Dedicated to Professor Bruno Scrosati on the occasion of his 70 th birthday
Considerable attention has been paid to electrochemical energy storage devices with both high energy and high power densities, because of their potential use in powering electric vehicles and portable electronic devices. Rechargeable lithium-based batteries are amongst the most promising candidates in terms of energy density, [1][2][3][4] whilst the achievement of high power density is hindered by kinetic problems of the electrode materials. For achieving a high rate capability of lithium batteries, rapid ionic and electronic diffusion is necessary. Extensive research work has focused on enhancing mixed conduction by doping the electrode materials with foreign atoms [4][5][6] or by admixing electronically conductive phases (electronic wiring through carbon, Ag, conducting polymers, etc.). [6][7][8][9][10][11][12][13][14][15][16][17] The wiring technique has been applied widely to micro-and submicro-sized particles (typically > 50 nm), but not to the 10 nm range, and has been most systemically studied by Jamnik et al. [14] A successful example of this is the well-known carbon-coating technique used in the synthesis of the LiFePO 4 electrode material. [9][10][11][12][13][14][15] However, the rate performance enhancement of such electrode materials is still limited, as availability or percolation of the electronically conducting phase and/or the electrolyte become insufficient at very high rates. Two recently reported optimization procedures intended for high rate performance may be mentioned in this context: 1) the use of nano-architectured electrodes consisting of the electrochemical plating of Fe 3 O 4 onto Cu nanorods acting as a current collector; [16] 2) the use of porous TiO 2 thin films. [17] Both designs lead to enhanced power performance but are naturally not meant for achieving high COMMUNICATION