The invention relates to lithium salts of the general formula (I) Li[P(OR 1 ) a (OR 2 ) b (OR 3 ) c (OR 4 ) d F e ] wherein 0 < a+b+c+d ≤ 5 and a+b+c+d+e = 6, and R 1 to R 4 are independently alkyl, aryl or heteroaryl groups, wherein at least two of R 1 ...