April/May 2021

10 MARKET NEWS Issue 2 2021 Power Electronics Europe www.power-mag.com into what specific material might be being developed for use. LMO (LiMn2O4) - firstly, commercially available high-manganese cathodes already exist in the form of the lithium-manganese oxide spinel, which was used for the 1st generation Nissan Leaf cars. However, it suffers from accelerated degradation at elevated temperatures, which leads to poor cycle life, hence the replacement of LMO with NMC in subsequent Nissan Leaf generations. With a theoretical capacity of only 148 mAh/g and an average discharge voltage of approximately 4.0-4.1 V, this cathode would lead to lower energy densities compared to cells using current state-of-the-art NMC or NCA layered oxides. LMP (LiMnPO4) and LMFP (LiMnxFe1-x¬PO4) - LMP shares the same olivine crystal structure as LFP but operates at a more positive voltage, increasing energy density. Cycle life tends to be low, due to the high manganese content, while the material has poor electronic and ionic conductivity, meaning that reasonable capacities are generally only measured at low charge/discharge rates. The addition of Fe to form LMFP can improve conductivity and cycle life but lowers the average voltage. LMFP may bridge the gap between LFP and NMC/NCA but the reversible capacities of LMP and LMFP are too low to reach the cell-level energy densities of cells using NMC/NCA. Li-Mn-rich (xLi2MnO3·(1 - x)LiMO3 where M = Ni, Mn, Co) - the lithium- manganese rich, layered-oxide cathode is one of only a few options, alongside conversion type cathodes, that offer a capacity improvement over current state-of-the-art NMC and NCA materials. However, stability and cycle life are poor and require considerable improvement before commercialization can be expected. BASF’s high manganese cathode, NCM 217, may refer to a Li-Mn- rich type material. This leaves LNMO as the most likely cathode VW were referring to. The high-voltage LNMO spinel (LiNi0.5Mn1.5O4) operates at a voltage of approximately 4.7 V vs. Li/Li+ and also holds potential as a high-power cathode due to its three-dimensional structure (improving Li diffusion pathways). However, its theoretical specific capacity is only 147 mAh/g, meaning it will not offer any advantage to specific energy or energy density over high-Ni NMC or NCA cathodes. Furthermore, key issues with LNMO revolve around its low cycle life and poor stability, especially at elevated temperatures, whilst its high voltage also necessitates developments to electrolytes. As outlined by Volkswagen themselves, the use of high-manganese cathodes represents a long-term strategy. Nevertheless, there is some commercial development of LNMO from the likes of Haldor Topsoe, NEI Corporation, and Targray. The potential for cost reduction that the material holds, without significantly reducing energy density, added to the possibility of eliminating cobalt consumption, suggests there is a future for this chemistry. The graph below shows how both nickel and cobalt intensity can be reduced by high manganese cathodes such as LNMO, offering a path to lower Li-ion battery costs. Given the trade-off between cost and different performance metrics from different Li-ion cathodes, a range of cathode materials will have to be employed by the Li-ion industry. Further detail and analysis of Li-ion technology trends, and their impact on battery material demand forecasts, can be explored in IDTechEx’s reports “Li-ion Batteries 2020-2030” and “Materials for Electric Vehicle Battery Cells and Packs 2021-2031”. www.IDTechEx.com/Research/ES The US ended 2020 with record wind and solar additions, beating previous highs in all sectors, according to BloombergNEF’s (BNEF) 1H 2021 Renewable Energy Market Outlook. The next ten years will see the US wind and solar fleet almost triple. The US is about to see five years of record large-scale solar capacity additions, adding over 20 GW each year. Both large- and small- scale solar will grow during the years of tax credit extensions. Over the coming decade customer-sited solar capacity maintains its pace, adding on average over 8 GW a year. Over a third of all new systems are built in California. Storage becomes more relevant for project economics as net metering is phased out. Onshore wind is set for another big year of build after a record beating 2020. Installs fall from 2022 as tax credits continue to be reduced. After tax credits are removed in 2026, build dips as projects rely only on the merchant market. Offshore wind looks set to be the big winner of the Biden presidency. The administration seems committed to resolving longstanding permitting bottlenecks and the sector will enjoy a new dedicated tax credit. However, this will still not be enough to hit the Biden administration’s stated goal of decarbonizing the power sector by 2035. “Even without details from the American Jobs Plan, wind and solar capacity additions will steadily grow over the decade, adding 287GW of solar and 115GW of wind. Solar in particular will see record growth in the next four years, adding over 25 GW each year across all sectors. However, more renewables will likely be needed to come close to the government’s target of zero emissions by 2035,” commented Tara Narayanan, BNEF lead US solar analyst. The American Jobs Plan also mentioned, in passing, a “Clean Energy Standard”, which, if anything like the Renewable Portfolio Standards implemented by certain states, could close that gap. However, such a standard is likely to prove contentious politically and would face a difficult passage through Congress if proposed, and potentially legal challenges from states and utilities. Tax credits certainly help the renewables sector grow, but a Clean Energy Standard is the hill on which the battle to fully decarbonize the US power sector could be won or lost.”If the US is to achieve a carbon free grid by 2035 then it would need to at the very least add around 70 GW of wind and solar a year from 2025 onwards - whereas our forecast sees an average of 43 GW per year after 2025. So while we see significant progress for the sector, there is still a significant gap between our outlook and the administration’s ambitions,” adds Tom Rowlands Rees, BNEF head of North America research. https://about.bnef.com/ US Record Wind and Solar Additions