgets because they have excellent cycle life as well as energy density and environment-friendly. In addition, they are also utilized in energy storage systems, hybrid battery-powered vehicles, and electric vehicles as well. , Polyanionic lithium iron phosphate (LiFePO 4 ) cathode material was reported by the Goodenough research group in 1997.…”

“…Undoubtedly, the issues of low electronic conductivity and sluggish lithium-ion diffusion must be resolved in order to encourage the practical application of olivine structure LiMnPO 4 materials in the cathode of lithium-ion batteries. , In this regard, various strategies have been reported; for example, the electrical conductivity may be efficiently increased by covering carbon-based compounds, ,, reducing the grain size to nanoscale can promote the diffusion of lithium ions, − forming solid solution stable crystal structure with the help of doped ions can reduce the influence of Jahn–Teller effect, − and selecting the crystal plane direction that facilitates lithium-ion diffusion can optimize the reversible capacity of materials. , …”

Dual Energy Storages by Sequential “Rocking Chair” and “Dual Ion” Processes of LiFe0.6Mn0.4PO4/Carbon Modified Graphite Flakes

“…To further address this issue, our group tried to find modification agents with electrochemical activity to replace the electrochemically inert metal oxides with the purpose to enhance cyclic capacity and cyclability of the graphite-based composite cathode simultaneously. In recent years, lithium iron manganese phosphates (LiFe x Mn 1– x PO 4 ) have attracted much attention to replace commercialized LiFePO 4 because of higher working potential of the redox couple Mn 2+ /Mn 3+ (4.1 V vs Li/Li + ) than that of Fe 2+ /Fe 3+ (3.4 V vs Li/Li + ). − Thereby, enhanced energy density of LiFe x Mn 1– x PO 4 is realized. − The electrically semiconductive or insulative nature of LiFe x Mn 1– x PO 4 makes it become a very suitable candidate to substitute the metal oxides as a modification agent . Moreover, the working potential of the redox couple Mn 2+ /Mn 3+ is very close to the initial intercalation potential of the graphite cathode (∼4.3 V vs Li/Li + ).…”

One Stone Three Birds: Na–Zr Co-Doping and Li6Zr2O7 Coating Enhance the Structural Stability and Electrochemical Performance of the LiNi0.8Co0.1Mn0.1O2 Cathode Material

“…However, the traditional high nickel ternary cathode materials have poor structural stability so that capacity occurs fading. Researchers employ many methods to modify it, such as single-crystal method, coating, and doping. – The single-crystal method efficiently inhibits the generation of microcracks, alleviates the surface side reaction, and prolongs the cycle life. However, the rate performance is delayed by the huge size of the single-crystal particle and the extensive lithium-ion transport channels. – Coating is a common means of forming a coating on the surface of the cathode material by a dry or wet method.…”