LiFePO4 is really nice for home energy storage. With great cost, a good safety profile, an excellent cycle life and a decent energy density it has become one of the dominant energy storage chemistries.
Watch the video to discover how LiFePO4 became the dominant battery chemistry in China and how the Chinese battery industry is leading the market now.
For those who are interested in the LFP cells inside the B300 and B300S , the cells are cylindric and rated at 3.2 VDC and 4 Ah. The arrangement is 16 in series and 15 in parallel. So 16 x 3.2 = 51.2 VDC, and 15 x 4 = 60 Ah. The total watt-hours are 51.2 x 60 = 3072 Wh with a total of 16 x 15 = 240 cells.
I don’t know the setup in the new B300K, but I am guessing that the arrangement has a different number of cells in parallel. For just 2,764.8 Wh the battery must keep the same 51.2 VDC output, so it has the same 16 in series (16 × 3.2 = 51.2 VDC). So its amperage drops to 2764.8 ÷ 51.2 VDC = 54 Ah. Using smaller 3 Ah cells we can see it must have 18 cells in parallel. So my final conclusion is 16 in series and 18 in parallel, 16 x 18 = 218 cells. This is my calculating guess. I wonder if Bluetti can confirm the numbers.
Edit: The B300K may use larger capacity cylindric cells, too. For the 54 Ah capacity, the cell array can be 6 Ah x 9, or 9 Ah x 6. These arrays will be smaller than the 4 Ah x 15 in the B300 and B300S.
@Raymondjram @TheQuickFox
Confirmed by the technical team: The B300K contains 16 in series and 2 in parallel, totaling 32 cells; each cell is 3.2V/27Ah, and the battery pack is 51.2V/54Ah. 
This information means that Bluetti now uses larger prismatic cells instead of cylindric cells for the B300K. I knew that they were more compact, but never expected that the cells were larger with 27 Ah capacity.
Does the new Elite 300 use larger cells, too?
Yes, the Apex300 is also the same as the B300K cell capacity. 