*5.1. Comparison between Systems*

It is reasonable to compare this waterjet-based recycling approach with the recycling processes presented by Buchert et al., namely LithoRec II, EcoBatRec and LiBRi [30,33,34], however, the comparability of the systems should be ensured beforehand or the differences should be considered. By considering the scope definitions, because of differences in the system boundaries, it is difficult to compare the different systems. One of these differences is based on the studies by Buchert et al. [30,34] that evaluated material flows which leave the system boundary via credits, which was deliberately omitted in this study. Table 2 shows the pure direct debits from the cited studies. It is worthwhile mentioning that, in this study, transportation was considered, and therefore, debits for transportation of TBs are not included in the values presented here. More important than the comparison of the abovementioned methodological framework conditions, is the function of these recycling approaches. This is because the recyclates from the LithoRec II, EcoBatRec and LiBRi processes are not comparable with the recyclate from the recycling process presented here. By comparing the LithoRec II process and this waterjet-based recycling process, the differences are clearer. As described in Section 3.1, this waterjet-based recycling process separates cathode coating from the rest of the cell and aims to proportionately add the obtained recyclate directly to a new cathode coating. In contrast, the products of the LithoRec II process are nickel, manganese and cobalt in a sulphate solution, and lithium as lithium hydroxide [30], which can be used again for cathode coating production.

**Table 2.** A comparison of the global warming potential (GWP) and the cumulative energy consumption of different recycling approaches using the functional unit of 1 kg of traction batteries. The system boundaries are adjusted to each other.


Therefore, the comparison in Table 2 must be considered carefully and is not intended to be a benchmark, but rather to highlight the possible advantages of a direct recycling process as compared with the indirect recycling route. Buchert et al. [30,33,34] focused on indirect battery recycling that used pyrometallurgical or hydrometallurgical processes to recover the raw materials of the cathodes, which contributed the most to the GWP of these recycling processes. In the LithoRec II process, hydrometallurgical processing caused about 70% of the total GWP of this process, while in the LiBRi process, the pyrometallurgical process step and the slag preparation caused 77% of the total GWP [33]. The biggest driver in the EcoBatRec study was mechanical treatment with 33%, however, the product of the EcoBatRec recycling approach required further treatment, for example by the hydrometallurgical process as used in the LiBRi approach [34].

#### *5.2. Comparison between Products*

The benefits of this method of adding recovered battery-grade cathode material to the new NMC active material up to a certain proportion are that almost the entire production chain of new cathode coating can be avoided for this proportion, and furthermore, the mining of primary raw materials is not necessary to this extent. While the DeMoBat project determines whether such an approach is possible and, if so, up to what proportion admixtures can be realised without having to record too great a loss of quality in the product (new traction batteries), this study quantifies the possible savings for the GWP of cathode coatings through this procedure.

Since significant production steps to produce cathode coating from primary materials could be neglected, a comparison of the active material recycled in the way described here with cathode coating from primary production is reasonable. Accardo et al. [35] claimed that the stoichiometric composition of the NMC materials played a minor role for the GWP, which was why, in this study, only the addition of recyclate to NMC111 material is illustrated. Dai et al. [36] reported a GWP of 16.1 kg CO2e for 1 kg of NMC111 cathode material [36], which is 100 times higher GWP potential than the cathode material (recyclate) obtained through the waterjet-based battery recycling. The savings that can be achieved by blending different mass fractions of recyclate to the primary cathode material are described in Figure 6, which shows that blending 10% and 20% recyclate can save 9.3% and 18.6% CO2e, respectively. Due to the very low GWP of the recyclate, the GWP of the cathode material can be reduced by approximately the same percentage as the recyclate content. The NMC111 cathode material studied by Dai et al. [36] has a share of about 40% in the GWP of the entire TB, which makes it possible to estimate the impact of the admixture for the GWP of the entire battery. Consequently, the GWP of a traction battery with NMC111 cells can be reduced by 4–8% by blending the abovementioned proportions. While Accardo et al. [35] illustrated that there are no significant differences in the GWP of different NMC compositions, at the same time, their study also showed that NMC111 material has the highest GWP, which suggests that the savings shown in Figure 6 represent the highest possible savings among the cathode coatings NMC111, NMC622, and NMC811.

**Figure 6.** Impact of recyclate admixture in different proportions on the GWP of NMC111 cathode material and the production stage of a traction battery.
