As we are talking about Sweden, a relatively cold country, a big chunk of energy consumption is about heating. And heat is a form of energy that is much easier to storage than electricity. I very much assume that even seasonal storage of heat is becoming a big thing in coming years, dwarfing any chemical battery capacity whatsoever. After all, for that, in the most basic form, you need a big enough pool of water connected to electric grid with a resistor and to district heating system with a heat exchanger.