To assess the generality of this nitrate additive strategy, different types of main salts and ether electrolyte systems were chosen. The lithium bis(fluorosulfonyl)imide (LiFSI)-based dilute electrolytes with NO3 -showed good compatibility with LiCoO2 and NMC532 cathodes under a cutoff voltage of 4.3 V, realizing high capacity retentions of 94.2% and 90.4%, respectively, for over 600 cycles (Figure ). More importantly, high-voltage tolerance of 4.3 V was also confirmed in the sodium (Na)-ion electrolyte system (Figure ). 1000-cycle Na-ion battery with Na Prussian blue (NaPB) was achieved in 1 M NaPF6 DME with 50 mM NaNO3. These results illustrate the feasibility of our strategy by adding tiny NO3 -to increase the high-voltage tolerance of dilute ether electrolytes.