Wired Porous Cathode Materials:  A Novel Concept for Synthesis of LiFePO₄

Abstract

To increase the power density of battery materials, without significantly affecting their main advantage of a high energy density, novel material architectures need to be developed. Using the example of LiFePO 4 , we demonstrate a simple, sol-gel-based route that leads to large (up to 20 µm) primary LiFePO 4 particles, each of which contains hierarchically organized pores in the meso and macro range. As the pores are formed due to vigorous gas evolution (mainly CO and CO 2 ) during degradation of a citrate precursor, they are perfectly interconnected within each particle. Elementary carbon, the other citrate-degradation product, is deposited on the walls of emerging pores. The superposition of a continuous 1-2 nm thick carbon film (electron conductor) on pores (ion conductor when filled with electrolyte) represents a unique architecture in which the electrons and ions are simultaneously supplied to the site of insertion in the particle interior. The material can operate at current rates up to 50 C while preserving a high tap density of ca. 1.9 g cm -3 .

Electrochemical characteristics of Li2−VTiO4 rock salt phase in Li-ion batteries

“…Addition of citric acid as a chelating agent and as a source of in-situ carbon leads to the formation of homogenously distributed particles in a porous carbon matrix. In our previous works [17,18] we showed that degradation of citric acid leads to the porous composite with a residue carbon which can act as a electron conductive coating [7].…”

In-situ XAS study on Li2MnSiO4 and Li2FeSiO4 cathode materials

“…The valence state of metal cation in the sample can be deduced from the energy shift of the absorption edge [21][22][23][24][25]. With increasing oxidation state each absorption feature in the XANES spectrum is shifted to higher energies.…”

Graphene-modified LiFePO4 cathode for lithium ion battery beyond theoretical capacity

“…Structural defects or other factors that may retard the Li þ diffusion further lower the actual capacity of the cathode. Current strategies to enhance the electrochemical performance of LFP include carbon coating on LFP (cLFP) [1][2][3][4][5][6] , metal doping [7][8][9] , and LFP particle size reduction [10][11][12][13][14][15] . The carbon coating process has been massively used in industry because the conductive carbon layer increases the electron migration rate during the charge/discharge processes.…”