Accurate XRD, often in combination with ND, has long been used to study electron density features in crystalline compounds. The method is particularly successful for light-atom systems in which the valence-to-core electron ratio is high. The same method is clearly applicable to the study of (typically) lithium insertion/extraction processes in TMO compounds; the greatest hinder has been the availability of sufficiently large single crystals, which do not then disintegrate into micron-size particles during the reaction. The case of V6O13 is especially advantageous in this context, however: millimeter-size crystals can be grown by CVT methods, which do not then exhibit severe cracking on lithium insertion, probably as a result of the layer-like nature of the structure. A sequence of single-crystal phases have now been studied in this way (LixV6O13 for x= 0, 1.0, 2.0 and 3.0) following in situ electrochemical synthesis in the composite cathode of a <Li| PE |V6O13> half-cell. The resulting structures have been solved, and their associated electron-density distributions carefully analysed by so-called Hirshfeld deformation electron density refinement. The method would appear to provide meaningful information relating to oxidation state changes occurring on lithium-ion insertion.