Electricity storage can be achieved in several ways:
At the present time global storage capacity is completely dominated by Pumped Hydro Storage at 99.3%. All types of battery are only 0.4%
In the future Hydrogen Gas could be used, but as yet this technology does not exist on industrial scale.
To compensate for the periods where the wind is off for a few days a large amount of storage would be necessary. A simple calculation can be made from the average wind production for 3 days which is about 500 GWh for the UK. This is greater than the global annual production of Li-ion Batteries, so such batteries or EV are impossible to use in the foreseeable future. s.