Eagle Graphite Reports Strong Early Results From Li-Ion Battery Tests

We are pleased to report positive early results from testing for lithium-ion battery anodes. This work is being performed as part of our ongoing graphite usage study.

Highlights

  • Lithium-ion coin cells were produced using anodes made from purified and spheronized graphite from Eagle Graphite’s quarry in British Columbia.
  • Both uncoated and coated graphite showed excellent ‘near theoretical’ results in initial charge-discharge cycling. In both cases, reversible capacity exceeded typical industry specifications for lithium-ion batteries.
  • The uncoated graphite is undergoing long-term cycling. After 55 cycles, 99.23% of the original reversible capacity remained, which is viewed as a very strong result.

A leading independent specialist laboratory is under engagement to optimize process and qualify graphite produced at our Black Crystal plant for high value markets. The ongoing research, begun in 2018, has already confirmed potential applicability of our graphite for a wide range of high value markets.

During this part of the study, CR2016 coin cells were prepared in accordance with typical industry standards using Li/Li+ counter electrodes, commonly known as a half-cell design. Graphite produced from Eagle Graphite’s Black Crystal quarry and processing plant was purified to at least 99.98 %wtC and spheronized to typical battery industry specifications. Anodes for the CR2016 cells were prepared using this spheronized and purified graphite, some with uncoated graphite, and some with graphite coated with soft carbon.

The independent laboratory has provided a report to the Company with results from galvanostatic cycling of the coin cells.

 

Results For Uncoated Graphite

The author of the report states “The electrochemical performance on the formation cycles is defined as excellent in that we are witnessing stable cycling with 361.94 mAh/g of reversible capacity on the first cycle. Considering that 372 mAh/g is a theoretical maximum for natural graphite, we define the result for Black Crystal as ‘near theoretical’ performance.”

Long-term cycling of the uncoated graphite is ongoing, with 55 cycles reported to date.

Capacity, mAh/g
Cycle Irreversible Reversible
1 404.19 362.77
5 367.02 362.74
10 368.56 362.41
25 365.30 363.09
55 361.48 359.98

Table 1: Results of long-term cycling with uncoated purified spheroidal graphite from Eagle Graphite’s Black Crystal Project.

The report’s author comments, “The data show that long-term cycling performance with the uncoated graphite is extremely stable. The registered reversible capacity loss, from 362.77 mAh/g to 359.98 mAh/g, amounts to a very low 0.77%, with 99.23% of the original reversible capacity remaining.”

Figure 1: Cycling data with uncoated purified spheroidal graphite of Eagle Graphite’s Black Crystal project. Cycles 1 through 55.

 

Results For Coated Graphite

Coated graphite “shows a significantly improved result versus that with he uncoated graphite, which manifests itself in a greater reversible capacity (364.78 mAh/g vs. 361.94 mAh/g for coated and uncoated graphites, respectively) and greatly diminished irreversible capacity loss (i.e. 7.53% vs. 10.45%, respectively, in the same order).”

Although the study did not include long term cycling of the coated graphite, the report notes that “cycling stability is usually even greater with coated samples.”

Typical battery industry specifications require initial reversible capacity of at least 350 mAh/g.

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