Energy storage primarily refers to the storage of electrical energy. It is also a term used in the context of oil reservoirs, representing the reservoir's ability to store oil and gas. While energy storage itself is not a new technology, from an industry perspective, it is a relatively new phenomenon and is still in its early stages.
To date, my country has not reached the level of the United States and Japan in treating energy storage as an independent industry and introducing special support policies. In particular, the commercialization model of the energy storage industry has not yet taken shape due to the lack of a payment mechanism for energy storage.
Lead-acid batteries are generally used for high-power battery energy storage applications, primarily for emergency power supplies, electric vehicles, and storing surplus energy from power plants. For low-power applications, rechargeable dry-cell batteries, such as nickel-metal hydride (NiMH) and lithium-ion batteries, can also be used. Let's take a look at the advantages and disadvantages of nine types of battery energy storage.
Advantages and disadvantages of battery energy storage (analysis of nine types of energy storage batteries)
I. Lead-acid batteries
Key advantages:
1. Raw materials are readily available and relatively inexpensive;
2. Excellent high-rate discharge performance;
3. Excellent temperature performance; can operate in environments ranging from -40℃ to +60℃.
4. Suitable for float charging, long service life, and no memory effect;
5. Used batteries are easy to recycle, which is beneficial to environmental protection.
Key drawbacks:
1. Low specific energy, generally 30-40 Wh/kg;
2. Its lifespan is shorter than that of Cd/Ni batteries;
3. The manufacturing process is prone to environmental pollution, so waste treatment equipment must be provided.
II. Nickel-metal hydride batteries
Key advantages:
1. Compared with lead-acid batteries, the energy density is significantly improved, with a gravimetric energy density of 65Wh/kg and a volumetric energy density increase of 200Wh/L;
2. High power density, capable of high-current charging and discharging;
3. Excellent low-temperature discharge characteristics;
4. Cycle life (increased to 1000 cycles);
5. Environmentally friendly and pollution-free;
6. Technology Comparison: Lithium-ion batteries are more mature.
Key drawbacks:
1. Normal operating temperature range: -15～40℃; high-temperature performance is poor.
2. Low operating voltage, operating voltage range 1.0～1.4V;
3. It is more expensive than lead-acid batteries and nickel-metal hydride batteries, but its performance is worse than that of lithium-ion batteries.
III. Lithium-ion batteries
Key advantages:
1. High specific energy;
2. High voltage platform;
3. Good cycle performance;
4. No memory effect;
5. Environmentally friendly and pollution-free; currently one of the most promising lithium batteries for electric vehicles.
IV. Supercapacitors
Key advantages:
1. High power density;
2. Short charging time.
Key drawbacks:
With low energy density, only 1-10Wh/kg, supercapacitors have too short a driving range and cannot be used as the mainstream power source for electric vehicles.
Advantages and disadvantages of battery energy storage (analysis of nine types of energy storage batteries)
V. Fuel Cell Power Batteries
Key advantages:
1. High specific energy, resulting in a long driving range for vehicles;
2. High power density, capable of high-current charging and discharging;
3. Environmentally friendly and pollution-free.
Key drawbacks:
1. The system is complex and the technology is not mature enough;
2. The construction of the hydrogen supply system is lagging behind;
3. High requirements for the levels of sulfur dioxide and other pollutants in the air. Due to severe air pollution in China, the lifespan of fuel cell vehicles is relatively short.
VI. Sodium-sulfur batteries
Advantages:
1. High specific energy (theoretical 760Wh/kg; actual 390Wh/kg);
2. High power (discharge current density can reach 200-300 mA/cm2);
3. Fast charging speed (fully charged in 30 minutes);
4. Long lifespan (15 years; or 2500-4500 cycles);
5. Pollution-free and recyclable (Na and S recovery rates are nearly 100%); 6. No self-discharge phenomenon and high energy conversion rate;
insufficient:
1. High operating temperature, ranging from 300 to 350 degrees Celsius. The battery requires heating and insulation during operation, resulting in a slow start-up.
2. Expensive, costing tens of thousands of yuan per kilowatt-hour;
3. Poor security.
VII. Flow Battery (Vanadium Battery)
advantage:
1. Safe and capable of deep discharge;
2. Large scale, no limit on tank size;
3. It has a very high charge and discharge rate;
4. Long lifespan and high reliability;
5. Zero emissions and low noise;
6. Fast charging/discharging switching, requiring only 0.02 seconds;
7. Site selection is not restricted by geographical location.
shortcoming:
1. Cross-contamination between positive and negative electrode electrolytes;
2. Some require expensive ion exchange membranes;
3. The two solutions have larger volumes and lower specific energy.
4. Low energy conversion efficiency.
8. Lithium-air batteries
Fatal flaw:
The solid reaction product, lithium oxide (Li₂O), accumulates at the positive electrode, blocking the contact between the electrolyte and air, thus stopping the discharge. Scientists believe that lithium-air batteries are 10 times more powerful than lithium-ion batteries and can provide the same amount of energy as gasoline. Lithium-air batteries absorb oxygen from the air to recharge, allowing them to be smaller and lighter. Many laboratories worldwide are researching this technology, but without a major breakthrough, commercialization may be another 10 years away.
9. Lithium-sulfur batteries (Lithium-sulfur batteries are a type of high-capacity energy storage system with great development potential)
advantage:
1. High energy density, with a theoretical energy density of up to 2600Wh/kg;
2. Low raw material costs;
3. Low energy consumption;
4. Low toxicity.
Although lithium-sulfur battery research has been going on for decades and has achieved many results in the last 10 years, it is still far from practical application.
Lithium-ion batteries are rechargeable batteries that rely on the movement of lithium ions between the positive and negative electrodes to function. During charging and discharging, Li+ ions repeatedly insert and extract between the two electrodes (during charging, Li+ ions extract from the positive electrode, pass through the electrolyte, and insert into the negative electrode, leaving the negative electrode in a lithium-rich state; the reverse occurs during discharging). Compared to traditional lead-acid and nickel-cadmium batteries, lithium-ion batteries offer advantages such as high energy density, long cycle life, good charge/discharge performance, high operating voltage, no memory effect, less pollution, and higher safety.
Lithium-ion batteries are broadly categorized by downstream applications into consumer lithium-ion batteries, power lithium-ion batteries, and energy storage batteries. Historically, lithium-ion batteries were initially primarily used in the 3C (computers, communications, and consumer electronics) sector, i.e., consumer lithium-ion batteries. With technological advancements and continuous improvements in battery performance, lithium-ion batteries have gradually been applied to power power tools, electric vehicles, and other transportation devices, i.e., power lithium-ion batteries. Since 2015, the development of the energy storage sector has created a new market demand for lithium-ion batteries; however, because the energy storage sector has lower requirements for battery technology, the batteries used are mainly power lithium-ion batteries that have been phased out or are surplus production from existing power lithium-ion battery companies, or batteries that have been recycled and reused.
From the perspective of market development speed, the growth rate of the 3C industry market peaked around 2010 and has been declining continuously, with the market gradually approaching saturation. The growth rate of consumer lithium-ion batteries has also been declining, although there was a slight rebound in 2017, the overall growth rate was still below 10%. Since 2014, the rapid development of the global new energy vehicle industry has led to a high-speed increase in lithium-ion battery shipments at an annual rate of 27% for nearly four years. By the end of 2017, the shipment volume of power lithium batteries reached 62.35 GWh, accounting for 42% of total lithium-ion battery shipments. In addition, from 2015 to 2017, energy storage batteries maintained a growth rate of around 40%, but their share in total lithium-ion battery shipments remained relatively small.
The power lithium battery industry is located in the midstream of the new energy power industry chain. The upstream mainly consists of the industrial chain links for producing raw materials needed for batteries (positive electrode, negative electrode, electrolyte, separator, packaging materials, and other components), as well as the upstream metal material production and mineral resource mining links (smelting of lithium, cobalt, and manganese metal compounds, and mining of cobalt, manganese, nickel, and graphite ores). The downstream mainly consists of new energy vehicle companies [categorized by vehicle type as passenger cars, commercial vehicles, and special-purpose vehicles; and by power source as pure electric vehicles and hybrid vehicles]. The main products of power lithium battery companies are battery cells, battery modules, and battery packs (see Table 1 for details). Furthermore, because some battery companies only produce battery cells and outsource their battery pack (PACK) business, some specialized sub-sectors for modules and PACKs have emerged between battery companies and automakers.
