Amorphous xLiF-FeSO4 (1 ≤ x ≤ 2) composites as a cathode material for lithium ion batteries

Although the synthesis is not so easy, LiFeSO4F, a high-voltage iron-based cathode, is attractive by virtue of its low cost and small environmental impact. We prepared amorphous xLiF-FeSO4 (1 ≤ x ≤ 2) using the dry ball-milling method. Moreover, we succeeded to synthesize tavorite-type LiFeSO4F by sintering amorphous LiF-FeSO4 at 280 °C. Amorphous 1.3LiF-FeSO4 exhibited the highest reversible capacity, of about 130 mAh g−1, among all the xLiF-FeSO4 series (1 ≤ x ≤ 2), with an average voltage of 3.5 V. In addition, we found that the obtained amorphous xLiF-FeSO4 cathodes have excellent cyclability and rate capability, also.