Preparation, characterisation and optimisation of lithium battery anodes consisting of silicon synthesised using Laser assisted Chemical Vapour Pyrolysis

Abstract

Suitability of silicon prepared using Laser assisted Chemical Vapour Pyrolysis (LaCVP) as a potential anode material in lithium batteries is systematically investigated. Its compositional, morphological, physical-chemical and electrochemical properties are compared to a current benchmark commercial silicon. Important differences in particle size and particle composition are found which, as shown, affect critically the rheological properties of the corresponding electrode slurries. In order to overcome the rheological problems of prepared nanosilicon, we introduce and optimise a spraying method instead of using the usual casting technique for slurry application. Interestingly, the optimised electrodes show similar electrochemical performance, regardless of the particle size or composition of nanosilicon. This unexpected result is explained by the unusually high resistance of electrochemical wiring in silicon-based electrodes (about 60 Ohm per 1 mg cm−2 of active material loading). Despite that, the optimised material still shows a capacity up to 1200 mA h g−1 at a relatively high loading of 1.6 mg cm−2 and after 20 cycles. On the other hand, by decreasing the loading to below ca. 0.9 mg cm−2 the wiring problems are effectively overcome and capacities close to theoretical values can be obtained.