Assessment of cathode active materials from the perspective of integrating environmental impact with electrochemical performance

A method was brought forward for assessing cathode active materials from a perspective that accounts for the environmental impact and the electrochemical performance. Then the integrated performance, referred to as the "final environmental impact", was quantified into a dimensionless score, EI _c (see Eq. (2)). Subsequently, four types of cathode active materials- LiFePO₄/C, LiFe_0.98Mn_0.02PO ₄/C, LiFe_0.98Ti_0.02PO₄/C, and FeF₃(H₂O)₃/C- were assessed. The results were: (1) the EIc sequence was LiFePO4/C (1.76E-02Pt) > LiFe_0.98Ti _0.02PO₄/C (1.74E-02 Pt) > LiFe_0.98Ti _0.02PO₄/C (1.66E-02Pt) >FeF₃(H ₂O)₃/C (4.98E-03 Pt), which meant FeF₃(H ₂O)₃/C was the optimal material and had the minimal final environmental impact. (2) With regard to the eleven impact categories, the category respiratory effects exerted by inorganics made up the largest percentage of the EIc for the four materials. (3) In the aspects of EIm (EI (Eco-indicator) value of a 1 kg cathode active material), average specific discharge capacity, and cycle life, the sub-optimal materials' sequence of theoretical potential for optimization was as follows: LiFe _0.98Ti_0.02PO₄/C > LiFe_0.98Mn _0.02PO₄/C > LiFePO₄/C. This meant that the final environmental impact of LiFePO₄/C was the most difficult to reduce, and the impact of LiFe_0.98Ti_0.02PO₄/C could not be reduced very easily. (4) To reduce the final environmental impact, the following concrete measures were recommended: (a) the optimization of the synthesis processes for smaller particle diameters; (b) the adoption of other surface-coating agents, utilizing (other) dopants; (c) the substitution of the energy-efficient instruments for the energy-intensive instruments; (d) the optimization of the synthesis processes to contain fewer electricity-intensive steps.