A Battery Without Cobalt, Without Lithium, and Better Than Graphite

Overview

Lithium-ion batteries — the batteries in every phone, laptop, and electric vehicle — depend on cobalt, 72% of which is mined in the Democratic Republic of Congo under conditions that include child labor. They also depend on lithium from a supply chain increasingly dominated by Chinese refiners.

Our research develops an entirely different kind of anode material: MBenes, two-dimensional sheets of chromium and boron just a few atoms thick. In our published work (Colloids and Surfaces A, 2024), we showed computationally using DFT and AIMD that fluorine-functionalized Cr₂B₂ achieves a sodium-ion storage capacity of 655 mAh/g — the highest of any MBene or MXene in the published literature — while chlorine-functionalized Cr₂B₂ reaches 818 mAh/g for lithium-ion storage. For comparison, commercial graphite anodes max out at 372 mAh/g.

Technical Highlights

• Materials: Cr₂B₂Cl₂ and Cr₂B₂F₂ — 2D transition metal borides (MBenes)
• Stability validated: dynamic (phonon), thermal (AIMD at 300 K for 10 ps), and mechanical (elastic constants)
• Metallic band structure: confirmed intrinsic conductivity, no barrier to electron transport
• Li diffusion barrier: 0.13 eV (Cr₂B₂F₂) and 0.20 eV (Cr₂B₂Cl₂) — lower than graphene (0.27 eV), MoS₂ (0.25 eV), and Ti₃C₂O₂ (0.28 eV)
• Na diffusion barrier: 0.14 eV (Cr₂B₂F₂) — comparable to best-in-class MXene structures
• Li storage capacity: 818 mAh/g (Cr₂B₂Cl₂) — 2.2× commercial graphite
• Na storage capacity: 655 mAh/g (Cr₂B₂F₂) — highest reported for any MBene or MXene
• Favorable OCV range for NIB: 0.20–0.71 V (Cr₂B₂F₂) — within desired 0.20–1.00 V window

Figure 8: Comparison of theoretical storage capacities of all MXene and MBene structures for both (a) LIB and (b) NIB with 'This study' starred at the top.

Supply Chain & Policy Relevance

Chromium (Cr): primary producers are Kazakhstan, South Africa, India, and the United States. Boron (B): Turkey and the United States are the world's largest producers. Sodium carbonate (the electrolyte basis for NIBs): Wyoming's Green River Basin holds the world's largest trona deposit — a purely domestic US resource. Zero cobalt. Zero lithium. Zero FEOC exposure. The IRA's 45X Advanced Manufacturing Credit and 30D Clean Vehicle Credit do not currently recognize sodium-ion as a distinct battery chemistry. Our research provides the published technical foundation for correcting that classification gap.

Key Publication