Olivine-Based Blended Compounds as Positive Electrodes for Lithium Batteries

Abstract

Blended cathode materials made by mixing LiFePO 4 (LFP) with LiMnPO 4 (LMP) or LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC) that exhibit either high specific energy and high rate capability were investigated. The layered blend LMP-LFP and the physically mixed blend NMC-LFP are evaluated in terms of particle morphology and electrochemical performance. Results indicate that the LMP-LFP (66:33) blend has a better discharge rate than the LiMn 1´y Fe y PO 4 with the same composition (y = 0.33), and NMC-LFP (70:30) delivers a remarkable stable capacity over 125 cycles. Finally, in situ voltage measurement methods were applied for the evaluation of the phase evolution of blended cathodes and gradual changes in cell behavior upon cycling. We also discuss through these examples the promising development of blends as future electrodes for new generations of Li-ion batteries.

Understanding rapid charge and discharge in nano-structured lithium iron phosphate cathodes

“…There is thus scope for significant improvements to be made to LFP cathodes by carefully tuning the electrical properties of the electrolyte and the electrode conduction network, a fact that has been noted previously by Johns et al [25] who demonstrate that changes to the electrolyte properties in a LFP cathode can result in increases in maximum discharge rate of around two orders of magnitude. Volumetric energy density and rate capability can also be improved by using a blend of differently sized electrode particles [27,28,47]. Liu et al [28] showed that by using a nano-micro structured LFP electrode it is possible to achieve higher compaction density, lower resistance, superior rate capability, and higher volumetric energy density whilst still maintaining excellent cycling stability [28].…”

Ternary Cathode Blend Electrodes for Environmentally Friendly Lithium‐Ion Batteries

“…Moreover, the high thermal stability significantly improves the safety of the blend electrode. [25][26][27][28][29][30] Partial substitution of iron with manganese increases the energy density of the material, which enables both excellent electrochemical performance as well as low cost electrode when mixed with NMC. [29,30] The third binary combination, LMFP and LMO, is free of cobalt and nickel, which makes this blend inexpensive and environmentally friendly.…”

“…The addition of phospo‐olivines such as LiFePO 4 also improve the rate capability of electrodes based on layered oxides. Moreover, the high thermal stability significantly improves the safety of the blend electrode [25–30] . Partial substitution of iron with manganese increases the energy density of the material, which enables both excellent electrochemical performance as well as low cost electrode when mixed with NMC [29, 30] .…”

A high-performance composite positive electrode based on graphene and Li (Ni1/3Co1/3Mn1/3)O2

“…Figure also indicates that NMC particles are fused together and form a macroporous structure. It is also reported that uniform distribution of particles can provide good the electrode‐electrolyte contact area and facilitating the transportation of Li + and electrons …”