Anisotropic ionic conductivity of LiMn1−Fe PO4 (0 ≤ x ≤ 1) single crystals

Abstract

We report AC-impedance studies on a series of high-quality LiMn 1−x Fe x PO 4 single crystals with 0 ≤ x ≤ 1. Our results confirm quasi-one-dimensional transport in LiFePO 4 with fast Li-diffusion along the b-axis. The conductivities along the crystallographic b-, c-and a-axis differ by a factor of about 10, respectively. Whereas, the activation energy E A of the effective diffusion process is particularly large for the b-axis and smallest for the a-axis. Remarkably, the b-axis ionic bulk conductivity of LiMn 0.5 Fe 0.5 PO 4 is of the same order of magnitude as in undoped LiFePO 4 , which implies similarly fast Li-transport even upon 50 % Mn-doping which, owing to the higher redox potential of the Mn 3+ /Mn 2+ -couple, yields enhanced energy density in lithium-ion batteries. The overall results of our impedance studies draw a far more complex picture than it would be expected from a simple one-dimensional ionic conductor. Our results suggest a strong contribution of crystal defects in real materials.

Study on annealing treatment of spinel LiNi 0 . 5 Mn 1 . 5 O 4 as cathode materials for high‐voltage lithium‐ion batteries

“…Among the development of renewable energy technology-ranging from ordinary lithium-ion batteries (LIBs) required for electronic mobile devices like phones, cameras, and laptops to the power LIBs required for transportation vehicles like electric and hybrid vehicles-LIBs are one of the most successful technologies, and these demands have driven the development of secondary LIBs. [4][5][6][7][8][9][10][11][12][13][14][15] The cathode material in the LIBs plays a critical aspect affecting the performance and also the main source of lithium ions in current commercial LIBs. Therefore, the development of advanced LIBs is largely determined by the highperformance cathode materials.…”

Insight into structural and electrochemical properties of Mg‐doped LiMnPO 4 /C cathode materials with first‐principles calculation and experimental verification

“…[2][3][4][5][6] Since "high voltage" cathode materials is an effective way to improve the energy density of batteries, the development of high voltage cathode materials with higher cost performance is a hot spot in the research of lithium ion batteries. [7][8][9] As far as the current research is concerned, the main research direction is LiMnNiO 4 (4.8 V) of spinel structure and LiMnPO 4 (4.1 V), LiCoPO 4 (4.8 V) and LiLiPO 4 (5.2 V) of olivine structure. Among these high voltage cathode materials, olivine structure LiMnPO 4 has the advantages of outstanding safety performance, low price, high energy density, good cycling stability, high potential platform (4.1 V vs Li/Li + ) and so on, which is a potential cathode material for high voltage.…”

“…However, as a single power source, LIB requires it to be able to store and release higher energy, which puts forward higher requirements for the energy density of battery materials, especially cathode materials 2‐6 . Since “high voltage” cathode materials is an effective way to improve the energy density of batteries, the development of high voltage cathode materials with higher cost performance is a hot spot in the research of lithium ion batteries 7‐9 …”

Growth and Optical Properties of the Whole System of Li(Mn1-x,Nix)PO4 (0 ≤ x ≤ 0.5) Single Crystals

“…[ 7 ] The anisotropic Li-ion diffusion is also the main reason for the electrochemical performance deviation of LiFePO 4, even synthesized under the same experimental conditions, due to different crystal faces exposed in the polycrystalline products [ 8 , 9 , 10 , 11 ]. In this regard, the single crystals of the LiMPO 4 family have certain advantages over their polycrystalline powders to investigate the anisotropic nature of the lithium exchange and electron transfer in this kind of material [ 12 , 13 , 14 ].…”