Correction to: Nature Energy https://doi.org/10.1038/s41560-018-0293-y, published online 26 November 2018.

In the version of this News & Views originally published, in Fig. 1b, the compounds containing barium were labelled incorrectly. The two labels reading ‘4BaH’ should have read ‘2BaH2’, the three labels reading ‘Ba2NH’ should have read ‘BaNH’, and the label ‘BaH’ should have read ‘BaH2’. In the main text, ‘Ba2NH’ should have read ‘BaNH’, and ‘BaH’ should have read ‘BaH2’. These errors have now been corrected.