small electrode area, large Li inventory reservoir, impedance associated with Li electrode, and excess electrolyte. Testing in full coin cell format eliminates the unrealistic Li reservoir and impedance aspects, but maintains the small area and large electrolyte excess (here a value of 20 g Ah -1 was used, compared with as low as 1 g Ah -1 for commercial Li-ion cells). Only through the manufacture and testing of full commercial-style pouch/cylindrical cells can representative performance data be revealed, particularly so in the case of rate capability which exhibits particular sensitivity to small changes in electrode impedance. To illustrate this, Figure shows the results of a rate capability test of LMFP and graphite materials in four cell formats: (i) LMFP HC, (ii) Graphite HC, (iii) LMFP\\Graphite full coin (FC) and (iv) pouch cells (PC). The testing protocol involved symmetric constant current (no CV) charging/discharging in the range 2.5 -4.5 V. Capacities exhibited during initial formation cycling at C/20 were reasonably close to the theoretical values for the materials i.e. 144 -154 mAh g -1 for LMFP and 352 mAh g -1 for graphite. At higher rates however, the capacity achieved by the graphite HC fell dramatically (e.g. 153 mAh g -1 at C/3), and the cell provided < 10 mAh g -1 at all rates > 1 C. This poor performance can be attributed to the high impedance of the lithium counter electrode (and not the graphite electrode itself). The lithium electrode present in the LMFP HC (which was initially identical to that in the graphite HC) does not suffer from the same impedance as, during first charge, lithium is plated onto the existing metal surface, forming a high surface area (and thus lower impedance) electrode. Anode HCs are thus entirely unsuitable for rate capability tests at all but very low areal capacities and can dramatically underestimate electrode performance. The LMFP HC and FC capacities mirrored each other well at all cycling rates, while the pouch cell matched well at low rates, but performs less well than coin cells at higher rates. This likely reflects the idealised current pathways within a coin cell i.e. extracted current is not funnelled through a small tab area. EIS spectra obtained after formation (Figure ) confirmed these trends, whereby the total (combined charge transfer and diffusion) graphite HC impedance (185 Ω cm 2 ) is significantly greater than that of the LMFP HC (60 Ω cm 2 ). The full coin cell impedance is lower still at 42 Ω cm 2 , while that of the pouch cell was 212 Ω cm 2 . Additionally, the pouch cell did not recover its full capacity when cycling was returned to C/3 (unlike the coin cells), reflecting . The graphite coat weight was adjusted to maintain an N:P ratio of approx. 1.2. At C/3, minimal difference (< 1 %) between the cells was observed, however at higher rates the capacities diverged dramatically. For example, at 10 C, the capacity of the 80 gsm cell (73 mAh g -1 ) was almost three times higher than that of the 135 gsm cell (24 mAh g -1 ). Impedance spectra were also obtained (Figure ). At first glance, the spectra (showing lower impedance for the 135 gsm cell) may seem to contradict the rate capability results, however they are reflective of the larger surface area (and thus lower impedance) in the case of the thicker 135 gsm electrode. Despite this observed lower impedance, the 135 gsm cell was subjected to far higher areal current densities than the 80 gsm cell (e.g. 20.0 vs 11.9 mA cm -2 at 10 C) resulting in lower observed capacity. Thus, a meaningful comparison of cell performance, particularly at higher rates, is only possible when coat weights are similar, and examination of high-rate performance is of limited value to real-world applications when low coat weights are utilised.