In the World Cup match against Afghanistan on June 18, EJG Morgan made 148 off 71 balls with 17 6s and (only) 4 4s.
This is the listing for the most 6s in an ODI innings (10 or more) after England’s innings:
The live link for future reference:
Morgan overtook these 3 who shared the ODI record:
RG Sharma, 16 6s in 209, I v A, Bengaluru, 02/11/2013
AB de Villiers, 16 in 149, SA v WI, Jo’burg, 18/01/2015
CH Gayle, 16 in 215, WI v Zim, Canberra, 24/202/2015.
(So Gayle held the previous World Cup record).
No one else has scored 10 or more 6s in an innings so far in the 2019 World Cup. The best is 5 by JJ Roy for Eng v BD and AJ Finch for Aus v SL.
While on this topic, let us see the records for the most 4s in all ODIs (20 or more):
The runaway winner is RG Sharma with his 33 4s and 9 6s in the ODI record score of 264 for I v SL at Kolkata on 13/11/2014.
The next two positions are also held by India’s SR Tendulkar and V Sehwag (25 each), followed by ST Jayasuriya and several others with 24, i.e. far behind RG Sharma’s outlier.
The World Cup record is held by MJ Guptill with his 24 4s and 11 6s for NZ v WI at Wellington on 21/03/2015.
During this World Cup, no one else has crossed 20 4s. The best is 16 by these: