It is interesting to look at the cell energy density roadmaps and include the production energy density of the cylindrical cell. Why the cylindrical cell? Well, it’s the most complete cell in terms of function as it has a case that contains the working forces over the lifetime. It normally has a venting system and to date it has lead on the chemistry roadmap.
Is 900Wh/kg credible when production cells have taken 30 years to move from 80Wh/kg to 300Wh/kg?
300Wh/kg at cell level is available now. It is difficult to believe the very significant increases in energy density predicted beyond 2025 when we look at what has been achieved to date. We should not underestimate the achievements to date either. Significant research, development and production process improvements have gone into the walk from 80Wh/kg of the first Sony cell to the 300Wh/kg being achieved 30 years later.
Amprius show a NMC811 cell with Silicon nano-wire anode that is at 450Wh/kg in 2020 and with a target of achieving 650Wh/kg in 2023. This is a pouch cell and so needs mechanical support, hence difficult to plot alongside a cylindrical production cells. However, this does show that maybe the technology listed in The Faraday Institution report could achieve the energy density numbers indicated.
- Is the battery R&D on course?
- Does it meet all of the other requirements of a battery cell?
- Can it be made?
- Does it need a significant structure to hold the cell together?
- Is the chemistry scalable?
- Can the cell be made in volume?
- Is it recyclable?
Energy density Wh/kg is one of the key cell metrics that we follow to observe the progress in cell chemistry and design. There are lots of cell energy density roadmaps and we would welcome inputs from research and production institutions.
References:
- David Anseán, “State of Health Determination of Lithium-ion Batteries”, IEEE Instrumentation and Measurement Society
- NEDO, “Aiming for a Breakthrough in the Transition to a Low-Carbon Society”, focus, 2018
- APC Roadmaps, to help the automotive industry accelerate innovation and overcome challenges
- “High Energy Density Lithium-Ion Cells with Silicon Nanowire Anode Technology”, AMPRIUS presentation to NASA
- The Faraday Institution, “High-energy battery technologies”, FARADAY REPORT – JANUARY 2020