On the one hand, there is support from global strategies and policies; on the other hand, there is the continuous improvement of power battery technology. Longer range and shorter charging time are directly related to users' commuting needs, which has brought new energy vehicles to our lives. In the future, they will replace traditional fuel vehicles and become inseparable from everyone's daily travel. Thus, people say: "The development of new energy vehicles is the development of battery technology."
lead-acid batteries
The earliest pure electric vehicles used lead-acid batteries, with lead and its oxides used as electrode materials and sulfuric acid solution as the electrolyte. This is the power source for most electric bicycles today, and its biggest advantage is its low cost. However, because lead-acid batteries have low energy density, they suffer from problems such as large size and small capacity. They cannot meet the requirements of a car's weight control, driving force consumption, and even the lifespan of more than 10,000 kilometers per year. Therefore, they could not be used on a large scale in mass-produced vehicles and were eventually phased out by car manufacturers.
Nickel-metal hydride batteries
Nickel-metal hydride (NiMH) batteries are very common in our daily lives, from early portable radios to today's rechargeable toothbrushes and other small appliances. The positive electrode is a nickel-metal hydride compound, and the negative electrode is a metallic hydride. Compared with lead-acid batteries, their energy density and charge/discharge cycles are significantly improved. In addition, the electrolyte is non-flammable and safe, and the manufacturing process is mature. Before it started making cars, BYD was the world's second-largest NiMH battery manufacturer.
However, due to their generally low charging efficiency, memory effect, and low operating voltage (making them unsuitable for high-voltage fast charging), nickel-metal hydride batteries are not ideal as a single power source for automobiles; they are better suited for assisting the engine. Toyota excels in this area, employing an Atkinson cycle engine paired with a nickel-metal hydride battery pack in its hybrid system. While the Atkinson cycle engine boasts high efficiency in the mid-range RPMs, it suffers from weakness at low and high RPMs. The nickel-metal hydride battery effectively addresses this issue, providing a significant boost to acceleration from a standstill and at high speeds.
With the widespread adoption of lithium-ion batteries, nickel-metal hydride (NiMH) batteries are trending towards complete replacement in automobiles. For example, Toyota's new generation hybrid system uses a more efficient engine + lithium-ion battery combination. Compared to lithium-ion batteries, NiMH batteries are not advantageous in terms of capacity, cycle life, and environmental friendliness. Their cost advantage has also been weakened by the vigorous development of lithium-ion batteries. This is precisely why NiMH batteries are gradually withdrawing from the automotive field.
lithium batteries
Lithium-ion batteries are currently the mainstream choice for new energy vehicles. Lithium compounds (such as lithium manganese oxide and lithium iron phosphate) are used as electrode materials, and graphite as the negative electrode material. Their advantages lie in high energy density, small size, light weight, and high charging efficiency. The main factors determining the type or performance of a lithium-ion battery are the materials used in its two electrodes, with the positive electrode material being the key at present. Common types include mainstream lithium iron phosphate, ternary materials such as lithium cobalt oxide, and nickel-cobalt-manganese, which differ in capacity, cost, low-temperature charging and discharging, and safety.
However, regardless of type, all lithium battery packs face the "natural enemy" of low temperature. Although the optimal operating temperature varies for different types of lithium batteries, the reduced activity of lithium ions below the optimal range has a significant impact on driving range. This has been reflected in our previous tests: electric vehicles equipped with lithium battery packs generally only achieve about 60% of their theoretical range in actual use during winter in northern regions, with a maximum of around 70%.
The negative impact of low temperatures is difficult to address from the battery itself, so many car manufacturers have tried to heat the battery packs by adding a separate temperature control system for the power battery. Most brands have found this approach to alleviate the problem to some extent, but the actual effect is not a very good solution, because the power consumption of the temperature control system in some electric vehicles is greater than the loss caused by low temperatures.
In this regard, General Motors is reportedly considering a partnership with South Korea's LG Group to procure products that integrate multiple temperature control components directly within the battery pack. This would not only provide cooling for the battery as currently available but also increase its temperature in cold weather. The implementation of this technology is highly anticipated; it is understood that GM's next batch of pure electric and plug-in hybrid vehicles will utilize this technology, replacing the battery packs currently supplied by Hitachi.
hydrogen fuel cells
Everyone knows that the combustion of H2 + O2 ultimately produces water, so hydrogen is an ideal clean energy source. Hydrogen itself releases a large amount of energy upon combustion, performs well at low temperatures, and most importantly, refueling is highly efficient. Refueling with hydrogen only takes 5 minutes to travel over 600 kilometers, and this figure still has room for improvement. All of these features far surpass those of existing lithium batteries.
Regarding the investment in hydrogen fuel cell vehicles, automakers in Japan and South Korea have long been conducting research and have now begun to deploy them on a small scale in their respective markets. For example, the Hyundai NEXO hydrogen fuel cell vehicle that I test drove before the Spring Festival has been widely used in the PyeongChang Winter Olympics and is now on the market.
So why isn't hydrogen, such a valuable energy source, widely available? Because obtaining hydrogen with current technology is too difficult. Everyone knows that hydrogen can be obtained by electrolyzing water, but the electricity consumed in electrolyzing water and then burning the hydrogen to finally turn it back into water is less efficient and costly than simply charging lithium batteries. Extracting hydrogen from oil and natural gas is a more cost-effective and technologically feasible option, but the quantities available are limited, which is why fuel cell vehicles are "only known by name, not widely adopted."
Graphene batteries
When discussing the power batteries for future new energy vehicles, the most reliable and discussed option is graphene batteries. To put it simply, there are two ways to use this material in conjunction with lithium batteries: one is to use graphene composite materials as a conductive agent in lithium batteries, and the other is to use it directly as a negative electrode. Both methods increase the activity of lithium batteries, thereby improving the driving range and charging speed of electric vehicles.
Graphene batteries can effectively address the shortcomings of lithium batteries, and their product characteristics are directly linked to the use of new energy vehicle users. The benefits of this material are indeed significant, and Samsung of South Korea has already announced that it has mastered this technology. However, cost is a major bottleneck. Graphene is not easy to obtain; it was initially used in the aerospace field. When and how to reduce costs will be a major challenge for this high-quality product to become accessible to ordinary consumers. No automakers have yet announced plans to focus on this area.
In simple terms, pure electric vehicles work by "charging and directly using electricity," while hydrogen fuel cell vehicles "burn" (chemically react) H2+O2 to generate electricity and water, essentially "burning hydrogen" to produce electricity. Both types of "batteries" are zero-emission. Electric vehicle lithium batteries have the problems of lower energy density, poor low-temperature activity affecting range, and slow charging speed, which hydrogen fuel cells completely avoid. Moreover, they are much more efficient, which is why hydrogen is considered a high-quality energy source.
Solid-state lithium batteries
Solid-state lithium batteries, as the name suggests, no longer use liquid electrolytes but instead use solid electrolytes. Their energy density far exceeds that of current mainstream lithium batteries, which means that pure electric vehicles can achieve higher or even comparable ranges to energy-saving gasoline vehicles. In addition, their charging efficiency has also made a qualitative leap compared to the current stage. It is reported that electric vehicles equipped with solid-state batteries can achieve an ideal charging speed of 800 kilometers per minute, which can be said to be the best core component of new energy vehicles.
Currently, some overseas energy and technology companies, as well as battery manufacturers like Panasonic, have begun research and development of solid-state batteries. Among automakers, only the three major Japanese automakers—Toyota, Honda, and Nissan—are involved in this area, a move driven by government support in Japan. Judging from the plans of various parties that have begun researching solid-state batteries, breakthroughs in cost, energy density, and manufacturing are expected by 2020. However, the widespread adoption of these research results in the new energy vehicle sector is not expected until 2030, which is still some distance away. This is why major automakers did not mention solid-state batteries when announcing their strategies for a global ban on the sale of gasoline-powered vehicles by 2025.
Many automakers and even emerging electric vehicle manufacturers have announced their future new energy vehicle plans. Stay tuned for more related content...
Summarize
On a larger scale, environmental protection seems to be a major global trend, and electricity is an essential energy source for people's lives. Therefore, new energy vehicles that use electricity as fuel are the easiest to implement and have the smoothest transition. From a practical point of view, after the ban on the sale of gasoline-powered vehicles in 2025, only new energy vehicles will be available for purchase. The quality of a car's battery is crucial. As this article discusses battery development, older battery types are gradually becoming obsolete, while some new battery technologies are still in the conceptual stage, and others will be available to everyone once the technical and cost challenges are overcome.
