Energy storage technology roadmap report - which battery will win?
Energy storage economy
Learn from the development history of photovoltaic and national energy storage technology.
Electrochemical energy storage technology ushered in opportunities
The Global Energy Interconnection Development Cooperation Organization predicts that the electricity consumption of the whole society will reach 17 trillion kWh in 2060, the per capita electricity consumption will reach 12,700 kWh, and the installed capacity of clean energy and new energy will account for more than 90%.
With the large-scale access of new energy sources, in order to overcome the intermittency and volatility of wind and photovoltaics, the entire power system is transforming from “source-grid-load” to “source-grid-load-storage”, and energy storage technology will become a new type of power system. the fourth essential element. Energy storage technology is currently mainly concentrated in two forms of pumped storage power plant and lithium-ion battery energy storage, like the recently popular 51.2v 200ah powerwall lithium ion battery：
Development path of household photovoltaic and energy storage technology in germany
Countries with the highest proportion of wind and solar power generation in 2020 include Sweden (19%), Germany (18%), Portugal (18%), the United Kingdom (17%) and Finland (17%), etc. The average share in Europe is 12-13% (The domestic data is less than 5%).
Since the installed capacity of Portugal, Sweden, and Finland is too small to be of reference significance, we mainly focus on Germany and the United Kingdom, of which Germany is used as the reference for the installed energy storage capacity behind the table, and the United Kingdom is used as the reference for the installed energy storage capacity before the table.
The development of domestic photovoltaic and energy storage technology in Germany depends on economy
The prosperity of photovoltaic power generation is at the same frequency as the policy orientation, and it is highly dependent on subsidies. In 1990, Germany formulated the “1000 Roof Plan”, which opened the prelude to the development of its photovoltaic industry;
In 1998, the government further proposed the “100,000 Roof Plan”, which greatly stimulated the German and global photovoltaic industry.
In 2000, Germany passed the “Renewable Energy Law”, and revised the Act three times in 2004, 2008 and 2012, clarifying the mandatory on-grid tariff for photovoltaic power generation, which led to the rapid growth of Germany’s photovoltaic installed capacity and became the world’s photovoltaic industry in one fell swoop. benchmark country.
From 2010 to 2012, the newly installed capacity of photovoltaic power generation in Germany exceeded 7GW for three consecutive years. At the same time, with the decline in the installed cost of photovoltaic power plants, the German government is also gradually reducing the feed-in tariff subsidies, and the growth rate of installed capacity has gradually stabilized.
In 2018, the government set a target of increasing the share of renewable energy in total electricity demand to 80% by 2040, and in 2021, this target was brought forward to 2030.
With the introduction of increasingly aggressive policy goals, the scale of newly installed photovoltaic capacity has increased year by year. By the end of 2021, Germany’s photovoltaic installed capacity will reach 59.9GW, and 5.3GW will be newly installed in 2021.
The newly installed photovoltaic capacity in Germany is mainly distributed, and the proportion of household photovoltaic installed capacity is on the rise.
German energy storage capacity:
The proportion of energy storage technology on the power consumption side continues to increase, with significant structural characteristics. The advancement of energy storage technology and the reduction of investment costs brought about by scale, combined with the high electricity bills that have risen year by year, have promoted the vigorous development of the German behind-the-meter energy storage technology market.
According to statistics, by the end of 2020, nearly 70% of German household photovoltaic power generation projects are equipped with battery energy storage technology systems, and the installed household energy storage capacity has exceeded 300,000, with a single-family scale of about 8.5kWh.
Energy storage technology system configuration:
With the increase in the proportion of energy storage on the electricity side, the ratio of installed power and capacity of electrochemical energy storage in Germany tends to be 1kW/2kWh.
Based on the data of newly installed photovoltaic and energy storage technology systems in recent years, German household photovoltaic installations tend to be equipped with 10%, 2h energy storage technology, which is similar to the current Chinese policy for centralized photovoltaic power generation projects.
Calculated based on the roof area of 200w/square meter for household rooftop photovoltaic and 100 square meters/household, the installed capacity of single-household photovoltaic system is about 20kw.
The average household energy storage technology is 8.5kwh, which basically matches the electricity consumption of a single household during the non-photovoltaic power generation period. The household energy storage technology system occupies a small space and is highly accepted by users. Household energy storage technology installations and photovoltaic installations are not necessarily related.
UK leads European energy storage technology market
Mainly based on the rapid growth of photovoltaic installed capacity
Photovoltaic power generation in the UK:
In 2014, the UK released the “Photovoltaic Power Generation Strategy”, focusing on supporting distributed (rooftop) photovoltaic systems.
In April 2016, the Renewable Energy Obligation Act (RO) subsidy for all PV projects ended; in 2018, the UK ended its support for rooftop solar projects.
UK energy storage technology :
After the rapid growth of photovoltaic installed capacity from 2014 to 2016, the proportion of photovoltaic power generation in the whole society has increased significantly, and the installed electrochemical energy storage capacity in the UK has increased significantly from 2016 to 2019.
By the end of 2020, the installed capacity of electrochemical energy storage technology in the UK was nearly 570MW, accounting for 47% of the installed capacity of energy storage in Europe.
The average configuration time of the front-mounted energy storage meters in the UK is nearly 1 hour, which mainly plays a role in improving the flexibility of grid connection (energy time shift) and grid stability (ancillary services).
In 2020, the newly installed capacity of energy time-shifting and ancillary service energy storage was 175MW and 62MW respectively, which together accounted for 80.6% of the newly installed capacity in the same year.
China’s economy brings a higher proportion of energy storage to distributed photovoltaics
Before 2017, the IRR of centralized photovoltaics was higher than that of distributed photovoltaics, mainly due to the subsidy factor; after 2018, the IRR of distributed photovoltaics achieved an overtake.
Based on the development history of photovoltaic energy storage technology in Germany, the installed capacity of distributed energy storage is mainly based on the electricity consumption of industrial enterprises and the difference between peak and valley electricity prices, reflecting the economy.
In the early days, more than 90% of the power of distributed installations was supplied to surrounding industries with high power consumption. In the later stage, as the cost of components continued to decline, the irr of distributed photovoltaics was further improved. For industries and commerce with low power consumption, the use of distributed + large storage The energy model will also reflect the economy.
Policies catalyze the development of the industry:
The support of national policies plays an important role in the development of the industry. Both the centralized photovoltaic grid-guided electricity price and the distributed photovoltaic kWh subsidy have played a great role in promoting the development of China’s photovoltaic industry in the early stage. In 2018, the subsidy declined, and the installed capacity also decreased accordingly.
As of 2020, China’s wind and solar power generation accounts for 7.5% of the total electricity consumption of the whole society, and the impact on the power grid is not great. It is estimated that the proportion of wind and photovoltaic power generation will reach the zero boundary of 25-30% in 2025. The policy promotes the increase of the proportion of supporting energy storage technology on the grid side and the power generation side.
China’s electricity-side energy storage economy:
Taking the 10MW/40MWH energy storage technology system as an example, the IRR of energy storage reaches 8.60% without considering tax incentives, and the IRR reaches 10.46% when tax incentives are considered.
High degree of industrial chain overlap
The road to industrialization of sodium power is smooth
The working principle of sodium-ion batteries is the same as the “rocking-chair” principle of lithium-ion batteries, and the reversible deintercalation of sodium ions (Na+) between positive and negative materials is used to achieve charge and discharge.
The sodium-ion battery is mainly composed of a positive electrode, a anode, a separator and an electrolyte, and is basically compatible with the production equipment of lithium-ion batteries, which reduces the difficulty of industrialization.
The best application of sodium ions in energy storage technology
Lithium raw material prices continued to rise. As of March 2022, the price of battery-grade lithium carbonate, the main raw material, exceeded 500,000 RMB per ton, a record high.
The abundance of lithium is low, with a crustal abundance of only 0.006%, and most of them are concentrated in South America, causing supply anxiety for major battery manufacturers.
According to the calculation of the sodium electricity leader Zhongke Haina, the sodium-ion battery material has a significant cost advantage, which is about 1/3 lower than that of the lithium iron phosphate battery.
The raw material cost of copper-based sodium-ion battery is 0.29RMB/Wh, the material cost of lithium iron phosphate battery is 0.43RMB/Wh, and the cost of lead-acid battery is 0.40RMB/Wh.
1)The sodium resource is abundant, the price is low and stable, and the price will remain at 1000-4000 RMB/ton in 10 years.
2)Element selection is cheaper;
3) The hard carbon and soft carbon used in the anode have lower process requirements, lower power consumption, and have low-cost potential;
4) Inexpensive aluminum foil for the anode current collector.
The energy density of sodium is basically the same as that of lithium iron phosphate
The energy density of sodium ions is basically the same as that of lithium iron phosphate, and the wide temperature range and safety performance are better.
The energy density of sodium-ion batteries is better than that of lead-acid, and is basically the same as that of lithium iron phosphate.
At present, the energy density of commercial sodium-ion batteries is 100-160 Wh/kg, which is significantly higher than the 30-50 Wh/kg of lead-acid batteries.
It is 10%~20% lower than the mature lithium iron phosphate battery, but it can achieve 200Wh/kg under the experimental conditions of sodium ion battery. Wide temperature range to widen alpine application scenarios. The applicable temperature is extended from -40 to 80°C. For a detailed comparison of the two batteries, please refer to lithium vs sodium battery.
The sodium electricity industry chain takes shape
The layout of the sodium battery industry chain inherits the lithium battery, which is conducive to the rapid introduction of industrialization. China’s sodium-ion battery industry chain is still in its infancy, and the industrial layout is not yet mature.
The structure of the sodium-ion battery industry chain is similar to that of lithium batteries, including upstream resource companies, midstream battery materials and cell companies.
Battery companies have been laid out one after another, and the Ningde era has promoted the formation of the industrial chain. At present, many companies including CATL, Zhongke Haina, Nai Innovation Energy, Penghui Energy, and Sunwoda have deployed sodium-ion batteries.
The difference of anode
Hard carbon materials are considered to be the anode materials with the most commercial potential for sodium-ion batteries due to their high specific capacity (about 300 mAh/g), low sodium storage voltage (the plateau voltage is about 0.1 V), long cycle life, and a wide range of sources. .
At present, the anodes used in commercial sodium-ion batteries are almost all hard carbons. Hard carbon is easier to synthesize than graphite. In the process of commercial application, hard carbon faces the problem of low coulombic efficiency in the first week, and its first-week coulombic efficiency in ester-based electrolytes is mostly around 50-80%.
Therefore, it is necessary to reduce its internal defects by improving precursors, improving synthesis conditions, etc., to prepare hard carbons with low porosity and fewer defects.
Among the Top 5 lithium ion battery anode material companies in China, Bettray has made the fastest progress, realizing mass production of hard carbon and soft carbon anodes. Anode enterprises such as Shanshan Co., Ltd., Putailai, and Xiangfenghua have successively developed sodium anode materials, which have successively entered the Chinese market. trial stage.
The specific capacity of Bertray’s hard carbon and soft carbon anode materials has reached 400mAh/g, breaking through the theoretical limit of graphite anode, with excellent low temperature, rate, cycle and safety performance, but there is still room for improvement in the first week efficiency, and the vibration Low density is not conducive to the improvement of battery energy density.
Due to the early industrialization of hard carbon and soft carbon anodes, the raw material choices of domestic and foreign manufacturers are still tending to be diversified.
Except Zhongke Hai Na uses Huayang Co., Ltd. anthracite to prepare soft carbon, the soft carbon anodes that have been supplied in batches mainly use coke raw materials, and lithium battery anode manufacturers can rely on existing coke suppliers to realize the layout of sodium battery anodes.
Determining factors of production cost after scale: raw material price, residual carbon rate (unit consumption), electricity cost (temperature and time). In general, the cost of hard carbon should be lower than that of artificial graphite, and the cost of soft carbon should be lower when anthracite is used.
Raw material prices: In the past, high-quality anode materials mainly used imported raw materials (mainly imported needle coke). Since 2021, the prices of the main raw materials for anode materials in China have shown an upward trend.
The downstream demand continues to grow, and the rise in raw material prices under the game of supply and demand is a foregone conclusion. The cost of anode material manufacturers is under pressure. Whether the pressure can be transmitted to downstream battery manufacturers depends on the bargaining power of enterprises based on technical barriers and customer resources.
Graphite anode material:
The unit consumption of natural graphite is relatively certain, and the unit consumption of artificial graphite fluctuates greatly. According to the data disclosed by the anode material manufacturer, the unit consumption is in the range of 1.21-2.28.
The unit consumption may vary with the difference in the proportion of petroleum coke and needle coke. Except for high-end artificial graphite, which mainly uses needle coke, the specific ratio of the raw material consumption of other negative materials of different qualities is unknown.
Hard carbon and soft carbon anode:
Phenolic resin molecules contain a large number of aromatic rings, and the residual carbon rate is higher than that of other macromolecules.
The residual carbon rate of biomass raw materials may be only 20%; the residual carbon rate of anthracite is about 50-80%, but the performance of soft carbon is weaker than that of hard carbon.
Whether it is soft carbon or hard carbon, since its temperature and time requirements are far lower than those of artificial graphite, the cost structure can refer to natural graphite, and the manufacturing cost (including electricity and energy consumption, etc.) after large-scale industrialization may be slightly higher than that of natural graphite (manufacturing The cost is 0.22RMB/ton).
Vanadium and hydrogen seek common ground
Flow battery for energy storage technology
Core advantages: fundamentally avoid deflagration – safety; extremely long working life – durable.
In addition to the general advantages of flow batteries, there are three advantages:
(1) Environmentally friendly All-vanadium redox flow battery is fully enclosed and operates with almost zero emissions.
(2) High residual value The vanadium element in the electrolyte is not lost, and the residual value is about 70%.
(3) Convenient recovery The electrolyte contains only a single transition metal, which is easy to extract. Miniaturized all-vanadium flow battery for use with household photovoltaics. The volume is 3-7 times that of lithium batteries.
Vanadium hydrogen isosystem
The stack is the core in the modular structure
The structure and principle of the all-vanadium redox flow battery is similar to that of the hydrogen fuel cell. The stack is the core component of the system, where the electrochemical reaction occurs and electricity is generated. The electrolyte or hydrogen is stored in an external storage tank.
In view of the small output power of a single battery cell, in practice, the overall output power is usually improved by stacking multiple cells in series to form a stack.
Taking the hydrogen fuel cell as an example, the stack is a composite assembly composed of bipolar plates and membrane electrodes alternately stacked, with seals embedded between the monomers, and the front and rear plates are pressed and fastened with screws.
Hydrogen fuel cell stacks are the core value of fuel cell systems, and Chinese electric stacks have shortcomings in terms of lack of core materials and key technologies.
Among the vanadium-hydrogen shared materials, the graphite bipolar plate has basically been produced in China, and the proton exchange membrane and the gas diffusion layer are still mainly imported.
Vanadium hydrogen solution
Gas Diffusion Layer (GDL):
Located between the gas flow field layer and the catalytic layer, it is mainly formed of carbon paper/carbon cloth after hydrophobic treatment and microporous layer coating. The quality of the gas diffusion layer mainly depends on the carbon paper substrate, and the quality of the substrate depends on the upstream carbon fiber.
In the preparation of carbon paper, the technical difficulty is mainly reflected in the refining/beating link. In this link, the degree of beating needs to be controlled to ensure that the length of carbon fiber cutting is moderate. The material selection and ratio of solutions such as binders and dispersants will affect the Properties of carbon paper.
The leading companies are Toray in Japan, SGL in Germany and AvCarb in the United States, among which Toray and SGL are all in the carbon fiber industry chain.
Proton exchange membrane (PEM):
The mainstream technology is perfluorosulfonic acid proton exchange membrane. PEMs tend to be thinner gradually, from tens of microns to tens of microns, reducing the ohmic polarization of proton transfer to achieve higher performance.
Chemours and Gore in the United States, the latter with the most abundant product series and the most practical application cases, are the leaders in the automotive fuel cell market. China is mainly the future of Dongyue, which is characterized by a complete fluorine-containing fine chemical industry chain.
Bipolar Plate (BP):
According to the material, it can be divided into graphite bipolar plate, metal bipolar plate and composite bipolar plate. At present, hydrogen fuel cells mainly use graphite plates or metal plates, and vanadium redox flow batteries tend to be composite plates.
The degree of Chinese production:
Graphite bipolar plate>metal bipolar plate>composite bipolar plate.
Hydrogen fuel cell:
In 2020, the market size of China’s hydrogen fuel cell bipolar plate will reach 310 million yuan, and the market share of graphite plates (including carbon-plastic composite plates) and metal plates will be 65% and 35% respectively. The plates tend to be evenly divided.
Data shows that in 2021, H1 metal bipolar plate shipments accounted for 45.0% of the total bipolar plate shipments (36.0% in the same period in 2020).
Vanadium flow battery:
The metal plate is basically ignored, and even the coated metal plate is difficult to work stably for a long time in an acidic liquid environment. Graphite bipolar plates (machined) are not favored because of the complex and expensive machining process.
Vanadium redox flow batteries mainly use carbon-plastic composite plates, because their thermoplastic or molding processes are relatively simple to machine, but the increase in resistivity caused by mixed polymer resins is still a problem that needs to be solved.
Due to its high corrosion resistance, high durability, and relatively low technical barriers, it is the first to achieve Chinese production, and it is demonstrated in the field of special vehicles and commercial vehicles that are less sensitive to volume but sensitive to durability.
However, the disadvantages of long production cycle, poor mechanical properties, high processing difficulty and high production cost of graphite bipolar plates cannot be ignored.
More and more companies in the market have successfully developed ultra-thin and ultra-fine graphite bipolar plates, breaking through the national requirement of 1.5mm thickness for a single group of graphite bipolar plates before 2025, and the power density has begun to approach Toyota’s first-generation metal The level of the bipolar plate.
Poor corrosion resistance and short life are obstacles to its application. However, with the continuous progress and breakthrough of the coating process, it is expected to achieve the same service life as the graphite plate.
With its excellent mechanical properties, high volume power density, low cost and easy mass production, metal bipolar plates will catch up in the process of large-scale application in passenger cars.
The degree of densification, the aspect ratio of the flow channel is higher, and the layout is smaller, which can enable the single board to support a higher power density, and reduce the number of boards required per kW, thereby reducing the difficulty and cost of stack integration.
At present, 100kW stacks generally require 350-400 single-core cells, while Ballard has realized that 140kW high-power stacks only need 309 cells, which greatly reduces the number of bipolar plates and improves stack power density.
Toyota Motor Corporation pioneered the use of metal bipolar plates and coatings on its Mirai fuel cell vehicle, addressing a range of issues including corrosion, cost and electrical conductivity.