Renault has revealed that over 99% of batteries in the Zoe E-tech vehicles sold since 2013 are still fully functional. The company claims its success is due to the lithium-ion batteries and intelligent battery management technology used in the EVs. Plus, a priority list was opened in the UK for the Megane E-Tech 100%, an EV with a 450 km (280 miles) range.
https://www.notebookcheck.net/Renault-announces-Zoe-E-Tech-battery-stats-as-Megane-E-Tech-100-Electric-UK-priority-list-opens.619226.0.html
Those aren't bad numbers when it comes to reliability, considering Renault has one of the worst cooling system, other manufacturers with proper cooling should be even significantly better.